Abstract:

Cassava is a starch crop, its root tuber is main economic product. How to increase starch content in the root tuber is a very important problem in cassava breeding and cultivation. The characters of anti-senility physiology and starch accumulation of six different cassava cultivars Xinxuan056, SC201, GR891, Fuxuan01, SC124, and Xinxuan048 were studied during the late growing period in this experiment. The result showed that the leaf and stem growth function of SC124 was most vigorous while that of SC201 was most feeble and that of Xinxuan056, GR891, Fuxuan01, and Xinxuan048 was on the suit level in the late growing period. The soluble sugar content, the peroxidase activity, the MDA content in the leaves and the starch accumulation in the root tubers of SC124 were the lowest. The soluble sugar content in the leaves and the starch accumulation in the root tubers of GR891 were higher than those in other cultivars. The MDA content in the leaves and the numbers of leaf abscission of SC201 were the highest and its starch accumulation in the root tubers was lower than that of other cultivars except SC124. The effect of leaf and stem growth in the late growing period on the starch accumulation in the root tubers of cassava was obvious. Not only the root tuber yield but also the starch accumulation in the root tubers obviously decreased if the leaves and stems senesced in the early stage of root tuber formation. But if the leaves and stems grew too vigorously, which hindered carbohydrate transferring from the leaves and stems to the root tubers in the middle or late root tuber formation stage, the yield of root tuber and the starch accumulation in the root tubers decreased. It is important to control the leaf and stem growth on a proper level in the middle or late stage of cassava root tuber formation. Meanwhile the characters of anti-senility physiology and starch accumulation can be used as the index as of selection in high starch content cultiars breeding of cassava.

Key words: Cassava, Variety, Anti-senility physiology, Starch accumulation