Responses Of The Double-Cropping Rice Population Growth And Nitrogen Uptake To Density And Nitrogen Management And The Diagnosis Based On NDVI

These experiments was carried out to study the effects of different density, nitrogen fertilizer and their interaction on population growth, grain yield, nitrogen uptake and utilization of double-cropping rice (conventional varieties) at Yingtan City, Jiangxi Province. The monitoring model between canopy NDVI and LAI, dry matter accumulation, plant nitrogen uptake was developed using the data of experiment with different nitrogen and years, and the models were tested using independent experiment data of 3 years. The main conclusions were as followed:1. The effects of different density on population growth, nitrogen uptake and utilization of early and late riceWith the density decreasing, the population tiller number, LAI and dry matter accumulation at different growth stages of early and late rice decreased significantly, plant nitrogen uptake at different growth stages of early rice increased gradually, while late rice first increased then decreased, the nitrogen use efficiency of early and late rice both first increased then decreased. Under low density, the tiller number, LAI and dry matter accumulation of wide row and short space treatment lower than the same row and space treatment, and under the high density the trend is inversed. Under the same basic seedling, the tiller number, LAI and dry matter accumulation at different growth stages of early and late rice decreased significantly when more less transplanting pits and more planting seedling number per pits. The highest grain yield of early and late rice appeared at the planting spacing of 10.0 cm×26.7 cm treatments.2. The effects of different nitrogen fertilizer on population growth, nitrogen uptake and utilization of early and late ricePopulation tiller number, LAI and dry matter accumulation at different growth stages of early and late rice were increasing with nitrogen rate increasing. Under the low nitrogen levels, the increase of basal nitrogen ratio decreased the plant nitrogen uptake and nitrogen use efficiency of early rice, and first increased then decreased with the increasing of basal nitrogen ratio when nitrogen content was higher. With the nitrogen rate increasing, plant nitrogen uptake of late rice increased, nitrogen translocation efficiency (NTE), physiological efficiency (NPE), agronomic efficiency (NAE), recovery efficiency (NRE), and partial factor productivity of applied nitrogen (PEP) were decreasing, with basal fertilizer increased, recovery efficiency (NRE), and partial factor productivity of applied nitrogen (PEP) were decreased significantly, but the nitrogen translocation efficiency (NTE), physiological efficiency (NPE) have no significant difference.Nitrogen fertilizer were significantly curve correlated with the early rice grain yield, the treatment with the highest grain yield, were 180 kg/hm2 nitrogen level, and the ratio of basal, tiller and panicle was 33:42:25, and the optimum nitrogen rate of late rice was 180 kg/hm2, the ratio of basal and panicle nitrogen was 6:4.3. The effects of different nitrogen fertilizer and density on population growth, nitrogen uptake and utilization of early and late riceDifferent density has different optimum nitrogen fertilizer, in the early growth period of double-cropping rice, the increase of nitrogen rate increased the tiller number, LAI and dry matter accumulation while treated in the same density, but first increased then decreased after the jointing stages. In the same density, plant nitrogen uptake of early rice increased with the nitrogen increased, but late rice were increased in the low density treatment, first increasing then decreasing in higher density. At the planting spacing of 13.3 cm×30.0 cm treatments, the grain yield of early and late rice were the highest, and the nitrogen rate were 195 kg/hm2,165 kg/hm2 respectively.4. The models of growth condition monitoring and nitrogen nutrition diagnosis of double-cropping rice based on canopy NDVIAnalysis the relationship between canopy NDVI and LAI, plant dry matter accumulation and nitrogen uptake using the data of 3 years field experiment with different nitrogen treatments. The results shows that canopy NDVI was highly significant linear correlated with LAI, plant dry matter and nitrogen uptake of early rice at tillering stage, and was highly significant index correlated at jointing and full heading stages. At the tillering stage, the canopy NDVI was highly significant linear correlated with LAI, and was highly significant index correlated at jointing and full heading stages, and canopy NDVI was highly significant index correlated with plant dry matter accumulation and nitrogen uptake at different growth stages. And the author establishments 18 monitoring models tested those models using 6 independent experiment data, the tested results shows that those monitoring models forecasts better.