小麦与蚕豆间作系统施氮对蚕豆赤斑病发生和冠层微气候的影响

通过田间小区试验,设N₀(0 kg·hm^-2)、N₁(45 kg·hm^-2)、N₂(90 kg·hm^-2)、N₃(135 kg·hm^-2)4个施氮水平,研究不同施氮水平下小麦与蚕豆间作对蚕豆赤斑病发生和冠层微气候的影响,探讨间作系统氮肥调控下冠层微气候变化及其与蚕豆赤斑病发生的关系.结果表明: 施氮提高了蚕豆单、间作种植模式下蚕豆赤斑病发病盛期的病情指数,增幅27.2%～58.0%,增加了病情进展曲线下面积(AUDPC),增幅15.0%～101.8%,N₃水平下赤斑病病情指数和AUDPC最高.施氮使蚕豆冠层温度降低0.2～1.1 ℃,冠层透光率降低1.7%～29.7%,冠层相对湿度增加0.5%～28.7%.与单作相比,间作蚕豆赤斑病病情指数显著降低36.3%～48.1%,AUDPC显著降低44.0%～53.6%,冠层温度和透光率分别提高2.1%～8.7%和12.0%～53.8%,相对湿度降低11.6%～31.6%.相关分析表明,冠层温度和透光率与赤斑病病情指数呈显著负相关,而湿度与病情指数呈显著正相关.表明高氮恶化了冠层微气候环境,加重了蚕豆赤斑病的发生和危害,而间作对蚕豆冠层微气候的改善是控制蚕豆赤斑病发展的重要原因.

Effects of N application on faba bean chocolate spot and canopy microclimate in wheat and faba bean intercropping system

A field experiment was conducted to examine the effects of nitrogen application levels, i.e. N₀ (0 kg·hm^-2), N₁ (45 kg·hm^-2), N₂ (90 kg·hm^-2), N₃ (135 kg·hm^-2), on the severity of chocolate spot and canopy microclimate in wheat and faba bean intercropping system, and to explore the relationship of canopy microclimate change and severity of chocolate spot. The results showed that the disease index of chocolate spot increased by 27.2%-58.0% in the peak infection stage, and the area under disease progress curve (AUDPC) increased by 15.0%-101.8% for both monocropped and intercropped faba bean after nitrogen application. The peak value of disease index and AUDPC appeared at N₃ (135 kg·hm^-2) level. After nitrogen application, canopy temperature decreased by 0.2-1.1 ℃ and canopy light transmittance decreased by 1.7%-29.7%, but canopy relative humidity increased by 0.5%-28.7%. Compared with monocropped faba bean, wheat and faba bean intercropped significantly decreased the chocolate spot disease index by 36.3%-48.1% and AUDPC by 44.0%-53.6%. Canopy temperature and light transmittance of intercropped faba bean increased by 2.1%-8.7% and 12.0%-53.8%, respectively. The canopy relative humidity was decreased by 11.6%-31.6%. There were significantly negative correlation between canopy temperature and light transmittance with disease index of faba bean chocolate spot. The canopy humidity was positively correlated with disease index. Our findings showed that high nitrogen application deteriorated canopy microclimate of faba bean that led to occurrence and harm of chocolate spot, and that the improvement of canopy microclimate by intercropping would be helpful for controlling faba bean chocolate spot.