The Effect Of Sowing Date And Density On Growth Period And Yield Of Direct-seeding Rice After Wheat In Yahhuai Area

In2007, this experiment tested sowing date and transplanting density on clay soil in stock seed farm of Fengtai, Huainan City, Anhui Province and the experimental variety is after wheat. In order to research the influence of growth period and yield on different sowing date and density, from2008-2009, in HuaiYuan County, WanDao68was taken as material for experimenting stage direct seeding and different sowing rates. The final results are as follows:1. The growth period of WanDao68depends on its sowing time, each growth stage and the whole growing period are basically identical on same sowing date but different density. From May5to June14, maturity date delays when sowing date was postponed, The whole growth period declines, mainly centralizes on vegetative growth stage before jointing stage. Late sowing has little effect on the number of days of each growing stage. Because late sowing makes the whole growth period shortened, so WanDao68can safely full heading and maturity in JiangHuai area even sowed on June14.however, sowing too late leads to yield reduction seriously then.2. Sowing time and density has great influence on yield of WanDao68under condition of seedling. From May25and after, with sowing date postponed, yield decreased obviously, but with transplanting density increased, yield increased. In this experiment, suitable seedling date is from May5to May15, suitable transplanting density is from300000/hm2to400000/hm2.Sowing time and transplanting density have different influence in component factors of yield. Because transplanting in the same period, early sowing, seedling age is long but spike number is less. Short seedling age means field premature meanwhile spike number is more when late sowing, but grain per spike declines with sowing date postponed, seed setting rate and1000-grain weight decline syychronously. Influence of different transplanting mainly shows in spike number, high density can obviously increase the number of ear, however, decrease of each kernel number, seed setting rate and1000-grain weight is not obvious.3. In YanHuai area, the harvest-time is in beginning of June. Transplanting date of seedling is from the first ten days to middle ten days of a month because of machine-harvesting. So it is suitable to arrange sowing date on may5to15,if use machine for transplanting,it is appropriate to sow on may25;sowing date of direct seeding rice should on June5to10,at least no late than June15.irrigating timely after planting.4. Under condition of direct seeding and same seeding rate, with sowing time postponed, number of starting point of tiller number is slightly higher but amount of individual plant tillers is less, so along with sowing date prolonged, number of tillers declines, not only the peak of highest number of stem and tiller declines but also the time delays, all these lead to the decrease of affective panicle number, those show that associate with delay of sowing time, because whole growth period of direct seeding rice and tillering stage are shortened, so highest number of stem and tiller and mature spike number obviously decreased, the more late sowing, the more obvious.5. Under condition of same sowing date but different seeding rate, it is important to increase basic seedling to ensure population quantity and high-yield of rice when sowing late. seeding rate of late sowing in production is the same as early sowing.because of less tillering, insufficient quantity of rice is the main reason of reduction in yield, but too many sowing rate will cause ladging and reduction in later stage.