Effects of N level on occurrence of wheat powdery mildew in wheat and faba bean intercropping system

摘要

Field trials were carried out in Shilin, Yunnan province to investigate the occurrence of wheat powdery mildew (Blumeria graminis) and its relation to N application levels and wheat N nutrition status in wheat (Triticum aestivum)/faba bean (Vicia Fabe L.) intercropping system. Results showed that, the occurrence of wheat powdery mildew was postponed 10 days and the incidence and severity decreased significantly in wheat and faba bean intercropping system compared with wheat monocrop. The incidence and severity of powdery mildew of intercropped wheat decreased by 16.45%-26.1% in comparison with that of monocrop of wheat, and the average control efficiency in intercropped wheat was 21.61% at different N supply levels. With increasing N level, the incidence and severity of powdery mildew increased markedly. At wheat booting stage, the incidence were 32.9%, 39.2%, 40.8%, 51.9% in wheat monocrop and were 27.5%, 30.0%, 32.5%, 38.0% in intercropped wheat at 0, 112.5, 225.0, and 337.5 kg N/hm~(-2) levels respectively. Powdery mildew incidence showed positively correlation with N level and total N content of wheat shoots. The research indicated that, higher N level was one of the major reasons for the occurrence and severity of wheat powdery mildew and wheat/faba bean intercropping could increase the resistance to this disease and reduce the damage to wheat growth and yield. The mechanisms behind this need to be studied further.