Field Crops Research ( IF 5.8 ) Pub Date : 2021-10-18 , DOI: 10.1016/j.fcr.2021.108308 Paul R. Grundy 1 , Gail M. Spargo 1 , Stephen J. Yeates 2 , Kerry L. Bell 3
Climate variability is a challenge to the reliable production of high yielding cotton, Gossypium hirsutum L. in the subtropics. Shifting the growing season earlier by sowing during late winter (August) to reduce the risk of exposure to unfavourable radiation, temperature and rainfall during mid-summer offered the potential to improve stagnating and variable yields. This study aimed to determine the effect of late winter sowing on establishment, growth, development and lint yield of cotton. Accepted knowledge from temperate climates suggested cold temperature stress would impede crop establishment, so the application of clear oxodegradable film to the soil surface at sowing to mitigate cold temperature stress was also explored.
Crop establishment, biomass accumulation and partitioning, light interception and lint yield were measured for cotton sown with and without film at intervals from early August to mid-September in four consecutive experiments (2013–2016). The application of film provided no benefits for establishment and only marginal improvement for crop growth and yield despite minimum temperatures being well below accepted chilling injury thresholds in temperate environments. Greater daily solar radiation levels both solarised the soil and shortened the duration of daily minimum temperatures, enabling successful crop establishment. Early sowing did not hinder crop production, and in 3 of the 4 experiments, lint yield was significantly higher (P < 0.001) for August (2314−3305 kg ha−1) than September-sown crops (2053−2290 kg ha−1). The impact of sowing time was further explored through the measurement of biomass and yield of 29 high input commercial crops sown between August and December in 2016–2019. Final biomass and lint yield declined (P < 0.001) by 2.89 g m-2 and 7.23 kg ha−1 for each day that sowing occurred after August 1. Combined analyses of the experiments and commercial crop data confirmed that late-winter sown crops had the highest daily growth rate between flowering and maturity, declining by 37 % for summer-sown crops. RUEg (glucose equivalent) of 2.27g MJ−1 PAR was not changed by sowing time. Late winter sowing best matched flowering and boll development with the summer solstice and a lower incidence of cloud or heat stress. An earlier harvest also reduced the risk of pre-harvest weathering, collectively enabling over 40 % higher yields than traditional spring sowing without additional crop inputs. Spring and later sowings coincided unfavourable climate with the more susceptible growth phases of late boll filling or early flowering respectively and declining solar radiation and temperatures prevented yield recovery for the latest summer-sown crops.
As the occurrence of excessive temperature-related weather events is expected to increase with climate change, particularly for the subtropics, this study demonstrates how a knowledge of crop response can be used to evolve sowing time strategies to better mitigate climatic risk.
中文翻译:
利用晚冬播种提高亚热带棉花产量以降低气候风险
气候变化对亚热带地区高产棉花Gossypium hirsutum L.的可靠生产构成挑战。通过在冬末(8 月)播种来提前改变生长季节,以减少在仲夏期间暴露于不利辐射、温度和降雨的风险,这提供了改善停滞和可变单产的潜力。本研究旨在确定晚冬播种对棉花建立、生长、发育和皮棉产量的影响。来自温带气候的公认知识表明低温胁迫会阻碍作物的生长,因此还探索了在播种时将透明的可氧化降解薄膜应用于土壤表面以减轻低温胁迫。
在连续四次试验(2013-2016 年)中,在 8 月初至 9 月中旬间隔种植有膜和无膜的棉花,测量了作物建立、生物量积累和分配、光拦截和皮棉产量。尽管最低温度远低于温带环境中公认的冷害阈值,但薄膜的应用对建立没有任何好处,而仅对作物生长和产量提供了边际改善。更大的每日太阳辐射水平既使土壤日晒,又缩短了每日最低温度的持续时间,从而使作物成功建立。早播不影响作物生产,在 4 个试验中的 3 个试验中, 8 月(2314-3305 kg ha -1)的皮棉产量显着更高(P < 0.001)) 比 9 月播种的作物 (2053−2290 kg ha -1 )。通过测量 2016-2019 年 8 月至 12 月间播种的 29 种高投入经济作物的生物量和产量,进一步探讨了播种时间的影响。8 月 1 日之后播种的每一天,最终生物量和皮棉产量下降 ( P < 0.001) 2.89 gm -2和 7.23 kg ha -1。开花和成熟之间的最高日增长率,夏播作物下降了 37%。RUE g(葡萄糖当量)为 2.27 g MJ -1PAR 不会因播种时间而改变。冬末播种与夏至和较低的云或热应激发生率最佳匹配开花和棉铃发育。较早的收获还降低了收获前风化的风险,在没有额外作物投入的情况下,与传统春播相比,总产量提高了 40% 以上。春季和后期播种恰逢不利的气候,分别是晚棉铃灌浆或早开花的更易受害的生长阶段,太阳辐射和温度的下降阻碍了最近夏播作物的产量恢复。
由于预计与温度相关的过度天气事件的发生会随着气候变化而增加,特别是对于亚热带地区,本研究展示了如何利用作物反应知识来制定播种时间策略,以更好地减轻气候风险。