[Root growth in rice and its response to soil density]

Studies on root growth and vertical distribution at tillering(TL), panicle initiation(PI), flowering(FL) and mature(MT) stages and effects of soil compaction on root growth were carried out with hybrid rice of Shanyou 63 and 65,002 in root box. The results indicated that root weight reached maximum at flowering stage and then decreased. With the advance of growth stage, percentage of deep roots(20-45 cm in soil) increased. Root weight increased at highest rate and deep roots formed during the period of TL to PI. With increased soil weight density below 20 cm, root weight and percentage of deep roots markedly decreased.