Abstract:

【Objective】To study the effects of agronomical character and leaf photosynthetic parameters by different concentrations of glyphosate on glyphosate island cotton in the hope of providing chemical skills for weeding.【Methods】Using glyphosate-resistant Xinchangmian 5 as the research object and spraying four concentrations of glyphosate1.25%, 2.5%, 5.0%, 10.0% at 10 leaf stage, respectively, then plant height, stem diameter, leaf stage and photosynthetic indexes were measured.【Results】Compared with the control, plant height, stem diameter, leaf stage, chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximum photochemical efficiency of PSⅡ(Fv/Fm) and potential activity of PSⅡ(Fv/Fo) with treated by four concentrations of glyphosate were all decreased in sea island cotton. The glyphosate with higher concentrations, the more dramatic decline. However, the intercellular CO₂ concentration (Ci) showed an increasing trend. The treatment by 1.25% and 2.5% had no difference with control after 14 days of spraying, and the agronomic traits returned to the normal level after 24 days.【Conclusion】The growth trends reduce significantly by spraying 4 concentrations of glyphosate at the bud stage. More than 5% concentration of glyphosate affect the growth seriously sea island cotton Xinchangmian 5, so it is suggested that concentration below 2.5% of glyphosate be applied in production.

Key words: sea island cotton; glyphosate; agronomic traits; photosynthesis; chlorophyll fluorescence parameters

摘要：

【目的】研究不同浓度草甘膦对海岛棉农艺性状及叶片光合作用的影响,为棉花化学除草提供技术指导。【方法】以抗草甘膦海岛棉新品系新长棉5号为研究对象,于棉花10叶期喷施1.25%、2.5%、5.0%、10.0%4种浓度草甘膦,测定分析株高、茎粗、叶期及光合指标的变化。【结果】4种浓度草甘膦处理后的海岛棉株高、茎粗、叶期、叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ的潜在活性(Fv/Fo)相比对照均呈下降趋势,草甘膦浓度越高,下降越明显;而细胞间CO₂浓度(Ci)呈升高趋势。1.25%处理于喷药后14 d生理指标与对照无差异,24 d农艺性状逐步恢复到对照水平。【结论】现蕾期(10叶期)喷施4种浓度的草甘膦会显著降低海岛棉的生长势,5%以上浓度处理影响海岛棉生长,新长棉5号田间化学除草使用草甘膦2.5%以下浓度为宜。

关键词: 海岛棉, 草甘膦, 农艺性状, 光合作用, 叶绿素荧光参数