Physiology And Management Of Fertilizer And Water Of Rice Seedlings Under Dry Land Nursery

Although the cultivation technique of rice on dry seedbed developed rapidly, some problems such as physiological advantage of dry scedbed seedling (DSS), the applying of fertilizer on seedbed, and water management hadn抰 been solved perfectly. The experiments with two genotypes rice, 502 (upland rice) and 9516 (Japonica rice), were conducted by applying different amount and form nitrogen on dry seedbed and wet seedbed to develop the growth and physiological characteristic of DSS. The result showed as follows: DSS of 9516 got more nitrogen, N03-N, soluble protein, chlorophyll, nitrate reductase activity than wet seedbed seedling (WSS). The NO3~-N concentration of DSS was 28.09-30.93 times as much as that of WSS. DSS absorbed nitrogen from paddy more quickly and the accumulation of nitrogen in seedling rapidly than WSS when transplanted to paddy field. Soluble sugar and starch of DSS was increasing 44.19-100.41% and 14.76-21.06% than that of WSS respectively. DSS had more soluble sugar and starch in sheath, whereas WSS had more soluble sugar in leaf and more starch in sheath. The ability of roots emergency, vigor and the surface area of DSS roots were higher than those of WSS significantly. The relative water content and MDA of DSS were higher than those of WSS. As contrast, the concentration of praline and activity of SOD, CAT, AsA-POD increased. After transplanting, MDA of WSS was less than that of WSS, the activity of protecting enzymes was higher than those of WSS, which would do well to the growth of DSS. The concentration of ABA in the leaf and root of WSS increased significantly, but the concentration of CTK and GA in leaf and root of WSS decreased obviously than DSS. The decreasing of IAA in the leaf and the increasing of IAA in the root did help to improve osmotic regulation and the formation of branch roots. DSS of upland rice (502) had the same tendency as that of iaponica rice, but difference was more content and activity. Because of heavy injury of transplanted, the content of material or enzyme activity of upland rice DSS decreased more and had a longer time for reviving than that ofjaponica rice. DSS of middle amount of nitrogen treatment, showed best in material accumulation and physiological reaction. The rice, which applied less nitrogen, grew less. So the seedbed applying nitrogen fertility must be proper. DSS of applying more N03-N nitrogen, increased the concentration of nitrogen content, soluble protein in leaf and root, chlorophyll content, and the content of nitrogen and chlorophyll kept increasing After transplanting. Nitrate reductase activity and concentration of soluble sugar and starch of DSS that fertilized with more N03-N nitrogen, increased obviously, especially in leaf and root that could improve the utilization efficiency of N03ThJ. The relative water content and proline concentration in leaf of DSS that fertilized with more N03-N nitrogen increase significantly, but the concentration of MDA and activity of SOD, CAT, AsA-POD decreased obviously, which showed the seedling applied N0-N had stronger osmotic regulation ability. After transplanting, the root vigor of DSS that fertilized with more N03-N nitrogen still had significant strong so that seedling was easy to live. The concentration of ABA in leaf and root of DSS that fertilized with more N03-N nitrogen decreased, but its concentration of CTK and GA in leaf and root increased, the content of IAA in the leaf increased and the content of IAA in root decreased. The co...