Study On Stereo-structuring Rice Seedling Raising Substrate In A Locking Stype Room

Rice is an important food crop in China. The yield and quality of rice is a great event relating to people’s livelihood in our country. As the saying goe s good seedling half depending on field, good seedling predicting a bumper year, so the poor quality of seedlings is the key problem of limiting the rice production. Rice seedling raising in cold region of Heilongjiang province faces many problems, such as frequent extreme weather, short of out-soil resources, covering an large area. Researching stereo-structuring rice seedling raising substrate in a locking stype room can effectively solve the problems that rice seedling raising faces at present. The specific contents are as follows:(1)The demand of p Hysical and chemical properties of seedling raising substrate is relatively small bulk density, larger porosity, acidic p H. Between 12 substrate species, only the control group(CK1) can not meet those demands with large density and small porosity. And substrate is several times higher than the control group(CK1) in total nitrogen, total p hosphorus, total potassium available nitrogen, available phosphorus and available potassium.(2)In the test a set of seedling raising process for stereo-structuring rice seedling raising in a locking stype room was put out to adapt to its characteristics o f high degree of automation, control precision and so on. The nursery trays were covered by plastic film to keep the temperature and humidity and there was no need to control the soil moisture as well as the lighting. But the air temperature should be controlled at 34℃ to guarantee the seeds to emergence smoothly. During the green time, the seedlings were much sensitive to light, so the light intensity should be controlled at half of total lightings to avoid the strong light. At this stage, the air temperature, the air humidity, the soil moisturewas, and the p H were set at 30℃, 70%, 8% and 4.5~5.5 respectively. Relatively, the greenning time was short, usually around 6 hours. After the greening stage was the stage of one leaf one bud, during which the light intensity was increased to total light and the rest of the parameters were the same with the greening stage. During the stage of two leaves one bud,light intensity maintained at the total light and the air temperature, the air moisture, soil moisture and p H was 28℃, 60%, 15%, 4.5~5.5 respectively. The stage of three leaves one bud was broke into two periods. During the early stage, light intensity was the to tal light and the air temperature, the air moisture, soil moisture and p H was 28℃, 60%, 15%, 4.5~5.5 respectively. The second stage of three leaves one bud was the refining stage. Light intensity was controlled at the total light and the air temperature, air moisture, soil moisture and p H was 18 ℃, 50%, 15%, 4.5~5.5 respectively.(3)This study selected the best substrate which is suitable for stereo-structuring rice seedling raising substrate in a locking stype room. In the test, the compound substrate of adding grinding rice husk and grinding corn stalk(M and T) is more beneficial to the growth of the rice seedling than a single substrate(CK). the compound substrate of adding grinding corn stalk(T) is superior to the compound substrate of adding rice husk(M). Adding different amount of the organic material also has a great influence on the seedling growth. The seedlings performs best in every character, organic material contenting in 60%(M2 and T2), and the other two processing was not significant. Finally it is concluded that to processing T2(corn stalk(60%) + black soil(20%) + perlite(20%) performs best in the seedlings agronomic index, biomass index and mechanical index.(4)This study explores a rule about water supply for stereo-structuring rice seedling raising substrate in a locking stype room. Study on saturated water-holding capacity, water loss rate, seedling physiological wilting time, seedling physiological wilting water content, seedling permanent wilting time, seedling permanent wilting water content, a conclusion was reached that C2(corn stalk(60%) + black soil(20%) + perlite(20%)) is one of the most energy saving, water saving substrate. For substrate C2, the saturated water holding capacity(the upper limit water supply at one time) of is 97.56%. From its early wilting water content 10.9% to permanent wilting water content 5.22%, it takes about 19 hours. At the stage of one leaf and one new bud, water should be proper controlled to grow root. At that time the low water content is 8% between early wilting water content and permanent wilting water content. After the stage of one leaf and one new bud, the low water content is 15% with the increasing demand. This is helpful for saving water, and can promote the growth of the seedlings.