Does late water deficit induce root growth or senescence in wheat?

Abstract

Drought frequently limits productivity in rain-fed systems. To investigate water-stress impacts on post-anthesis root development in wheat, three experiments were conducted with two cultivars, Scout and Mace, grown in 1.5m tubes under well-watered conditions or post-anthesis water-stress. Shallow roots of both genotypes appeared to senesce between heading and maturity under well-watered conditions, whereas moderate water stress tended to increase post-heading shallow-root senescence in Mace but stimulated growth in Scout. For deep roots, net growth in biomass was observed for both genotypes under well-watered conditions between heading and maturity, whereas under moderate water stress, only Scout maintained net growth, with net senescence being observed for Mace. Severe water stress resulted in root senescence at all depths for both genotypes. Above ground, Scout retained leaf greenness for only slightly longer than Mace under well-watered conditions. In contrast, under moderate water stress, Mace showed rapid post-anthesis leaf senescence while Scout was affected little if at all. Grain biomass per plant was similar between genotypes in well-watered conditions but more reduced for Mace under moderate stress. Post-anthesis differences in root growth and senescence can strongly influence water use and grain filling in drought-prone environments. Screening for this could assist breeding for drought tolerant varieties. HighlightWater deficit induced post-heading root senescence and/or growth in wheat dependant on genotypes and conditions. Root senescence was associated to leaf senescence, earlier plant maturity and reduced plant yield.