[Effects of maize and pea intercropping on the total grain yield of community under different planting densities.]

Under plastic-film fully-mulched ridge-furrow cropping, we studied the effects of within-row-intercropping on total grain yield of community using pea plants inserted into the maize rows with spacing of 40, 50 and 60 cm, respectively, in the Loess Plateau in 2014 and 2015. The result showed that there was significant increase in total grain yield of the community when two pea plants were inserted into the maize rows with spacing of both 40 and 50 cm, while pea plants inserted into the maize row with 60 cm spacing had no significant effects on total grain yield of the community compared to maize monoculture with the same plant spacing in 2014. In 2015, in contrast, when pea plants were inserted into the maize rows with plant spacing of 40 and 50 cm, no significant effect was observed even though there was an increasing trend in total grain yield of the community, while it increased significantly when two pea plants were inserted into the rows with spacing of 60 cm. The more abundant rainfall in 2014 than in 2015 induced the varied effects of intercropping pea plants on increasing the total grain yield of the community between the two cropping seasons. Gene-rally, the total grain yield of the community reached the highest under two pea plants intercropped with spacing of 40 cm. No matter whether in monocultures only with maize or in intercropping with both maize and peas, grain yield decreased significantly with increase of maize plant spacing in current experiment.