中文摘要：

为完善以玉米-大豆套作系统为核心的三熟模式配套栽培技术,提高玉米-大豆套作体系下大豆的产量,研究了小麦（A1）、豌豆（A2）、蚕豆（A3）及马铃薯（A4）4种前作处理和施氮0（B1）,30（B2）和60（B3）kg·hm-23种水平对大豆农艺性状、干物质积累及产量的影响。结果表明：前作豌豆和蚕豆处理与前作小麦相比,提高了大豆茎粗、分枝数和R2、R8期的单株干物质积累量,降低了株高,其中,前作为蚕豆处理的大豆茎粗、分枝数、单株干物质积累量比前作为小麦处理的高3.5%、5.9%和5.7%,产量也较小麦前作平均高197.94 kg·hm-2;不同前作下各施氮处理对大豆农艺性状及产量的影响表现不一致,前作蚕豆、豌豆处理,大豆株高和分枝数随施氮量的增加而升高,茎粗和产量随施氮量的增加呈先增后降的趋势;而前作小麦和马铃薯处理的大豆株高、茎粗、分枝数和产量则均随施氮量的增加而提高;所有处理中以A3B2处理组合大豆农艺性状较好,产量最高,即前作蚕豆和施氮30 kg·hm-2时有利于玉米-大豆套作体系下大豆农艺性状的改善和产量的提高。

英文摘要：

The relay-sowing system of maize-soybean is a new cultivation technique in hilly area of southwest China. Field experiments were conducted to determine the optional preceding crop and nitrogen fertilizer. Four different interplanting preceding crops of wheat（ A1）,peas（ A2）,beans（ A3） and potato（ A4） and 0 kg·hm- 2（ B1）,30 kg·hm- 2（ B2） and 60 kg·hm- 2（ B3）three kinds of nitrogen levels were set to analyze the effect on soybean agronomic traits,dry matter accumulation and yield. The results showed that among the different preceding crops treatments,the yield of soybean increased with the treatment of preceding crop beans. Under the conditions of preceding crop beans,the soybean reached the highest yield,followed by treatment peas.Compared with its preceding crop wheat（ A1）,the treatment of peas and beans increased the soybean stem diameter,number of branches and dry matter accumulation of period R2,R8,decreased plant height. Among four preceding crops treatments,compared with the preceding crop wheat,under the conditions of preceding crop beans（ A3） the soybean stem diameter increased3. 5%,number of branches per plant increased 5. 9%,dry matter accumulation increased 5. 7%,the soybean yield exceeded197. 94 kg·ha- 1. Plant height,number of branches and plant dry matter accumulation of soybean increased with the increas of nitrogen level in different preceding crops treatments. Effects of the different nitrogen fertilizer treatments on the different preceding crops were different. Under the treatmens of preceding crop broad bean and pea,the plant height,number of branches and plant dry matter accumulation increased with increasing nitrogen level. Under the preceding crops treatments of peas and beans,soybean field with increasing nitrogen rate increased firstly and then decreased. It can reach the highest field with the nitrogen level 30 kg·ha- 1Proceding crops treatments of wheat and potato,the soybean field with increasing amount of nitrogen is increased,The hightest field