Broughton Katrina J, Conaty Warren C
Agriculture and Food, CSIRO, Narrabri, NSW, Australia.
Front Plant Sci. 2022 May 10;13:893994. doi: 10.3389/fpls.2022.893994. eCollection 2022.
More frequent droughts and an increased pressure on water resources, combined with social licence to operate, will inevitably decrease water resources available for fully irrigated cotton production. Therefore, the long-term future of the cotton industry will require more drought tolerant varieties that can perform well when grown in rainfed cropping regions often exposed to intermittent drought. A trait that limits transpiration (TR) under an increased vapour pressure deficit (VPD) may increase crop yield in drier atmospheric conditions and potentially conserve soil water to support crop growth later in the growing season. However, this trait has not been tested or identified in cotton production systems. This study tested the hypotheses that (1) genetic variability to the TR VPD trait exists amongst 10 genotypes in the Australian cotton breeding programme; (2) genotypes with a TR VPD trait use less water in high VPD environments and (3) variation in yield responses of cotton genotypes is linked with the VPD environment and water availability during the peak flowering period. This study combined glasshouse and field experiments to assess plant transpiration and crop yield responses of predominantly locally bred cotton genotypes to a range of atmospheric VPD under Australian climatic conditions. Results indicated that genetic variation to the limiting transpiration VPD trait exists within cotton genotypes in the Australian breeding programme, with five genotypes identified as expressing the TR VPD trait. A modelling study suggests that this trait may not necessarily result in overall reduced plant water use due to greater transpiration rates at lower VPD environments negating the water conservation in high VPD environments. However, our study showed that the yield response of cotton genotypes is linked with both VPD environment and water availability during the peak flowering period. Yield performance of the TR genotype was improved at some high VPD environments but is unlikely to out-perform a genotype with a lower yield potential. Improved understanding of integrated plant- and crop-level genotypic responses to the VPD environments will enhance germplasm development to benefit cotton production in both rainfed and semi-irrigated cotton systems, thereby meeting the agricultural challenges of the twenty-first Century.
更频繁的干旱以及水资源压力的增加，再加上运营所需的社会许可，将不可避免地减少可用于完全灌溉棉花生产的水资源。因此，棉花产业的长期未来将需要更多耐旱品种，这些品种在雨养种植区（经常遭受间歇性干旱）种植时能表现良好。在蒸汽压亏缺（VPD）增加的情况下限制蒸腾作用（TR）的性状，可能会在更干燥的大气条件下提高作物产量，并有可能在生长季节后期保持土壤水分以支持作物生长。然而，这一性状在棉花生产系统中尚未得到测试或鉴定。本研究检验了以下假设：（1）澳大利亚棉花育种计划中的10个基因型存在对TR VPD性状的遗传变异；（2）具有TR VPD性状的基因型在高VPD环境中用水较少；（3）棉花基因型产量反应的差异与开花高峰期的VPD环境和水分供应有关。本研究结合温室和田间试验，在澳大利亚气候条件下，评估了主要为本地培育的棉花基因型对一系列大气VPD的植物蒸腾和作物产量反应。结果表明，澳大利亚育种计划中的棉花基因型存在对限制蒸腾VPD性状的遗传变异，有5个基因型被鉴定为表现出TR VPD性状。一项建模研究表明，由于较低VPD环境下较高的蒸腾速率抵消了高VPD环境下的节水效果，这一性状不一定会导致植物总体用水量减少。然而，我们的研究表明，棉花基因型的产量反应与开花高峰期的VPD环境和水分供应都有关。TR基因型在一些高VPD环境下的产量表现有所改善，但不太可能超过产量潜力较低的基因型。更好地理解植物和作物水平对VPD环境的综合基因型反应，将有助于种质资源的开发，从而使雨养和半灌溉棉花系统的棉花生产受益，进而应对21世纪的农业挑战。
