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  • Drought effects on cotton (Gossypium hirsutum L.) fibre quality and fibre sucrose metabolism during the flowering and boll‐formation period
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2020-01-16
    Min Gao; John L. Snider; Hua Bai; Wei Hu; Rui Wang; Yali Meng; Youhua Wang; Binglin Chen; Zhiguo Zhou

    The cotton (Gossypium hirsutum L.) crop is an indeterminate species that is most sensitive to drought stress during the flowering and boll‐formation stage of development. To evaluate the effect of water deficit on fibre quality and carbon metabolism at different fruiting branches (FB), multiple controlled experiments were conducted. The cotton cultivar Siza 3 was used under three soil relative water content (SRWC): control (CK, SRWC (75 ± 5) %), moderate drought stress (MDS, SRWC (60 ± 5) %) and severe drought stress (SDS, SRWC (45 ± 5) %) treatment, imposed at the beginning of the flowering of FB6–7. Fibre quality was significantly affected by drought level and fruiting branch location on the plant. Compared to the CK, under MDS and SDS, sucrose content and sucrose synthase (SuSy) activity decreased prior to 24 days post‐anthesis (DPA; the fibre elongation phase), which caused low fibre turgor pressure. This decreased the rate of fibre elongation and final fibre length. Moreover, from 24 to 38 DPA (during fibre thickening), low fibre sucrose content led to insufficient UDP‐glucose (UDPG; uridine diphosphate glucose) for cellulose synthesis. Furthermore, more of the existing UDPG was allocated to the synthesis of callose instead of cellulose, which resulted in lower cellulose accumulation and decreased fibre strength. The magnitude of the drought stress effect on fibre qualities, as well as the formation process, was strongly influenced by fruiting branch position, where differences were most pronounced for fruiting branches further away from the base of the plant.

    更新日期:2020-01-17
  • Detection of major weather patterns reduces number of simulations in climate impact studies
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2020-01-12
    Behnam Ababaei; Ullah Najeeb

    With climate change posing a serious threat to food security, there has been an increased interest in simulating its impact on cropping systems. Crop models are useful tools to evaluate strategies for adaptation to future climate; however, the simulation process may be infeasible when dealing with a large number of G × E × M combinations. We proposed that the number of simulations could significantly be reduced by clustering weather data and detecting major weather patterns. Using 5, 10 and 15 clusters (i.e., years representative of each weather pattern), we simulated phenology, cumulative transpiration, heat‐shock‐induced yield loss (heat loss) and grain yield of four Australian cultivars across the Australian wheatbelt over a 30‐year period under current and future climates. A strong correlation (r2≈1) between the proposed method and the benchmark (i.e., simulation of all 30 years without clustering) for phenology suggested that average duration of crop growth phases could be predicted with substantially fewer simulations as accurately as when simulating all 30 seasons. With mean absolute error of 0.64 days for phenology when only five clusters were identified, this method had a deviation considerably lower than the reported deviations of calibrated crop models. Although the proposed method showed higher deviations for traits highly sensitive to temporal climatic variability such as cumulative transpiration, heat loss and grain yield when five clusters were used, significantly strong correlations were achieved when 10 or 15 clusters were identified. Furthermore, this method was highly accurate in reproducing site‐level impact of climate change. Less than 7% of site × general circulation model (GCM) combinations (zero for phenology) showed incorrect predication of the direction (+/−) of climate change impact when only five clusters were identified while the accuracy further increased at the regional level and with more clusters. The proposed method proved promising in predicting selected traits of wheat crops and can reduce number of simulations required to predict crop responses to climate/management scenarios in model‐aided ideotyping and climate impact studies.

    更新日期:2020-01-13
  • NDVI‐based estimates of evapotranspiration of winter wheat indicate positive effects of N fertilizer application on agronomic water‐use efficiency
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-01
    Philipp Drerup; Holger Brueck; Dejene Eticha; Heinrich W. Scherer

    Yield increases by fertilizer application impose higher crop water use, as biomass production is positively correlated with transpiration. To quantify effects of N fertilizer supply on evapotranspiration (ET) of winter wheat, a field experiment with three nitrogen rates (N0, N120 and N230) under non‐water‐limited conditions was performed during 2014 and 2015. Normalized difference vegetation index (NDVI) was used to derive crop coefficients which were used to calculate N effects on bare soil evaporation (E), transpiration, evapotranspiration (ET), grain yield and harvest index (HI). E during the early post‐winter growth period was measured with micro‐lysimeters and compared with model estimates. N fertilizer supply resulted in lower cumulative E, and increases in grain yield were higher than increases in ET, resulting in a higher agronomic water‐use efficiency (WUEY). HI of treatment N120 was higher than that of treatment N230 indicating that HI was not the main reason of higher WUEY of treatment N230. It is concluded that estimates of ET under variable N supply require consideration of N‐induced effects on canopy development which could be successfully monitored by NDVI measurements. N supply increases ET and WUEY potentially imposing a trade‐off between water conservation and efficiency of water use for crop production.

    更新日期:2020-01-13
  • Global warming: Antioxidant responses to deal with drought and elevated temperature in Stylosanthes capitata, a forage legume
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-15
    Ricardo Borjas‐Ventura; Antonio Sergio Ferraudo; Carlos Alberto Martínez; Priscila Lupino Gratão

    Drought can be more frequent and severe along with elevated temperatures (eT). To deal with the climate change impact on plants, we need to understand the plant biochemical performance. Nowadays, there is a lack of information about the antioxidant response of plants, mainly growing in field conditions and under the future climatic scenario. In this context, we carried out this experiment to analyse the antioxidant responses of the forage legume Stylosanthes capitata Vogel (in field condition) to eT and water deprivation. This work had four treatments: control, eT (+2°C above ambient canopy temperature), wS (water deprivation) and eT + wS. Temperature free‐air controlled enhancement (T‐FACE) system was used for warming, and samples were taken 17, 24 and 46 days after warming exposure at time periods of 6:00 a.m. and 12:00 p.m. The eT + wS treatments decreased catalase, superoxide dismutase (SOD) and ascorbate peroxidase activities, especially at 46 days. Nevertheless, glutathione (GSH) content was not modified by eT + wS treatments. Also, we determined an important inverse relation among SOD‐GR‐GSH and MDA‐H2O2. In conclusion, combined stresses provoked detrimental effects of enzymatic antioxidant responses. Furthermore, we highlighted the importance of SOD‐GR and GSH to avoid damages of reactive oxygen species in S. capitata grown under climate change. In addition, we suggest an adequate irrigation management in order to improve the antioxidant systems to face the eT, successfully; besides, we consider that the uses of tolerant cultivars are key under climate change conditions.

    更新日期:2020-01-13
  • Kaolin and seaweed‐based extracts can be used as middle and long‐term strategy to mitigate negative effects of climate change in physiological performance of hazelnut tree
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-09
    Sandra Cabo; Maria Cristina Morais; Alfredo Aires; Rosa Carvalho; Núria Pascual‐Seva; Ana Paula Silva; Berta Gonçalves

    Spraying plants with exogenous substances have gained more attention due to its potential to reduce the negative impacts of heat and water stress in a climate‐changing environment. Therefore, the effects of spraying kaolin and Ascophyllum nodosum with and without irrigation on leaf gas exchange parameters, plant water status, electrolyte leakage, cuticular waxes, plant hormones and antioxidant enzymes, proline, malondialdehyde (MDA) content and lipid peroxidation of membranes of hazelnut trees were studied. Six different treatments with kaolin (K), A. nodosum (An), irrigation (I), kaolin with irrigation (Ki), A. nodosum with irrigation (Ani) and no irrigation (control) during two consecutive years (2016–2017) were applied in a hazelnut orchard of ‘Grada de Viseu’ cultivar located in Moimenta da Beira region, Northern Portugal. Results showed that K and An were effective for reducing hazelnut heat and drought stress by increasing the water relative content (RWC), net CO2 assimilation (A), water use efficiency (A/gs) and reducing the leaf mass per area (LMA), electrolyte leakage (EL). Moreover, concentration of ABA, MDA, proline and lipid peroxidation of membranes, as well the average content of antioxidant enzymes, was lower, suggesting that under K and An, plants have a better physiological performance than without these two exogenous substances. Nonetheless, these benefits only appear to be significant in the second year of the experiment showing that the use of both substances to mitigate climate change adverse effects should be considered as a long‐term strategy.

    更新日期:2020-01-13
  • Effects of Epichloë endophyte infection on growth, physiological properties and seed germination of wild barley under saline conditions
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-09-05
    Zhengfeng Wang; Chunjie Li; James White

    Wild barley (Hordeum brevisubulatum) is a grass that inhabits alkalized meadows in northern China. An asexual Epichloë bromicola endophyte was detected in seeds and leaf sheaths in all wild barley samples from Gansu Province, China. In this research, we determined the effects of the E. bromicola endophyte on growth, physiological properties and seed germination of wild barley under salt stress through a set of experiments. Our results demonstrate that endophyte‐infected (E+) plants produced more tillers, higher biomass and yield, higher chlorophyll content and superoxide dismutase activity than endophyte‐free (E−) plants under high salt stress. Seed germination parameters of E+ biotype were significantly higher than those of E− plants when NaCl concentration reached 200 and 300 mM. Our results demonstrate that E. bromicola endophytes increased tolerance to salt stress in wild barley by increasing seed germination and growth, and altering plant physiology.

    更新日期:2020-01-13
  • Photosynthesis, fluorescence and mesophyll conductance responses to increasing salinity levels in Jatropha curcas at early vegetative stages
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-28
    María Ascensión Dorta‐Santos; Ignacio Barriola; Diego Fernán Wassner; Edmundo Leonardo Ploschuk

    Salinity is often a great limitation in marginal environments with potential for developing alternative non‐edible crops for biodiesel, and the physiological responses involved in the recovery of plants subjected to high salinity are poorly studied. The aim of this study on Jatropha curcas is to identify salinity tolerance responses of net photosynthesis rate under saturating irradiances (Amax), its recovery capacity and the role of mesophyll conductance (gm) over Amax. Two experiments were performed with seedlings in pots under outdoor conditions and hydroponic conditions, respectively, with salinity intensities ranging from 3 to 12 dS/m, their isosmotic treatments with polyethylene glycol (PEG) and controls without abiotic stress. Amax and growth rate were mainly affected by salinity effects in all the ranges, with a drastic 60% drop in dry biomass under 6 dS/m, revealing a significant sensitivity of this species. However, a surprising increase in Amax was promoted by the presence of NaCl, with respect to their respective isosmotic treatments with PEG, although it was still lower than the unstressed plants. This advantage disappeared from 9 dS/m, but negative effects of NaCl toxicities were never detected. The photochemical apparatus resulted extremely resistant in this species, since Fv/Fm and leaf greenness were affected only at 12 dS/m. So, gm was strongly and linearly associated with Amax. This association derives from the overall range of stress intensities tested, thus appearing as the main useful trait for enhancing photosynthesis depletion under salinity stress, without losses of the water use efficiency. A drastic 75% drop was also detected in the electron use for photosynthesis, revealing that Amax would also be modulated by metabolic impairments under salinity. Moreover, full recovery after only 8 days was observed, confirming the high resistance of the species to NaCl stress even under very high salinities. This study contributes to a better understanding of the physiological processes involved in the response of J. curcas to salinity during early vegetative stage, generating possibilities for improving tolerance of this species under environments exposed to salinity.

    更新日期:2020-01-13
  • Effect of allele combinations at Ppd‐1 loci on durum wheat grain filling at contrasting latitudes
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-09-15
    Jose M. Arjona; Conxita Royo; Susanne Dreisigacker; Karim Ammar; Joan Subirà; Dolors Villegas

    Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty‐five spring durum genotypes carrying all known allele variants at Ppd‐1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd‐B1a) and the latest (Ppd‐A1b/Ppd‐B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn‐sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring‐sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd‐B1a and GS105/Ppd‐B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.

    更新日期:2020-01-13
  • Impact of heat stress on pod‐based yield components in field pea (Pisum sativum L.)
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-09-12
    Yunfei Jiang; Donna L. Lindsay; Arthur R. Davis; Zhifa Wang; Dustin E. MacLean; Thomas D. Warkentin; Rosalind A. Bueckert

    Elevated temperatures associated with climate change result in crops being exposed to frequent spells of heat stress. Heat stress results in reduced yield in field pea (Pisum sativum L.); it is therefore important to identify cultivars with improved pod and seed retention under heat to mitigate this loss. Objectives were to investigate the effect of heat stress on phenology, yield and pod‐based yield components. Sixteen pea cultivars were evaluated at normal and late (hot) seeding dates in the field in Arizona 2012 and in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 7 days) during reproductive development. We measured variation in the pattern of pod retention at four‐node positions on plants, seed retention by ovule position (stylar, medial and basal) within pods and screened cultivars for pod retention, seed retention and yield. Heat stress reduced seed yield by accelerating the crop lifecycle and reducing pod number and seed size. Heat stress had the most damaging effect on younger reproductive growth (flowers and pods developed later), resulting in ovary abortion from developing flowers. Heat also accelerated seed abortion in all ovule positions within pods. Two high‐yielding cultivars under control temperature, “Naparnyk” and “CDC Meadow”, maintained high yield in heat, and “MFR043” had the lowest yield. Cultivars “40‐10” and “Naparnyk” retained the most ovules and seeds per pod, and “MFR043” aborted seeds when exposed to heat. In half of the cultivars, ovules at the basal peduncle end of pods were likely to abort while ovules at the medial and stylar end positions developed into seeds. For seven of the field cultivars, ovules at the medial pod position also produced mature seeds. Cultivars “40‐10”, “Naparnyk” and “CDC Meadow” had greater pod and ovule retention or maintained high yield under heat stress, and were identified as heat‐tolerant cultivars. Our results allow for a better understanding of pod‐based yield components in field pea under heat stress and developing heat‐tolerant cultivars.

    更新日期:2020-01-13
  • Grain‐filling response of winter wheat (Triticum aestivum L.) to post‐anthesis shading in a humid climate
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-11
    Seiji Shimoda; Yoichi Sugikawa

    To assess the impacts of clouds during the grain‐filling period on the leaf senescence and yield of wheat (Triticum aestivum L.), we conducted a 4‐year plot shading experiment in a well‐drained Andosol in northern Japan. Plants were shaded after the beginning of anthesis in mid‐June, which corresponds to a naturally cloudy period in the study region. The effect of shading depended on its synchronization with soil drying, which affected leaf senescence. Grain yield was determined by solar radiation at the beginning of the grain‐filling period, except in 2015, which was a dry year. Later anthesis in 2016 and 2017 significantly reduced the number and weight of individual grains in the shading treatments. Moreover, “Kitahonami”, with late anthesis, showed a significantly slower increase in the individual‐grain weight during the grain‐filling process after shading than “Yumechikara”. When the duration between anthesis and shading was short, shading significantly reduced the number and weight of grains, and later anthesis makes it more likely that regional reduced light levels are encountered, resulting in fewer grains; the sensitivity of individual‐grain weight to shading synchronized with an increase in grain protein contents. Our results suggest that in wet years, later anthesis makes it easier to encounter regional reduced light and fewer grains; in addition, insufficient light limits photosynthesis under shade and decreases yield.

    更新日期:2020-01-13
  • Oxidative damage in forage rape (Brassica napus L.) seeds following heat stress during seed development
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-29
    Muhammad Rashid; John G. Hampton; Martin L. Shaw; M. Philip Rolston; Khan Mir Khan; Dave J. Saville

    A short period (240°C hr; Tb = 25°C) of heat stress (30°C day/25°C night) during forage rape (Brassica napus L.) seed development or at seed physiological maturity can reduce seed vigour, but the extent of oxidative damage associated with this short heat stress was not known. Heat‐stressed seeds were assessed for malondialdehyde (MDA) content, hydrogen peroxide (H2O2) accumulation, antioxidant enzyme activity, adenylate energy charge and seed ultrastructural integrity, and compared with that of non‐heat‐stressed seeds. Heat stress increased both MDA content and H2O2 accumulation by 35%–50%, reduced antioxidant enzyme activity by between 12% and 67%, and significantly reduced adenosine energy charge. Transmission electron microscope images showed clear evidence of seed deterioration in heat‐stressed seeds, including ruptures in cell wall and plasma membranes, fused lipid bodies and damaged mitochondria. Heat stress at physiological maturity caused more oxidative damage than the same heat stress during seed development. Seed vigour decreased as H2O2 accumulation increased and antioxidant enzyme activity decreased, but no direct relationship between lipid peroxidation and seed vigour was established. The extent of damage resulting from even shorter periods of heat stress (<240°C hr) before or at seed physiological maturity requires investigation.

    更新日期:2020-01-13
  • The mechanical roles of the clasping leaf sheath in cereals: Two case studies from oat and wheat plants
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-09-10
    Wei Wu; Bao–Luo Ma

    Stem lodging is a common problem in cereal crop production and a main constraint for grain yield improvement. The leaf sheath that surrounds and protects the hollow internodes of stem could provide the plants with a great physical support. However, this biomechanical function has been ignored for several decades in cereal crops. This study aimed to examine the biomechanical properties of basal stem internodes and lodging susceptibility of the whole plants with or without the clasping leaf sheath in wheat (Triticum aestivum L.) and oat (Avena sativa L.) among different genotypes and agronomic practices (including planting densities and nitrogen application rates). The main objective was to quantify the mechanical role of the leaf sheath in oat and wheat crops by a “safety factor” method. On average, the leaf sheath contributed 40%, 68% and 38% of the overall stem bending strength, flexural rigidity and safety factor, in oat, while it accounted for 11%, 24% and 10%, respectively, in wheat plants. The significant contribution of the leaf sheath is due to its vital role in enlarging the peripheral position (i.e., second moment of area) and stiffness (i.e., Young's modulus). The contribution ratios (%) were found to be higher in oat than in wheat plants, due to the greater mass density of leaf sheath and more proficient/prevailing stay‐green capability in oat genotypes. This study emphasizes the important mechanical role of clasping leaf sheath on stem internodes of cereals and indicates that the stay‐green trait of the leaf sheath can be exploited to design appropriate varieties with improved lodging resistance and great yield potential.

    更新日期:2020-01-13
  • Pasture restoration improvement methods for temperate degraded pastures and consequences of the climatic seasonality on soil–pasture complex
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-10-08
    Constanza A. Descalzi; Ignacio F. López; Peter D. Kemp; José Dörner; Iván Ordóñez

    Short persistence of renovated pastures is a major problem for pastoral production systems. Pasture species establishment, species performance and persistency and their relationships with soil–water attributes following pasture improvement methods were evaluated over two years. Fertilised naturalised pasture (FNP), non‐fertilised naturalised pasture (NFNP), Lolium perenne–Trifolium repens cultivated pasture (CP), L. perenne–T. repens direct‐drilled pasture (DP), and Bromus valdivianus, Holcus lanatus, Dactylis glomerata, L. perenne and T. repens direct‐drilled pasture (DDP) were established as a randomised complete block design. Pastures were limed, fertilised and sheep‐grazed. Plant growth compensatory mechanisms, by decreasing tiller number and increasing tiller size, equalised pasture yield during the establishment. In both years, the improved pastures yield was greater than that of NFNP. In the second year, DDP and FNP reached the higher pasture growth rate, with a seasonality diminishment. During the second summer, soil matrix potential at 0–20 cm soil profile exceeded the permanent wilting point, resulting in the pasture growth rate of NFNP and the sown pastures ranging from 0.0 to 3.6 kg DM/ha per day, while for FNP, it was 17.8 kg DM/ha per day. Sown species, fast‐growing species spontaneous colonisation and growth were all stimulated in the improved pastures over species that tolerate stress, improving agronomical and ecological pasture features.

    更新日期:2020-01-13
  • Crop water stress index for scheduling irrigation of Indian mustard (Brassica juncea) based on water use efficiency considerations
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-27
    Navsal Kumar; Arunava Poddar; Vijay Shankar; Chandra Shekhar Prasad Ojha; Adebayo Johnson Adeloye

    The study was conducted to determine the feasibility of canopy temperature based crop water stress index (CWSI) for scheduling irrigation of Indian mustard (Brassica juncea). Field crop experiments were conducted in Hamirpur, Himachal Pradesh (India) during three consecutive cropping seasons (2015, 2016 and 2017). The experimental field was divided into five plots with different levels of irrigation treatments based on depletion of total available soil water (TASW) in the crop root zone. The maximum soil moisture depletion (SMD) of TASW at 10%, 30% and 50%, full irrigated (non‐stressed) and extremely dry (full stressed) conditions were maintained in respective plots. Relationships were developed between canopy‐air temperature differential (TC‐TA) and vapour pressure deficit (VPD) for non‐stressed and fully stressed conditions to generate non‐water‐stressed baseline (NWSB) and maximum water‐stressed baseline (MWSB) baselines for Indian mustard crop. The CWSI was computed for different SMD of TASW by using a proven empirical approach based on the baselines. The irrigation treatment corresponding to 30% SMD with a mean CWSI of 0.4 resulted in optimal yield and maximum water use efficiency. Results of the study suggest that established CWSI value can be used to detect stress and schedule irrigations for Indian mustard.

    更新日期:2020-01-13
  • Identification of new QTL for salt tolerance from rice variety Pokkali
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2020-01-06
    Tianxiao Chen; Yajun Zhu; Kai Chen; Congcong Shen; Xiuqin Zhao; Sergey Shabala; Lana Shabala; Holger Meinke; Gayatri Venkataraman; Zhong‐Hua Chen; Jianglong Xu; Meixue Zhou

    Salt stress is an ever‐present threat to rice production worldwide. Rice salinity tolerance is complex, both genetically and physiologically. The success and effectiveness in selecting salt‐tolerant rice variety require the identification of QTL for the tolerance and closely linked molecular markers. In the present study, a RIL population consisting of 148 lines, derived from a cross between IR29 (salt‐sensitive) and Pokkali (salt‐tolerant), was used to identify new QTL for salt tolerance and investigate the relationships between salt stress caused injury and the changes in different physiological and morphological traits at the seedling stage. 14,470 high‐quality SNP markers generated by the Rice 56K SNP array were converted to 1,467 bin markers for linkage mapping. A high‐density genetic linkage map covering 1,680.9 cM was constructed, with the physical to genetic distance ratio being 222 Kb/cM. In total, 23 QTL for different salt tolerance indices were identified, including the previously reported Saltol which is currently used in breeding programmes. Three QTL for salt injury score (SIS) were located on chromosomes 1, 4 and 12, all being closely related to the long‐distant Na+ transport from roots to shoots. These QTL showed additive effects, thus can be effectively used in breeding programme to pyramid various tolerance genes.

    更新日期:2020-01-07
  • Effect of rice straw biochar and irrigation on growth, dry matter yield and radiation‐use efficiency of maize grown on an Acrisol in Ghana
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-12-11
    Eric Oppong Danso; Adam Yakubu; Emmanuel Arthur; Edward B. Sabi; Stephen Abenney‐Mickson; Mathias N. Andersen

    In order to determine whether the current low productivity associated with rainfed cultivation on degraded soils in Ghana can be improved by biochar amendment and irrigation, field experiments with maize were conducted over two seasons in 2017 and 2018. Rice straw biochar at rates of 0 t/ha (B0), 15 t/ha (B15) and 30 t/ha (B30) was combined with irrigation regimes of full irrigation (I100), deficit irrigation (I60) and no irrigation (I0). The I100 treatment was irrigated to field capacity every 3–4 days according to time domain reflectometry measurements while the I60 treatment received 60% of the irrigation amount given to I100 but with the same irrigation frequency. The I0 treatment was not irrigated. In both seasons, the B30 treatment recorded the highest total dry matter yield (TDMY), intercepted photosynthetically active radiation (IPAR) and radiation‐use efficiency (RUE) and these were significantly (p ≤ .05) higher than B0 except for RUE in 2017. Irrigation regimes did not significantly affect TDMY, IPAR and RUE in 2017 but compared to I100, I0 significantly reduced TDMY, IPAR and RUE in the relatively dryer 2018 season. Measured ratio vegetation indices differentiated biochar treatments earlier in the 2018 season than during 2017 and increase of leaf chlorophyll content indices with biochar rate in both seasons indicated that biochar amendment improved nitrogen uptake. Our study demonstrated that rice straw biochar is capable of increasing TDMY, IPAR and RUE of maize grown on degraded soils in Ghana. The study further showed that TDMY, IPAR and RUE of deficit irrigated maize for two seasons were similar to the counterpart fully irrigated maize and may be a viable water management option for farmers in Ghana to save irrigation water resources.

    更新日期:2020-01-04
  • Morphological, physiological and biochemical aspects of osmopriming‐induced drought tolerance in lentil
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-12-11
    Muhammad Farooq; Leila Romdhane; Mayaa K. R. A. Al Sulti; Abdul Rehman; Walid M. Al‐Busaidi; Dong‐Jin Lee

    Lentil (Lens culinaris Medik.) is an important grain legume crop, mostly grown in semi‐arid environments and often faces intermittent drought spells during different growth stages, which severely hamper its yield. This study, comprising of three separate experiments, was conducted to evaluate the potential of seed priming with CaCl2 in improving drought tolerance in lentil. In the first experiment, lentil seeds were hydroprimed (water) or osmoprimed with 0.5 and 1% CaCl2; while non‐primed seeds were taken as control. In the second and third experiments, lentil seeds were subjected to pre‐optimized osmopriming (1% CaCl2) and hydropriming followed by surface drying or re‐drying of primed seeds to original weight. The first two experiments were conducted in petri plates, while, in experiment 3, seeds were planted in plastic pots containing peat moss, maintained at 75% water holding capacity (WHC; well‐watered) or 50% WHC (water deficit). Hydropriming and osmopriming improved seed germination, seedling growth, biomass production, chlorophyll intensity, sugar accumulation and reduced the oxidative stress in lentil under water deficit. However, osmopriming (1% CaCl2) was more effective than the hydropriming in improving the lentil growth, biomass production, Ca accumulation and sugar metabolism under both well‐watered and water deficit conditions. Seed surface drying, after priming, was more beneficial in improving the lentil performance, under both well‐watered and water deficit conditions, than re‐drying to original weight. Osmopriming (1% CaCl2) increased the seeding dry weight (67%), SPAD value (140%), leaf Ca concentration (56%), α‐amylase activity (55%), total soluble sugars (48%) and reduced malanodialdehyde content (35.9%) and total antioxidant activity (29.2%) than un‐primed seeds under water deficit. In conclusion, osmopriming improved the lentil performance under optimal and water deficit conditions through early and synchronized emergence, better sugar and Ca accumulation which reduced the oxidative damage and resulted in better seedling growth and biomass production.

    更新日期:2020-01-04
  • Combined effects of soil silicon and drought stress on host plant chemical and ultrastructural quality for leaf‐chewing and sap‐sucking insects
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-12-10
    Natália C. Teixeira; Janete Oliveira S. Valim; Maria Goreti A. Oliveira; Wellington G. Campos

    It was postulated that Si‐mediated plant resistance to herbivory changes with soil water status, increasing when plants are under drought stress. We subjected collard (Brassica oleracea) to such soil variables and assessed plant responses and effects on the leaf‐chewing larvae of Plutella xylostella and the sap‐sucking aphid Brevicoryne brassicae. Silicon accumulated in collard leaves independently of soil water conditions, but it influenced mainly drought‐stressed plants. Silicon suppressed harmful effects of drought on leaf and root length and raised leaf water content and stomatal size to the same conditions of well‐watered plants. Drought stress reduced hemicellulose and cellulose, but Si did not influence them or lignin. Combination of drought and Si increased total and soluble leaf nitrogen. Drought decreased total glucosinolates, but Si increased such defence metabolites to similar concentrations that were found in well‐watered plants. Nutritional changes mediated by drought and Si in fibre, leaf water content, soluble nitrogen and glucosinolates did not increase insect performance in any feeding guild. Instead, caterpillars performed worse in drought‐stressed or Si‐treated collards, mainly in plants under combined conditions. Silicon improved plant resistance to drought and herbivore stresses.

    更新日期:2020-01-04
  • Impact of waterlogging and temperature on autumn growth, hardening and freezing tolerance of timothy (Phleum pratense)
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-12-10
    Marit Jørgensen; Torfinn Torp; Jørgen Alexander Barosen Mølmann

    Precipitation has generally increased in Norway during the last century, and climate projections indicate a further increase. The growing season has also become longer with higher temperatures, particularly in autumn. Previous studies have shown negative effects of high temperatures and, depending upon temperature conditions, contrasting effects of waterlogging on hardening capacity of timothy. We studied effects of waterlogging on seedlings of timothy (Phleum pratense, cv. Noreng) under three pre‐acclimation temperatures: 3°C, 7°C, 12°C, and in autumn natural light in a phytotron at Holt, Tromsø (69°N). After temperature treatments, all plants were cold acclimated at 2°C for three weeks under continued waterlogging treatments. Freezing tolerance was determined by intact plants being frozen in pots at incremental temperature decreases in a programmable freezer. Waterlogging resulted in a higher probability of death after freezing, and a significantly reduced regrowth after three weeks at 18°C, 24 hrs light in a greenhouse. Increasing pre‐acclimation temperatures also had a clear negative effect on freezing tolerance, but there was no interaction between temperatures and waterlogging. The results indicate that waterlogging may have negative implications for hardening of timothy and may contribute to reduced winter survival under the projected increase in autumn temperatures and precipitation.

    更新日期:2020-01-04
  • A strategy of ideotype development for heat‐tolerant wheat
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-29
    Smi Ullah; Helen Bramley; Tariq Mahmood; Richard Trethowan

    Heat stress significantly limits yield in many wheat‐growing areas globally including north‐western NSW. While various traits linked to high‐temperature tolerance have been identified, the combination of traits that optimize the heat tolerance of wheat has not been established in most environments. A total of 554 genotypes were evaluated in the field at different times of sowing in north‐western NSW for three consecutive years to develop a heat‐tolerant wheat ideotype for this environment. The later sown experiments were exposed to higher temperatures at the critical reproductive and grain‐filling stages of development. The impact of high temperature was greatest at anthesis, and eventual grain yield was reduced by between 4% and 7% with every 1°C rise in average maximum temperature above the optimum of 25°C. High temperature reduced yield, plant height, grain weight and days to anthesis and maturity, and increased the percentage of screenings and grain protein content. Genotypes that produced higher yield under heat stress had shorter days to flowering and maturity, higher NDVI during grain filling, greater chlorophyll content at the milk stage of grain fill, taller plants, greater grain weight and number, and lower screenings compared with the benchmark cultivar Suntop. The genotype closest to the predicted heat‐tolerant wheat ideotype identified from trait ranges had 79.6% similarity.

    更新日期:2020-01-04
  • Early response of barley embryos to low‐ and high‐dose gamma irradiation of seeds triggers changes in the transcriptional profile and an increase in hydrogen peroxide content in seedlings
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-27
    Polina Yu Volkova; Gustavo T. Duarte; Ludivine Soubigou‐Taconnat; Elizaveta A. Kazakova; Stéphanie Pateyron; Vladimir S. Bondarenko; Sofia V. Bitarishvili; Ekaterina S. Makarenko; Roman S. Churyukin; Maria A. Lychenkova; Irina V. Gorbatova; Christian Meyer; Stanislav A. Geras’kin

    At low intensity, certain stress conditions may have a positive effect on growth and development of plants (eustress). Growth stimulation of barley plants after gamma irradiation of seeds in low doses was observed as an increase in root and shoot lengths. Hydrogen peroxide concentrations in shoots of irradiated plants were significantly higher than in control, while the opposite effect was observed in the roots. To elucidate the molecular basis of growth stimulation after gamma irradiation of barley seeds, we performed the transcriptomic analysis of barley embryos at different stages of seed germination. The transcriptomic data were correlated with morphological parameters and the hydrogen peroxide levels in irradiated and control plants. These data indicate that the growth stimulation by low‐dose irradiation involves the transcriptional control of genes related to phytohormones, antioxidant system, late embryogenesis abundant proteins and cell wall components, with possible involvement of jasmonate and ABA signalling. Gamma irradiation of seeds at dose 100 Gy caused significant growth inhibition and promoted expression changes in transcripts related to cell cycle arrest, DNA damage repair and antioxidant system.

    更新日期:2020-01-04
  • The effect of different biochars on the growth and water use efficiency of fenugreek (Trigonella foenum‐graecum L.)
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-27
    Zahra Bitarafan; Fulai Liu; Christian Andreasen

    In two identical pot trials, we investigated the effect of different biochars on the growth and water use efficiency (WUE) of fenugreek (Trigonella foenum‐graecum L.) grown with and without water stress. Plants were grown in pots with and without biochar. Rice husk (RH), standard rice husk (SRH), standard wheat straw (SWS) or standard oilseed rape straw (SOS) biochars were added at a rate of 2% by weight. Irrigation was reduced from 80% of field capacity to 40% in half of the pots to create water stress when 50% of the plants flowered. No significant interaction was observed between irrigation and biochar treatments. Water stress resulted in smaller plants (11.5%), fewer pods (16.1%) and reduced 100‐seed weight (12.6%), seed yield (20.1%) and plant dry weight (55.0%). All standard biochars increased plant dry weight in a range of 18%−25% compared with the controls. There was no significant effect of biochar on the number of pods and seed weight. Only RH, SWS and SOS biochar increased the number of seeds pod−1 by 9.0%−14.5% compared with the controls regardless of water stress. RH and SOS biochars increased seed yield by 16.7 and 21.6%, respectively. RH, SWS and SOS biochar increased the WUE by 17.3%, 10.1% and 16.2% regardless of water stress, respectively. Based on the experiment, we recommend farmers to add biochar whatever type they have available. However, RH and SOS seem to be better than the others are, as they seem to be able to increase seed yield and WUE considerably.

    更新日期:2020-01-04
  • Effect of intermittent drought on grain yield and quality of rice (Oryza sativa L.) grown in Rwanda
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-27
    Alphonsine Mukamuhirwa; Helena Persson Hovmalm; Rodomiro Ortiz; Obedi Nyamangyoku; Maria Luisa Prieto–Linde; Anders Ekholm; Eva Johansson

    The climate change will contribute drought and temperature extremes to rice growing systems, especially when cultivated in equatorial regions. To evaluate opportunities to cultivate and breed drought‐tolerant rice, seven rice cultivars were evaluated in Rwanda for recurring morphological drought scores, grain yield and components, and quality characteristics. The cultivation conditions, that is site and drought treatment, impacted morphological drought scores, growth and yield attributes, while cultivar affected quality attributes. Thus, site showed a higher impact on grain yield and components than drought and cultivar, with generally a reduced grain yield at the low‐temperature site, as a result of low spikelet fertility. Morphological drought scores were generally increased by drought, while drought at the reproductive stage at the high‐temperature site was negative for yield and its components. The cultivars “Intsindagirabigega” and “Jyambere” were adapted to high‐temperature site conditions. The cultivar “Intsindagirabigega” had the highest amylose content, and “Mpembuke,” the highest antioxidant capacity. Thus, climate change with increased temperature and drought extremes may increase rice productivity in cool areas, while especially drought at reproductive stage will be detrimental in low altitude areas with high temperature. Cultivar variation indicated opportunities for selection and breeding of climate change tolerant rice cultivars which should be of immediate priority.

    更新日期:2020-01-04
  • Phenological and physiological evaluation of first and second cropping periods of sorghum and maize crops
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-18
    Maria Antonia Machado Barbosa; Kacilda Naomi Kuki; Pedro Santos Peno Bengala; Emilly dos Santos Pereira; Angélica Fátima de Barros; Sebastián Giraldo Montoya; Leonardo Duarte Pimentel

    Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water‐use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water‐use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water‐use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree‐days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water‐use efficiency, indicating that both crops respond differentially to environmental changes during the growing season.

    更新日期:2020-01-04
  • Tropospheric ozone pollution reduces the yield of African crops
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-13
    Felicity Hayes; Katrina Sharps; Harry Harmens; Ieuan Roberts; Gina Mills

    Northern, Southern and Equatorial Africa have been identified as among the regions most at risk from very high ozone concentrations. Whereas we know that many crop cultivars from Europe, north America and Asia are sensitive to ozone, almost nothing is known about the sensitivity of staple food crops in Africa to the pollutant. In this study cultivars of the African staple food crops, Triticum aestivum (wheat), Eleusine coracana (finger millet), Pennisetum glaucum (pearl millet) and Phaseolus vulgaris (bean) were exposed to an episodic ozone regime in solardomes in order to assess whether African crops are sensitive to ozone pollution. Extensive visible leaf injury due to ozone was shown for many cultivars, indicating high sensitivity to ozone. Reductions in total yield and 1,000‐grain weight were found for T. aestivum and P. vulgaris, whereas there was no effect on yield for E. coracana and P. glaucum. There were differences in sensitivity to ozone for different cultivars of an individual crop, indicating that there could be possibilities for either cultivar selection or selective crop breeding to reduce sensitivity of these crops to ozone.

    更新日期:2020-01-04
  • Atmospheric humidity and genotype are key determinants of the diurnal stomatal conductance pattern
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-12
    Xinying Zhang; Yajing Wang; Guirong Huang; Fu Feng; Xiaoying Liu; Rui Guo; Fengxue Gu; Xin Hu; Ziguang Yang; Xiuli Zhong; Xurong Mei

    Great understanding of the genotypic difference in diurnal stomatal conductance (gs) pattern and the key determinants of the pattern is important for saving water by adopting cultivars appropriately. Fifteen wheat genotypes were studied under different soil conditions and various meteorological conditions with pot cultivation in rain shelter for two years. Genotype and air humidity were found to be key determinants of diurnal gs pattern. All genotypes under low relative humidity (LRH) and most genotypes under high relative humidity (HRH) displayed a gradual decline pattern from morning through the afternoon. Under moderate relative humidity (MRH), all genotypes present a single‐peak curve pattern, but they differed in peak time, which may lead to unreliable gs comparison between genotypes and get ostensible contrasting materials. The stomatal conductance was significantly different among genotypes under LRH and the increased gs magnitude is also significantly different when it was compared between LRH and HRH. The present results provide new thinking for selecting and adopting appropriate cultivars with specific stomata traits for the area with various meteorological conditions.

    更新日期:2020-01-04
  • Cover Image
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-11-27
    Jesse A. Mayer; John C. Cushman
    更新日期:2020-01-04
  • Field evaluation of AtDREB2A CA overexpressing sugarcane for drought tolerance
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-04-30
    Wagner Rodrigo de Souza; Nelson Geraldo de Oliveira; Felipe Vinecky; Ana Paula Ribeiro; Marcos Fernando Basso; Raphael Augusto das Chagas Noqueli Casari; Bárbara Andrade Dias Brito da Cunha; Karoline Estefani Duarte; Thaís Ribeiro Santiago; Polyana Kelly Martins; Carlos Eduardo Aucique‐Perez; Sílvio Carlos Cristofoletti Júnior; Alexandre Lima Nepomuceno; Carlos Antônio Ferreira de Sousa; Adilson Kenji Kobayashi; Kazuo Nakashima; Kazuko Yamaguchi‐Shinozaki; Hugo Bruno Correa Molinari

    Climate change is undoubtedly altering the atmosphere, occasioning extreme temperatures that can cause weather calamities such as droughts and floods. Among the major constraints limiting crop production, drought is one of the most important. Sugarcane (Saccharum spp. hybrid) is considered an important economic crop not only for sugar production, but also for ethanol generation, serving as an expandable green alternative to crude oil use. To take advantage of the use of sugarcane as renewable source for bioethanol production, it is important to increase its productivity without increasing land use, which includes cultivation under hostile conditions, such as water‐limited environments. Previously, we demonstrated that stress‐inducible overexpression of the transcription factor AtDREB2A CA conferred drought tolerance in sugarcane subjected to water deficit under greenhouse conditions. In the present work, the AtDREB2A CA transgenic sugarcane lines were evaluated in the field in two representative seasonally dry regions of Brazil. The results demonstrated that the AtDREB2A CA sugarcane lines presented higher yield and productivity when compared to non‐transformed plants under drought, representing a suitable strategy for the development of new drought‐tolerant cultivars.

    更新日期:2020-01-04
  • Summer drought decreases Leymus chinensis productivity through constraining the bud, tiller and shoot production
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-11
    Junfeng Wang; Yujie Shi; Yunna Ao; Dafu Yu; Jiao Wang; Song Gao; Johannes M. H. Knops; Chunsheng Mu; Zhijian Li

    Extreme drought events can directly decrease productivity in perennial grasslands. However, for rhizomatous perennial grasses it remains unknown how drought events influence the belowground bud bank which determines future productivity. Ninety‐day‐long drought events imposed on Leymus chinensis, a rhizomatous perennial grass, caused a 41% decrease in the aboveground biomass and a 28% decrease in belowground biomass. Aboveground biomass decreased due to decrease in both the parent and the daughter shoot biomass. The decreases in daughter shoot biomass were due to reductions in both the shoot number and each individual shoot weight. Most importantly, drought decreased the bud bank density by 56%. In addition, drought induced a bud allocation change that decreased by 41% the proportion of buds that developed into shoots and a 41% increase in the buds that developed into rhizomes. Above results were supported by our field experiment with watering treatments. Thus, a 90‐day‐long summer drought event decreases not only current productivity but also future productivity, because the drought reduces the absolute bud number. However, plasticity in plant development does partly compensate for this reduction in bud number by increasing bud development into rhizomes, which increases the relative allocation of buds into future shoots, at the cost of a decrease in current shoots.

    更新日期:2020-01-04
  • Role of light‐intensity‐dependent changes in thiol and amino acid metabolism in the adaptation of wheat to drought
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-30
    Mónika Gyugos; Mohamed Ahres; Zsolt Gulyás; Gabriella Szalai; Éva Darkó; Balázs Végh; Ákos Boldizsár; Zsuzsa Mednyánszky; Rup Kumar Kar; Narottam Dey; Livia Simon‐Sarkadi; Gábor Galiba; Gábor Kocsy

    Light‐intensity‐dependent (low, normal and high) differences in thiol and amino acid metabolism during drought were compared in wheat seedlings. The drought‐tolerant genotype (Plainsman) recovered better than the sensitive one (Cappelle Desprez) after the stress as shown by growth and photosynthetic parameters, the levels of which were greater in low and high light, respectively. Glutathione as an antioxidant contributed to this difference, since its level was twofold greater in Plainsman throughout the experiment. In addition, the accumulation of most amino acids even increased in normal light during drought in Plainsman, while such change occurred in Cappelle Desprez only in high light. The higher contents of proline, glutamate and γ‐aminobutyrate are especially important because of their involvement in the protection against drought. The transcription of certain genes related to amino acid and glutathione metabolism and various antioxidants was even induced by higher light intensities before drought, which can contribute to the subsequent increase in the amount of the corresponding metabolites during stress. Increase in light intensity activated various protective mechanisms including greater accumulation of glutathione, proline and other amino acids during drought, which contributed to the efficient recovery of wheat after stress.

    更新日期:2020-01-04
  • Root morphological traits of winter wheat under contrasting environments
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-08-01
    Bin Peng; Xiuwei Liu; Xuejun Dong; Qingwu Xue; Clark B. Neely; Thomas Marek; Amir M. H. Ibrahim; Guorong Zhang; Daniel I. Leskovar; Jackie C. Rudd

    Roots strongly influence the growth and yield of field crops. We characterized root morphological traits of 10 winter wheat varieties in order to determine the extent they were influenced by the environments and impacted grain yield under two irrigation regimes at Bushland (a cooler, drier site with clay loam soil) and Uvalde (a warmer, wetter site with clay soil) in Texas, USA, from 2015 to 2017. Major root traits, including root diameter, specific root length (SRL), root surface area (SSA), tissue mass density (TMD), root length density (RLD), and root weight density, were measured and related to one another and to grain yield. RLD of wheat decreased but SRL and SSA increased with soil depth. Irrigation was second to environment in affecting root traits. Compared with Uvalde, the environment of Bushland promoted deeper root growth, higher TMD, but reduced SRL and SSA. Water deficit inhibited RLD and root: shoot ratio at Bushland, but moderately promoted them at Uvalde. Both SRL and RLD were positively associated with grain yield, with the former relation stronger under drought. The dichotomy of “conservative” versus “acquisitive” root strategy partially explained the variations of root traits of winter wheat in contrasting environments.

    更新日期:2020-01-04
  • The early stress response of maize (Zea mays L.) to chloride salinity
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-22
    Xudong Zhang; Christian Zörb; Markus Kränzlein; Bastian L. Franzisky; Hartmut Kaiser; Christoph‐Martin Geilfus

    Chloride is a micronutrient required for photosynthesis but when applied in the concentration of a macronutrient, it may also promote growth by regulating turgor. However, if chloride accumulates excessively, it can induce toxicity. The aim of this study was to identify physiological dysfunctions in maize (Zea mays L.) that arise in response to excessive chloride ion accumulation. For this, a novel water sensor was employed for the first time allowing the in vivo measurement of water content in the plant by using two near IR‐wavelengths with different absorption of water. This enabled to analyse whether water imbalances occurred. Chloride was given together with calcium as companying counter cation. Results show that most of the tested maize genotypes were able to maintain growth, photosynthesis and normal water content when stressed with concentrations as high as 757.1 mg chloride/kg soil dry matter. Leaf blades accumulated only 8.5 mg chloride/g dry matter, with the most genotypes not even showing salt stress necrosis at the leaves. A comparison between more tolerant and more sensitive genotypes revealed that restriction of chloride root‐to‐shoot translocation is a trait of chloride tolerance.

    更新日期:2020-01-04
  • Potential involvement of rapeseed (Brassica napus L.) metallothioneins in the hydrogen peroxide‐induced regulation of seed vigour
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-08-08
    Agnieszka Mierek‐Adamska; Karolina Kotowicz; Anna Goc; Justyna Boniecka; Julia Berdychowska; Grażyna B. Dąbrowska

    Germination is a crucial process in crop plant life cycle that determines future yield. Hydrogen peroxide plays a significant role in both dormancy release and seed ageing. The potential of the rapeseed metallothioneins (BnMT1‐4) as reactive oxygen species scavengers was investigated. In the presence of H2O2, bacterial cells expressing BnMT1‐4 had higher growth rate than control cells. However, such effect was not observed in an oxidative stress oversensitive yap‐1Δ yeast mutant strain expressing BnMT1‐4. Next, it was shown that H2O2, up to 100 and 10 mM, promotes rapeseed germination rate and seedling growth, respectively. Moreover, it was demonstrated that in seeds germinating in the presence of H2O2, the expression of seed‐specific BnMT4 decreases to a high extent in a dose‐ and time‐dependent manner. It was shown that the decline in BnMT4 mRNA level, accelerated by up to 10 mM H2O2 treatment, correlates positively with increased rapeseed germination and early growth, underscoring the plausible role of BnMT4 as a H2O2 scavenging protein that level has to be downregulated in conditions where the compound is needed. Finally, it was demonstrated that H2O2 could be used as a priming agent of rapeseeds.

    更新日期:2020-01-04
  • Heat, wheat and CO2: The relevance of timing and the mode of temperature stress on biomass and yield
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-05-24
    Petra Högy; Lorenz Kottmann; Iris Schmid; Andreas Fangmeier

    Atmospheric CO2 enrichment affects C3 crops both directly via increased carbon gain and improved water use efficiency and indirectly via higher temperatures and more frequent climatic extremes. Here we investigated the response of spring wheat (Triticum aestivum L. cv. Triso) to CO2 enrichment (550 vs. 380 µmol/mol) and heat, applied as a constant +4°C increase or a typical heat wave either before or after anthesis, or as two typical heat waves before and after anthesis. We applied a climate chamber approach closely mimicking ambient conditions. CO2 enrichment increased above‐ground biomass and yield by c. 7 and 10%, but was not able to compensate for adverse heat stress effects, neither before nor after anthesis, with few exceptions only. Yield depression due to heat stress was most severe when two heat waves were applied (−19%). This adverse effect was, however, compensated by CO2 enrichment. Applying heat stress before or after anthesis did not exert different effects on yield for both +4°C warming and heat wave application. However, +4°C depressed yield more than a heat wave at ambient CO2, but not so at elevated CO2. Thus, the interactive effects were complex and prediction of future wheat yield under CO2 enrichment and climate extremes deserves more attention.

    更新日期:2020-01-04
  • Spraying exogenous synthetic cytokinin 6‐benzyladenine following the waterlogging improves grain growth of waterlogged maize in the field
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-11
    Baizhao Ren; Juan Hu; Jiwang Zhang; Shuting Dong; Peng Liu; Bin Zhao

    6‐Benzyladenine (6‐BA, a synthetic cytokinin) could improve the ability to resist adversity. However, very little attention has been given to its role in alleviating waterlogging damages on grain growth. A field experiment was performed to investigate effects of exogenous 6‐BA after waterlogging for 6 days at the third leaf stage (V3‐WL + 6‐BA) or the sixth leaf stage (V6‐WL + 6‐BA) on grain filling, and endogenous hormone of summer maize hybrids DengHai605 (DH605) and ZhengDan958 (ZD958), which were planted popularly in China. Exogenous 6‐BA alleviated waterlogging damages on grain filling by improving grain weight and volume, which was beneficial to yield increase. Grain yield of DH605 under V3‐WL + 6‐BA and V6‐WL + 6‐BA increased by 16% and 12%, respectively, compared with that of V3‐WL (waterlogging at the third leaf stage) and V6‐WL (waterlogging at the sixth leaf stage), while the corresponding values for ZD958 increased by 20% and 15%, respectively. Moreover, exogenous 6‐BA alleviated waterlogging damages on grain endogenous hormone content by increasing levels of endogenous indole‐3‐acetic acid, zeatin riboside, and gibberellic acid, and decreasing level of abscisic acid in grain of waterlogged summer maize during grain‐filling periods. Clearly, exogenous 6‐BA improved grain‐filling characteristics, and endogenous hormone, resulting in a significant yield increase of waterlogged summer maize.

    更新日期:2020-01-04
  • Nutritional and mineral content of prickly pear cactus: A highly water‐use efficient forage, fodder and food species
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-16
    Jesse A. Mayer; John C. Cushman

    Increased demand for food requires us to investigate livestock forage and fodder crops that can be grown over a wide range of locations where their cultivation will not compete with that of the food supply. A large portion of the southwestern United States consists of underutilized semi‐arid land. Crops typically used for livestock fodder or forage have high‐water demands that make them uneconomical or unsustainable for semi‐arid and arid regions. The growth rate and low‐input requirements of prickly pear cactus (Opuntia ficus‐indica) make it an excellent candidate for forage or fodder supplementation or replacement in these regions. Previous reports about forage quality data on Opuntia have been scattered across multiple locations, growing conditions and cultivars. Here, we report on the forage quality and mineral content of Opuntia ficus‐indica grown under both field and greenhouse conditions. Crude protein was 71 and 264 g/kg of dry mass for field and greenhouse conditions, respectively. Field‐grown plants showed higher acid and neutral detergent fibre content than greenhouse‐grown plants reflecting higher cellulose, hemicellulose and lignin accumulation. Nutritional values were also compared to requirements of cattle to determine what deficiencies might need to be addressed through supplementation. These data suggest that Opuntia can be used in combination with other feed sources to reduce the demand of resource‐intensive forage crops for raising livestock in dryland areas.

    更新日期:2020-01-04
  • Combined application of nitrogen and phosphorus to enhance nitrogen use efficiency and close the wheat yield gap on varying soils in semi‐arid conditions
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-26
    Therese M. McBeath; Vadakattu V. S. R. Gupta; Rick S. Llewellyn; Sean D. Mason; Christopher W. Davoren; Raymond L. Correll; Ben Jones; Anthony M. Whitbread

    A primary driver of the wheat yield gap in Australia and globally is the supply of nitrogen (N) and options to increase N use efficiency (NUE) are fundamental to closure of the yield gap. Co‐application of N with phosphorus (P) is suggested as an avenue to increase fertiliser NUE, and inputs of N and P fertiliser are key variable costs in low rainfall cereal crops. Within field variability in the response to nutrients due to soil and season offers a further opportunity to refine inputs for increased efficiency. The response of wheat to N fertiliser input (0, 10, 20, 40 and 80 kg N ha‐1) under four levels of P fertiliser (0, 5, 10 and 20 kg P ha−1) was measured on three key low rainfall cropping soils (dune, mid‐slope and swale) across a dune‐swale system in a low rainfall semi‐arid environment in South Australia, for three successive cropping seasons. Wheat on sandy soils produced significant and linear yield and protein responses across all three seasons, while wheat on a clay loam only produced a yield response in a high rainfall season. Responses to P fertiliser were measured on the sandy soils but more variable in nature and a consistent effect of increased P nutrition leading to increased NUE was not measured.

    更新日期:2020-01-04
  • Elevated CO2 affects plant nitrogen and water‐soluble carbohydrates but not in vitro metabolisable energy
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2019-07-22
    Joe Francis Panozzo; Cassandra Kiely Walker; Pankaj Maharjan; Debra L. Partington; Chris J. Korte

    The effects of elevated concentrations of atmospheric CO2 (e[CO2]) on the nutritive value of wheat vegetative matter and grain as a feedstock for ruminants were investigated in a study undertaken at the Australian grains free‐air CO2 enrichment (AGFACE) facility. The study included two commercial wheat cultivars (Janz and Yitpi) and two genetic selections from a Seri/Babex population (SB003 and SB062) which had previously been characterised for low and high water‐soluble carbohydrate accumulation efficiency. The trial was grown under ambient (~390 µmol/mol) and elevated (~550 µmol/mol) CO2 conditions, and plants harvested at tillering, anthesis and physiological maturity. Composition analyses to determine the nutritive value for ruminant feed were undertaken on stems, leaves and grain. Plant and grain nitrogen were reduced in the e[CO2] treatments, and as expected, the water‐soluble carbohydrates increased. All genotypes responded to e[CO2] with the effects of altered composition evident within 60 days of sowing. Determinants of ruminant feed quality such as neutral and acid detergent fibre and estimated in vitro metabolisable energy were not significantly affected. The reduced plant and grain N will impact on the nutritive value and supplementation may be required. The impact of e[CO2] on chemical composition of wheat plants may be greater if the predicted climate change is associated with concomitant abiotic stress such as high ambient temperature or low soil moisture.

    更新日期:2020-01-04
  • Susceptibility of Faba Bean (Vicia faba L.) to Heat Stress During Floral Development and Anthesis.
    J. Agron. Crop Sci. (IF 2.960) Pub Date : 2018-01-23
    J Bishop,S G Potts,H E Jones

    Experiments were conducted over 2 years to quantify the response of faba bean (Vicia faba L.) to heat stress. Potted winter faba bean plants (cv. Wizard) were exposed to temperature treatments (18/10; 22/14; 26/18; 30/22; 34/26 °C day/night) for 5 days during floral development and anthesis. Developmental stages of all flowers were scored prior to stress, plants were grown in exclusion from insect pollinators to prevent pollen movement between flowers, and yield was harvested at an individual pod scale, enabling effects of heat stress to be investigated at a high resolution. Susceptibility to stress differed between floral stages; flowers were most affected during initial green-bud stages. Yield and pollen germination of flowers present before stress showed threshold relationships to stress, with lethal temperatures (t50) ˜28 °C and ~32 °C, while whole plant yield showed a linear negative relationship to stress with high plasticity in yield allocation, such that yield lost at lower nodes was partially compensated at higher nodal positions. Faba bean has many beneficial attributes for sustainable modern cropping systems but these results suggest that yield will be limited by projected climate change, necessitating the development of heat tolerant cultivars, or improved resilience by other mechanisms such as earlier flowering times.

    更新日期:2019-11-01
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