The effects of terminal heat stress on pollen and ability of seed setting in barley genotypes (Hordeum vulgare L.)

In this research, the effects of different temperatures treatments including (25 (control), 30, 35, 40 and 50 0C) on pollen germination, pollen tube growth, and pollen morphology were investigated in vitro, and also the effect of late sowing date as heat stress on the number of pollen, also yield and yield components of 10 barley genotype was evaluated in field condition. At 50 0C this decrease was 72 and 60% for germination and length of pollen tube on average. High temperature significantly decreased pollen germination and pollen tube length in all genotypes. Genotypes showed different responses to temperature treatments, indicating different levels of tolerance among genotypes. In vitro, genotypes were divided into three groups according to the TSRI index as tolerant (Jounob, Reyhan 03, Zehak, Nosrat, Khoram), semi-sensitive (Yousef, Izeh, and Mahour) and sensitive (Abidar and Nimrooz) genotypes. Heat stress influenced pollen morphological aberrations, so that high temperature was removed the ornamentation of axin surface. Heat stress led to a decrease in the number of pollen grains per spike (90 %), yield and yield components (40%). These approaches showed that pollen performance may provide useful information to facilitate the investigation of heat-tolerant genotypes in breeding programs suitable for warm climates.