混播比例对热研2号柱花草和飞机草早期生长竞争能力的影响

为明确热研2号柱花草(Stylosanthes guianensis cv.Reyan No.2)与飞机草(Chromolaena odorata(L.)R.M.KingH.Robinson)生长早期的竞争关系,探索飞机草替代控制的途径和管理策略。设置总株数固定(8株),5种柱花草和飞机草分株数混播比例(柱∶飞=8∶0、6∶2、4∶4、2∶6、0∶8)盆栽试验,就各混播比例下2种植物在浇水频率1次/2 d、生长30 d的生长情况和相对竞争能力进行定量分析。结果表明:随着柱花草混播株数的减少,柱花草和飞机草的相对株高、相对平均生长速度、相对单株总生物量和总生物量分配至根、茎和叶的相对生物量均逐渐降低;但飞机草的相对根长、相对根冠比和根生物量质量分数均逐渐减小、茎生物量质量分数无显著变化、叶生物量质量分数逐渐增大,而柱花草的各对应指标反之。柱花草比例较高时(柱∶飞为6∶2)2种植物的相对产量总和显著大于1,2种植物间无种间竞争现象,4∶4和2∶6时相对产量总和均与1相比无显著差异,2种植物间存在资源竞争;混播群落中柱花草的竞争平衡指数均显著小于0,说明生长早期柱花草的相对竞争能力比飞机草弱。下一步进行生长中期、晚期竞争试验和肥力、刈割等其他因素影响试验来确定柱花草替代控制飞机草的可能性。

Effects of Mixed Sowing Proportion on the Competitive Ability Between Stylosanthes guianensis cv. Reyan No. 2 and Chromolaena odorata During Early Growth

The experiment was conducted to investigate the competitive interaction between Stylosanthes guianensis cv. Reyan No. 2 and Chromolaena odorata (L.) R. M. King & H. Robinson at different mixed sowing proportion, and to explore the methods of controlling the invasive weed C. odorata displaced by S. guianensis. The above two species were grown for 30 days at 5 mixed sowing proportions (8 plants total number per pot, and plant numbers proportion of S. guianensis and C. odorata were 8:0, 6:2, 4:4, 2:6 and 0:8 per pot) in the pot experiment. The growth response and relative competitive ability of the two species were evaluated at same watering treatment ( 1 time/2d, 70% of the maximum water-holding capacity of the soil per watering). As S. guianensis mixed sowing number decreased, the relative plant height, relative average growth rate, relative total biomass per plant, relative biomass of total biomass allocation to root, stem and leaf of S. guianensis and C. odorata both gradually decreased. For C. odorata, the relative root length, relative biomass ratio of root to shoot and root biomass fraction gradually decreased, stem biomass fraction no significant change, and leaf biomass fraction gradually increased with decreasing of S. guianensis numbers at mixed sowing, but the corresponding indexes of S. guianensis were just contrary. When the rate of S. guianensis to C. odorata was 6:2, the relative yield totals of two plants was significantly greater than 1, and there was no interspecific competition between two mixed sowing plants, but the relative yield totals and 1 did not have significant difference when mixed sowing proportions were 4:4 and 2:6, and had resource competition between the two plants. Competitive balance index of S. guianensis was significantly less than 0 under the mixed proportion 6:2, 4:4, and 2:6. These indicated that the relative competitive ability of S. guianensis was weaker than that of C. odorata during early growth. Further experiment is needed to study the competitive changes of the two plants in the whole growth period and the effects of fertility and cutting management on the competitive abilities to determine whether C. odorata could be the replacement control by using S. guianensis as a competitor.