Short and long term effects of suboptimal temperature during germination stage on cultivars Sabalan,Omid,Bisotoon,Sardari, and Golghermez were studied. These varieties were exposed to 3,6,12,15,18,21 and 24+0.5 C. IN all varieties germination characteristics of seedling such as germination percentage ,time to 0% emergence, shoot and root length under 3,6,9 and 24 C were singnificantly affected. Thus in a seperate experiment, these treatments were applied durring germination and after vernalization of the seedlings, the seedlings were transfered to optimum temperature of 24 C. The vegetative and reproductive characteristics of the cultivars were compared.
Suboptimal temperature reduced germination percentage,Number of germinated seedling at 3 C were 12% lower than 24C. Time to 50% emergence at 3 was twice the 24C. Cultivar Golghermez germinated faster than other varieties. Non of the cultivars produced normal seedlings at temperatures lower than 2C.Low teperature retarded vegetative growth as well as time of appearance of spikes. It also shortened grain filling period as much as 7 to 10 days, depending on the variety. Yield of cultivars exposed to 3,6, and 9C during germination were reduced about 43, 35 and 27% respectively compared to 24C. In general, increasing temperature from 3 to 24C increased yield in all varieties.However,cultivars Omid and Sabalan responded better to higher temperature than others.
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