Temperature Effect On Coleoptile Length in Tall and Semidwarf Wheat.

Coleoptile length of wheat is critical for its seed emergence and stand establishment. In general, coleoptile length is positively correlated with plant height. But coleoptile length is also affected by environmental factors such as temperature. Coleoptile length for five varieties, two tall ones and three semidwarf ones, were studied under a range of temperatures, from 4 to 30⁰C. The experiment was conducted in both growth chamber and field. Our growth chamber results showed that coleoptile length was getting longer under lower temperature. However, the coleoptile reached its full length at 18⁰C for the tall varieties and at 4⁰C for the semidwarf varieties. At high temperature (18⁰C and over), tall varieties had longer coleoptile than the semidwarf ones. But, semidwarf varieties had similar or even longer coleoptile than the tall varieties at low temperature (4 or 11⁰C). This resulted was confirmed with our field experiment. Our results indicate that those semidwarf varieties with short coleoptile length could also be planted as deep as the tall varieties if they are planted in the late fall.