玉/豆套作模式下玉米播期与密度对大豆农艺性状及产量的影响

Effect of Maize Sowing Time and Density on the Agronomic Characters and Yield of Soybean in Relay-planting System of Maize and Soybean

为完善"麦/玉/豆"新三熟模式的配套栽培技术,寻求玉豆套作体系下获取玉米、大豆共同高产的最佳玉米播期和密度;通过大田试验,采用玉米播期与密度二因素裂区设计,研究了不同玉米群体对玉/豆模式下大豆农艺性状及产量的影响。结果表明:玉米适当晚播(3月26日～4月5日)和密植(4.8～6万株.hm-2)有利于玉米产量的提高;玉米早播(3月6日)与稀植(3.6万株.hm-2)能降低大豆株高、增加茎粗、缩短结荚高度、增加分枝数,提高20cm～60cm层分枝荚数、粒数和60cm以上层主茎荚数与粒数,比晚播(4月15日)处理增产40.42%,比高密度(6万株.hm-2)处理增产35.79%;玉米适当早播(3月6日～3月26日)和适度密植(4.8万株.hm-2)有利于玉豆套作体系总产量和总产值的提高。

The relay-sowing system of ＂wheat/maize/soybean＂ is a new cultivation technique in hilly area of southwest China. Field experiments were conducted to determine the optimal sowing time and sowing density that benefit for both heigh yield of maize and soybean under relay-sowing system of maize and soybean. Split plot design were adopted, with maize sowing time （from March 16 to April 15 ）as main plots, sowing density （from 3.6 × 10^4 plant. ha^-1 to 6.0 × 10^4 plant.ha^-1 ） as sub-plots. Soybean were planted on June 10 under the density of 13.78 plant.ha^ -1. The agronomic traits of plant height, stem diameter, height of lowest pod and branch number, and yield components of soybean were determined after harvest. The results indicated that it was benefit to improve the yield of maize with properly late sowing（ from March 26 to April 5 ）and high sowing density （from 4.8 × 10^4 plant.ha^-1 to 6 × 10^4 plant.ha^-1 ）. With early sowing（ March 6 ） and low sowing density （ 3.6 ×10^4 plant.ha^-1 ） of maize, plant height of soybean reduced, stem diameter and branches increased, height of lowest pod shortened, pods and seeds in the height between 20 cm and 60 cm of branch increased, and pods and seeds over 60 cm of main stem also increased. In comparison with late sowing （April 15 ）and high sowing density （6 ×10^4 plant.ha^- 1 ）, the yield of soybean under early sowing and low sowing density of maize increased by 40.42% and 35.79%, respectively. It was beneficial to improve the total yield and output value in relay- sowing system of maize and soybean with properly early sowing （from March 26 to April 5）and high sowing density（4.8 × 10^4 plant.ha^-1）.