Effect Of Nitrogen Application On Growth, Starch Accumulation, Rice Yield And Quality Of Cold-region Japonica Rice Under Salt Stress

Heilongjiang province is an important area for cold-region japonica rice in China, ranked first in the national rice production. Salt stress is one of the major abiotic stress factors restricting crop yield, and leads to reduce photosynthesis in rice, decline rice yield, quality degradated. Now it has seriously affected the stability of Chinese salt rice production. Nitrogen is one of the basic elements of cold-region japonica rice, and also one of the most sensitive factors affec ting the rice growth. Appropriate application of nitrogen fertilizer can increase rice yield and quality. Therefore, research on the formation mechanism of the aerial part dry matter, grain starch, rice yield and quality of cold-region japonica rice under salt stress not only has the great theoretical value, but also has important practical use. In this test, Longdao 5, Songjing 6 and Mudanjiang 30 were fieid-grown as material. In normal irrigation and salt stress setting six levels of nitrogen application(0 kg/ha,50 kg/ha, 100 kg/ha, 150 kg/ha, 200 kg/ha, 250 kg/ha), study on the influence of nitrogen application on growth, aerial part dry matter, starch accumulation, rice yield and quality of cold-region japonica rice under salt stress, to determine the theoretical basis for the Appropriate application of nitrogen fertilizer in salt damage areas. The main conclusions of this experiment are as follows:(1)Salt stress significantly inhibited the Plant height and tiller of rice. But as the nitrogen application increasing, there is an increasing number of plant height and each tiller number of rice. Compared with normal irrigation, the Plant height and tiller of Longdao 5 has been least affected, Mudanjiang 30 has been most affected, Songjing 6 was in between under salt stress.(2)Salt stress significantly decreased SPAD values of rice functional leaf, and there were significant differences among different varieties. But as the nitrogen application increasing, there is an increasing number of SPAD values of rice functional leaf. In normal irrigation and salt stress, it is a maximum for SPAD values of rice functional leaf of the three varieties at N250.(3)Salt stress significantly decreased the leaf area index, the high efficiency leaf area of heading period. But as the nitrogen application increasing, there is an increasing number of the leaf area index. In a certain range, the high efficiency leaf area of heading period increased with the increase of nitrogen application. In normal irrigation, it is a maximum f or the high efficiency leaf area of heading period of the three varieties at N150, and the maximum at N200 under salt stress.(4)Salt stress significantly decreased the aerial part dry matter accumulation, the export percentage and transport percentage of the matter in stem and sheath. There were significant differences among different varieties. The aerial part dry matter accumulation increased with the increase of nitrogen application.And in a certain range, the export percentage and transport percentage of the matter in stem and sheath increased with the increased of nitrogen application.(5)Salt stress significantly decreased ADPG pyrophosphorylase, the soluble starch synthase and starch branching enzyme activity of cold-region japonica rice at grain-filling stage, and significantly delayed the time of peak activity. There were significant differences among different varieties. In a certain range, ADPG pyrophosphorylase, the soluble starch synthase and starch branching enzyme activity increased with the increase of nitrogen application. In normal irrigation, it is a maximum for ADPG pyrophosphorylase, the soluble starch synthase and starch branching enzyme activity of the three varieties at N150, and the maximum at N200 under salt stress.(6)Salt stress significantly inhibited the accumulation of the total starch, amylose, amylopectin of cold-region japonica rice at grain-filling stage, and there were significant differences among different varieties. In a certain range, the total content of starch, amylose content, amylopectin content increased with the increase of nitrogen application. In normal irrigation, it is a maxi mum for the total content of starch, amylose content, amylopectin content of the three varieties at N150, and the maximum at N200 under salt stress.(7)Salt stress significantly influenced the panicle characteristics of cold-region japonica rice, and led to reduce rice yield significantly. Compared with normal irrigation, Longdao 5 has been least affected, Mudanjiang 30 has been most affected, Songjing 6 was in between under salt stress. Panicle length of the three varieties had shorted, primary branch numb er, second branch number, effective panicle number, grain number per spike, seed rate, housand seed weight and the measured yield of each basin had reduced, empty primary branch number, empty second branch number, empty grain rate had raised. In a certain range, the panicle length, primary branch number, second branch number, effective panicle number, grain number per spike, seed rate, housand seed weight and the measured yield of each basin increased with the increase of nitrogen application. Empty primary branch number, empty second branch number, empty grain rate straightly increased with the increase of nitrogen application. In normal irrigation, it is a maximum for the measured yield of each basin of the three varieties at N150, and the maximum at N200 under salt stress. Through the correlation it knows that there was very significant positive correlation between the panicle length, primary branch number, second branch number, effective panicle number, grain number per spike, housand seed weight and yie ld.(8)To some extent salt stress had reduced rice milling quality. In a certain range, the milling quality increased with the increase of nitrogen application. In normal irrigation, it is a maximum for the three varieties at N150, and the maximum at N200 under salt stress. Salt stress significantly influenced rice appearance quality, led to reduce grain length-width ratio, increase chalkiness and the rate of chalkiness. In a certain range, the grain length-width ratio increased with the increase of nitrogen application. Chalkiness and the rate of chalkiness straightly increased with the increase of nitrogen application. Under salt stress, rice cooking quality degradated, it reduced grain gel consistency, increased amylose content. In a certain range, the a mylose content of three varieties increased with the increase of nitrogen application. grain gel consistency straightly reduced with the increase of nitrogen application. In normal irrigation, it is a maximum for the three varieties at N150, and the maximum at N200 under salt stress. Meanwhile, salt stress led to rice nutritional quality degradate, lysine and tryptophan content reduced, protein content increased. lysine, tryptophan and protein content increased with the increase of nitrogen application.