Abstract: Seedlings standing and establishment is a special process for broadcasted rice. And whether the seedlings could establish timely is the basis of high yield. In this research, rice cultivar Nanjing 44 was adopted, and five treatments with different seedling poses and with or without soil were set artificially including the upright seedlings with soil (USWS), the leaning seedlings with soil (LESWS), the lying seedlings with soil (LASWS), the lying seedlings without soil (LASWTS), the upright seedlings without soil (USWTS). The morphological and physiological changes were studied during the process of seedling standing and establishment. Results were as follows: (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. (8) Theoretical yield and practical yield were all shown as below: USWS>LESWS>USWTS>LASWS> LASWTS. 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.

Key words: Broadcasted seedlings, Standing and establishment, Morphology, Physiology