Wheat powdery mildew and foliar N concentrations as influenced by N fertilization and belowground interactions with intercropped faba bean

Abstract

Wheat (Triticum aestivum L.) production by intercropping with faba bean (Vicia faba L.) has increased in popularity but is often associated with severe wheat powdery mildew (Blumeria graminis (DC.) Speer). Very little is known about the effects of below-and aboveground interspecific interactions on wheat nitrogen (N) nutrition and occurrence of wheat powdery mildew. A greenhouse pot experiment examined four N application rates and three belowground partition types (plastic film, nylon mesh partition or no partition) to study N nutrition and interactions between wheat and faba bean growing together. A field experiment investigated three N application rates and growth of wheat in monoculture and intercropped with faba bean with or without belowground plastic film partitions between wheat and faba bean. Disease incidence (DI) and disease severity index (DSI) were assessed at flowering stage and wheat leaves were sampled and analyzed for N. Foliar N was enhanced substantially by N addition in greenhouse and field conditions and also by belowground interactions (no partition compared with plastic film partition) in the pot experiment (all P < 0.001). There was a significant synergistic effect between N rate and belowground interactions on the enhancement of wheat N uptake (P < 0.01) in the pot experiment. DI and DSI of mildew increased markedly with increasing N rate in both experiments (all P < 0.001). In the pot experiment DI and DSI showed no marked differences among belowground partitions (both P > 0.05) but belowground interactions had soil but promoting disease with 0.05 g added N kg -1 soil. In the field experiment DI and DSI showed no significant differences between wheat monoculture and intercropping (both P > 0.05). However, the contributions of below-and aboveground interactions to disease control were different under different N rates, with interspecific root interactions increasing DI and DSI under different N rates and aboveground interactions increasing DI and DSI under zero-N application but decreasing DI and DSI at 150 and 300 kg N ha -1 . The data suggest that the microclimate in the field and biological control mechanisms due to belowground interactions in wheat-faba bean associations may influence the incidence and severity of wheat powdery mildew.

Wheat Growth Is Stimulated by Interspecific Competition after Faba Bean Attains Its Maximum Growth Rate

“…The practice of cereal and legume intercropping often results in increased resource self-sufficiency and higher yield Yu et al, 2015). The present finding is in accordance with the results of previous research (i.e., intercropping of wheat and faba bean resulted in a yield advantage over the corresponding monocultures based on LER; Chen et al, 2007;Agegnehu et al, 2008). In the present study, we found wheat and faba bean intercropping enhanced wheat P acquisition but exerted no effect on faba bean P acquisition (Table 6).…”

“…These studies clearly confirmed that the interactions were dynamic within and among species during the growing season, and plant interaction stimulated N and P transfer from faba bean to wheat during certain growth stages (Li et al (2014a. Increasing attention has focused on wheat and faba bean intercropping (Xiao et al, 2004;Chen et al, 2007;Qiao et al, 2016), but so far there has been no clear clue on interspecies competition and facilitation during their coexisting development stages under field conditions, particularly at different nutrient levels. Increasing attention has focused on wheat and faba bean intercropping (Xiao et al, 2004;Chen et al, 2007;Qiao et al, 2016), but so far there has been no clear clue on interspecies competition and facilitation during their coexisting development stages under field conditions, particularly at different nutrient levels.…”

“…However, these findings were derived from pot experiments, which do not accurately reflect crop performances under field conditions. Increasing attention has focused on wheat and faba bean intercropping (Xiao et al, 2004;Chen et al, 2007;Qiao et al, 2016), but so far there has been no clear clue on interspecies competition and facilitation during their coexisting development stages under field conditions, particularly at different nutrient levels.…”

Grain Legumes

“…Similarly, mixed results were found for effects of intercropping cowpea on insect pests (Jackai and Daoust 1986). Also, intercropping wheat with faba beans can lead to higher disease infection with powdery mildew (Blumeria graminis) in wheat (Chen et al 2007), possibly because of higher levels of foliar N in wheat leaves, and also because of a moister climate in the intercrop than in the wheat monocrop.…”

Temporal and spatial dynamics of wheat powdery mildew in Sichuan Province, China

“…Powdery mildew exhibits an extended logistic period in extremely susceptible plant varieties (Wang and Zhang, 1998) and the occurrence and severity of this disease are determined by weather factors (Te Beest et al, 2008). The spatial epidemiology of wheat powdery mildew was affected mainly by wind and airflow, and the temporal dynamics were affected primarily by temperature and humidity (Bruggmann et al, 2005;Chen et al, 2007;Johnson et al, 1994;Last, 1953;Moschini and P erez, 1999;Schepers et al, 1996;Te Beest et al, 2008). The relationship between weather and disease epidemics was examined by Johnson et al (1994) using linear discriminant and logistic regression analyses.…”