| Ratooning rice is the reharvested crop from the first cropping plants, which is generated from sprouted dormancy buds and grows to produce effective panicles at rice stake after the first crop was harvested with the aid of a certain cultivation management. Because it has the advantages of short growth period, high output, saving labour and cost, the technology has become an important part of light and simplified farming system in rice planting region of Southern China. In recent years, the area of ratooning rice has been expanded and the yields of rationing rice have been improved year after year. So it is playing an increasingly important role in protecting our country food security. However, the production levels of ratooning rice in different regions are in great disparity. Even though under the condition without differences in light and temperature distribution in the same area, the large difference in the production levels can be observed . All these show that ratooning rice yields are closely related to cultivation technique system. Therefore, further to clarify the mechanisms of high and stable yield formation and its regulation has became an urgent problem for the development and promotion of ratooning rice. In this study, eco-physiological characteristics of high yield formation under different cultivation modes and different nitrogen application strategies for the first cropping rice and its nitrogen utilization efficiency were investigated. Accordingly, comparative proteomics and bioinformatics were applied to study the molecular physiological mechanisms of ratooning bud sprout and its growth at different levels of fertilizer applciation for ratooning bud development and grain filling of the first cropping rice at different levels of fertilizer application for rationing bud development, aiming at further understanding the effect of different cultivation and regulation technology on the graing yield of ratoon rice. The main results were summarized as follows:1. Eco-physiological characteristics of high yielding formation of early rice and its ratooning crop under different cultivation modesThe result showed that compared with traditional cultivation mode, the dry-raising seedlings of super high-yielding cultivation patterns were more healthy and dwarf, higher resisttant ablity, greater absorptive and assimilative capacity. The strong tillering seedlings were helpful to improve the ablity resistant to cold stress and senescence in favor of early sowing, turning green and root germination earlier after transplanted. During the entire period of early rice and its ratooning crop growth, the rice crop under super high-yield cultivation mode possessed the obvious physiological biochemistry superiority, exhibiting its lower cell membrane peroxidation, stronger resistance to any stresses, longer duration of leaf function, more active metabolism of carbon and nitrogen, stronger ability of dry matter production and energy accumulation, higher energy operating efficiency, smoother energy flow than those under traditional cultivation mode. So the rice plants under super high-yield cultivation mode had the advantages as follows, early tillering, lower tillering node , shorter productive tiller stage, more productive panicles, heavier 1000-grain weight in the first cropping rice , and sprouting early and quckly, shortening productive axillary buds stage significantly, increasing the number of tiller and productive panicles in ratoon rice. All these had laid the important physiological ecological foundation for achieving high yield in the first cropping rice and its ratooning plants But the N production efficiency of super high-yield cultivation mode was lower than that of traditional cultivation mode.2.Eco-physiological machinery in terms of effects of different nitrogen application strategies on grain yield and nitrogen utilization efficiency in the first cropping rice and its ratooning plantsTo furter understand the effects of different fertilizer application regime on grain yield and nitrogen utilization efficiency of ratoon rice, photosynthetic production,dry matter accumulation and Nitrogen Utilization Efficiency( NUE )in early rice and its ratooning crop were studied at different nitrogen rates but in the same total nitrogen supply (225.00kg.hm-2 N-fertilizer ) applied in basal dressing, tiller dressing and panicle dressing respectively in the first cropping rice . The result indicated that nitrogen reductase (NR) activity and chlorophyll contents as well as net photosynthetic rate of leaf in the first cropping rice at the middle and late growth stage were significantly improved with properly increasing the proportion of N supplies in the same stage. At the same time, the rate of phloem sap was also enhanced, especially at the booting stage of the first cropping rice. These in turn resulted in improved enzymatic condition for nitric nitrogen to be deoxidized into ammonium one and synthesis of amino-acid, insured the absorption of moisture and nutrient,synthesis of amino-acid and rootstock hormone, and also ensured the nutrition supply from full-tillering stage to ripening stage.Thereby, properly decreasing the proportion of N supplies in the early growth stage and increasing the proportion of N supplies in the middle and late growth stages were favorable to decreasing the ineffective tillers, optimizing the population structure and significantly improving the net assimilation rate (NAR) and crop growth rate (CGR) in the middle and late growth stage of the first crop for ratoon rice.These in turn led to increased net dry matter accumulation and significantly increased spikelet number per m2, spikelet number per panicle and sink sizes. As a result, these factors engendered large sink size and plentiful source and made the yield and NUE(Nitrogen Utilization Efficiency)of the first crop significantly enhanced. But, to the NUE(Nitrogen Utilization Efficiency)and the yield of the ratoon crop, the effect is not significant.3.Compararive proteomic analysis of effects of different nitrogen application strategies on grain yield and nitrogen utilization efficiency in the first cropping rice and its ratooning plantsThe effects of different fertilizer treatments for ratooning bud development on differentially expressed proteins and the corresponding physiological characteristics of rice functional leaves in the late grain filling of early rice were studied by using comparative proteomics combined with bioinformatics and related physiological indicators. The results indicated that the proteins of early rice leaves related to photosynthesis and resistance showed obvious changes after the fertilizer treatment for rationing bud development. Fertilizer treatments for the bud development can not only significantly slow down the decreased amplitude of photosynthesis-related proteins in expression abundance, but also significantly increase the expression abundance of resistance-related protein. These in turn improved the resistance of first cropping rice, and reduced the membrane peroxidation of rice functional leaves, consequently delayed the senescence rate of flag leaf, relatively enhanced the chlorophyll content and photosynthetic rate of rice functional leaf, prolonged the function duration of rice flag leaf, thereby increased the source supply ability , dry matter accumulation, the largest and the averaged grain filling rate of inferior grains in the late filling phase of early rice. As a result, the dry matter accumulation of inferior grains was sigificantly increased at different grain filling phases of early rice, consequently, significantly enhanced the seed-setting rate and yield of early rice.4.Comparative proteomic analysis of the effect of different fertilizer treatments on sprout and growth of ratooning budsThe effects of different fertilizer treatments for the promotion of ratooning bud development on differentially expressed proteins and the corresponding physiological characteristics of rationing rice were studied by using comparative proteomics combined with bioinformatics and related physiological indicators. The results indicated that the proteins of ratooning buds related to energy metabolism, germination and growth, resistance showed obvious changes after the fertilizer treatment for rationing bud development. Fertilizer treatment for rationing bud development can significantly slow down the decreased amplitude of NDPK proteins in expression abundance, and significantly improve the expression abundance of oxygen-evolving photosystemâ…¡complex protein and cytochrome b6 / F Complex protein. So that ratooning buds mediated by fertilizer treatment had relatively stronger energy synthesis and photolithoautotrophic capabilities, which were favorable to the formation of photosynthetic energy for carbon assimilation and better meet the energy and material needs of ratooning bud growth and differentiation. Fertilizer treatment for rationing bud development can also relatively reduced the expression abundance of actin-depolymerizing factor protein, abscisic acid-inducible protein and germin-like protein in the early germination and growth of ratooning buds, and relatively increased the expression abundance of translationally-controlled tumor protein homolog protein and germin-like protein in the late germination and growth of ratooning buds, which inhibited the cell wall formation and reinforcement in the early sprout and growth of ratooning buds, improved the actin content of ratooning buds and promoted cell division and elongation of ratooning buds. In addition,Fertilizer treatment for bud development can still improve the expression abundance of resistance-related protein, which enhanced the ability to resist external biotic and abiotic stress and the adaptability to adverse environment. Therefore, compared with non-fertilizer treatment for rationing bud development, the percentage of alive bud and the length of ratooning buds in fertilizer treatment for the promotion of bud development were significantly higher from the 2nd bud accounted from the top to the 5th bud from the top. As a result, fertilizer treatment for the promotion of bud development significantly improved effective panicle, seed setting rate and grain yield of rationing rice, aiming to get high yielding and large increment in rationing rice production. |
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