Study On Yield Formation Mechanism Of Japonica Rice In Cold Region Under Different Cold Water Stress Days At Tillering Stage

Heilongjiang province is an important base for Japonica Rice production in China, and is located in Northeast of China, the chilling injury occurred frequently, it is one of the main disasters in Heilongjiang province are limiting rice production and caused serious influence on rice production. The tillering stage of the rice is not only an important period of dry matter accumulation and effective panicle formation, but also prerequisite to obtain high yield of rice. If the occurrence of chilling injury at tillering stage, to reduce the tiller number and plant height, leaf color chlorosis, the photosynthetic efficiency decreased, growth stage was delayed, resulting in the number of spikes, kernels per spike and yield declining. Therefore, study on yield formation mechanism of Japonica in cold region under different cold water stress days at tillering stage not only has the theory value, and has important practical significance to stabilize and improve the yield of rice. Study on different days of water stress at tillering stage of rice growth, aerial part dry matter accumulation and distribution and yield formation, to provide a theoretical basis for the high yield and stable yield of rice. Dongnong 428 and Songjing 10 and Longdao 7 was used as test material.The main conclusions of this experiment are as follows:(1) At tillering stage, cold water stress significantly inhibited the growth of rice. Three varieties of rice plant height and growth speed was affected by the cold water stress at tillering stage, with the increase of cold water stress days affected the greater the influence. Short term cold water stress has no significant effect on plant height, excessive cold water stress will extend the height growth time. In the cold water stress, the tiller of rice growth slowly or even stop, so that the highest tillering number, the tillering rate of growth and die was significantly decreased. Tiller growth rate gradually recovered after cold water stress the end, but the peak date of tiller was delay, with the increase of cold water stress days affected the greater the influence. The leaf area index, the high efficiency leaf area and the leaf growth speed significantly decreased with the increase of cold water stress days, and there were significant differences among different treatments.(2) At tillering stage, cold water stress significantly influence of dry matter accumulation of rice. Three varieties of the aerial part dry matter accumulation, the crop growth rate, the export percentage of the matter in stem and sheath, the contribution percentage of the matter in stem and sheath, the amount of dry matter translocation before abloom, the amount of dry matter accumulation after abloom was significantly decreased with the increase of cold water stress days, and there were significant differences among different treatments. The main stem and tillers of rice stem dry matter weight was significantly decreased with the increase of cold water stress days, and the tiller stem are more sensitive to cold stress than the main stem.(3) At tillering stage, water stress affects the leaf area index and indirect influence on Grain Filling Characteristics of three rice cultivars. The initial growth potential, the maximum grain filling rate and the mean grain filling rate gradually decreased, the grain filling peak was delayed, the grain filling time prolonged with the increase of cold water stress days.(4) The yield of rice was significantly decreased with the increase of cold water stress days, and there were significant differences among different treatments. The effective panicle number, Total grain number per spike, the 1000 grain weight and the seed setting rate was significantly decreased with the increase of cold water stress days, and there were significant differences among different treatments. The productive tiller percentage increased gradually with the increase of cold water stress days. Dongnong 428 and Longdao 7’s D0 and D3-D9 have no significant difference, the difference with D12,D15 is especially striking. Songjing 10’s D0 and D15 have significant difference, and there was no significant difference with the other treatment. Through the analysis of factors of production, cold water stress at tillering stage was decreased the yield mainly by reducing the number of panicles.(5) In the cold water stress at tillering stage condition, the plant height, the highest tillering number, the leaf growth speed, the leaf area index, the high efficiency leaf area, the total dry matter accumulation, the amount of dry matter translocation before abloom, the amount of dry matter accumulation after abloom, the effective panicle number, total grain number per spike, the 1000 grain weight and the seed setting rate were significantly or highly significantly positively correlated with yield. The productive tiller percentage were highly significantly negative correlated with yield.