Effects Of Slow/Controlled Release Nitrogen Fertilizers On Nitrogen Utilization And Yield Formation Of Rice Under Different Transplanting Seedling Ages And Water Managements

Slow/controlled release nitrogen fertilizers, providing a gradual nutrient supply for a long time period, improve nitrogen fertilizer use efficiency and reduce nitrogen leaching losses. However, the effectiveness of slow/controlled release nitrogen fertilizers will be strongly affected by the environmental conditions, especially by water conditions, in the planting region. Field experiments were conducted to investigate the effects of slow/controlled release nitrogen fertilizers on nitrogen utilization and yield formation of irrigated rice(Oryza sativa L.) under different transplanting seedling ages (including 3-leaf,5-leaf and 7-leaf) and water managements (including controlled irrigation, alternate wetting and drying irrigation and flooding irrigation), in 2012 and 2013. Different nitrogen use methods contained urea single basal application, urea applying with ratio of base:tillering:earring= 5:3:2, sulfur coated N fertilizer single basal application and resin coated N fertilizer single basal application. The main results were as follows:1. Effects of slow/controlled release nitrogen fertilizers on rice yield and its components under different seedling ages and water managementsPanicle number of 3-leaf and 5-leaf were significantly higher than that of 7-leaf. However, different seedling ages affected spikeletes per panicle,1000-grain weight, seed-setting rate and grain yield insignificantly. Panicle number, spikeletes per panicle and 1000-grain weight of alternate wetting and drying irrigation and flooding irrigation were significantly higher than those of controlled irrigation. Slow/controlled release fertilizers showed a yield increase under different seedling ages and water managements, as compared with urea single basal application and urea applying with ratio of base:tillering:earring= 5:3:2. Different types of nitrogen fertilizer significantly affected panicle number, spikeletes per panicle and yield. There was a significant interactive effect between water management and slow/controlled release nitrogen fertilizers application on panicle number, spikeletes per panicle and rice yield. Effects of synergistic effect of types of nitrogen fertilizer and water managements on panicle number, spikeletes per panicle and yield were observed.2. Effects of slow/controlled release nitrogen fertilizers on growth characteristic of rice under different seedling ages and water managementsThe date for the corresponding growth period of 5-leaf and 7-leaf delayed differently, as compared with 3-leaf indicating that vegetative period extended accordingly and the reproductive period shorten of middle/long-age seedling rice. Tillering dynamics and leaf area index were 5-leaf> 3-leaf>7-leaf after full heading stage. In the consideration of different water managements, maxium tillers number reached the highest under flooding irrigation condition. However, tillering dynamics uner alternate wetting and drying irrigation was slightly higher than that under flooding irrigation and both were significantly higher than controlled irrigation.The change of leaf area index kept consistent with the change of tillering dynamics. The biggest falls in leaf area index appeared in 15 days after full heading. Moreover, leaf area index deceased by 36.49% under controlled irrigation,30.47% under alternate wetting and drying irrigation and 32.31% under flooding irrigation respectively. When taking different types of nitrogen fertilizer into consideration, slow/controlled release nitrogen fertilizers inceased tillering dynamics and leaf area index and was higher than urea single basal application and urea applying with ratio of base:tillering:earring= 5:3:2.3-leaf and 5-leaf and slow/controlled release nitrogen fertilizers guaranteed tillering dynamics and maintained a relatively higher leaf index to a certain degree.From full heading stage to maturity stage, root dry matter accumulation of 3-leaf and 5-leaf was significantly higher than that of 7-leaf. Root/shoot ratio of 3-leaf and 5-leaf was significantly higher than that of 7-leaf. All those indicated that 3-leaf and 5-leaf contributed to the root distribution deep into the soil and maintaining root activity. Root dry matter accumulation, total root length, total root surface area, total root volume, deep root distribution and root activity under slow/controlled release nitrogen fertilizers were significantly higher than that under urea single basal application and urea applying with ratio of base:tillering:earring= 5:3:2.3. Effects of slow/controlled release nitrogen fertilizers on dry matter accumulation of rice under different seedling ages and water managementsDry matter accumulation, the maximum increasing rate of biomass accumulation (Vm) and average increasing rate of biomass accumulation (V) of 5-leaf were higher than that of 3-leaf and minimized in 7-leaf. Different water managements affected dry matter accumulation dynamic regulation differently. Dry matter accumulation, Vm and Fwere alternate wetting and drying irrigation> flooding irrigation> controlled irrigation. Urea single basal application and urea applying with ratio of base:tillering: earring= 5:3:2 led to an early beginning time for biomass accumulation rate increased rapidly a short period for rapid accumulation, and beginning time for biomass accumulation rate increased rapidly appeared later using slow/controlled release nitrogen fertilizers but Vm, y and days to the maximum increasing rate, as a result, a higher accumulation of dry matter could be realized.4. Effects of slow/controlled release nitrogen fertilizers on nitrogen utilization of rice under different seedling ages and water managementsNitrogen accumulation in different organs at jointing stage of 7-leaf remained a relatively high level, however, nitrogen accumulation of 3-leaf and 5-leaf were more than that of 7-leaf gradually with the process of growth stage. N translocation in stem and leaf of 5-leaf and 7-leaf were higher than that of 3-leaf, and N increasing in panicle of 3-leaf and 5-leaf were higher than that of 7-leaf. The differences of N harvest index, N use efficiency for biomass production and N use efficiency for grain production were insignificant, N translocation, N increasing in panicle, partial factor productivity of applied nitrogen and N use efficiency in leaf and stem were 5-leaf> 3-leaf> 7-leaf.Nitrogen accumulation in different organs and plants, N translocation and N increasing in panicle at jointing stage of alternate wetting and drying irrigation reached the top, and then flooding irrigation, controlled irrigation the lowest. N translocation efficiency, N translocation conversion rate, N use efficiency for biomass production and N use efficiency of controlled irrigation remained a relatively high level. Partial factor productivity of applied nitrogen and N agronomic efficiency were the highest under alternate wetting and drying irrigation.During early stage, there exsited a relatively low nitrogen accumulation with urea applying with ratio of base:tillering:earring=5:3:2, and then compensated for application of tillering fertilizer and earring fertilizer. At maturity stage, total nitrogen accumulation was higher than that of urea single basal application, but was still lower than that of slow/controlled release nitrogen fertilizers. N translocation of leaf and stem, partial factor productivity of applied nitrogen, N agronomic efficiency and N use efficiency with application of slow/controlled release nitrogen fertilizers were higher than other types of nitrogen application. However, an inverse result for N harvest index, N use efficiency for biomass production and N use efficiency for grain production took hold.There was a significant interactive effect between water management and slow/controlled release nitrogen fertilizers application on dry matter accumulation, nitrogen absorption, transportation and distribution and yield. Moreover, there existed significantly positive correlations between yield component factors and nitrogen increasing in panicle, nitrogen translocation and distribution at heading stage. The application of slow/controlled release nitrogen fertilizers enhanced nitrogen use efficiency and maintained heavy and adequate panicles under controlled irrigation condition; Under alternate wetting and drying irrigation, the beneficial effect of using slow/controlled release nitrogen fertilizers was attributed to better nitrogen accumulation capacity and more coordinated nitrogen distribution in rice plant, which results from slowing the release of nitrogen into the soil relative to regular fertilizer and water conditions, and improving synchronization with crop N requirements during crop growth. Under flooding irrigation condition, slow/controlled release nitrogen fertilizers reduced ineffective tillering and nitrogen losses of leaching and penetrating, resulting in high earbearing tiller percentage. In conclusion, the right combination of transplanting seedling age, water management and nitrogen could coordinate the growth of both overground and underground part; keep a high photosynthetic rate and root absorption ability, increase nitrogen use efficiency, nitrogen accumulation, distribution and tillering synamic and spikelets and biomass and realize high yield. The right combination of transplanting seedling age, water management and nitrogen has the potencial of increasing yield by 8.04%-19.16%, compared with that of the region.