阔世玛对谷子幼苗叶片光合特性及可溶性物质含量的影响

为明确阔世玛(Sigma Broad)对谷子幼苗叶片光合特性和可溶性物质含量的影响,以张杂谷5号和晋谷21号为试验材料,分别于施药后7 d测定不同浓度(0、7.5、15.0、30.0、60.0 mg·L^-1)的3.6%阔世玛水分散粒剂对叶片气体交换参数、叶绿素荧光参数、光合关键酶活性和可溶性物质含量的影响。结果表明,谷子叶片的净光合速率(Pn)、磷酸烯醇式丙酮酸羧化酶(PEPC)活性、丙酮酸磷酸双激酶(PPDK)活性、苹果酸脱氢酶(NADP-MDH)活性以及表观光合电子传递速率(ETR)均随着阔世玛浓度的增加而降低,阔世玛浓度高于15 mg·L^-1时均与CK差异显著;而2个品种的苹果酸酶(NAD-ME)和1,5-二磷酸核酮糖羧化酶(Rubisco)活性以及可溶性物质含量均随着阔世玛浓度的增加呈先升高后降低的趋势,NAD-ME活性、还原糖、蔗糖和可溶性蛋白含量均在阔世玛浓度为15 mg·L^-1时达到最大值。综上所述,阔世玛处理会降低光系统反应中心的活性及光合作用暗反应过程中的关键酶PEPC、NADP-MDH和PPDK的活性,导致叶片Pn降低,影响Rubisco和NAD-ME的活性以及糖的代谢。本研究明确了阔世玛影响谷子光合作用的生理机制,为阔世玛在谷子田间的安全使用提供了理论基础。

Effects of Sigma Broad on Photosynthesis Characteristics and Soluble Substances Content in Leaves of Foxtail Millet

To better understand the physiological mechanism behind the phenomenon of decreased photosynthetic rate when foxtail millet seedlings are treated with Sigma Broad, different concentrations (0, 7.5, 15.0, 30.0, 60.0 mg·L^-1) of 3.6% Sigma Broad were sprayed at the five-leaf stage of Zhangzagu 5 and Jingu 21, and gas exchange parameters, photosynthetic key enzyme activities and soluble matter content were determined and analyzed after 7 days later. The results showed that the net photosynthetic rate (Pn), ETR, the activities of phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), NADP-malate dehydrogenase (NADP-MDH), were reduced with the increasing of Sigma Broad at 15 mg·L^-1. The NAD-malic enzyme (NAD-ME), Ribulose-1, 5-bisphosphate carboxylase oxygenase (Rubisco) activities and soluble substances content increased first and then decreased with the increased concentration of Sigma Broad in the two varieties, and the maximum values of NAD-ME, reducing sugar, sucrose and soluble protein were all appeared at the treatment of 15 mg·L^-1 for both varieties. In summary, Sigma Broad making the obvious damages to the net photosynthetic rate in leaves of foxtail millet is partially due to that the activities of PSⅡ photochemical, PEPC, NADP-MDH, and PPDK were reduced, and the activities of Rubisco and NAD-ME and the metabolism of sugar were affected.