Effects of narrow-wide row planting patterns on canopy photosynthetic characteristics, bending resistance and yield of soybean in maize‒soybean intercropping systems.

With the improvements in mechanization levels, it is difficult for the traditional intercropping planting patterns to meet the needs of mechanization. In the traditional maize‒soybean intercropping, maize has a shading effect on soybean, which leads to a decrease in soybean photosynthetic capacity and stem bend resistance, resulting in severe lodging, which greatly affects soybean yield. In this study, we investigated the effects of three intercropping ratios (four rows of maize and four rows of soybean; four rows of maize and six rows of soybean; six rows of maize and six rows of soybean) and two planting patterns (narrow-wide row planting pattern of 80-50 cm and uniform-ridges planting pattern of 65 cm) on soybean canopy photosynthesis, stem bending resistance, cellulose, hemicellulose, lignin and related enzyme activities. Compared with the uniform-ridge planting pattern, the narrow-wide row planting pattern significantly increased the LAI, PAR, light transmittance and compound yield by 6.06%, 2.49%, 5.68% and 5.95%, respectively. The stem bending resistance and cellulose, hemicellulose, lignin and PAL, TAL and CAD activities were also significantly increased. Compared with those under the uniform-ridge planting pattern, these values increased by 7.74%, 3.04%, 8.42%, 9.76%, 7.39%, 10.54% and 8.73% respectively. Under the three intercropping ratios, the stem bending resistance, cellulose, hemicellulose, lignin content and PAL, TAL, and CAD activities in the M4S6 treatment were significantly greater than those in the M4S4 and M6S6 treatments. Compared with the M4S4 treatment, these variables increased by 12.05%, 11.09%, 21.56%, 11.91%, 18.46%, 16.1%, and 16.84%, respectively, and compared with the M6S6 treatment, they increased by 2.06%, 2.53%, 2.78%, 2.98%, 8.81%, 4.59%, and 4.36%, respectively. The D-M4S6 treatment significantly improved the lodging resistance of soybean and weakened the negative impact of intercropping on soybean yield. Therefore, based on the planting pattern of narrow-wide row maize‒soybean intercropping planting pattern, four rows of maize and six rows of soybean were more effective at improving the lodging resistance of soybean in the semiarid region of western China.

Effects of different patterns of maize-straw application on soil microorganisms, enzyme activities, and grain yield.

The present study aimed to assess the influences of corn straw application on the soil microbial organisms, soil enzyme activities and the grain yield. Four treatments were evaluated: (i) The straw was ploughed into soil using a fence hydraulic turning plow with ploughing depth of 30-40 cm(PD). (ii) The self-developed straw deep returning machine was used to bury 30-40 cm in the sub-surface layer of soil (SD). (iii) The straw was mulched and no tillage sowing(M). (iv)Without straw application(CK). Soil samples of different deep(0-20 cm, 20-40 cm soil layer) were taken during the corn growth stage to determinesoil biological characteristics.Our results suggested that soil microorganisms were not increased by straw mulching. Straw deep ploughing and returning (PD treatment) could effectively improve the phospholipid fatty acids(PLFAs) of bacteria, actinomycetes, and fungi, the activities of urease,invertase,dehydrogenase and polyphenoloxidase, even the grain yield. In 20-40 cm subsoil layer, the effects were more obvious than those of topsoil. The mean yield of PD treatment was higher than SD,M and CK. The results showed that the PLFA signatures and soil enzyme were both sensitive to the changes of soil environment condition by the application of straw. In the actual field production, we should adopt the appropriate way of straw returning to the field to achieve not only the improvement of soil quality, but also the increase of grain yield.