Studies On The Effects Of Different Cultivation Patterns On The Growth And Yield Of Double Cropping Rice

Rice is an important food crops in China.With decrease in land area,great yield increase in double-cropping rice was necessary to ensure food security.There were large gaps between rice yield potential and the actual rice yield under the super high-yielding cultivation patterns.Field experiments were conducted to examine the yield expression of double cropping rice under different cultivation patterns in Dajin town,Wuxue City from 2005 to 2007.The results show as follows:1.The yields of double cropping rice under high-yielding cultivation patterns were significantly higher than that under conventional cultivation pattern.The high-yielding cultivation pattern integrated servel high yielding cultivation technologies,such as combinant of early rice variety with late maturity and late rice with late maturity,drainage nursery management,border check,site-specific nutrient management and dry nursery.The yields of double cropping rice under high-yielding cultivation patterns were 17.54～20.41 t/ha during 2005-2007,the average grain yield was 19.18 t/ha per year.However,the grain yields of double cropping rice under conventional cultivation pattern were 11.82～14.26 t/ha,with the average grain yield of 12.83 t/ha per year.Averagely,grain yield under high-yielding cultivation pattern increased by 6.35 t/ha in comparison with that under conventional cultivation pattern.The yield of early rice was increased by 56%and of late rice by 44%by high-yielding cultivation pattern.Among yield components,the panicle number and spikelets per panicle under high-yielding cultivation pattern were significantly higher than those under conventional cultivation pattern.In addition,there were significant differences in grain yield among different seedling raising methods and among plant seedling ages.Grain yield of dry -raised seedlings is significantly higher than that of water-raised seedlings under the same seedling age. Besides,30 day-old seedlings yielded more than 45 day-old seedlings. 2.Aboveground biomass,tiller number per m²,and plant height at different growth stages were significantly higher under high-yielding cultivation pattern than conventional cultivation pattern.In addition,biomass at maturity stage under high-yielding cultivation pattern was significantly higher than that under conventional cultivation pattern.The total biomass of rice plant under dry nursery was significantly higher than that under water soaked nursery.3.At early stage,there was no difference in leaf photosynthetic rate between the two cultivation patterns.However,at late stage,the leaf photosynthetic rate was significantly higher under high-yielding cultivation pattern than under conventional cultivation pattern, as well as leaf area index,N accumulation.These may be the physiological basis for the higher grain yield under high-yielding cultivation pattern.4.There were significant differences in leaf-related traits at full heading stage among different cultivation patterns.The length,width,and area of flag leaf and the 2^nd leaf were higher under high-yielding cultivation pattern than under conventional cultivation pattern. However,the length,width,and area of the 5^th leaf were lower under high-yielding cultivation pattern than under conventional cultivation pattern.Under high-yielding cultivation pattern,the order in leaf length was 2-3-1-4-5,while the order was 2-3-4-5-1 under conventional cultivation pattern.5.In comparison with conventional cultivation pattern,the yields of three simplified high-yielding cultivation patterns were higher.Among yield components,panicle number and spikelets per m² were significantly higher under high-yielding cultivation patterns than under conventional cultivation pattern,as well as the leaf area index at full heading stage and biomass production at maturity stage.