采用盆栽实验研究了Zn (0、1.0、5.0、10.0和20.0 mg·kg ^-1)对不同油菜品种(‘罗平金菜子’ (Brassica juncea)、‘二牛尾’ (B. juncea)、‘溧阳苦菜’ (B. juncea)、‘南通黄油菜’ (B. chinensis)、‘H33’ (B. napus))的光合特性、根尖细胞超微结构及籽粒富锌的影响。结果显示, 5个油菜品种在品种之间、Zn处理浓度之间, 根、茎、叶、籽粒及植株干重、光合特性、Zn含量和积累量的差异性均达到显著水平; 品种与Zn浓度的交互效应也达到显著水平。在Zn ≤ 5.0 mg·kg ^-1范围内, Zn增加了超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶活性、净光合速率(P_n)、气孔导度(G_s)以及蒸腾速率(T_r), 提高了油菜茎、叶、籽粒干重及总干重。油菜产量(籽粒干重)在5.0 mg·kg ^-1 Zn时达到最大值, 各品种分别较对照增加了37.7%、23.4%、29.5%、82.6%和18.0%。在Zn处理浓度为20.0 mg·kg ^-1时, ‘罗平金菜子’、‘二牛尾’、‘南通黄油菜’和‘溧阳苦菜’根尖细胞出现不同程度的线粒体肿胀、细胞壁增厚、细胞核萎缩且内容物较少, 而‘H33’中根尖细胞结构较CK处理差异不明显, 细胞结构较为完整。5个品种的籽粒Zn积累量随Zn浓度先增加, 在5.0 mg·kg ^-1 Zn时达到最大值, 然后下降。‘二牛尾’的籽粒Zn含量和籽粒Zn积累量在5.0和10.0 mg·kg ^-1 Zn处理时为5个品种最高或次高, 分别为172.34和164.10 mg·kg ^-1、2.932和2.575 mg·pot ^-1。

Aims Our objectives were to reveal differences in physiological characteristics, photosynthesis, ultrastructure of root tip cell and grain Zinc (Zn) accumulation in different varieties of rape under different Zn treatments.
Methods Pot experiments were carried out. Zn treatments were 0, 1.0, 5.0, 10.0 and 20.0 mg·kg ^-1, and five varieties of rape were ‘Luopingjincaizi’ (Brassica juncea), ‘Erniuwei’ (B. juncea), ‘Liyangkucai’ (B. juncea), ‘Nantonghuangyoucai’ (B. chinensis) and ‘H33’ (B. napus). All experiments were performed in triplicate, and pots were arranged in a completely randomized design inside a greenhouse.
Important findings The dry weights of roots, leaf, straw, grain and plant, physiological characteristics and concentration and accumulation of Zn significantly differed among the different varieties and Zn treatments. The activities of antioxidant enzymes, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), and dry weights of plant, straw, leaf and grain increased at Zn ≤ 5.0 mg·kg ^-1. The highest yields of grain for the five varieties were all observed in the 5.0 mg·kg ^-1 Zn treatment and were 37.7%, 23.4%, 29.5%, 82.6% and 18.0% greater than the control, respectively. Ultrastructural damage was found in the root-tip cells for ‘Luopingjincaizi’, ‘Erniuwei’, ‘Nantonghuangyoucai’ and ‘Liyangkucai’ in the presence of 20.0 mg·kg ^-1 Zn and included mitochondria inflation, cell-wall thickening, nucleus atrophy and decreased contents of nucleus, while unaltered structure of the root-tip cells was observed in ‘H33’. Grain Zn accumulation for the five varieties increased at Zn ≤ 5.0 mg·kg ^-1, and decreased at Zn > 5.0 mg·kg ^-1. Highest concentration and accumulation of Zn in grains were observed in ‘Erniuwei’ at 5.0 and 10.0 mg·kg ^-1 Zn (172.34 mg·kg ^-1, 2.932 mg·pot ^-1 and 164.10 mg·kg ^-1, 2.575 mg·pot ^-1) treatment, respectively.