Effects of Spraying Zinc on Leaves on the Photosynthetic Characteristics and Its Related Physiological Parameters of <i>Brassica napus</i>

本文以甘蓝型油菜为材料，在田间栽培条件下研究了叶面喷锌对油菜叶片光合作用、叶片金属元素含量和叶片表观形态的影响。用英国生产的TPS-1型便携式光合仪测定喷锌组和对照组的油菜光合作用日变化，并用微波消解法测定喷锌组与对照组的叶片金属元素含量。结果表明：喷锌后的油菜叶片净光合速率和水分利用率提高，同时油菜的蒸腾速率和气孔导度降低；喷锌后的油菜叶片金属元素含量显著提高，与对照组相比，Fe含量提高了321.52%，Ca含量提高了158.73%，Zn、Mn、Mg及Cu的含量分别提高了50.57%、48.51%、11.54%和0.9%；油菜对锌的最大耐受浓度为0.3% ZnSO4∙7H2O，超过此浓度，油菜的受害叶片数目增加，叶片的受害面积增大。最后确定油菜叶面的最佳喷锌浓度为大约0.1% ZnSO4∙7H2O。In this paper, spraying zinc on leaves of Brassica napus was performed to investigate the effects of zinc on the photosynthetic characteristics, leaf metal content and exterior form of Brassica napus in the field under natural light conditions. The diurnal variations of photosynthetic characteristics in the zinc group and control group were measured by TPS-1 portable photosynthesis system made in England. Moreover, leaf metal element contents of the two groups were determined by microwave digestion method. The results revealed that spraying zinc on leaves enhanced net photosynthesis rate and water use efficiency of Brassica napus, and reduced transpiration rate and stomatal conductance of Brassica napus simultaneously. The metal element content of spraying zinc on leaves of Brassica napus increased significantly, compared with the control group, iron content increased by 321.52%, and Ca, Zn, Mn, Mg, and Cu content increased by 158.73%, 50.57%, 48.51%, 11.54%, and 0.9%, respectively. The maximum tolerant concentration of Zn for Brassica napus was 0.3% ZnSO4∙7H2O. The number and the area of the damaged leaves increased when zinc concentration exceeded 0.3%. In conclusion, about 0.1% ZnSO4∙7H2O was recommended as the optimal exogenous zinc concentration for Brassica napus.