Mechanism Of Seedling Standing And Establishment Of Broadcasted Rice And It's Regulation

The field experiments were conducted in the experimental farms of agricultural college of Yangzhou university using Nanjing 44 as material to study the Mechanism of seedling standing and establishment of broadcasted rice and it's regulation.The main results are as follows:1.Standing and establishment of the upright seedlings came earlier than the leaning seedlings the and the lying seedlings, the upright seedlings' biomass,N accumulation, net assimilation rate, lodging resistance and harvest yield were higher than the that of the seedlings and the lying seedlings; The rate of the upright seedlings was highest under the conditions that the soil of top 5-6 cm was soft and the broadcasting height was 3 m, which was 81%;The rate of the upright seedlings decreased gradually as water depth increased; The plastic trays with bigger hole should be chose moderately for ..raising seedling and the height of seedling should be controlled at 10-16 cm when broadcasting. The upright seedlings'growth status at different stages was better than the leaning seedlings and the lying seedlings, significantly the lying seedlings. Increasing the rate of upright seedlings made for high yield of broadcasted rice effectively. Under the condition that the soil at the depth of top 5-6 cm was soft, the broadcasting seedlings were low and broadcasting height was from 3 to 4 m it would have best seedling standing.2.The morphological and physiological changes of seedling standing and establishment of broadcasted rice seedlings:(1)The crown of the lying seedlings bent its lower side that produced more new roots as a pivot for standing. In the curvature zone of the lying seedling, actively elongated cells of the lower side grew faster than those of the upper side, which led to an asymmetric growth. (2) The time of seedling standing of LESWS,LSWS and LSWTS was 4 d,8 d and 12 d, respectively. (3)USWS and LESWS produced more roots during seedling standing period, whose activity was stronger. (4) The water content of the seedlings without soil decreased fast during the early period then increased during the later period, which was near to that of the seedlings with soil from 10 days after transplanting. (5) The chlorophyll contents of LASWS, LASWTS and USWTS were lower than those of USWS and LESWS during the early period, Those of all treatments restored to the normal level from 10 days after transplanting except LASWTS.(6) Total soluble sugar of any treatment's roots and aboveground part was consumed at two days after transplanting, then that in aboveground plants of LASWTS and USWTS began to increase. USWS and LESWS consumed more total soluble sugar. (7) The N, P and K accumulation increased in root and aboveground parts. The average increasing rates of N, P and K accumulation were higher in the seedlings with soil than in the seedlings without soil and also higher in the upright seedlings than in the lying seedlings.And it could be concluded that, the time of seedling standing and establishment was earlier in the seedlings with soil than in the seedlings without soil and also earlier in the upright seedlings than in the leaning and lying seedlings. Therefore, in production we should choose the seedlings with soil, increase the proportion of the upright seedlings and reduce the proportion of the lying seedlings, as a result, improve the population quality for broadcasted rice.3.The standing of broadcasted seedlings is the basis of high yield broadcasted rice, and the speed of physiological standing of broadcasted rice seedlings decides the broadcasted rice's population quality and productivity. In this research, rice cultivar named Najing 44 was adopted as material, and the effects of the different cultivation methods on broadcasted rice seedlings were studied during the process of seedling standing and establishment. Results showed that:the standing of broadcasted seedlings with intact soil was faster than the seedlings with non-intact soil.moreover, the roots and the leaf area grew better than the seedlings with non-intact soil; The younger the seedling age, the faster the seedling standing, but the roots were on the contrary; Increasing the base fertilizer quantity moderately will help the standing of broadcasted seedlings; the standing time of seedlings under the condition that the soil at the depth of top 5-6cm was mud was shortest, And the growing status above and below ground was better than the seedlings in 1～2cm soft soil and significantly better than the seedlings in hard soil; The optimal temperature for seedling standing was 30℃; Strong seedlings were better than weak seedlings in standing. Therefore, choosing the young age seedlings with intact soil under the conditions that the top soil is mud, increases the base fertilizer quantity and the temperature is about 30℃,it would have best physiological seedling standing.