Studies On The Standardized Technical Systemsof Dry Stress Seedling Nursing And Thin Transplantation Of Paddy Rice

In this project, integrating with Ningxia actual paddy rice production, a research was undertaken to solve the faced outstanding problems and improve Ningxia paddy rice production through studying on the methods for appropriate seedling nursing based on the cultivation of dry stress seedling nursing and thinning transplantation in the field and the field trials for the suitable planting density and the technical guidelines for standardized paddy rice cultivation. The main outcomes were as follows:1.The impact of seeding date and seeding quantity on rice yielding. The seeding date and seeding quantity were proponent factors in determination of rice yields. To raise vigor seedlings was started with early seedling nursing and thin seeding in the field nursery. Vigor seedlings were crucial to high yields of paddy rice. One of the agronomic methods for predicting the yield to be over 650kg/666.7m~2( with the probability more than 95%).was that the seeding date should be in between 1-10 April and the seeding quantity in field nursery ranged from 50-160 g/m2.2.The relationship between transplanted quantity of seedlings by hand and the vigor of growth of seedling and its yielding. The transplanted quantity of seedlings at low level was associated with well vigor seedlings and after transplantation the yielding got higher and the transplanted quantity of seedlings at high level the yielding was low after transplantation. At present the paddy rice production with transplanting by hand, the seeding quantity in field nursery should be kept less than 220g/m2.3.The relationship between seeding quantity by machine and the growth vigor of seedling and its yielding. The amount of seeding by machine had obvious impacts on the growth vigor of seedlings. The relatively small amount of seeding per unit area made a good effect, and it was in flavor of keeping high living rate after transplanting and the index such as heading stage and yielding were also well. In consideration of actual production conditions it was good for the amount of seeding by machine being 670g-780g/m2 and the density of transplanting 5-6 seedlings per hole.4.The primary studies on the cultivation of dry stress nursing of seedlings concluded that the density of transplanting was 50,000/ 666.7m2; the spacing of 30×13 in between rows and holes cm and 3 seedlings per hole, this density of planting under the present production conditions, was an appropriate option, with which the tillering potential could be brought into full play, and individual plant developed fully, and the structure of whole plants community was rational. It aimed at strengthening the vigor of growth of individuals and promoting the growing of field plants community as a whole, and obtaining the big spike and finally realizing the high yielding.5.The N fertilizer application rate under the practice of dry stress seedlingnursing and thin transplantation shows that under the thin transplanting conditions the yielding could reach the highest with an application of 15kg pure N per 666.7 m~. The marginal yield increased along with the increase of application of N [cililizer ranging between 10 and 15kg. The answers from the regression equation explained that the rate of application of N fertilizer with the highest level of yield was 1 5.93 kg, the optimum application of N fertilizer being 14.49kg. With the increase of application of N fertilizer the tillering could be improved markedly. When and as the application of 15kg N fertilizer followed, the effective tillering went to the highest, and the structure of plant community in the field as a whole turned to rational, individuals grew well and the yielding related three key factors went into balance.6.The field trials for base fertilizers application based on the cultivation of dry stress seedling nursing and thin transplanting showed that the base fertilizers had better be dressed deep into the whole plough horizons and the reached maximum yield was up to 749.6kg. The reasons for the high yielding were concerned with an application of fertilizers deep in plough horizon, by which the fertilizers dispersed into lower soil layers and therefore the rate of utilization became into high level that satisfactorily met the nutritive requirements of plants during their growth of life. Therefore it resulted in the enlarged plant community in the field per unit area, and the increased numbers of harvested spikes, improved growing conditions of individuals plants and large heads and raised numbers of seed grains.7.Through the trails for dry stress seedling nursing in the field nursery controlled with the conventional practice adopted by and keeping records of a lots of pilot areas in the farmer's fields, it was put forwards the relatively matured technical guidelines for standardized paddy rice cultivation with the dry stress seedling nursing and thin transplantation, indicating the establishing of the technical systems of paddy rice cultivation with dry stress seedling nursing and thin transplantation suitable to Ningxia ecological conditions. To it, the vigor of growth of seedlings under the management of dry stress seedling nursing was better and the yielding of paddy rice transplanted in the fields was higher at large, this rice cultivation practice showed a protruding role played in improving its yielding. In contrast with the conventional cultivation in seedling nursing, the whole growing period was shortened by or advanced. Thanks to rational thin plantation, as a result of it, the structure of plant community in the field became optimizing, the potential of yield increasing could be fully developed, and the rational shape of growth of individual plant could be set up so that the condition of preventing the occurrence of pest insects and diseases was created; though the number of effective spikeiets was reduced, the number of seed grains got increased and the weight of 1000 seed grains improved instead; the key factors in the forming of yielding reached an optimized integration, the quality of rice product was improved and cost of production reduced ,and yielding and economic efficiency increased as well.