| Rice is one of the most important and popula crops in the world. Heilongjiang province is the largest Japonica rice producing area in China, and it has extremely important status for the national food security. However, the chilling injury frequently occurrenced in Heilongjiang province as it is in cold rice region. And the chilling injury has serious impacts on the formation of rice yield. Nitrogen is one of the essential nutrients for crop growth and development.It plays a very important role in agricultural production and it is also one of the basic agronomic measures to increase the yield of rice. Now, the effects of nitrogen fertilizer on the growth characteristics and yield formation of rice under low temperature stress has less reasearch.In order to understand the effects of nitrogen application on the characteristics of growth, the dry matter accumulation and transportation aboveground, yield and quality in Japonica rice under cold water stress at tillering stage, Dongnong428, Longdao7 and Songjing10 were used as materials. The Japonica rice was subjected to 7 nitrogen application treatments. The purpose of this experiment was to provide the scientific and rational theory of nitrogen application and reducing the chilling injury for Japonica rice. The main conclusions are as follows:(1) The plant heihgt, the tiller number, the growth rate of the plant heihgt and the tiller, the maximum tiller number, the leaf area index, the effective leaf area rate and the efficient leaf area rate of heading stage decreased under cold water stress during the tillering stage. The extent of decline for the cold-resistant variety Dongnong428 was less than the cold-weak variety Songjing10, Longdao7 was bewteen them. With the increase of nitrogen application under cold water stress during the tillering stage, the growth rate of the plant heihgt and tiller accelerated, the maximum tiller number and the leaf area index increased, the plant height and tillering stage delayed, the effective tiller rate decreased, the effective leaf area rate and the efficient leaf area rate reduced.(2) The of dry matter accumulation aboveground, the rate of dry matter accumulation aboveground, the DMTBA, the DMAAA, the EPMSS and the TPMSS decreased under cold water stress during the tillering stage. The extent of decline for the cold-resistant variety Dongnong428 was less than the cold-weak variety Songjing10, Longdao7 was bewteen them. With the increase of nitrogen application under cold water stress during the tillering stage, the dry matter accumulationaboveground of different stage accelerated, the dry accumulation of stem and leaf increased and the dry accumulation of paricle decreased between heading stage and mature stage.The rate of dry matter accumulation aboveground between heading stage and mature stage, the DMTBA, the DMAAA, the EPMSS and the TPMSS was close to the control under the 100kg·hm-2 nitrogen application, which was significant difference between other theatments.(3) The initial growth potential, the maximum grain filling rate, the mean grain filling rate decreased, the grain filling peak and the grain filling time delayed under cold water stress during the tillering stage. The extent of decline for the cold-resistant variety Dongnong428 was less than the cold-weak variety Songjing10, Longdao7 was bewteen them. With the increase of nitrogen application under cold water stress during the tillering stage, the initial growth potential, the maximum grain filling rate and the mean grain filling rate decreased, the grain filling peak and the grain filling time delayed.(4) The effective tiller number, spike number, kernel number, 1000-grain weight, seed setting rote and yield decreased under cold water stress during the tillering stage. The extent of decline for the cold-resistant variety Dongnong428 was less than the cold-weak variety Songjing10, Longdao7 was bewteen them. With the increase of nitrogen application under cold water stress during the tillering stage, he effective tiller rate 1000-grain weight and seed setting rate decreased. The spike number, kernel number, yield and the CRI value of yield was close to the control under the 100kg·hm-2 nitrogen application, which could significantly reduce the loss of yield under cold water stress at the tillering stage.(5) The brown rice rate, the milled rice rate and the head rice rate decreased, the grain aspect ratio decreased, the percentage of chalky grain and the chalkiness accelerated, the amylose content rised and the gel consistency decreased under cold water stress during the tillering stage.The change of decline for the cold-resistant variety Dongnong428 was less than the cold-weak variety Songjing10, Longdao7 was bewteen them. With the increase of nitrogen application under cold water stress during the tillering stage, The brown rice rate, the milled rice rate and the head rice rate decreased, the grain aspect ratio, the percentage of chalky grain and the chalkiness accelerated, the amylose content rised and the gel consistency decreased.(6) The ffective tiller rate, the effective leaf area rate and the efficient leaf area rate of heading stage, the DMTBA, the DMAAA, the effective tiller number, the spike number, the kernel number, the 1000-grain weight, the seed setting rote were signicantly or highly significantly negative correlated with yield under cold water stress during the tillering stage.(7) The most optimal quality of Japonica Rice is at 75kg·hm-2 nitrogen application under cold water stress during the tillering stage. The most optimal yield of Japonica Rice is at 100kg·hm-2 nitrogen application under cold water stress during the tillering stage, and it had significant difference with other treatments. The quality of 100kg·hm-2 was just worse than the 75kg·hm-2 nitrogen application, but there was not significant difference between them. So comparisoned with the performance of the yield and quality, the 100kg·hm-2 nitrogen fertilizer was the most benefit to alleviate the loss of the yield and quality under the cold water stress in tillering stage. |
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