尿素与除草剂甲基二磺隆复合处理对紫苏生理特性和产量的影响

The Combination Treatment With Urea and Mesosulfuron-methyl on the Photosynthesis and Yield of Perilla frutescens( L. ) Britt.

为探讨尿素与甲基二磺隆对紫苏光合特性指标和籽粒产量的影响,本试验研究了适宜紫苏生长的最佳除草、施肥条件,对六叶期紫苏幼苗先后喷施尿素（0、1、2、4、8 g·L^-1）和甲基二磺隆（0、0.175、0.35、0.7、1.4 m L·L^-1）处理。结果表明,甲基二磺隆显著降低紫苏叶片的叶绿素含量指数,净光合速率和气孔导度也均不同程度降低,胞间CO2浓度升高,说明甲基二磺隆降低了紫苏的光合作用;叶绿素荧光分析显示,除草剂甲基二磺隆显著降低了光化学荧光淬灭系数、PSⅡ最大光化学效率、PSⅡ潜在活性及PSⅡ实际光化学效率,而非光化学淬灭系数则呈上升趋势。表明紫苏在甲基二磺隆处理下发生了光抑制,同时叶绿体的PSⅡ正常功能受阻;8 g·L^-1的尿素处理效果相同;而1-4 g·L^-1浓度的尿素处理则效果相反。1-4 g·L^-1的尿素和不同浓度的甲基二磺隆先后处理,比单用甲基二磺隆处理效果好,先施4 g·L^-1的尿素,后施0.7 m L·L^-1甲基二磺隆为最佳处理方案,能显著提高紫苏的光合速率,并使其光系统Ⅱ维持较高的光化学效率。该施药模式可为紫苏田平衡除草施肥和安全高产提供理论基础。

Perilla with six leaves was exposed to combination treatment with urea（ 0,1,2,4 and 8 g·L^- 1） and mesosulfuron-methyl（ 0,0. 175,0. 35,0. 7 and 1. 4 m L·L^- 1） of different concentration to confirm the best treatment style. Effect of combination treatment on photosynthetic index and seed yield of Perilla frutescens（ L.） Britt. Was investigatea by using the randomized block design experiment. Results showed that the chlorophyll content index（ CCI）significantly,and photosynthetic rate（ Pn） and stomatal conductance（ Gs） were reduced at different levels. While the intercellular CO2concentration（ Ci） was increased under the mesosulfuron-methyl treatments. It suggested that mesosulfuron-methyl significantly decrease the photosynthesis. The result also show that mesosulfuron-methyl significantly decreased maximum PSII photochemical efficiency, effective quantum yield of photochemical energy conversion in PSII,PSII potential activity and photochemical quenching of variable Chl fluorescence; and decreased non-photochemical Chl fluorescence quenching. It was indicated that mesosulfuron-methyl impaired PSII and blocked the electron transport in light reaction,treatment with urea of moderate concentration（ 1 to 4 g·L^- 1） could improve the negative effect contributed by mesosulfuron-methyl alone,while high concentration（ 8 g·L^- 1） could aggravate this effect. The photosynthesis and PSII photochemical efficiency were improved when treated by 4 g·L^- 1urea first and then by 0. 7 m L·L^- 1mesosulfuron-methyl. This combination of urea and mesosulfuron-methyl was the best treatment,this study could provide a theoretical basis for the balance of fertilization,weeding,security and high yield in Perilla field.