| Traditional paddy rice production is characterized by large water consumption, low water-/nitrogen-use efficiency and large emission of green house gas. With the increasing scarcity of water resources, traditional paddy rice production is facing unprecedented challenges recently. Therefore, water-saving rice production system has been attracted widely attention among researchers. Ground Cover Rice Production System (GCRPS) is a new water-saving rice cultivation technique which was developed in recent two decades. However, previous studies on GCRPS mainly covered yield performance at single water and nitrogen condition, while productivity and resource use efficiency of GCRPS under different water and nitrogen management has been rarely reported until now. Moreover, due to the film cover sheet it is difficult in topdressing, which may cause nitrogen deficiency in the late growth period. In addition, manganese/iron and other trace element deficiency might occur in aerobic conditions in GCRPS due to the decrease of water content and increase of soil Eh. Therefore, to coordinate crop growth, resource utilization and yield formation from cultivation, water and nitrogen nutrient management plays important role in improving the productivity and stability of GCRPS.Based on the background above, this study included three parts:1. a comprehensive field experiment (2012-2013), conducted in Fangxian Shinyan Hubei, mainly focused on evaulation of production system (GCRPSsat, GCRPS80%,Paddy) combined with nitrogen application on yield, water-/nitrogen-use efficiency, yield formation and crop growth;2. a long-term field experiment (2003-2012), conducted at Zhangwan Shiyan Hubei, mainly compared effect of nitrification inhibitor, controlled-release fertilizer and urea plus with manure on yield, yield components, crop growth rate and nitrogen uptake rate were assessed;3. a hydroponic experiment (2013-2014), conducted in greenhouse in Goettingen University, studied the effect of nitrogen form and manganese conentration on growth, photosyntheis and trace element nutrition of rice plant. The main findings are as follows:1. The2-year comprehensive field experiment:compared to Paddy, GCRPSsat and GCRPS80%,①grain yield was significantly increased by8.6%and8.9%, because productive tillers was significantly increased;②the amount of irrigation was saved by54%and84%, water use efficiency of irrigation and total water supply, nitrogen agronomic efficiency and recovery efficiency were all significantly increased;③during the maximum tillering stage, the photosynthesis rate of leaf tended to increase; the d13C of leaf and shoot were significantly increased and were significantly correlated with water use efficiency of irrigation and total water supply;④the root biomass, root length density, root surface area and root volumn were significantly increased; and root distributed in the deep soil layer were promoted.2. The10-year long-term field experiment,①application of controlled-release urea or the combination of manure significantly increased crop growth and nitrogen uptake rate in reproductive phase, improved number of spikelets and percentage of filled grains, which contributed significantly higher grain yield;②application of urea plus nitrification inhibitor satisfied the needs of amonium nitrogen for rice, but aggravated the nitrogen lack in reprodctive phase; dereased the spikelet numbers and percentage of filled grains, and did not enhance grain yield and nitrogen use efficiency;③application of organic manure alone significantly decreased aboveground biomass production in early growth stages, indicating N shortage in the vegetative stage, which decreased grain yield. In conclusion, with consideration of practical production, the combination of organic manure with mineral N fertilizer is optimized N fertilizer management to improve yield and efficiency productivity in GCRPS.3. The hydroponic experiment,①under0μmol/L of manganese in nutrient solution, compared to nitrate-nitrogen, the tillers, biomass and net photosynthesis rate were significantly lower, the iron and copper content in shoot were significantly higher under ammonium, and the symptoms of manganese deficiency were enhanced;②under0.28and1.12μmol/L of manganese in nutrient solution, with the increase of Mn concentration in nutrient solution, the tillers, biomass of shoot and root were significantly increased when ammonium nitrogen was applied, while nitrate nitrogen didn’t increase the tillers and biomass significantly. The manganese content in plant shoot were all significantly increased under both ammonium and nitrate nitrogen;③the manganese content in plant shoot was significantly correlated with the maximum tiller number, the biomass and accumulated water consumption, and the correlation was enhanced with the incease of ammonium nitrogen in solution. Aerobic rice had similar performance as lowland rice. Compared to lowland rice, aerobic rice have lower trend of manganese absorption. |
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