Effect Of Planting Seedlings And Nitrogen Levels On Canopy And Yield Of High Yielding Japonica Rice Varieties

Rice is the most important crop in the world which provides food and nutrition for more than 50 percent of the world's population,and it is very relevant to world food security.Rice also is one of the most important crops in China.Our country is a big world in producing and consuming rice.The area of rice accounts for 30%of the total area of food crops,and the yield of rice accounts for more than 40%of total yield.There are more than 50 percent people eating rice as the staple food.According to some scholars' predict that the production of rice must increase by 14%to meet the growing needs of population by 2030 in China.Because of the progress of urbanization and the change of environment,the rice planting area has basically reached saturation.How to produce more rice on existing arable land?There are only two ways,one is to research higher yield potential varieties,another is to improve cultivation measures.Japonica rice is one of the main cultivated rice.Although the planting area of Japonica rice only account for 25%,almost all of the Japonica rice is consumed as ration,because the rice's quality is better.In recent years,there are many people having made a lot research in Japonica rice and having produced many varieties,including some good varieties,but these varieties didn't play high yielding potential since these cultivation measures adjusting to those varieties are lacking.In order to investigate the effect of different planting seedlings on physiological characters of rice population and rice individual and yield,we chose some high yielding Japonica rice varieties as the experimental material.On this basis,we chose two high yield varieties responding to different planting densities,treating with different planting densities and different nitrogen level,to investigate the effect of different treatments on yield and physiological basic of experimental rice.This aim is to provide theory for high yielding cultivation of high yielding rice of Jiangsu province.The main results are as follows:1.At the condition of field,four high yielding rice(Nanjing4'5 Nanjing49,Nanjing 94140 and Huaidao 5)were selected as the test material,setting four different densities which are 2,3,4,5 seedlings per hill,managing with normal water and fertilizer.The study found Nanjing 49 and Huaidao 5 could achieve higher yield at 2 to 4 seedlings per hill,and the yield at 5seedlings per hill deceased markedly,the yield of Nanjing 45 and Nanjing 94140 didn't show significant difference at different planting seedlings.Nanjing 49 could achieve higher yield at lower planting seedlings,because the plant have more spikelet per panicle,larger leaf base angle,higher Fv/Fm,more dry matter after flowering at lower planting seedlings;Huaidao 5 could achieve higher yield at 2 to 4 seedlings per hill,because the plant have more effective panicle,more spikelet per panicle,larger leaf area at late of growth,higher Fv/Fm,more dry matter after flowering at lower planting seedlings.2.To investigate the modest cultivation measures further,at the condition of experimental materials(Nanjing 49 and Huaidao 5)seeding in basin,we set two different planting densities in a hill(2 and 5 seedlings per hill)and two different nitrogen level(MN and HN).The results showed that the yield of Nanjing 49 didn't show significant differences at different treatments,the yield of Huaidao 5 at 2-MN is the lowest and no significant differences at other treatments.Increasing the amount of nitrogen could improve chlorophyll content,the activity of carbon and nitrogen metabolism enzyme,the capacity of photosynthesis,but didn't improve yield effectively.So Nanjing 49 treated with 2-MN and Huaidao 5 treated with 2-HN is better.In summary,in the basis of breeding high yielding varieties,to consummate cultivation measure adjusting to high yielding variety is one of the most important methods to play high yielding potential.In the cultivation of high yielding varieties in the future,improving the ability of products of photosynthesis translating to yield,the method of great variety with great cultivation measure could promise to produce more yield.