Different Kinds Of Cassavas Starch Accumulation Research On Physiological Ang Biochemical Characteristics

Cassava, whose roots are rich in starch, is one of the world’s three tuberous crops. Studying on the mechanism of starch accumulation in cassava’s tuberous roots plays an important role in obtaining cassava germplasm with high yield and starch. This research has been made in five cassava cultivars with different starch contents as experimental materials, Southern China 124(SC124), Fuxuan 01(FX01), Kasetsart 50(Ku50), Argentina 7(C4), Xinxuan 048 respectively. Five cassava varieties are studied in four key growth stage (seedling stage, formation, root bulking and root maturity) under the field conditions. Research contents include photosynthetic physiological parameters, fluorescence kinetics, light compound contract respectively content differences in leaf, stem cortex, root and starch degradation enzyme and enzyme activity related enzymes etc. We hope to clarify the cassava starch accumulation of efficient mechanism through the analysis of physiological and biochemical characteristics in leaf, stem and root under the field conditions. According to the results, we found all five cultivars represent "midday depression" phenomenon. High starch varieties is higher than low starch varieties in net photosynthetic rate. The photochemical efficiency of Fv/Fm under light adaptation and Pn and starch content positively related. Chlorophyll content was an important indicator of cassava’s photosynthetic intensity and the decrease of chlorophyll content directly led to low photosynthetic capacity. Chlorophyll content and the accumulation of starch positively related. Soluble total sugar and starch content in cassava root showed a negative correlation relationship, stems and leaves of soluble sugar and starch content positively related. The starch degradation of Cassava negatively related to enzyme activity and starch content, the activity of AGPase, SuSy in the root and activity of SPS in the leaf and starch content positively related. The order of tuberous root starch content in the stage of root maturity from high to low successively was Ku50, FX01, Xinxuan048, C4 and SC124. We did comparative research on the high and low starchy cassava cultivars in physiological and biochemical aspects and tried to provide a new theoretical basis for the mechanism of starch accumulation with high efficiency in cassava’s tuberous roots and new cultivars’breeding.