Effects of nitrogen on the tolerance of brown planthopper, Nilaparvata Lugens, to adverse environmental factors

The effect of nitrogen content in rice plants on the tolerance of brown planthopper (BPH), Nilaparvata lugens Stal to high temperature, starvation and insecticide, was studied in the laboratory at International Rice Research Institute (IRRI), Philippines. Survival of nymphs and adults, fecundity and egg hatchability were significantly increased by the increase of nitrogen content in host plants at 38℃. Moreover, the survival of nymphs,fecundity and egg hatchability were significantly higher in BPH populations on rice plants with a high nitrogen regimen than those on rice plants with a low nitrogen regimen.Meanwhile, the tolerance of female adults to starvation and nymphs to growth regulator buprofezin on rice plants with a high nitrogen regimen were slightly increased. This indicates that the tolerances of BPH to adverse environmental stresses were positively increased by the application of nitrogenous fertilizer. The outbreak potential of BPH induced by the excessive application of fertilizer in rice fields was also discussed.     

Using iron fertilizer to control Cd accumulation in rice plants: A new promising technology

Effects of two kinds of iron fertilizer, FeSO4 and EDTA·Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA·Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA·Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentra- tion in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA·Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentra- tion of iron, copper and manganese element in rice grain and also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA·Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils.     

Additive and additive × additive interaction make important contributions to spikelets per panicle in rice near isogenic (Oryza sativa L.) lines

Epistasis plays an important role in the genetic basis of rice yield traits. Taking interactions into account in breeding programs will help the development of high-yielding rice varieties. In this study, three sets of near isogenic lines (NILs) targeting three QTLs for spikelets per panicle (SPP), namely qSPP1, qSPP2 and qSPP7, which share the same Zhenshan 97 genetic background, were used to produce an F 2 population in which the three QTLs segregated simultaneously. The genotypes of the individual F 2 plants at the three QTLs were replaced with three markers that are closely linked to the corresponding QTLs. These QTLs were validated in the F 2 and F 3 popula- tions at the single marker level. qSPP7 exhibited major pleiotropic effects on SPP, plant height and heading date. Multifactor analysis of variance was performed for the F 2 population and its progeny. Additive × additive interaction between qSPP2 and qSPP7 had significant effects on SPP in both the F 2 population and its progeny. Both additive and additive × additive interactions could explain about 73% of the total SPP phenotypic variance. The SPP performance of 27 three-locus combinations was ranked and favorable combinations were rec- ommended for rice breeding in different ecosystems.     

Balanced nitrogen economy as a flexible strategy on yield stabilizing and quality of aquatic food crops in wetland ecosystem

In wetland ecosystem, nitrogen along with other elements and its management is most imperative for the production of so many aquatic food, non-food and beneficial medicinal plants and for the improvement of soil and water characteristics. With great significant importance of INM (integrated nutrient management) as sources, emphasizing on management on nitrogen as a key element and its divergence, a case study was undertaken on such aquatic food crops (starch and protein-rich, most popular and remunerative) in the farmers' field of low-lying 'Tal' situation of New Alluvial Zone of Indian subtropics. The study was designed in factorial randomized block design, where, three important aquatic food crops (water chestnut (Trapa bispinosa Roxb.), makhana (Euryale ferox Salisb.) and water lily (Nymphaea spp.) as major factor and eleven combinations of organic and inorganic sources of nutrients as sub-factor was considered in the experiment. It revealed from the results that the production of fresh kernels or nuts of water chestnut (8.571 ha-1), matured nut yield of makhana (3.06 t ha-1) and flower stalks of water-lily as vegetables (6.38 t ha-1) including its nutritional quality (starch, protein, sugar and minerals) was remarkably influenced with the application of both organic (neem oilcake @ 0.2 t ha-1) and inorganic sources (NPK @ 30:20:20 kg ha-1 along with spraying of NPK @ 0.5% each over crop canopy at 20 days interval after transplanting) than the other INM combinations applied to the crops. Among the crops, highest WCYE (water chestnut yield equivalence) exhibited in makhana due to its high price of popped-form in the country, which is being exported to other countries at now. Sole application of both (organic and inorganic sources) with lower range did not produce any significant outcome from the study and exhibited lower value for all the crops. Besides production of food crops, INM also greatly influenced the soil and water characterization and it was favourably reflected in this study. The physico-chemical characteristics of soil (textural class, pH, organic carbon, organic matter, ammoniacal nitrogen, nitrate nitrogen, available nitrogen, phosphorus and potassium) are most important and contributed a significant improvement due to cultivation of these aquatic crops. Analysis of such wet bodies represented the water characteristics (pH, BOD, COD, CO3 =, HCO3-, NO3- N, SO4-S and Cl-) were most responsive, adaptable and quite favourable for the cultivation of these crops in this vast waste unused wetlands for the mankind without any environmental degradation.     

基于GIS的农田土壤、作物特征空间变异性及其相互关系

The objective of this research was to investigate the variability and the quantitative relationships among soil nutrients and crop growth status and yield. All data were analyzed by both classical statistics and geostatistics based on GIS. Soil properties included soil pH, total N, organic matter, available P and available K, while crop growth status was indicated by SPAD, LAI and SPAD × LAI. All parameters except soll pH exhibited spatial correlation.Soil total N and organic matter, SPAD, LAI and SPAD × LAI were all correlated to rice yield. Kriged interpolation maps provided good indication of the spatial variability in crop yield and growth status. Spatial interpolation and correlation analysis proved that SPAD × LAI was more indicative of crop growth status than individual variables, and useful for implementing growth season and topdressing as needed.     

Simulating the rice yield change in the middle and lower reaches of the Yangtze River under SRES B2 scenario

As one of the most important crops in China, rice accounts for 18% of the country’s total cultivated area. Increasing atmospheric CO₂ concentration and associated climate change may greatly affect the rice productivity. Therefore, understanding the impacts of climate change on rice production is of great significance. This paper aims to examine the potential impacts of future climate change on the rice yield in the middle and lower reaches of the Yangtze River, which is one of the most important food production regions in China. Climate data generated by the regional climate Model PRECIS for the baseline (1961–1990) and future (2021–2050) period under IPCC SRES B2 scenario were employed as the input of the rice crop model ORYZA2000. Four experimental schemes were carried out to evaluate the effects of future climate warming, CO₂ fertilization and water managements (i.e., irrigation and rain-fed) on rice production. The results indicated that the average rice growth duration would be shortened by 4 days and the average rice yield would be declined by more than 14% as mean temperature raised by 1.5 °C during the rice growing season in 2021–2050 period under B2 scenario. This negative effect of climate warming was more obvious on the middle and late rice than early rice, since both of them experience higher mean temperature and more extreme high temperature events in the growth period from July to September. The significance effect of the enhanced CO₂ fertilization to rice yield was found under elevated CO₂ concentrations in 2021–2050 period under B2 scenario, which would increase rice yield by more than 10%, but it was still not enough to offset the negative effect of increasing temperature. As an important limiting factor to rice yield, precipitation contributed less to the variation of rice yield than either increased temperature or CO₂ fertilization, while the spatial distribution of rice yield depended on the temporal and spatial patterns of precipitation and temperature. Compared to the rain-fed rice, the irrigated rice generally had higher rice yield over the study area, since the irrigated rice was less affected by climate change. Irrigation could increase the rice yield by more than 50% over the region north of the Yangtze River, with less contribution to the south, since irrigation can relieve the water stress for rice growing in the north region of the study area. The results above indicated that future climate change would significantly affect the rice production in the middle and lower reaches of the Yangtze River. Therefore, the adverse effect of future climate change on rice production will be reduced by taking adaptation measures to avoid disadvantages. However, there is uncertainty in the rice production response prediction due to the rice acclimation to climate change and bias in the simulation of rice yield with uncertainty of parameters accompanied with the uncertainty of future climate change scenario.     

Simulating the rice yield change in the middle and lower reaches of the Yangtze River under SRES B2 scenario

As one of the most important crops in China, rice accounts for 18% of the country’s total cultivated area. Increasing atmospheric CO₂ concentration and associated climate change may greatly affect the rice productivity. Therefore, understanding the impacts of climate change on rice production is of great significance. This paper aims to examine the potential impacts of future climate change on the rice yield in the middle and lower reaches of the Yangtze River, which is one of the most important food production regions in China. Climate data generated by the regional climate Model PRECIS for the baseline (1961–1990) and future (2021–2050) period under IPCC SRES B2 scenario were employed as the input of the rice crop model ORYZA2000. Four experimental schemes were carried out to evaluate the effects of future climate warming, CO₂ fertilization and water managements (i.e., irrigation and rain-fed) on rice production. The results indicated that the average rice growth duration would be shortened by 4 days and the average rice yield would be declined by more than 14% as mean temperature raised by 1.5 °C during the rice growing season in 2021–2050 period under B2 scenario. This negative effect of climate warming was more obvious on the middle and late rice than early rice, since both of them experience higher mean temperature and more extreme high temperature events in the growth period from July to September. The significance effect of the enhanced CO₂ fertilization to rice yield was found under elevated CO₂ concentrations in 2021–2050 period under B2 scenario, which would increase rice yield by more than 10%, but it was still not enough to offset the negative effect of increasing temperature. As an important limiting factor to rice yield, precipitation contributed less to the variation of rice yield than either increased temperature or CO₂ fertilization, while the spatial distribution of rice yield depended on the temporal and spatial patterns of precipitation and temperature. Compared to the rain-fed rice, the irrigated rice generally had higher rice yield over the study area, since the irrigated rice was less affected by climate change. Irrigation could increase the rice yield by more than 50% over the region north of the Yangtze River, with less contribution to the south, since irrigation can relieve the water stress for rice growing in the north region of the study area. The results above indicated that future climate change would significantly affect the rice production in the middle and lower reaches of the Yangtze River. Therefore, the adverse effect of future climate change on rice production will be reduced by taking adaptation measures to avoid disadvantages. However, there is uncertainty in the rice production response prediction due to the rice acclimation to climate change and bias in the simulation of rice yield with uncertainty of parameters accompanied with the uncertainty of future climate change scenario.     

Eco-physiological responses of the declining population Spartina anglica to N and P fertilizer addition

Nitrogen and phosphorus are both important life elements. N, P and combined N-P fertilizers were added to the declining population Spartina anglica Hubbard in coastal China. Some growth parameters and eco-physiological responses of S. anglica to different fertilizer treatments (N, P and combined N-P fertilizer addition with high, medium and low levels, respectively) were measured. The fertilizer addition had a highly significant effect on the dynamics of its height-growth, number of leaves, number of roots and total biomass. Only N addition had a significant effect on leaf area and leaf thickness in all fertilizer treatments. On the dynamics of its height-growth, the effect of N addition was the most apparent, and the effect of N-P addition was not greater than those of N and P addition separately. The photosynthesis rate was enhanced and the yield was the highest with the highest N, the highest N-P and the medium P addition. The rates were higher than those of CK by 19.08 μmol·m^?2·s^?1, 15.47 μmol·m^?2·s^?1 and 11.23 μmol·m^?2·s^?1, respectively. The activity of SOD and POD increased with the treatments after freshwater stress for 14 days. Effects of medium N and P addition were significant for SOD activity. However, POD activity was significantly higher with the treatment of higher N and higher N-P addition. In a word, fertilizer addition improved the growth of the declining population S. anglica. The results indicated that the decline of S. anglica was correlated with the nutriment deficiency in soil, especially with the lack of N.     

Effect of planting date and nitrogen fertilization on photosynthesis and soluble carbohydrate contents of cotton in relation to silverleaf whitefly （Bemisia tabaci biotype “B”） populations

The impacts of planting date and nitrogen fertilization on cotton （Gossypium hirsutum L.） photosynthesis and soluble carbohydrate contents in relation to silverleaf whitefly, Bemisia tabaci （Gennadius） biotype “B”, populations were examined in field experiments. Cotton planted in late April and early June was treated with 0, 112, 168 and 224 kg/N hectare in soil using urea fertilizer. The mean photosynthetic rate of April-planted cotton was 4%-20% higher than that of June-planted cotton early in the season, but 10%- 18% lower than that of June-planted cotton late in the season. The photosynthetic rates for both planting dates were positively correlated with levels of added nitrogen. While levels of glucose for both planting dates were positively correlated with nitrogen levels, fructose and sucrose levels were not. The mean levels of fructose were up to 40% lower, while that of sucrose were up to 59% higher, in April-planted cotton than in June-planted cotton. Levels of photosynthetic rate or stomatal conductance were not correlated with adult whitefly densities for either planting date. Levels of glucose and fructose were positively correlated with whitefly densities only for June-planted cotton late in the season.     

Impacts of population growth and economic development on the nitrogen cycle in Asia

Asia is the major consumer of fertilizer nitrogen and energy in the world, and consequently shares a considerable proportion of the world creation of reactive nitrogen (Nr). However, if estimated on per capita basis, Asia is characterized by a lower arable land area, fertilizer nitrogen consumption, energy consumption, and gross domestic product, as well as lower daily protein intake. To meet the increasing needs for food and energy for the growing population combined with the improvement of living standards, Nr will inevitably increase. The present study estimates the creation of Nr and the emissions of various N compounds into environment in Asia currently and in 2030. In comparison with the world averages, the lower fertilizer nitrogen and energy use efficiencies, and the lower use of animal wastes for agriculture imply that there is potential for moderating the increase in Nr and its impacts on the environment. Strategies for moderating the increase are discussed.     

15N标记水稻控释氮肥对提高氮素利用效率的研究

本文应用^15N示踪技术研究了水稻对空控释氮肥和尿素氮吸收利用效率的影响以及氮的去向,结果表明：施肥后11天内,水稻控释氮肥和尿素的NH3挥发损失分别占施入氮量的0.69%和1.81%,NH3的挥发损失在施肥后第5天时达到最大值,此后逐渐降低。水稻控释氮肥和尿素氮的淋溶损失分别占施入氮量的0.95%和1.02%,水稻控释氮肥氮的淋溶损失在水稻整个生长期间均比较平缓,施肥后40天时略有上升,此后又缓慢降低。用氮素平衡帐中的亏缺量和缺量扣除氨的损失量后计为硝化-反硝化损失量的结果表明,水稻控制氮肥氮的硝化-反硝化损失量占施氮量的3.46%,而尿素氮在硝化-反硝化损失量却高达37.75%,肥料氮在土壤中的残留主要集中在0～35cm的土层中,达91.4%-91.5%,残留在35cm以下土层中的氮甚微,水稻控制氮肥残留在土壤中的氮量略高于尿素处理。水稻控释氮肥利用率高达73.8%,比尿素高出34.9%,水稻控释氮肥氮利用率高的原因是因氮从颗粒中缓慢释放、受淋溶、氨挥发、尤其受硝化-反硝化途径损失的氮较少。在施等氮量的条件下,施用水稻控制氮肥的稻谷产量比尿素的增产25.5%,达到p=0.05的显著水平。     

Nitrogen transformation processes in relation to improved cultural practices for lowland rice

Summary Inappropriate method and timing of N fertilizer application was found to result in 50–60% N losses. Recent nitrogen transformation studies indicate that NH₃ volatilization in lowland rice soils is an important loss mechanism, causing a 5–47% loss of applied fertilizer under field conditions. Estimated denitrification losses were between 28 and 33%. Ammonia volatilization losses from lowland rice can be controlled by i) placement of fertilizer in the reduced layer and proper timing of application, ii) using phenylphosphorodiamidate (PPD) to delay urease activity in flooded soils, and iii) using algicides to help stabilize changes in floodwater pH. Appropriate fertilizer placement and timing is probably the most effective technique in controlling denitrification at the farm level. The effectivity of nitrification inhibitors as another method is still being evaluated. With 60–80% of N absorbed by the crop derived from the native N pool, substantial yield gains in lowland rice are highly possible with resources already in the land. Extensive studies on soil N and its management, and an understanding of soil N dynamics will greatly facilitate the decrease in immobilization and ammonium fixation in the soil and the increase in N availability to the rice crop. Critical research needs include greater emphasis on N transformation processes in rainfed lowland rice which is grown under more harsh and variable environmental regimes than irrigated lowland rice.     

稻麦轮作体系下有机肥施用对作物产量和土壤性质影响的整合分析

为明确稻麦轮作系统有机肥施用对作物产量和土壤性质的影响,本研究搜集已公开发表的文献数据,利用meta分析法定量分析了有机肥类型(普通有机肥、生物质炭、秸秆)、施用策略(单施有机肥、有机肥配施部分化肥、有机肥配施全量化肥)、施用年限(短期、中期、长期)对稻麦产量和土壤性质的影响及其对不同土壤条件(酸性、中性、碱性)的响应。结果表明: 与单施化肥相比,有机肥施用对水稻和小麦的增产效应相近,分别为3.1%和3.0%。有机肥施用对土壤性质的提升效果更明显,显著降低了土壤容重(5.7%),显著提高了土壤有机质、全氮、全磷、碱解氮、速效磷和速效钾含量,以及微生物生物量碳、氮,增幅在11.7%～38.4%。不同类型有机肥中,生物质炭和普通有机肥对土壤性质的改良效果优于秸秆;与单施有机肥相比,有机肥配施化肥的作物增产效果更好,而土壤性质改良效果较差;随着有机肥施用年限增加,作物增产和土壤肥力提升效应逐渐增强;在酸性土壤条件下有机肥施用对作物的增产效果最显著。土壤容重与稻麦周年产量呈显著负相关,而土壤全氮、速效磷、速效钾含量和微生物生物量氮与稻麦周年产量呈显著正相关关系。     

控释氮肥对抗除草剂转基因水稻田土壤甲烷排放的影响

采用温室盆栽和静态箱-气相色谱法,研究了控释氮肥对抗除草剂转基因水稻和亲本常规水稻稻田土壤甲烷(CH4)排放的影响。供试土壤为潴育型水稻土,氮肥种类为尿素和控释氮肥。结果表明,与对照(尿素)相比,控释氮肥提高了水稻分蘖数、株高、生物量及产量。水稻品种对CH4季节性排放规律没有明显影响,CH4排放通量基本表现为,自水稻移栽后逐渐升高,移栽后62—92 d出现峰值,而后逐渐降低至水稻收获。与对照相比,控释氮肥可显著降低CH4排放通量和全生育期累积排放量。抗除草剂转基因水稻稻田土壤CH4排放通量和累积排放量均显著低于亲本常规水稻。研究认为,一次性基施控释氮肥和种植抗除草剂转基因水稻对有效减缓稻田甲烷排放具有重要意义。     

The nitrogen fertilization of spring barley

Summary From 1971 to 1979 field trials with increasing rates of fertilizer nitrogen on spring barley with sugar beet as the preceding crop were conducted on a farm on sandy loam in the south western part of The Netherlands. Prior to sowing and fertilizing soil samples were taken and analysed for mineral nitrogen (N_min). The average yield increase through application of fertilizer nitrogen was only 750 kg of grain per ha per year, the maximum yield being about 5 tonnes per ha. In the case of a fixed rate of fertilizer nitrogen per annum it can be derived from the response curves that 60 kg of N would have given the smallest average yield deficit (170 kg grain per ha) in comparison with maximum yields. With an N-advisory system based on soil analysis the average yield deficit would be at a minimum (163 kg of grain per ha) with a value for mineral soil nitrogen+fertilizer nitrogen totalling 120 kg N per ha.No relationship was found between optimum rate of fertilizer nitrogen and the amount of mineral soil nitrogen at the end of the winter. This was ascribed to the relatively small variation in mineral soil nitrogen and the weak response of the crop to fertilizer nitrogen.Promising results from nitrogen fertilizing systems based on soil analysis can be expected from more responsive crops like winter wheat, sugar beets and potatoes.With the average yield deficit compared with maximum yield as a characteristic, the usefulness of any N-advisory system can be compared, taking a fixed rate of nitrogen system as a standard.Seconded by the Agricultural Bureau of the Netherlands Fertilizer Industry (LBNM).     

施氮水平对两种水稻产量影响的动态模拟及施肥优化分析

借助水稻生长模型ORYZA-0和氮肥管理模块,通过田间和水槽的水稻氮肥试验,对水稻模型和N素动态模块进行了验证。结果表明,模型模拟的不同N素水平水稻生物量、产量同实际测定值明显呈正相关。其中,氮肥用量160kg·hm^-2为最佳经济施氮量,通过获得的水稻参数和氮肥应用曲线模拟的氮肥运筹结果表明：1)在低N(N<100kg·hm^-2)水平下,氮肥应在移栽后35d内全部施入;2)当施氮量为100～200kg·hm^-2时,N应在移栽后45d内全部施入;3)当施氮量N>200kg·hm^-2时,氮肥应在移栽后60d内全部施入;4)随着施氮量的增加,后期施肥比重可略为增加。总体来看,模型不仅能较准确地模拟水稻生长动态,而且可以模拟水稻N吸收和积累的行为动态,从大田晚稻的氮肥运筹模拟结果可看出,氮肥应用次数越多,越接近施氮应用积累曲线的连续施氮产量模拟值(6199kg·hm^-2),但是在实际生产中这会增加农民的用工量和生产成本,难以让农民接受。因而在生产实际中既能让生产者接受,又不致较多地影响产量和收入,在160kg·hm^-2(纯N)施用量下的最佳施肥方案为N素化肥分4次按0．2：0．3：0．3：0．2的比例,分别于移栽后5、20、30和40d施入,可获得5916kg·hm^-2的产量。     

稻茬冬小麦氮肥吸收、残留和损失特性

为推进稻茬小麦氮肥合理施用,采取田间¹⁵N示踪技术研究了施氮量(0、150、225、300 kg·hm^-2,分别表示为N₀、N₁₅₀、N₂₂₅、N₃₀₀)对氮肥回收、残留、损失和籽粒产量的影响。结果表明: 随施氮量增加,小麦植株不同来源氮素积累量显著增加,氮肥回收率则显著下降。基肥氮以越冬至拔节期在植株中的积累量最高,追肥氮以拔节至开花期积累量最高;成熟期各处理追肥氮在植株中的积累量均高于基肥氮,N₁₅₀处理植株中土壤氮的积累量高于肥料氮,N₂₂₅、N₃₀₀处理呈相反趋势。随施氮量增加,成熟期0～100 cm土层氮肥残留量显著增加,肥料氮在60～100 cm土层残留比例逐渐升高。小麦全生育期氮肥损失量和损失率均随施氮量增加而增加,基肥氮损失量以播种至越冬期最高,追肥氮损失量以拔节至开花期最高。综合考虑籽粒产量,N₂₂₅处理可作为稻茬小麦氮肥推荐用量,相应的籽粒产量为6735 kg·hm^-2,氮肥回收率、土壤残留率和损失率分别为42.6%、34.0%和23.3%。     

Uptake of fertilizer nitrogen and soil nitrogen by rice using15N-labelled nitrogen fertilizer

Data from five field experiments using labelled nitrogen fertilizer were used to determine the relative effects of soil nitrogen and fertilizer nitrogen on rice yield. Yield of grain was closely correlated with total aboveground nitrogen uptake (soil+fertilizer), less closely correlated with soil nitrogen uptake and not significantly correlated with fertilizer nitrogen uptake. When yield increase rather than yield was correlated with fertilizer nitrogen uptake, the correlation coefficient was statistically significant.Contribution from the Laboratory for Flooded Soils and Sediments, Agronomy Dept., Louisiana Agri. Exper. Sta., Louisiana State Univ., Baton Rouge, LA 70803, and Univ. of Florida, Agricultural Research and Education Center, Sanford, FL 32771.     

不同供氮水平下施硅对辣椒产量与营养品质及其养分吸收利用的影响

为探究不同供氮水平下施硅对辣椒产量、果实品质及养分吸收利用的影响，以辣椒品种‘奥黛丽’为试验材料，采用基质栽培，设置正常施氮肥（1.0N：260.9 kg/667 m2）、氮肥减施40%（0.6N：149.1 kg/667 m2）、氮肥减施60%（0.4N：104.3 kg/667 m2）、不施氮肥（0N：0 kg/667 m2）4个不同供氮（基施）水平和2个硅肥（根施）水平（0 mmol/L、1.5 mmol/L），研究不同供氮水平下硅对辣椒产量、品质及氮肥利用效率的影响效应，并筛选出最佳施肥处理，旨在为辣椒的增产提质提供理论基础和技术参考。结果表明：（1）0.6N供氮水平较1.0N、0.4N和0N供氮水平下的辣椒果实产量分别提高了7.18%、74.14%和87.99%，施硅处理后则进一步促进了果实产量，其中0.6N供氮水平下施硅较正常供氮量下的辣椒果实产量提高了15.33%；（2）0.6N供氮水平更有利于促进辣椒果实中可溶性糖、还原糖、可溶性蛋白、维生素C含量的提高和可滴定酸、NO3?含量的降低，施硅后不同供氮水平下辣椒果实品质均显著提高；（3）0.6N供氮水平更有利于辣椒果实矿质元素的积累与土壤氮肥利用率的提高，其中0.6N供氮水平较1.0N供氮水平下的氮肥利用率与氮肥农学效率分别显著提高了97.57%和69.20%，施硅处理后不同供氮水平下辣椒果实矿质元素含量与土壤氮肥利用率均显著提高；（4）通过对辣椒产量及果实品质指标的主成分分析，结果表明，0.6N+Si处理下的综合得分最高，即氮肥减施40%配施1.5 mmol/L的外源硅肥对辣椒产量、品质及氮肥的吸收利用促进效果最佳。     

The effect of deep placement and surface application of nitrogen fertilizers at different light intensities on growth and yield of wetland rice

Summary Lowland rice (RD 3) was cultivated in containers of clay soil submerged with 5 cm water under controlled conditions in the phytotron. Deep placement of urea supergranules 5 cm in the soil significantly enhanced both plant growth and fertilizer efficiency when the plants were cultivated under high light intensity (70 Wm^–2). At the highest urea level grain yield increased 119% above the control level, while growth and fertilizer efficiency was not as high when deep placement of calcium nitrate was used.The application of urea prills and calcium nitrate (18.4g Nm^–2) in two split doses on the soil surface increased grain yield as much as 91% above the control level. At the lower nitrogen concentration (9.2 g N m^–2), the urea prills were more efficient than calcium nitrate as indicated by the grain yield. The height of those plants fertilized by surface application was affected by the concentration and not the type of fertilizer. The number of tillers, however, was significantly higher on urea fertilized plants.When the rice plants were cultivated under low light intensity 930 Wm^–2), neither the nitrogen fertilizers nor the method of application had a significant effect on growth and yield.