| Rice is one of the main food crop, and more than half of the world population depends on rice as the staple food, so high and stable yield of rice has a very important significance to safeguard world food security. Although rice is originated in the swamp habitat, oxygen is still necessary for normal growth and development. Booting to heading stage is the biggest demand for oxygen and water, and watering will lead to lack of oxygen in the rice rhizosphere. The contradiction between supply and demand of oxygen and water is very prominent, which is one of the factors restricting rice yield under the conventional cultivated condition. In this study, Paddy rice Yuefu, upland rice IRAT109, introgression lines IL392(With paddy rice YueFu as the recipient and upland rice IRAT109as the donor, an introgression line of IRAT109, developed from successive backcrosses and selfings, combined with molecular marker-assisted selection), the large panicle rice variety Xinfeng2and conventional Japonica cultivar YunongJing6in the rice area along the Yellow River Valley as experimental materials, hydroponics and field cultivation experiment were taken at the Science and Technology Park of Henan Agricultural University from2012to2013. Oxygen content in the rice root growth environment is artificially controlled, with water controlling, oxygen aeration, and panicle fertilization with furrowing and ridging, deep tillage. The research intends to study on the danamics and reciprocal interaction between soil oxygen and water during the rice middle and late stage, the effects of different oxygen supply on root growth, rhizosphere soil microbial activity, yield formation, and aging characteristics, to discuss the influential effect of oxygen-water synergy in soil on rice root activity, enzyme activity related with senescence of root and leaves, grain-filling characteristics, and so on. It will help to further clarify the internal physiological mechanism of rice yield increase under the soil oxygen-water synergy condition, which has important theoretical and practical significance for cultivation regulation to improve rice yield. The results are as follows:1. The preliminary study on the change law of soil oxygen and water content suggests, while the soil was saturated with water under alternate wetting and drying, soil oxygen was almost impossibly detected by Firesting oxygen. While soil water content at the5cm soil depth decreased gradually as soil slowly dried up, soil oxygen content increased. During flowering, grain-filling and maturity stages of rice, daily soil oxygen content initially decreased and then increased later in the day, with the lowest value generally appearing at14:00-15:00. Soil water content fluctuated but gradually decreased during the day. Soil temperature increased initially and then decreased later in the day, with peak value generally appearing at15:00-16:00. At flowering, grain-filling and maturity stages, a significantly negative correlation was noted between soil oxygen content and soil water content. Although soil water content was negatively influenced by soil temperature, the correlation between soil oxygen content and soil temperature was insignificant. Under alternate wetting and drying irrigation, a reciprocal relationship existed between soil oxygen content and water content in paddy fields during late growth stages of rice. Thus through moderate alternate dry-wet management measure, soil water and soil oxygen balance in root-zone soil layer was adjusted to some extent.2. The results of hydroponic experiment under different oxygen concentration suggested, root total length of YueFu shortened with dissolved oxygen concentration increasing, and root surface area, total volume, average diameter under hyperoxia and normoxia state were higher than that under hypoxia state. For IL392, the order of these root morphology indexes from high to low was normoxia, hyperoxia, hypoxia. For upland rice IRAT109, total root length, root surface area and total volume under hypoxia state were higher than that under normoxia and hyperoxia state, and increasing oxygen could increase root average diameter. Comparing with that under normoxia state, shoot and root dry weight among three rice varieties increased under hyperoxia and hypoxia state. Under hypoxia state, the root system of paddy and upland rice can formed aerenchyma, and that there was some difference among different varieties. After the treatment of different dissolved oxygen concentration, activity of antioxidant enzymes showed different changing tendency along with different varieties. Under hypoxia state, for all the different varieties, SOD activity increased, but POD activity decreased. Under hyperoxia and hypoxia state, CAT activity and MDA content of IL392enchanced, but upland rice IRAT109showed the opposite trend, and MDA content of YueFu reduced, the change CAT activity had no significant difference.3. The results of field plot test under the different increasing oxygen treatments suggested that, under the condition of clay soil, soil invertase, urease, phosphatase activity increased through artificial aeration (1WO2,3WO2) and water controlling (CW). Aeration treatments improved rice root bleeding, and at grain-filling stage, improved SOD, POD activity, and reduced MDA content. And that they increased glutamine synthetase activity and soluble protein content of leaves, which could effectively retard root senescence, maintain high root vigor. Aeration treatments increased thousand kernel weight of grain, so that to improve rice yield. Alternate wetting-drying irrigation and water controlling treatments increased yield due to the increase of panicles number and spikelets per panicle. Under the condition of sandy loam soil, the change of soil enzyme activity was complex, difference existed between different years. At the grain-filling stage, comparing with the control (WW), the treatments of aeration and alternate wetting-drying irrigation generally lower root bleeding. Water controlling treatment improved SOD and POD activity of root, decreased MDA content, while the effect of two aeration treatments was not obvious, especially for3WO2. Water controlling treatment improved POD activity of leaves, reduced SOD activity and MDA content, but there were no change law and obvious effect under the condition of aeration treatments. However, glutamine synthetase activity and soluble protein content of leaves increased under the aeration and water controlling treatments.Comparing with the control, yield reduced due to the decrease of panicles number and spikelets per panicle under the aeration and water controlling treatments. And yet, comparing with the control, yield improved under the alternate wetting-drying irrigation treatment, the difference did not reach significant level.4. The effects of aerobic cultivation on increasing rice yield were investigated. The results suggest, at the middle growth stage, compared with the control (BA), soil enzyme activities were increased significantly by different treatments of deep tillage and panicle fertilization, and the bleeding intensity at the basal internode and neck-panicle node were also improved significantly. The greatest was detected by DD treatment between the two treatments with deep tillage and panicle fertilization. The different treatments of deep tillage and panicle fertilization improved grain filling rate of superior and inferior grains, especially the initial grain filling rate and maximum grain filling rate of superior grains, improved grain-filling process, and finally increased grain yield of rice. |
PDF Full Text Request