Effects Of Density And Nutrient Management On Growth And Yield Of Direct-Seeded Rice In Cold Area

In recent years, direct seeded rice in our country is developing rapidly. In many provinces, it has become the main means of rice planting, but in the cold area especially Heilongjiang province direct seeding technique is still a blank. The trial was carried out in2012and2013. In2012, the test was implemented by a set of plot tests, used Longjing31as the tested rice cultivar, setted up three densities, M1(spacing12×30cm,5-7seeds per hole), M2(spacing12×30cm,8-10seeds per hole) and M3(spacing10×30cm,8-10seeds per hole) under nutrient management. In2013, employed micro-plot experiment, used LongQing2as the tested rice varieties, set up two planting way, direct seeding (PI) and transplanting (P2), two fertilization methods, optimized fertilization (F1) and conventional fertilization (F2). Meanwhile, a field comparison test was carried out, tested rice cultivar was Longjin5, set up two planting modes namely direct seeding and transplanting, transplanting as the control. The objective was to study the effects of density and nutrient management on population development, dry matter accumulation and yield of direct-seededrice, compare the growth differences in direct-seeded rice and transplanted rice, so as to provide theoretical basis and technical measures to increase direct-seeded rice yield in cold area The results as follows:There were some differences between direct-seeded and transplanted rice in growth period. Compared with transplanted rice, the time of direct-seeded rice into seedling stage was28days later, the time into panicle initiation stage8days later, and the time into maturity stage4-5days later; but the whole growth period was23days shorter, of which the time before panicle initiation stage was20days shorter.Appropriate density and nutrient management optimization can significantly improve rice population structure of direct-seeded rice, improve the spike rate. Higher density can strengthen the growth of tillers, tiller population showed a larger trend of up and down, excessive ineffective tillers come out, which lead to the lower spike rate. In this experiment, low-density M1, has a most reasonable population structure, the highest spike rate, reaching more than80%. Optimized fertilization can significantly improve the seeding rice spike rate, compared with conventional fertilization, whose spike rate increase of5.4%by reducing basal fertilizer application increased panicleAppropriate density and optimized nutrient management could ensure suitable dry matter accumulation of direct-seeded rice in early days. Under low density treatment, the contribution to grain yield of the dry matter accumulations and net substance assimilations after heading was significantly higher than that under middle density and high density treatments. Optimized nutrient management increased the proportion of late nitrogen fertilizer, which could promote dry matter accumulation in the late growth of rice. Under optimized fertilization treatment, both the spike accumulation and the total accumulation were the largest in every dry matter accumulation process. There was a significant positive linear correlation between dry matter accumulations after the heading stage and the yield (r=0.7124). There was also a significant positive linear correlation between the contribution of dry matter accumulation to yield and the yield (r=0.7734).As the density increased, the effective spikes increased, the grain number decreased, the maturing rate and grain weight didn’t change significantly, and the yield dropped. In this experiment, low density had the highest yield9.25t· hm-1, increased by8.4%and14.9%(P<0.01) than medium-density and high-density. By optimizing fertilization can increase the derict-seeded rice grain weight, seed setting rate and grain number, thus significantly improve the yield, P1F2yield improved7.2%compared with P1F1, P2F2improved8.1%(P<0.05) compared with P2F1production. In filed comparison test, yield of direct-seeded rice increase8.1%(P<0.05) compared to transplanted rice.