Truncation of grain filling in wheat (Triticum aestivum) triggered by brief heat stress during early grain filling: association with senescence responses and reductions in stem reserves

Abstract

Abstract. Short heat waves during grain filling can reduce grain size and consequently yield in wheat (Triticum aestivum L.). Grain weight responses to heat represent the net outcome of reduced photosynthesis, increased mobilisation of stem reserves (water-soluble carbohydrates, WSC) and accelerated senescence in the grain. To compare their relative roles in grain weight responses under heat, these characteristics were monitored in nine wheat genotypes subjected to a brief heat stress at early grain filling (37 C maximum for 3 days at 10 days after anthesis). Compared with the five tolerant varieties, the four susceptible varieties showed greater heat-triggered reductions in final grain weight, grain filling duration, flag leaf chla and chlb content, stem WSC and PSII functionality (F v /F m ). Despite the potential for reductions in sugar supply to the developing grains, there was little effect of heat on grain filling rate, suggesting that grain size effects of heat may have instead been driven by premature senescence in the grain. Extreme senescence responses potentially masked stem WSC contributions to grain weight stability. Based on these findings, limiting heat-triggered senescence in the grain may provide an appropriate focus for improving heat tolerance in wheat.

Initial response of phenology and yield components of wheat (Triticum durumL., CIRNO C2008) under experimental warming field conditions in the Yaqui Valley

“…The reduction of phenophase occurrence time has been studied in several crops and the effect of this reduction originates from biochemical processes alteration, mainly in the synthesis of substances translocated to the spikes ( Shirdelmoghanloo et al, 2016 ). This reduction in phenophase occurrence time sometimes modifies the expression of structural genes regulators of proteins synthesis, such as glutamine, and its mobilization to the spikes ( Royo et al, 2016 ).…”

“…In the present study, the high photosynthetic activity contributed to maintain the grain mass, although the number of full grains decreased and the number of vain grains increased (these two variables were the main causes of yield decrease) ( Table 1 ). It is likely that during photosynthesis, under some stressing condition, an important proportion of photoasimilates is used for the synthesis of secondary metabolites, used for plant protection, ( Shirdelmoghanloo et al, 2016 ). Also, during plants exposure to adverse conditions, the macromolecules are degraded to their monomeric bases for osmoregulation and starch remobilization ( Chandra et al, 2017 ).…”

Metabolic Reprogramming in Chloroplasts under Heat Stress in Plants

“…Short heat waves during grain filling can reduce grain size and consequently yield in wheat ( Triticum aestivum L.). The four susceptible varieties of wheat showed greater heat-triggered reductions in final grain weight, grain filling duration and chlorophyll contents in flag leaves under heat stress, suggesting that grain size effects of heat may be driven by premature senescence [ 69 , 70 ].…”

Global warming is reducing the tillering capacity and grain yield of wheat in Yaqui Valley, Mexico

“…Warming stresses may cause a grain yield reduction through a reduction of spike number per m 2 (Shirdelmoghanloo et al, 2016) and an increase of non-viable pollen production, which makes grain formation difficult (Siebers et al, 2017). Currently, increased seed densities are used to overcome the temperature effect on tillering capacity reductions in a productive manner in agronomic practices (Lazzaro et al, 2018), which greatly increase seeding costs (Chandra et al, 2017).…”