刈割对白三叶生长状况及越夏性的影响

摘要

在亚热带地区，热害胁迫是影响白三叶生产的主要因素之一。为了探讨提高白三叶牧草产量的栽培技术措施，试验设计1 cm、4 cm、7 cm 3个留茬高度和15 d、30 d、45 d 3个刈割周期，组合成9个刈割处理，分析不同处理下白三叶生长状况和越夏性能。结果表明：白三叶单株根干重、单株茎节数及越夏率随留茬高度和刈割周期的增加而升高，而牧草产量只随留茬高度先增后减，受刈割周期影响不显著；留茬7 cm且刈割周期不低于30 d最利于白三叶根系、茎节的生长和越夏力的提高，与其他处理间差异极显著(P＜0.01)；留茬高度是影响牧草产量的主效因子，其中以留茬4 cm处理为佳，且极显著高于其他留茬处理(P＜0.01)，但同一留茬水平下不同刈割周期间差异不显著。根系的生长状况和茎节数量多少是影响白三叶越夏性强弱的直接因子，相关性分析结果显示，越夏率具有与单株茎节数和单株根干重一致的变化趋势，呈极显著正相关，相关系数分别为0.966和0.930。本研究结果说明，留茬4 cm、刈割周期不少于30 d可获得较高的白三叶牧草产量；较高的留茬(7 cm)则对白三叶根系的生长有利，并可提高其越夏能力。%Heat stress is one of the major factors causing yield loss of white clover production in subtropical regions. To evaluate the impact of heating regimes on forage production and plant heat resistance, 9 treatments were set up, which involved three cutting heights (1 cm, 4 cm and 7 cm) and three cutting intervals (15 d, 30 d and 45 d). The results showed that dry root mass, node numbers and heat-resistance were enhanced with the increase of cutting height and cutting interval. As cutting height increased, forage production was elevated firstly, and then declined, but forage production was not affected by the alteration of cutting intervals. White clover exhibited the most vigorous shoot development and root growth with a cutting height of 7 cm and 30 d plus cutting intervals, meanwhile, heat resistance was improved as well, and plant grew much better than those in other treatments (P＜0.01). The highest forage production was achieved at a cuttingheight of 4 cm, which was significantly higher than that in other treatments ( P＜0. 01 ). Under the same cutting height, no marked variation was observed between forage productions with different cutting intervals. Heat resistance of white clover was found to be positively correlated with node numbers and dry root mass, with the correlation coefficients being 0. 996 and 0. 930, respectively. In practice, 4-cm cutting height and 30 d plus cutting intervals were suggested for higher white clover forage production, while to improve plant heat resistance, 7-cm cutting height was recommended for better root proliferation.