Effects of Drought Stress on Pollen Sterility, Grain Yield, Abscisic Acid and Protective Enzymes in Two Winter Wheat Cultivars

Abstract

Drought stress induced pollen sterility is a detrimental factor reducing grain number in wheat. Exploring the mechanisms underlying pollen fertility under drought conditions could assist breeding high-yielding wheat cultivars with stress tolerance. Here, by using two Chinese wheat cultivars subjected to different levels of polyethylene glycol (PEG)-induced drought stress, possible links between pollen fertility and stress tolerance were analyzed under different levels of drought stress at the young microspore stage. In both cultivars, higher grain number reduction was observed under condition of lower water availability. Overall, the drought tolerant cultivar (Jinmai47) exhibited less grain number reduction than the drought sensitive cultivar (Shiluan02-1) under all stress conditions. Compared with Shiluan02-1, Jinmai47 exhibited superior physiological performance in terms of leaf photosynthetic rate, ear carbohydrate accumulation, pollen sink strength, pollen development and fertility under stress. Moreover, Jinmai47 showed a lower increase in endogenous abscisic acid in ears than Shiluan02-1. Furthermore, higher levels of superoxide dismutase (SOD) and peroxidase (POD) activities were also found in the drought tolerant cultivar Jinmai47 under PEG stress, compared with the drought sensitive cultivar Shiluan02-1. Changes in these physiological traits could contribute to better pollen development and male fertility, ultimately leading to the maintenance of grain number under drought stress.

Effects of Shading Stress on Grain Number, Yield, and Photosynthesis during Early Reproductive Growth in Wheat

“…We found that shading stress at preanthesis significantly decreased grain number, which was consistent with previous reports (Fischer and Stockman, 1980). However, a key factor controlling grain number is related to pollen development during the YM stage (Dong et al, 2017). Previously, it has been reported that drought and cold stress at this stage seriously reduced grain number in crops (Thakur et al, 2010;Liu et al, 2015a).…”

“…However, a key factor controlling grain number is related to pollen development during the YM stage (Dong et al, 2017). These results confirm that the YM stage is the most sensitive stage with regard to grain number determination in plants subjected to shading stress (Dong et al, 2017;Ji et al, 2017). In this study, shading stress during the YM stage significantly reduced grain number of the main stem.…”

“…Especially in Kenong9204, grain number of the main stem was reduced by >60% even in the 2-d shading groups, and no ear formation was observed at all in the 6-d shading groups. These results confirm that the YM stage is the most sensitive stage with regard to grain number determination in plants subjected to shading stress (Dong et al, 2017;Ji et al, 2017). The reduction of grain number resulting from shading at preanthesis is due to a higher spikelet sterility rate (Acreche et al, 2009;Gu et al, 2017).…”

“…Wheat yield is determined by three major components, including ear number, grain number per ear, and grain weight, with grain number being the key target for improving grain yield (Fischer, 2011;Slafer et al, 2014). However, a key factor controlling grain number is related to pollen development during the YM stage (Dong et al, 2017). However, a key factor controlling grain number is related to pollen development during the YM stage (Dong et al, 2017).…”

Optimizing irrigation and determining the most sensitive development stage to drought in barley (Hordeum vulgare L.) in a semi-arid environment

“…It should be noted that the same decrease in leaf water potential and in grain yield was recorded during the heading stage (50%) underwater deficit. These reductions could be explained by sterile pollen or decreased pollen numbers reducing the final grain number per ear (Fahad et al 2017, Honsdorf et al 2017, or by the high accumulation of abscisic acid in the ear (Dong et al 2017). According to- Dong et al (2014), water deficit induces pollen sterility and, consequently, reduces the number of grains.…”