Mild preflowering drought priming improves stress defences, assimilation and sink strength in rice under severe terminal drought

Abstract

Drought stress is a prominent and persisting constraint for sustaining global rice (Oryza sativa L.) production. Priming with mild drought can be effective in reducing the impact of severe terminal drought stress affecting seed set and grain filling in rice. The cultivars N22 (drought tolerant), NSIC Rc222 and IR64 (high yielding, drought sensitive) were tested for short-term mild drought priming before flowering and subsequently exposed to severe drought stress either at the highly sensitive flowering or at the early grain filling stage under greenhouse conditions. Drought stress increased oxidative damage and reduced photosynthesis and sink enzymatic activity, ultimately reducing seed set (20–46%) and grain yield (22–68%) across cultivars. However, priming with mild drought significantly reduced oxidative damage, and increased photosynthesis, stomatal conductance and enzymatic activity, contributing to improved sink strength, thereby significantly reducing seed set (7–18%) and grain yield (12–59%) losses. The higher activity of key enzymes associated with sink strength such as cell wall invertase and sucrose synthase in primed plants probably reduced drought-induced losses at the grain filling stage. The findings support mild drought priming before flowering as a promising strategy for reducing yield penalty by providing partial protection against subsequent severe terminal drought stress. However, application of mild drought priming at the field level would need further investigation.

Water‐deficit stress alters intra‐panicle grain number in sorghum

“…Stress targeted to coincide with grain-filling in the main panicle, would lead to similar stress exposure during pollen/pistil developmental stages in the primary and other later tillers leading, to a proportionally greater reduction in grain number (Table 2). A similar phenomenon has been documented in other crops including wheat (Onyemaobi, Liu, Siddique & Yan, 2016) and rice (Bahuguna, Tamilselvan, Muthurajan, Solis, & Jagadish, 2018), demonstrating the extreme sensitivity of gametogenesis to water-deficit stress across cereals.…”

Increased tolerance to Phytophthora cinnamomi in offspring of ink-diseased chestnut (Castanea sativa Miller) trees

“…Stress memory may increase a plant's survival chances by improving its tolerance abilities and may provide a mechanism for adaptation (Avramova 2019). Priming with mild drought during the flowering stage was shown to be effective in reducing the impact of subsequent severe terminal drought stress in Oryza sativa (Bahuguna et al 2018). Drought priming in parental plants was recently reported to induce drought tolerance in offspring (Wang et al 2018;Vivas et al 2019).…”

Conventional and contemporary approaches for drought tolerance rice breeding: Progress and prospects

“…This reduction in yields may extend up to 88% during the flowering stage and up to 52% during the grain filling stage (Yambao & Ingram, 1988). At the flowering stage, drought results incomplete panicle exertion which results in approximately 30% spikelet sterility; a 20%-46% reduction in seed set is also reported across a range of rice types with various panicle lengths (Bahuguna et al, 2018). However, drought stress had no significant effect on the appearance or nutritional quality of grain, with the exception of a considerable increase in the proportion of chalky kernels or chalkiness (Yang et al, 2018), as well as protein.…”