Increasing temperatures are adversely affecting various food crops, including legumes, and this issue requires attention. The growth of two cool‐season food legumes, chickpea and lentil, is inhibited by high temperatures but their relative sensitivity to heat stress and the underlying reasons have not been investigated. Moreover, the high‐temperature thresholds for these two legumes have not been well‐characterised. In the present study, three chickpea (ICCVO7110, ICC5912 and ICCV92944) and two lentil (LL699 and LL931) genotypes, having nearly similar phenology with respect to flowering, were grown at 30/20°C (day/night; control) until the onset of flowering and subsequently exposed to varying high temperatures (35/25, 38/28, 40/30 and 42/32°C; day/night) in a controlled environment (growth chamber; 12 hr/12 hr; light intensity 750 µmol m⁻² s⁻¹; RH‐70%) at 108 days after sowing for both the species. Phenology (podding, maturity) was accelerated in both the species; the days to podding declined more in lentil at 35/25 (2.8 days) and 38/28°C (11.3 days) than in chickpea (1.7 and 7.1 days, respectively). Heat stress decreased flowering–podding and podding–maturity intervals considerably in both the species. At higher temperatures, no podding was observed in lentil, while chickpea showed reduction of 14.9 and 16.1 days at 40/30 and 42/32°C, respectively. Maturity was accelerated on 15.3 and 12.5 days at 38/28°C, 33.6 and 34 days at 40/30°C and 45.6 and 47 days at 42/32°C, in chickpea and lentil, respectively. Consequently, biomass decreased considerably at 38/28°C in both the species to limit the yield‐related traits. Lentil was significantly more sensitive to heat stress, with the damage—assessed as reduction in biomass, reproductive function‐related traits (pollen viability, germination, pollen tube growth and stigma receptivity), leaf traits such as membrane injury, leaf water status, photochemical efficiency, chlorophyll concentration, carbon fixation and assimilation, and oxidative stress, appearing even at 35/25°C, compared with 38/28°C, in chickpea. The expression of enzymatic antioxidants such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and non‐enzymatic antioxidants declined remarkably with heat stress, more so in lentil than in chickpea. Carbon fixation (assessed as Rubisco activity) and assimilation (assessed as sucrose concentration, sucrose synthase activity) were also reduced more in lentil than in chickpea, at all the stressful temperatures, resulting in more inhibition of plant biomass (shoot + roots), damage to reproductive function and severe reduction in pods and seeds. At 38/28°C, lentil showed 43% reduction in biomass, while it declined by 17.2% in chickpea at the same time, over the control temperature (30/20°C). At this temperature, lentil showed 53% and 46% reduction in pods and seed yield, compared to 13.4% and 22% decrease in chickpea at the same temperature. At 40/30°C, lentil did not produce any pods, while chickpea was able to produce few pods at this temperature. This study identified that lentil is considerably more sensitive to heat stress than chickpea, as a result of more damage to leaves (photosynthetic ability; oxidative injury) and reproductive components (pollen function, etc.) at 35/25°C and above, at controlled conditions.

中文翻译：

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两种冷季豆类植物鹰嘴豆和小扁豆在生殖阶段的热敏感性差异与花粉功能，光合能力和氧化损伤的反应有关

温度升高对包括豆类在内的各种粮食作物产生不利影响，这一问题需要引起注意。高温抑制了两种凉爽的豆类食物鹰嘴豆和小扁豆的生长，但尚未研究它们对热应激的相对敏感性及其根本原因。此外，这两种豆类的高温阈值还没有很好的特征。在本研究中，在开花方面具有几乎相似的物候特性的三种鹰嘴豆（ICCVO7110，ICC5912和ICCV92944）和两种扁豆（LL699和LL931）基因型在30/20°C（昼/夜；对照）下生长，直到开花开始，随后在受控环境（生长室； 12小时/ 12小时；光照强度750）下暴露于变化的高温（35 / 25、38 / 28、40 / 30和42/32°C；白天/晚上）微摩尔米^-2 秒^-1; 两个品种在播种后第108天的相对湿度为RH-70％。两种物种的物候学（荚果，成熟度）均加快。在35/25（2.8天）和38/28°C（11.3天）时，小扁豆的结荚天数比鹰嘴豆（分别为1.7天和7.1天）下降更多。在两个物种中，热胁迫都大大降低了花荚和荚果的成熟间隔。在较高温度下，在小扁豆中未观察到荚果，而鹰嘴豆在40/30和42/32°C下分别减少了14.9和16.1天。鹰嘴豆和小扁豆的成熟度分别在38/28°C的15.3天和12.5天，40/30°C的33.6天和34天以及42/32°C的45.6天和47天加速。因此，两个物种的生物量在38/28°C时都大大降低，以限制与产量相关的性状。小扁豆对热应激更为敏感，包括生物量减少，生殖功能相关性状（花粉活​​力，发芽，花粉管生长和柱头接受性），叶片性状（如膜损伤，叶片水分状况，光化学效率，叶绿素浓度，碳固着和同化）鹰嘴豆甚至在35/25°C时也出现氧化应激，而38/28°C时出现。酶促抗氧化剂如超氧化物歧化酶，过氧化氢酶，抗坏血酸过氧化物酶，谷胱甘肽还原酶和非酶促抗氧化剂的表达随着热胁迫而显着下降，在小扁豆中比在鹰嘴豆中更明显。在所有胁迫温度下，小扁豆的碳固定（评估为Rubisco活性）和同化（评估为蔗糖浓度，蔗糖合酶活性）也比鹰嘴豆降低更多，导致更多抑制植物生物量（枝+根），损害生殖功能以及豆荚和种子严重减少。在38/28°C时，在控制温度（30/20°C）下，扁豆的生物量减少了43％，而鹰嘴豆则下降了17.2％。在此温度下，小扁豆的豆荚和种子产量降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究发现，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，原因是鹰嘴豆在35/25°C和更高温度下对叶片（光合能力；氧化损伤）和生殖成分（花粉功能等）的伤害更大。控制条件。生殖功能受损，豆荚和种子严重减少。在38/28°C时，在控制温度（30/20°C）下，扁豆的生物量减少了43％，而鹰嘴豆则下降了17.2％。在此温度下，小扁豆的豆荚和种子产量降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究表明，在35/25°C和更高温度下，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，这是由于对叶子（光合能力；氧化损伤）和生殖成分（花粉功能等）的损害更大。控制条件。生殖功能受损，豆荚和种子严重减少。在38/28°C时，在控制温度（30/20°C）下，扁豆的生物量减少了43％，而鹰嘴豆则下降了17.2％。在此温度下，小扁豆的豆荚和种子产量降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究发现，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，原因是鹰嘴豆在35/25°C和更高温度下对叶片（光合能力；氧化损伤）和生殖成分（花粉功能等）的伤害更大。控制条件。在控制温度（30/20°C）下，扁豆的生物量减少了43％，而鹰嘴豆同时下降了17.2％。在此温度下，小扁豆的豆荚和种子产量降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究发现，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，原因是鹰嘴豆在35/25°C和更高温度下对叶片（光合能力；氧化损伤）和生殖成分（花粉功能等）的伤害更大。控制条件。在控制温度（30/20°C）下，扁豆的生物量减少了43％，而鹰嘴豆同时下降了17.2％。在此温度下，小扁豆的豆荚和种子产量降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究表明，在35/25°C和更高温度下，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，这是由于对叶子（光合能力；氧化损伤）和生殖成分（花粉功能等）的损害更大。控制条件。小扁豆的豆荚和种子产量分别降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究发现，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，原因是鹰嘴豆在35/25°C和更高温度下对叶片（光合能力；氧化损伤）和生殖成分（花粉功能等）的伤害更大。控制条件。小扁豆的豆荚和种子产量分别降低了53％和46％，而同一温度下鹰嘴豆的降低了13.4％和22％。在40/30°C下，小扁豆不产生任何荚果，而鹰嘴豆在此温度下几乎不产生荚果。这项研究发现，在35/25°C及以上温度下，扁豆对鹰嘴豆比对鹰嘴豆更敏感，原因是鹰嘴豆在35/25°C和更高温度下对叶片（光合能力；氧化损伤）和生殖成分（花粉功能等）的伤害更大。控制条件。