| The key to the rice seedling factory is tray nursing seedlings in the mechanization technology of rice planting. Presently the main problem for transplanting is that moisture of seedling controlled difficultly, small seedling flexibility, intertwining force weak, blight and bacterial wilt often occurs, resulting in seedling quality poor and lack of seedlings. In the light of the above problems in the rice planting mechanization, this study carried out greenhouse experiments and tested the fertility characteristics, seedling-raising effects, environment ecological evaluation of three kinds of seedling raising matrixes. In order to select seedling matrixes that had the best effect and was suitable for mechanical transplanting. Then in the screening out of the matrixes, taking measures on the basis of optimization and improvement, such as adding different amount of water retaining agent of cross-linked polyacramide on tray seedling-nursery rice, coating for seed different kinds of seed coating agent, adding seedling chemical regulation agent. Analyzing the effect of seedling quality and physiological biochemical on seedling, in order to screen factory seedling matrixes and improve comprehensive quality of seedlings. The main results were as follows:(1) The three kinds of seedling raising matrixes are rich in fertility with the nutrient content of 26.629-32.770 milligrams per kilogram. Zhongxiang matrix has a balanced nutrient and the pH is more suitable for the demand of disc seedling-nursery. It is better using matrix than the nutrition soil as seed cover soil. Zhongxiang matrix has the best effect for seedling-nursery and Xinghua matrix, rising matrix is followed successively. When Nutritional soil was used as seed-cover soil and different ratio of matrixes were used as subsoil, the 100% matrix had the best effect for seedling-nursery, and the 40% matrix plus 60% natural soil, the 30% matrix plus 70% natural soil, the 50% matrix plus 50% natural soil was followed successively. When matrix was used as seed-cover soil and different ratio of matrixes were used as subsoil, the 100% matrix had the best effect and 40% matrix plus 60% natural soil,50% matrix plus 50% natural soil,30% matrix plus 70% natural soil was followed successively, and different seed cover soil is slightly different. The potential ecological risk index for the three substrates was between 252.23-303.43, which is in middle to strong ecological risk level of hazard and Hg and Cd are the main pollution factors’matrixes. The 40% matrix plus 60% natural soil is recommended for seedling-nursery taking cost-saving and effect-improving into consideration. At the same time, the raw material selection is need to be considered in the production of matrixes in order to reduce or avoid heavy metal pollution. The risk of heavy metal accumulation should be paid attention in planting process despite the quantity of the heavy metal is limited by substrate bringing into field.(2) The plant height, leaf age, sheath length, lengthen and width of the leaves after adding water retaining agent were all improved compared with the control that non-water retaining agent(check). The width of treatments was significantly influenced by the water retaining agent and their width was higher than that of check. The average sheath length was 3.51 and the maximum root length, stalk width, fresh weight of hundred seedlings with 20g water retaining agent per tray were increased significantly. The fresh and dry weight of hundred seedlings significantly raised 18.56g、2.71g with 15g water retaining agent per tray. Some physiological index reached maximum such as chlorophll content, root activity, SOD activity with 15g treatment reached highest as 9.35 mg/g·FW、4.60μg/(g·h·FW)、129.18μ/g-FW. CAT activity had no obvious change from 5g to 15g water retaining agent per tray, however the activity would decrease over the range. The content of super-oxide anion radical was highest with 15g treatment and its content decreased rapidly to stable over the range, which perhaps destroyed the cell structure. MDA content had no obvious change below 15g water retaining agent per tray, but the content increased obviously over 20g water retaining agent per tray. It could increase the chlorophll content for good biological activity’s function enzyme such as SOD and improve the root activity for the growth of underground part with 15-20g water retaining agent per tray, then increasing the seedling quality.(3) The three kinds of seed coating agents (prochloraz imidacloprid, hymexazol, prochloraz) inhibited the seed germination, reduce emergence rate. However, seedling root, lengthen and width of the leaves, the fresh and dry weight of hundred seedlings were increased significantly, which enhanced the seedling quality comprehensively. The effect which seed was coated by prochloraz imidacloprid was best. The fresh and dry weight of hundred seedlings, aerial part than the control without seed coating agent (check) were increased by 0.25%,0.19%,0.33%. Otherwise, seed coating agent could increase the chlorophyll content, SOD activity and decrease MDA content. Overall, the seed coating agents of prochloraz imidacloprid and prochloraz are recommended for seedling quality and physiological index.(4) The three kinds of seed strengthen agents (common seed strengthen agent, Yumiaowang 1, Yumiaowang 2) were used to compare their physiological characteristics and seedling quality effects on rice seedling. The chlorophyll content of seedlings with seed strengthen agents was more improved significantly than the control, which was suitable for machine transplanting. Physiological indexes of seedlings after applying seed strengthen agents were increased such as SOD, POD, CAT activity.The three kinds of seedling raising matrixes are rich in fertility. Without adjustable acid, Zhongxiang matrix was suitable for the growth of pH 4.5-5.5 which closer to drought nursery seedlings. And the totally content of N:P:K was an equilibrium, more conducive to the growth of rice seedlings. Moreover, the rooting, rooting ability, intertwining force of seedling with seed coating agents, water retaining agent, seed strengthen agents was enhanced. Therefor, the comprehensive quality of seedling was improved. |
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