间作系统氮调控对小麦氮钾营养及条锈病发生的影响

通过探讨间作和施氮对小麦植株氮钾养分吸收、分配及条锈病发生的影响,明确氮钾养分吸收和分配与小麦条锈病发生的关系,以期为合理施肥实现控病增产提供理论依据。在云南安宁和峨山两地布置田间小区试验,研究3种施氮水平(0 kg×hm~(–2)、90 kg×hm~(–2)和180 kg×hm~(–2))和2种种植模式(小麦单作、小麦||蚕豆间作)对小麦植株氮钾含量与分配以及小麦条锈病发病率及病情指数的影响。结果表明,施氮增加了小麦产量,且间作增产效应显著;与单作相比,间作小麦平均显著增产31.9%(安宁)和18.0%(峨山);小麦||蚕豆间作产量优势明显,土地当量比为1.20～1.37(安宁)和1.16～1.27(峨山),但间作增产优势随施氮量增加而降低。施氮在提高产量的同时也加重了小麦条锈病危害,随施氮量增加,单、间作小麦条锈病的发病率和病情指数均呈增加趋势。间作有较好的控病效果,与单作相比,间作小麦发病率、病情指数分别显著降低9.6%～22.0%、23.7%～33.7%(安宁)和29.5%～36.5%、29.3%～39.6%(峨山)。施氮增加了小麦植株氮含量,且主要累积在叶片,叶片氮含量占氮吸收总量的41.3%～47.4%(安宁)和35.9%～44.1%(峨山);但间作显著降低小麦植株氮含量,并显著提高钾含量,因而显著降低了叶片氮/钾比。相关性分析表明,小麦条锈病发病率和病情指数与植株氮含量、叶片氮/钾比呈显著正相关,与钾含量呈极显著负相关。施氮增加了小麦植株氮含量,提高了叶片氮/钾比,进而加剧小麦条锈病发生;而间作则通过增加钾含量,降低小麦植株氮含量及叶片氮/钾比,平衡小麦植株内氮钾养分而增强小麦对条锈病的抗性。

Effects of N application on nitrogen and potassium nutrition and stripe rust of wheat in an intercropping system

In order to provide a theoretical basis for rational fertilization to achieve disease control and yield increase of wheat, the effects of nitrogen (N) application levels and intercropping on the absorption and distribution of N and potassium (K) and the occurrence of stripe rust of wheat were studied. A field experiment with three N application rates-0 kg(N)·hm^-2 (N0), 90 kg(N)·hm^-2 (N1), 180 kg(N)·hm^-2 (N2)-and two planting patterns (wheat monocropping, and wheat and faba bean intercropping) were set up in Anning and Eshan, Yunnan Province to study the effect of N application rate and intercropping with faba bean on the content and distribution of N and K, and the incidence and disease index of wheat stripe rust. The results showed that wheat yeld was considerably increased by N application, especially in intercropping. Compared with monocropping, intercropping significantly increased wheat yield averagely by 31.9% (Anning) and 18.0% (Eshan). The yield advantage of wheat-faba bean intercropping was obvious and the land equivalent ratio (LER) was 1.20-1.37 (Anning) and 1.16-1.27 (Eshan) at the N0-N2 levels. However, the yield-increasing effect of intercropping was decreased with increase in the N application rate. N application not only increased the yield, but also aggravated the damage of wheat stripe rust, and therefore, the incidence and disease index were increased by 2.4%-30.0% and 5.6%-38.5% in Anning, and 6.4%-22.4% and 5.3%-43.2% in Eshan, respectively. Intercropping with faba bean presented a better control effect on wheat stripe rust than monocropping. The incidence and disease index of wheat stripe rust were reduced by 9.6%-22.0% and 23.7%-33.7% (Anning) and 29.5%-36.5% and 29.3%-39.6% (Eshan), respectively. The N content was increased by N application, which mainly accumulated in the leaves, accounting for 41.3%-47.4% (Anning) and 35.9%-44.1% (Eshan) of total N absorption. However, the N content was considerably reduced by 17.8%-21.8% (Anning) and 16.2%-16.9% (Eshan), whereas the K content was significantly increased by 22.6%-23.0% (Anning) and 16.2%-18.3% (Eshan), and thus the N/K ratio in the leaves was significantly reduced under intercropping system, compared with that under monocropping system. The correlation analysis showed that the incidence and disease index of wheat stripe rust were positively correlated with the plant N content and leaf N/K ratio, and negatively correlated with the K content. The N content in wheat plants and the N/K ratio in the leaves were increased by N application and thus, the occurrence of wheat stripe rust was aggravated. On the contrary, intercropping enhanced wheat resistance to stripe rust by increasing K content and reducing plant N content and N/K ratio in the leaves, and balancing N and K nutrients in wheat plants.