Abstract:

In order to explore the effects of nitrogen fertilizer and density interactions on the occurrence of diseases， insect pests and yield of rice， Liangyou 3905 was used as the material， and a split-plot test design was adopted. The nitrogen application rate was the main plot， and the plant density was the sub-plot. There were 4 nitrogen application rates including 0.0（N0），82.5（N82.5），165.0（N165），247.5 kg·hm^-2（N247.5） and 4 plant densities including 15×10⁴（D1），21×10⁴（D2），27×10⁴（D3），33×10⁴ plants·hm^-2（D4）. The occurrence of rice blast， stem borer and floret sterility， yield and yield components of each treatment were analyzed. The results showed that nitrogen application rates and plant density had significant and interactive effects on the incidence of rice blast， stem borer infestation and floret sterility. Compared with the N0 treatment， the application of nitrogen fertilizer increased the incidence of rice blast and disease index by 1.8~47.1 and 0.9~37.6 percentage points， respectively， while the incidence of stem borer initially increased and then decreased， ranging from -0.4 to 1.3 percentage points， and floret sterility decreased by 0.6~2.9 percentage points. The occurrence and severity of rice blast were significantly positively correlated with planting density， which increased by 1.2~3.0 and 0.7~3.1 percentage points， respectively， compared to D1. Both the incidence of stem borer and floret sterility showed a decreasing trend with increasing density， reducing by 0.7~1.2 and 0.9~1.8 percentage points， respectively， compared to D1. The yield increased with nitrogen application rates and plant density within a certain range. The application of nitrogen significantly increased the effective number of spikes and the number of grains per spike by 9.6%~25.1% and 18.4%~30.4%， respectively. Densification had a greater effect on the effective number of spikes， with an increase ranging from 25.1%~30.6%. The yield was maximum at 7 328 kg·hm^-2 under the treatment of N165D3. Continuing to increase nitrogen or density led to a decrease in yield. Appropriate combination of nitrogen and density significantly increased the effective number of spikes per unit area and balance the yield components for high yields. Based on the conditions of this experiment， binomial regression analysis and modeling revealed that the optimal nitrogen application rate was 182.18 kg·hm^-2， while the optimal planting density was 26.90×10⁴ plants·hm^-2. It was anticipated that the reinforcement of rice blast control on this basis would result in a further increase in yields. Above results provided theoretical foundation and technical support for the advancement of environmentally sustainable， high-yield and high-efficiency rice production.

Key words: nitrogen fertilizer, density, rice, pests and diseases, yield

摘要：

为探究氮肥与密度互作对水稻病虫害发生和产量的影响，以杂交稻两优3905为材料，采用裂区试验设计，主区为氮肥用量，设置0.0（N0）、82.5（N82.5）、165.0（N165）、247.5 kg·hm^-2（N247.5 ）共4个氮水平，副区为种植密度，设置15×10⁴（D1）、21×10⁴（D2）、27×10⁴（D3）和33×10⁴蔸·hm^-2（D4）共4个密度水平，对各处理稻瘟病、螟虫和颖花败育的发病情况及产量和产量构成因素进行分析。结果表明，氮肥用量和种植密度对水稻稻瘟病、螟虫和颖花败育的发生有显著影响，且存在交互作用。与N0处理相比，增施氮肥使稻瘟病发病率和病情指数分别增加1.8~47.1和0.9~37.6百分点；螟虫发病率表现为先升高后降低，变幅在-0.4~1.3百分点；颖花败育减少0.6~2.9百分点。稻瘟病的发生和发病程度与种植密度呈显著正相关，各处理较D1分别增加1.2~3.0和0.7~3.1百分点；螟虫和颖花败育均随密度增加呈下降趋势，各处理较D1分别减少0.7~1.2和0.9~1.8个百分点。产量在一定范围内随氮肥用量和种植密度的增加而增加，施氮使有效穗数和每穗粒数显著增加9.6%~25.1%和18.4%~30.4%，种植密度对有效穗数影响更大，增幅在25.1%~30.6%。产量在N165D3处理下达到最大，为7 328 kg·hm^-2，在此基础上继续增氮或增密均会导致减产，合理的氮密组合可显著提高单位面积有效穗数，平衡各产量构成因素而实现高产。在本试验条件下，通过二项回归分析和模型计算得出，适宜的氮肥用量为182.18 kg·hm^-2，适宜种植密度为26.90×10⁴蔸·hm^-2，在此基础上加强稻瘟病防治有望进一步提高产量。研究结果为水稻绿色高产高效发展提供理论依据和技术支撑。

关键词: 氮肥, 密度, 水稻, 病虫害, 产量