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Abstract: The paper confirms the sowing time, rate and ecological standards of seedling and the index of management and control of temperature and sunlight practically in the various methods of open—close ways of drought raising of rice seedling, through many years' field text, and combining with practical experience, according to the cultural methods of transplanting used in the northen rice regions of our country.The critical walue of relative sunlight intensity was 15% within the rice seedling colony, and the index of leaf area was about 10.The accumulated temperature that the seedling needed from sowing to various seedling age was: before 3-6 leaves, 100-130 degree-day; within 6-10 leaves increased to 270 degree-day perleaf.When the leaf area index gained to some a given limited value, the sowing rate increased, the accumulated temperature decreased and seedling period reduced,reversly made the seedling period lenthen.The sowing rate of big seedling transplanted by hand was 150-200g/m~2, the seedling age of it 5-6 leaves,the dry weight of every seedling was 150-160mg, and the accumulated temperature 600-700 degreeday.But for the middle seedling transplanted by machine, the sowing rate was 500-600g /m~2, seedling age 3.0-3.5 leaves, the dry weight of every seedling 55-60mg, and the accumulated temperature 250-350 degree-day.For the seedling of late transplanting, the sowing rate was 50-75g/m~2, seedling age 8-9 leaves and dry weight of every seedling 500-600mg,the accumulated temperature 800-900 degree-day.

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