Effect Of Mechanical-Transplanting Density On Yield And Lodging Resistance In Different Types Of Rice

The field experiment was conducted in the experimental farm of Yangzhou University in 2013-2014. Using Indica-Japonica hybrid rice Yongyou 2640, Yongyou 1640, Indica hybrid rice Fengliang youxiang 1, Xinliangyou 6380, conventional Japonica rice Nanjing 9108, Wuyunjing 24 which have been widely grown in the southern China as materials, setting six planting densities. On this basis, we studied the effect of planting densities on the rice yield and its components, photosynthetic material production, lodging resistance and the content of chemical components of stalk. All of these are aimed to find a proper planting density in different type of rice.The main results are as follows.1. The effect of transplanting density on rice yield and its structure was different because of variety types. The yield of Indica-Japonica hybrid rice and Indica hybrid rice were highest in treatment of D. The yield of D was 6.99% and 9.85% higher than A and F. The yield of conventional Japonica rice was highest in treatment of E. The yield of E was 22.63% and 4.2% higher than A and F. The spike number of same variety decreased as the reduction of density, and the grain number per spike presented opposite trend. The different transplanting densities have less effect on 1000-grain weight and seed setting rate, and no significant difference between different teatments.2.With the increasing of transplanting densities, the dry matter weight of jointing stage increased, and the dry matter weight of heading stage and maturity increased firstly and then decreased. From jointing stage to heading stage, the leaf area duration increased, the net assimilation rate decreased and the crop growth rate increased firstly and then decreased. From heading stage to maturity, both the leaf area duration and crop growth rate increased firstly and then decreased, the net assimilation rate decreased. The amount of dry matter accumulation of Indica-Japonica hybrid rice and Indica hybrid rice were highest at 13.9 cm×30.0 cm. And the amount of dry matter accumulation of conventional Japonica rice was highest at 11.7cm×30.0 cm.3. With the increasing of transplanting densities, lodging index of three types of rice increased, and stem diameter, plumpness of the internode and dry weight of a unit internode in three types of rice decreased. The difference of lodging resistance exsisted in different types of rice. Apparent lodging rate, lodging index, plant height, and height of central gravity showed the trend of conventional Japonica rice<Indica-Japonica hybrid rice<Indica hybrid rice. Plumpness of the internode at 30 d after heading showed Indica-Japonica hybrid rice>Indica hybrid rice> conventional Japonica rice.4.With the increasing of transplanting densities, SiO2 content, K content and starch content of stalk showed decreasing trend. At heading stage, soluble sugar content of stalk increased with the increasing of transplanting densities. But at 30d after heading and maturity, with the increasing of transplanting densities, soluble sugar content of stalk decreased. The difference of chemical composition content exsisted in different types of rice. SiO2 content, soluble sugar content of stalk and starch content of stalk showed conventional Japonica rice> Indica-Japonica hybrid rice> Indica hybrid rice. K content showed Indica-Japonica hybrid rice> conventional Japonica rice>Indica hybrid rice.