Abstract
BackgroundShort episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.). Two independent experiments were conducted to quantify the effects of HT during anthesis and grain filling periods on photosynthesis, leaf lipidome, and yield traits in wheat. In experiment I, wheat genotype Seri82 was exposed to optimum temperature (OT; 22/14 °C; day/night) or HT (32/22 °C) for 14 d during anthesis stage. In experiment II, the plants were exposed to OT or HT for 14 d during the grain filling stage. During the HT stress, chlorophyll index, thylakoid membrane damage, stomatal conductance, photosynthetic rate and leaf lipid composition were measured. At maturity, grain yield and its components were quantified.ResultsHT stress during anthesis or grain filling stage decreased photosynthetic rate (17 and 25%, respectively) and grain yield plant− 1 (29 and 44%, respectively), and increased thylakoid membrane damage (61 and 68%, respectively) compared to their respective control (OT). HT stress during anthesis or grain filling stage increased the molar percentage of less unsaturated lipid species [36:5- monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG)]. However, at grain filling stage, HT stress decreased the molar percentage of more unsaturated lipid species (36:6- MGDG and DGDG). There was a significant positive relationship between photosynthetic rate and grain yield plant− 1, and a negative relationship between thylakoid membrane damage and photosynthetic rate.ConclusionsThe study suggests that maintaining thylakoid membrane stability, and seed-set per cent and individual grain weight under HT stress can improve the photosynthetic rate and grain yield, respectively.
Highlights
Short episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.)
The maximum fluorescence yield (Fm; relative units) and photosynthetic rate decreased by 12 and 17%, respectively due to HT stress compared to optimum temperature (OT) (Fig. 1e and k)
Significant (P ≤ 0.05) increase in the molar percentage of less unsaturated lipid species containing two polyunsaturated acyl chains such as 36:5- (18:2/18:3 combination) MGDG and digalactosyldiacylgylcerol (DGDG) species was observed due to HT stress compared to OT (Fig. 3a, b)
Summary
Short episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.). Two independent experiments were conducted to quantify the effects of HT during anthesis and grain filling periods on photosynthesis, leaf lipidome, and yield traits in wheat. Research indicates that most of the wheat-growing regions of the world are experiencing episodes of above-optimum temperatures leading to a significant decrease in grain yield [1,2,3,4]. If the occurrence of HT coincides with sensitive stages of wheat, it will cause significant negative impacts on grain yield. Barkley et al [2] have shown that 1 °C increase in projected temperature during reproductive stages could decrease grain yield by 21%. It is important to breed HT tolerant genotypes to sustain wheat production
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