Effect Of Different Cultivation Measures On Yield And Quality In Direct Seeding Rice

Effects of different cultivation measures (sowing date, densities, fertilizer management and water management) on the grain yield and quality of direct seeding japonica rice were studied. In this research, we explore the culture technique of high yield and fine quality, and so as to provide the theoretical and practical references for safe and high efficiency production of direct seeding rice. The experiments were carried out at the Experimental Farm of Lixiahe Agricultural Research Institute of Jiangsu Province during 2007-2009, the main results were as follows:1. Effect of sowing date on grain yield and rice quality of direct seeding rice With the delay of sowing date, the days of all growth stage and the days from sowing to heading of all varieties were significantly shorted, but the filling stage was stable; With the delay of sowing date, the leaf emergence rate was rised, the total number of main stem leaves and the grain field were decreased overall, the decline of grain field was mainly due to the decline of setting percentage and thousand-kernel weight; the brown rice rate,milled rice rate and head milled rice of rice decreased, chalkykernel, chalkiness, the amylose content and protein content were increased, while gel consistency decreased.2. Effect of Different Densities on yield and Quality in Direct Seeding Rice In the density limits of 75-120×104 plant/hm2, the yield increased as direct seeding density increased , but with planting density continuous increasing, the yield decreased. In the density limits of 75-120×104 plant/hm2, there were no significant difference between treatments in the the percentage of brown rice, milled rice and head milled rice, and with planting density continuous increasing, processing quality become poor. In the density limits of 75-165×104 plant/hm2, with direct seeding density increased, the chalkiness rate and degree increased, gel consistency decreased and protein content increased, and the cooking and eating quality became poor. 3. Effect of fertilizer management on yield and rice quality of direct seeding riceBetween 0-450 kg/hm2 nitrogen fertilizing, with the N fertilizer application increased, the effective panicles increased, while the grains per panicle, setting percentage and 1000-grain weight were opposed. The yield increased with N fertilizer application increasing from 0 kg/hm2 to 270 kg/hm2, but decreased when N more than 270 kg/hm2. The yield under N fertilizer model [(basal fertilizer + tillering fertilizer): (head dressing)=6:4] was highest; increasing fertilizing of phosphate and potassium under applying the same nitrogen significantly enhanced grain yield. Under the nitrogen fertilizing of 270 kg/hm2 and the N fertilizer model [(basal fertilizer + tillering fertilizer): (head dressing)=6:4], the nutritional efficiency of N, biomass yield and economic coefficient were increased significantly, and then increased the rice yield. With the raise of N fertilizer application and panicle fertilizer application , the grain quality of direct seeding rice grain reduced.4. Effect of water management on yield and quality in direct seeding riceThe chlorophyll content and photosynthetic rate of the flag leaves declined more quickly as plants approaching maturity under moderate dry-wet alternate and severe dry-wet alternate irrigation than under well watered, it indicated that the water deficits enhanced senescence. Compared with moderate dry-wet alternate irrigation and severe dry-wet alternate irrigation, the remobilized C reserve and reallocation of pre-fixed 14C from stems to grains increased by 9.2 to 14.1% and 23 to 43% separately under well watered. The grain yield of moderate dry-wet alternate irrigation in both experiments was increased by 6.8 to 19.7%, but that of severe dry-wet alternate irrigation was reduced. The chalky rice rate and chalkiness of moderate dry-wet alternate irrigation were reduced, while increased the peak viscosity and breakdown values; in addition, the decreased hot viscosity, final viscosity and setback values were increased, but those of severe dry-wet alternate irrigation plants was opposed.