Effects of Plant Spacing on Grain Yield and Population Quality in Mechanically-transplanted Rice with Good Tasting Quality

【Objective】The mechanical transplanting density plays an important role in grain yield and quality in rice. However, the effects of plant spacing on grain yield and population quality of mechanically transplanted rice with good tasting have not been clearly understood. Clarifying the optimal plant spacing for good tasting rice could lay a theoretical and practical basis for high yielding and good quality in mechanical cultivation.【Method】In this experiment, three rice cultivars with good tasting quality (Nanjing 9108, Nanjing 5055 and Nanjing 46) in Jiangsu Province were used as materials, and the effects of plant spacing (10 cm, 12 cm, 14 cm, 16 cm and 18 cm) on their grain yield and population quality were investigated under mechanical transplanting when the row spacing was fixed at 30 cm.【Result】Productive tillers rate, high efficient leaf area index, grain leaf ratio (grain weight/leaf area), canopy net photosynthetic rate after heading and dry matter accumulation from heading to maturity were the highest under the plant spacing of 12 cm in above three rice cultivars. Grain yields tended to increase at first and then decrease with the increase of the plant spacing, and the relationship of quadric curve was found between grain yield and plant spacing. The optimal plant spacing for grain yield in Nanjing 9108, Nanjing 5055 and Nanjing 46 ranged from 11.6 cm, 11.6－12.3 cm and 10.8－11.4 cm in two years according to the curve equation, respectively. 【Conclusion】When the row spacing was fixed at 30 cm, the plant spacing of 11－12 cm was helpful to improve the population quality and increase grain yield, and it could be used as the optimal plant spacing for the typical rice cultivars with good tasting in Jiangsu Province under mechanical transplanting.