种植方式对玉米大豆套作体系中作物产量、养分吸收和种间竞争的影响

为探寻玉米-大豆套作体系下作物间的资源竞争关系,揭示玉米-大豆套作系统的增产机理,本研究以玉米-大豆套作系统(简称玉豆套作)为对象,通过2 a大田定位试验,研究了玉豆套作带状连作(A1)、玉豆套作带状轮作(A2)、玉豆套作等行距种植(A3)、玉米单作(A4)、大豆单作(A5)5种种植方式对玉米、大豆的产量、养分吸收及种间竞争能力的影响。结果表明,与单作和等行距种植相比,带状种植的玉米产量降低、大豆产量显著增加,A2的大豆产量分别比A5和A3高25.5%和89.2%。与带状连作相比,带状轮作促进玉米增产和对N、P、K的吸收,玉米籽粒产量及植株N、P、K的吸收总量分别提高7.5%、18.5%、9.1%、14.1%。与大豆单作相比,带状套作显著增加了大豆的经济系数和养分收获指数,A2的经济系数和植株N、P、K收获指数分别增加40.9%、11.9%、20.6%、39.9%。带状种植方式下,玉米对N、P、K的竞争力弱于大豆(Ams0,CRms1),但带状轮作提高了玉米的种间竞争力和营养竞争比率。玉米-大豆套作体系下,相对带状连作和等行距种植,带状轮作种植有利于玉米与大豆间的和谐共生,促进了玉米、大豆对养分的吸收,提高了系统的产量和土地当量比率(LER)。

Effect of planting patterns on crop yield, nutrients uptake and interspecific competition in maize-soybean relay strip intercropping system

To deal with the contradiction between population growth and land shortage, maize-soybean relay strip intercropping system has become increasingly popular and widely adopted in Southeast China. The conventional maize-soybean relay strip intercropping system used by farmers have not been good for high maize-soybean yields and nutrient uptake. To therefore explore the characteristics of competition for resources between crops and the mechanism of yield increase under maize-soybean relay strip intercropping system, a two-year field experiment was conducted where the effects of planting patterns on crop yield, nutrient uptake and interspecies competition for resources were investigated. The tested planting patterns included maize-soybean relay intercropping in continuous strips with wide-narrow rows (A1), maize-soybean relay intercropping in rotation strips with wide-narrow rows (A2), maize-soybean relay intercropping in continuous strips with equal rows (A3), maize monoculture (A4) and soybean monoculture (A5). The density of maize and soybean under relay intercropping was equal to that under monoculture. The results showed that compared with monoculture and equal width spacing, relay strip intercropping decreased maize grain yield while increased soybean bean yield significantly. Maize grain yield under A2 treatment was 4.9% and 5.7% lower than those under A4 and A3 treatments, respectively. However, soybean bean yield under A2 treatment was 25.5% and 89.2% higher than those under A5 and A3 treatments, respectively. Compared with A1 treatment, maize grain yield and N, P, K uptake increased under A2 treatment. The maize grain yield and N, P, K uptake under A2 treatment were 7.5%, 18.5%, 9.1% and 14.1% higher than those under A1 treatment. However, yield and N, P, K uptake of soybean were not significantly different between A2 and A1 treatments. Compared with the monoculture treatments, the economic coefficient and nutrient harvest index of soybean in maize-soybean relay strip intercropping systems significantly increased. The economic coefficient and N, P, K harvest indexes of soybean under A2 treatment increased by 40.9%, 11.9%, 20.6% and 39.9%, respectively. In maize-soybean relay strip intercropping systems, maize competition was weaker than that of soybean for N, P, K (A_ms<0,CR_ms<1). However, rotation helped improve interspecific competition and nutrient competition ratio of maize. In 2013, interspecific competition was close to 0 while nutrient competition ratio was close to 1 under A2 treatment. Comparison of A2 with A1 and A3 treatments showed that rotation benefited harmonious symbiosis between maize and soybean. This symbiosis enhanced nutrient uptake of both maize and soybean, subsequently increasing yield and land equivalent ratio (LER) of the cropping system.