鸭舌草对水稻生长和产量性状的影响及其防治经济阈值的研究

鸭舌草是稻田的恶性杂草,严重危害水稻生长发育,降低水稻产量。通过研究稻田鸭舌草的危害及其防治经济阈值,可以达到规范稻田鸭舌草防除体系、推动杂草防除现代化和减少除草剂对生态环境污染的目的。采用大田试验研究了不同密度的鸭舌草对水稻生长发育和产量性状的影响及其防治经济阈值。研究结果表明,本试验条件下,当鸭舌草密度为80株·m-2时,鸭舌草积累的生物量(鲜重)达17 t.hm-2,地上部吸收的N、P、K养分分别为32.66 kg·hm-2、9.17 kg·hm-2和58.17 kg·hm-2。在鸭舌草的竞争下,田间光照状况恶化,水稻生长受到抑制。鸭舌草密度为80株·m-2的处理与无鸭舌草对照相比,水稻株高下降20%,有效穗下降46%,穗长下降11%,而水稻空粒数增加3.5倍,导致产量降低55%。平方根模型可以较好地拟合鸭舌草密度(x)与水稻产量损失率(y)间的关系y=8.437 1+5.024 9sqrt(x),F=177.42,P<0.000 3]。在水稻产量为6 000~9 000 kg·hm-2时,人工防除鸭舌草的经济阈值为4.0~14.8株·m-2;而4种化学除草剂10%苄嘧磺隆WP、10%吡嘧磺隆WP、48%灭草松水剂、56%二甲四氯钠粉剂(辉县)]计算的经济阈值较低,为1.0~1.6株·m-2。结果说明,鸭舌草对水稻生长有抑制作用,并导致水稻产量损失;而经济阈值的计算表明,化学除草剂防治鸭舌草具有明显的经济优势。

Effects of Monochoria vaginalis on growth and yield properties of rice and its control economic threshold estimation

Sheathed monochoria Monochoria vaginalis (Burm. F.)] is a troublesome weed in rice (Oryza sativa L.) fields. Understanding damages of sheathed monochoria and economic threshold of control in rice fields could standardize sheathed monochoria control measures, promote weed control modernization and reduce herbicide pollution. A field experiment was conducted to study damages of sheathed monochoria to rice growth and yield along with economic threshold of prevention by manual weeding and herbicides use. The study set different densities (0 plant·m^-2, 1 plant·m^-2, 5 plant·m^-2, 10 plant·m^-2, 20 plant·m^-2, 40 plant·m^-2 and 80 plant·m^-2) of sheathed monochoria in rice field. The results showed that fresh biomass of sheathed monochoria at 80 plant·m^-2 was 17 t·hm^-2, with accumulated N, P, and K in weed shoots of 32.66 kg·hm^-2, 9.17 kg·hm^-2 and 58.17 kg·hm^-2, respectively. Rice was severely inhibited due to competition with sheathed monochoria for both nutrients and sun light. In comparison with the control, plant height, effective ear number and ear length of rice dropped by 20%, 46% and 11%, respectively at sheathed monochoria density of 80 plant·m^-2. However, blighted rice grain number increased by 3.5 folds, which resulted in rice yield drop by 55%. The optimum regression for rice yield loss rate (y) and sheathed monochoria density (x) was a square root model of y=8.437 1+5.024 9sqrt(x) at F=177.42 and P < 0.000 3. For 6 000~9 000 kg·hm^-2 rice yield, the sheathed monochoria economic threshold for manual weeding was 4.0~14.8 plant·m^-2. Also for 6 000~9 000 kg·hm^-2 rice yield, it was 1.0~1.6 plant·m^-2 for application of 10% Bensulfuron-methyl WP, 10% Pyrazosulfuron WP, 48% Bentazon and 56% MCPA sodium salts. The results suggested that sheathed monochoria severely inhibited rice growth and yield. Also chemical pesticides were efficient in controlling weeds based on estimated economic thresholds of control.