Temperature dependence of growth in maize seedlings and excised coleoptile segments

The effect of temperature in the range 22-32℃ and 25-40℃ on elongation growth of maize seedlings and coleoptiles excised from them was studied, respectively. It was found that elongation of maize seedling’s organs (root, mesocotyl and coleoptile) increased with increasing temperature in the range 22-32℃. However, when coleoptile segments excised from seedlings grown at highest temperature (32℃) were incubated at various temperatures (25, 30, 35, and 40℃) and in the presence of IAA their elongation growth was always lower compared to segments excised from seedlings grown at 22 and 27℃. Simultaneous measurements of elongation growth and external medium pH indicated that proton extrusion increased with increasing medium temperature from 25 to 35℃. The results presented here show that the temperatures at which the maize seedlings were cultivated are crucial for temperature dependence of a coleoptile segment’s elongation growth.