تاثير طول دوره آبگيري و پسابش بر بقاي گياهچه سه رقم گندم

Effects of hydration and dehydration period on coleoptiles, root growth, and seedling survival of 3 wheat cultivars after rehydration

Wheat ( Triticum aeslivum L.) seedlings may meet dehydration between seed imbibition and emergence, particular in dryland fanning. This laboratory experiment was conducted to study the effects of hydration and dehydration period lengths on the coleoptile and root growth, seedling survival, and their ability to resume growth (after rehydration) of 3 wheat cultivars. Golestan, Khans-I and Tajan seed cultivars were germinated for 4, 6 and 8 days in without drought stress condition. Then, seedlings were dehydrated for 2, 4 and 6 days and rehydrated. Number of normal seedling, lenghts of coleoptile and root, and dry weights of seed residues were measured after 7 days. Results showed that when seedlings were grown under suitable moisture conditions for 4 days or less (unpublished data) before dehydration, the length of dehydration periods had no effect on the number of normal seedlings after rehydration, but an increase in the time of dehydration resulted to decreas the coleoptile and root length of 3 cultivars. Dehydration reduced normal seedlings and root lenghts, significantly, when seedlings were placed under normal conditions before dehydration for 6 days or more. Reduction in coleoptile lenghts as affected by dehydration was singnificant only for the treatment 8 days growth under suitable moisture conditions before dehydration, Dehydration period length had no effect on dry weights of seed residues in treatment 4 days growth under suitable moisture conditions before dehydration, while when seedlings were grown under suitable conditions for 6 days, increasing dehydration time followed by significant increase in dry weights of seed residues. In 8 days growth under suitable conditions before dehydration, increasing dehydration period length caused significant increase in seed residues only in Golestan cultivar. These results demonstrate that dehydration tolerance reduces as wheat seedlings develop. On the other hand, the length of dehydration can be effective on the ability of regrowth after rehydration. So this ability decreases as the length dehydration period increases.