Sehgal Akanksha, Sita Kumari, Kumar Jitendra, Kumar Shiv, Singh Sarvjeet, Siddique Kadambot H M, Nayyar Harsh
Department of Botany, Panjab University, Chandigarh, India.
Indian Institute of Pulses Research, Kanpur, India.
Front Plant Sci. 2017 Oct 17;8:1776. doi: 10.3389/fpls.2017.01776. eCollection 2017.
Rising temperatures and drought stress limit the growth and production potential of lentil ( Medikus), particularly during reproductive growth and seed filling. The present study aimed to (i) investigate the individual and combined effects of heat and drought stress during seed filling, (ii) determine the response of lentil genotypes with contrasting heat and drought sensitivity, and (iii) assess any cross tolerance in contrasting genotypes. For this purpose, eight lentil genotypes (two drought-tolerant, two drought-sensitive, two heat-tolerant, two heat-sensitive) were either sown at the normal time (second week of November 2014), when the temperatures at the time of seed filling were below 30/20°C (day/night), or sown late (second week of February 2015) to impose heat stress (temperatures > 30/20°C (day/night) during reproducive growth and seed filling. Half of the pots in each sowing environment were fully watered throughout (100% field capacity) while the others had water withheld (50% of field capacity) from the start of seed filling to maturity. Both heat and drought, individually or in combination, damaged cell membranes, photosynthetic traits and water relations; the effects were more severe with the combined stress. RuBisCo and stomatal conductance increased with heat stress but decreased with drought and the combined stress. Leaf and seed sucrose decreased with each stress in conjunction with its biosynthetic enzyme, while its (sucrose) hydrolysis increased under heat and drought stress, but was inhibited due to combination of stresses. Starch increased under heat stress in leaves but decreased in seeds, but drastically declined in seeds under drought alone or in combination with heat stress. At the same time, starch hydrolysis in leaves and seeds increased resulting in an accumulation of reducing sugars. Heat stress inhibited yield traits (seed number and seed weight per plant) more than drought stress, while drought stress reduced individual seed weights more than heat stress. The combined stress severely inhibited yield traits with less effect on the drought- and heat-tolerant genotypes. Drought stress inhibited the biochemical processes of seed filling more than heat stress, and the combined stress had a highly detrimental effect. A partial cross tolerance was noticed in drought and heat-tolerant lentil genotypes against the two stresses.
气温上升和干旱胁迫限制了小扁豆（Medikus）的生长和生产潜力，尤其是在生殖生长和种子灌浆期间。本研究旨在：（i）研究种子灌浆期间高温和干旱胁迫的单独及联合影响；（ii）确定对高温和干旱敏感性不同的小扁豆基因型的响应；（iii）评估不同基因型之间的交叉耐受性。为此，选用了8个小扁豆基因型（2个耐旱型、2个干旱敏感型、2个耐热型、2个热敏感型），要么在正常时间（2014年11月的第二周）播种，此时种子灌浆时的温度低于30/20°C（昼/夜），要么晚播（2015年2月的第二周）以施加热胁迫（生殖生长和种子灌浆期间温度>30/20°C（昼/夜））。在每个播种环境中，一半的花盆始终充分浇水（田间持水量的100%），而其他花盆从种子灌浆开始到成熟都不浇水（田间持水量的50%）。高温和干旱单独或联合作用都会损害细胞膜、光合特性和水分关系；联合胁迫的影响更严重。核酮糖-1,5-二磷酸羧化酶/加氧酶（RuBisCo）和气孔导度随热胁迫增加，但随干旱和联合胁迫而降低。叶片和种子中的蔗糖随着每种胁迫与其生物合成酶一起下降，而其（蔗糖）水解在高温和干旱胁迫下增加，但由于胁迫组合而受到抑制。淀粉在叶片中随热胁迫增加，但在种子中减少，但在单独干旱或与热胁迫组合时，种子中的淀粉急剧下降。与此同时，叶片和种子中的淀粉水解增加，导致还原糖积累。热胁迫对产量性状（单株种子数和种子重量）的抑制作用大于干旱胁迫，而干旱胁迫对单粒种子重量的降低作用大于热胁迫。联合胁迫严重抑制产量性状，对耐旱和耐热基因型的影响较小。干旱胁迫对种子灌浆生化过程的抑制作用大于热胁迫，联合胁迫具有高度有害影响。在耐旱和耐热的小扁豆基因型中发现了对这两种胁迫的部分交叉耐受性。
