迎茬夏大豆荚而不实发生规律及预防措施

Law of Occuring Pods Without Peas of Alternate Cropping' s Summer Soybeans

在黄淮平原一年两熟的耕作制度下,夏大豆迎茬1￣4年,单株空荚发生率增加8.8￣35.3个百分点;大豆减产12.1%￣44.9%;迎茬年限与单株空荚发生率呈极显著正相关,r=0.9895**;单株空荚发生率与产量呈极显著负相关,r=-0.9945**。夏大豆迎茬每增加1年,单株空荚发生率约增加8.8%;单株空荚率每增加1%,大豆约减产43.6kg/hm2。迎茬造成大豆荚而不实和减产的生理生态效应为:株高降低,有效分枝、单株荚数及粒重减少,百粒重降低;土壤微生物区系发生不良变化,根腐病、霜霉病及灰斑病等真菌性病害发生程度加重;土壤速效性磷、钾、硼等大量、微量营养元素含量明显亏缺;根系生长受阻,根系活力下降。预防迎茬大豆荚而不实的措施有:合理轮作倒茬;选用耐迎茬商豆1099等优良大豆品种;氮磷钾硼肥平衡施用;应用植物生长调节剂;防治病虫害等。

During two harvests of one year in Huanghuai Plain, Summer soybeans are alternated for 1-4 years, the incidence of pods without peas per plant increaces 8.8-35.3 per cent;The soybeans＇yield reduces 12.1%～44.9%;There is an obvious positive correlationbetween the incidence ofindividual seedless pod and the year length of alternate cropping, r=0.9895＊＊;while the incidence of individual seedless podhas notable inverse correlation with the yield, r=-0.9945＊＊.Summer soybeans are alternated by adding one year, the rate of individual seedless pods increases about8.8%;While the rate of individual seedless pods increasesby per l%,soybeans＇yield drops about 43.6kg/hm2.The biological effects of alternatecropping which cause pods without peas and yield reduction are as follow： lowness of plant height, efficient branches, reduction of individual pods＇ number and seed weight, drop of 100-seed weight; Bad variation of soil micrpflora, Those fungoid diseases such as root, downey mildew and gray speck of soybean become more serious ;Those minim nutritive elements＇ contents wane obviously ,such as quickly availablephosphor, Kalium Potass, Boron ,etc;Root＇s growth suffocate, root vigor drops, here are the prevententive measures： Reasonableirrigation and drainage. Choices of anti-alternate cropping＇s good seeds such as Shang soybean 1009, ete;Balanced use of N, P, K, Boron fertilizers; Use of plant growth Regulators; Prevention of pests and plant diseases, etc.