Abstract:

The experiment aims to clarify the effects of leaf-picking on the characteristics of the source and sink organs of cassava cultivars with different plant types. Using compact cultivars of 'SC205', 'GR4' and umbrella cultivars of 'SC12', 'SC15' as experiment materials, four leaf-picking treatments and non leaf-picking treatment were designed to study the differences in plant morphology, dry matter production, nitrogen accumulation and leaf nutrient quality. The results showed that with the number of source leaves decreased, the tuber yield per plant, dry matter production and nitrogen accumulation of mature plants decreased. The lower the number of source leaves in plant, the greater the leaf-picking ratio, the smaller the sink source ratio, the shorter the plant height, the thinner the stem diameter and the tuber diameter, and the shorter the tuber length. As the number of source leaves increased, the soluble total sugar content in the leaves showed an increasing trend, while the sucrose and total starch content in the leaves first increased and then decreased. As the leaf-picking stage progresses, the soluble total sugar and total starch content of the leaves increased, while the sucrose content decreased. Among different plant types, the content of soluble total sugar, sucrose and total starch in the leaves of compact cultivars was higher than that of umbrella cultivars. The number of source leaves retained by cassava plants is too small, the leaf removal ratio is large, resulting in a decrease in plant dry matter quality and nitrogen accumulation, the growth of plants and tubers will be restricted, and the yield of tubers will be decreased.

Key words: cassava, leaf-picking, plant type, source characteristics, sink features