不同生育阶段剪叶量对大豆品种南农99-6农艺和品质性状的影响

Influence of Different Defoliation Rates at Different Growth Stages to Agronomic and Quality Traits of Soybean Cultivar NN99-6

筛选大豆对叶片机械损失敏感的指标和时期,为评价大豆对食叶性害虫的耐虫性及制定虫害防治指标等提供参考。在大豆品种南农99-6不同生育阶段(V5、R1、R3、R5)进行不同程度(0%、16. 7%、33. 3%、50. 0%、66. 7%、83. 3%和100%)的剪叶处理,测定农艺和品质性状,以探究不同生育阶段不同叶片损失程度对农艺和品质性状的影响。结果表明:(1)不同剪叶量处理间,单株产量、单株荚数、四粒荚数、三粒荚数、二粒荚数和株高差异达极显著水平,主茎节数、一粒荚数和百粒重差异达显著水平,有效分枝数、每荚粒数及蛋白质含量和油脂含量没有显著差异;一粒荚、二粒荚、三粒荚和四粒荚的数量都有随剪叶量增加逐步减少的趋势。(2)平均单次33. 3%及以上的叶片损失可导致单株荚数显著减少; 50%及以上的叶片损失可导致单株产量显著降低;而100%叶片损失可导致百粒重显著降低。(3)不同生育期剪叶处理间百粒重、三粒荚数、单株荚数和单株产量差异达到或接近显著水平,而其它性状无显著差异。始荚期的叶片损失对单株荚数影响最大,而鼓粒始期的叶片损失对百粒重影响最大且同时影响单株荚数,因而R3和R5是叶片损失的敏感时期。(4)不同生育阶段与不同剪叶量间的互作对大豆农艺和品质性状的影响较小,都未达到显著水平。(5)该试验结果模拟了大豆受咀嚼式食叶性害虫危害的机械损伤影响,但不涉及取食时分泌唾液毒害和刺吸式口器害虫吸食的影响。(6)建议用虫害关键时期(R3) 33. 3%的剪叶量模拟咀嚼式食叶性害虫危害,以单株荚数损失率、百粒重损失率及单株产量损失率作为评价指标鉴定大豆的耐虫性。

To provide a reference for evaluating soybean tolerance against leaf-feeding insects and formulating pest control in- dicators, indicators and periods sensitive to mechanical loss of the blade are screened. The effects of different defoliation rates （0%, 16. 7%, 33.3%, 50. 0%, 66. 7%, 83.3% and 100% ） at different growth stages （V5, RI, R3, R5） on soybean cuhivar NN99-6 were evaluated to explore their influences to agronomic and quality traits. （i） Highly significant differences were found among different defoliation rates for pod number per plant, seed yield per plant, plant height and for number of two-, three- and four-seed pods, significant differences were found for number of nodes on main stem, number of one-seed pods and 100-seed weight, while there were no significant differences among effective branch number, seeds number per pod, protein and oil content. The number of one-, two-, three- and four-seed pods decreased gradually along with the increase of defoliation rates. （ii） On average, a 33.3% and above defoliation could lead to a significant reduction in pod number per plant, a 50% and above defoliation could lead to a significant decrease in seed yield per plant, while a 100% defoliation could resuh in a significant decrease in 100-seed weight. （iii） Among different defoliation stages, there showed significant or approximately significant differences for 100-seed weight, three-seed pod number, pod number per plant and seed yield per plant, while no significant difference was found for other traits. Defoliation at beginning podding stage （ R3 ） caused greatest influences on pod number per plant. While defoliation at the beginning of seed development stage （R5） caused the greatest influence on 100-seed weight and significant influenced on pod number per plant. Therefore, R3 and R5 were critical periods of leaf loss. （iv） The interactions between defoliation stages and defoliation rates showed a little influence on agronomic and quality traits, and did not reach a significant level. （v） This experiment simulated the mechanical damage of soybeans caused by leaf-chewing insects, but did not involve the effects due to saliva poisoning through feeding and sucking by phloem-sucking insects. （vi） It is suggested that 33.3% defoliation rate can be used to simulate damage of leaf-chewing insects at R3 stage which is a critical period for leaf-feeder damages, and the loss rate of pod number per plant, 100-seed weight and seed yield per plant can be used as indicators of tolerance to leaf-feeding insects.