肥料减施下玉米-大豆间作对作物产量和昆虫群落组成及多样性的影响

为探究肥料减施下玉米-大豆间作对作物产量和昆虫群落组成及多样性的影响,在玉米、大豆单作及二者间作下施以标准肥料750 kg/hm~2和减半肥料375 kg/hm~2,于作物生长期调查田间昆虫群落组成及多样性,并在收获期对玉米和大豆进行测产。结果表明:与单作玉米相比,间作玉米在施用标准肥料下的百株生物量、百株籽粒重和千粒重分别显著增加78.33%、85.35%和38.71%,而在施用减半肥料下则分别显著增加90.91%、135.73%和33.33%;相同种植模式下,与施用标准肥料相比,减半肥料使单作玉米百株籽粒重显著降低22.45%。与单作大豆相比,在施用标准肥料下,间作大豆的百株籽粒重和千粒重分别显著降低49.47%和11.54%,在施用减半肥料下,间作大豆的百株生物量、百株籽粒重和千粒重分别显著降低73.94%、50.51%和17.39%;相同种植模式下,与施用标准肥料相比,减半肥料使大豆在单作和间作下的百株籽粒重分别显著降低65.02%和65.73%,使间作下大豆的百株生物量和千粒重分别显著降低73.14%和17.39%。与单作相比,间作均显著降低了标准肥料和减半肥料处理下玉米和大豆害虫群落的物种数、多样性指数和均匀度指数,还显著降低了标准肥料和减半肥料处理下玉米天敌昆虫群落的物种数和优势度指数以及大豆天敌昆虫群落的物种数和均匀度指数。表明玉米-大豆间作能有效提高玉米产量,降低虫害发生,但对大豆生产不利,而间作条件下减施肥料对玉米产量的影响更小。建议在田间生产中可将夏玉米和大豆间作种植,更有利于通过生态学方法控制田间害虫发生和增加作物总体产量。

Effects of monoculture and intercropping of maize and soybean with reduced use of fertilizer on crop yields, insect community composition and diversity

To explore the effects of intercropping of maize with soybean with reduced use of fertilizer on crop yield and insect community composition and diversity, the monoculture and intercropping of corn and soybean were designed with standard application of fertilizer (750 kg/hm²) and half application of fertilizer (375 kg/hm²). The diversity of insect communities in the field was investigated during the growing period and the yields of corn and soybean were measured after these crops were harvested. The results showed that, compared with monoculture, intercropping incorporated with standard application of fertilizer increased the biomass, grain weight of 100 maize plants and 1 000-grain weight by 78.33%, 85.35% and 38.71%, respectively, while the halved application of fertilizer increased those by 90.91%, 135.73% and 33.33%, respectively. Compared with standard fertilizer treatment, halved fertilizer treatment reduced the grain weight of 100 plants of monoculture maize by 22.45%. Intercropping incorporated with the standard application of fertilizer reduced the seed weight of 100 soybean plants and 1 000-seed weight by 49.47% and 11.54%, respectively, and halved application of fertilizer reduced the biomass, seed weight of 100 soybean plants and 1 000-seed weight by 73.94%, 50.51% and 17.39%, respectively. Compared with standard fertilizer treatment, halved fertilizer treatment reduced the seed weight of 100 soybean plants by 65.02% and 65.73%, respectively, when monoculture and intercropping were adopted, and reduced the biomass of 100 soybean plants and 1 000-seed weight by 73.14% and 17.39%, respectively, while intercropping was adopted. As compared to monoculture, intercropping significantly reduced the number of species, diversity index and evenness index of maize and soybean pest communities when standard fertilizer and half fertilizer were used, and significantly reduced the number of species and dominance index of natural enemies of maize, and the number of species and evenness index of natural enemies of soybean. The results showed that intercropping of maize and soybean could increase maize yield effectively, but not for soybean yield, and reduce the occurrence of insect pests. It indicated that summer maize and soybean should be intercropped in the field, which would be more beneficial for controlling the occurrence of field crop insect pests and hence increase the overall yield through natural balance in the ecosystem.