Relationship Between Physiological Heterosis of Root and Shoot System of Hybrid Rice Shan—You 6

Lu Dingzi (Zhejiang Academy of Agricultural Sciences)  

Hybrid rice Shan-You 6 when grown as second crop followed the first rice crop showed superiority over its parental three lines and the conventional rice cultivars in root growth rate,nitrogen uptake and capacity to synthesize amino acids and root activity. Growth vigor of root system occurred at seed germination.α-amylase in the endosperm of the dry seed is the important physiological basis of high diastase activity at early germination,resulting in seedling growth vigor. The hybrid displayed its nitrogen uptake vigor in term of nitrogen uptake rate per plant.Nutrient uptake and dry matter production are closely related. The 31 kinds of free amino acids were separated from the bleeding sap of the hybrid rice,but the kinds and concentration of free amino acids were restricted by nutrition condition of shoot system. The root activity during the mid and late growth stages would be depressed due to nitrogen deficiency and poor aeration.Adequate nitrogen supply and improved aeration by irrigation management were effective to keep the root activity from antimely decline,thus protecting the leaves from pre-mature senescence.Moreover,the early diagnostic indices of heterosis and the indices in forecasting the rice yield are discussed.

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