Bramley Helen, Ranawana S R W M Chandima J K, Palta Jairo A, Stefanova Katia, Siddique Kadambot H M
The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia.
Plant Breeding Institute, School of Life and Environmental Sciences, The University of Sydney, Narrabri, NSW 2390, Australia.
Plants (Basel). 2022 Aug 21;11(16):2174. doi: 10.3390/plants11162174.
High temperature and water deficit are the most critical yield-limiting environmental factors for wheat in rainfed environments. It is important to understand the heat avoidance mechanisms and their associations with leaf morpho-physiological traits that allow crops to stay cool and retain high biomass under warm and dry conditions. We examined 20 morpho-physiologically diverse wheat genotypes under ambient and elevated temperatures (T) to investigate whether increased water use leads to high biomass retention due to increased leaf cooling. An experiment was conducted under well-watered conditions in two partially controlled glasshouses. We measured plant transpiration (T), leaf temperature (T), vapor pressure deficit (VPD), and associated leaf morpho-physiological characteristics. High water use and leaf cooling increased biomass retention under high temperatures, but increased use did not always increase biomass retention. Some genotypes maintained biomass, irrespective of water use, possibly through mechanisms other than leaf cooling, indicating their adaptation under water shortage. Genotypic differences in leaf cooling capacity did not always correlate with T (VPD) response. In summary, the contribution of high water use or the leaf cooling effect on biomass retention under high temperature is genotype-dependent and possibly due to variations in leaf morpho-physiological traits. These findings are useful for breeding programs to develop climate resilient wheat cultivars.
在雨养环境中，高温和水分亏缺是限制小麦产量的最关键环境因素。了解作物在温暖干燥条件下保持凉爽并维持高生物量的避热机制及其与叶片形态生理特征的关联非常重要。我们在环境温度和高温条件下研究了20种形态生理特征各异的小麦基因型，以探究水分利用增加是否因叶片降温增加而导致高生物量保持。在两个部分可控的温室中，在充分供水条件下进行了一项实验。我们测量了植物蒸腾作用（T）、叶片温度（T）、水汽压差（VPD）以及相关的叶片形态生理特征。在高温下，高水分利用和叶片降温增加了生物量保持，但水分利用增加并不总是能增加生物量保持。一些基因型无论水分利用情况如何都能维持生物量，可能是通过叶片降温以外的机制，这表明它们在缺水情况下具有适应性。叶片降温能力的基因型差异并不总是与T（VPD）响应相关。总之，高温下高水分利用或叶片降温对生物量保持的贡献取决于基因型，可能是由于叶片形态生理特征的差异。这些发现对培育适应气候变化的小麦品种的育种计划很有用。
