THE ROLE OF CROWN ROOTS FROM COLEOPTILAR NODE IN THE ROOTING AND DEVELOPMENT OF TRANSPLANTED RICE NURSLING SEEDLINGS

The root system of rice nursling seedlings is composed of a seminal ro ot and crown roots from coleoptilar node. The roots were cut at variou s locations, and the treated seedlings were grown for seven days after transplanting to clarify the role of the crown roots in the rooting a nd development. Even when the roots were cut at 1.5 cm from the base o f the root, growth of the seedlings was similar to that of the control . However, growth was significantly reduced when cut at a length of 0. 5 cm from the base. The growth of transplanted seedlings, including th e emergence rate of the third leaf, was barely influenced by excision of the root tips of a seminal root and four crown roots, but growth wa s severely reduced by cutting at the bases of a seminal root and the l ongest crown root. The growth of the transplanted seedlings decreased in accordance with the total root length remaining after the treatment s. These results indicate that the rooting and development of transpla nted nursling seedlings are reduced according to the total length of t he root remaining after treatment. It is conjectured that the crown ro ots from the coleoptilar node play a large role in the absorption of w ater and nutrients just after transplanting, and promote the rooting a nd development of transplanted nursling seedlings through emergence of the first nodal roots.