Effect of Low Temperature on Some Physiological Indices of Root System of Different Cold Sensitive Sugarcane Varieties

In order to study the effect of low temperature on some physiologic indices of sugarcane root system, two sugarcane varieties GT28（cold resistant) and YL6（cold sensitive) with 9 to 10 leaves were put into 0 ℃ biotron and the sugarcane root system samples were taken after 0, 2, 4 and 6 d respectively to determine the root activity, conductivity percentage, Ca²⁺-ATPase activity, MDA and proline content. The results were as follows: After low temperature stress, the root activity of two sugarcane varieties decreased with the extension of time, the root activity of GT28 was higher than that of YL6. After low temperature stress, the conductivity percentage of two sugarcane varieties increased with the extension of time, the conductivity percentage of YL6 was higher than that of GT28. Under low temperature stress, the proline content and MDA content of two sugarcane varieties increaed markedly with the extension of time, the MDA content of YL6 was higher than that of GT28, and the proline content of GT28 was higher than that of YL6. The Ca²⁺-ATPase activity of GT28 increased at first, then decreased, and the Ca²⁺-ATPase activity of YL6 decreased gradually all the time, the Ca²⁺-ATPase activity of GT28 was higher than that of YL6. It might be concluded that under the similar chilly stress, the chilly resistance cultivar could retain a higher root activity, Ca²⁺-ATPase activity, and proline content.