高锌胁迫下不同大白菜品种生长、Zn吸收及根系分泌物的研究

采用液培试验研究了高锌胁迫下不同品种大白菜生长、Zn吸收及Zn富集品种与一般品种根分泌物特点。结果表明，Zn胁迫显著抑制了6个品种大白菜生长。0.5<根系耐性指数(RTI)<1.0。随锌水平的增加大白菜地上部干重、RTI明显下降。大白菜地上部Zn含量、根系Zn含量均随锌胁迫的增加而增加。植株吸收的Zn主要积累在大白菜根部。供试锌水平下，以丰园高抗1号的地上部、根系Zn含量明显高于其它5个品种，最大值为251.1、273.6 mg/kg (40mg/L Zn), 以丰抗80地上部、根系Zn含量最低。培养介质pH随锌水平增加先升高，然后下降。大白菜2个品种根系分泌物中检测到草酸、酒石酸、苹果酸3种低分子量有机酸，主要氨基酸包括丝氨酸、异亮氨酸、缬氨酸、赖氨酸（含量大于1.0μg/10 g干土）。锌胁迫降低了大白菜根系分泌的低分子量有机酸、氨基酸总量。Zn富集品种丰园高抗1号根系分泌的低分子量有机酸，加Zn与否都高于一般品种攻关2号。2个品种根分泌物中低分子有机酸和氨基酸含量与种类不同，尤其是低分子有机酸含量与种类不同是大白菜品种之间Zn吸收差异的重要原因

Study of Zn Stress on Plant Growth, Zn uptake and Root Exudates in Different Cultivars of Chinese Cabbage

Solution experiment was carried out to evaluate the influence of Zn stress on plant growth, Zn uptake among six cultivars of Chinese cabbage (Brassica campestris L. ssp. Pekinensis (Lour) Olsson), and characteristic of root exudates of two different Zn accumulation Chinese cabbage cultivars. The results showed that Zn stress significantly inhibited the plant growth of Chinese cabbage. 0.5< root toleration index (RTI)<1.0. Shoot dry weights and RTI obviously decreased with increasing Zn levels. Zn concentrations in shoot and root increased as Zn levels increased. Plants accumulated more Zn in shoot. Zn concentrations in shoot and root were evidently higher in Fengyuan 1 than in other cultivars, the maximums of Zn concentrations in Fengyuan 1’s shoot and root were all recorded at 40 mg/L by 251.1, 273.6 mg/kg DW, respectively. The minimums of Zn concentrations in shoot and root were found in Fengkuang 80. Along with the increase of Zn levels, solution pH was decreased first, and then enhanced. Oxalic acid, tartaric acid and malic acid (low-molecular-weight organic acids) were detected in root exudates of Chinese cabbage (monocotyledon plant). Dominant amino acids of root exudates of ryegrass were serine, isoleucine, valine, lysine (C≥1.0μg/10 g dry soil). Root exudates (low-molecular-weight organic acids and amino acids) were inhibited by Zn stress. Whether under Zn treatment or no, the low-molecular-weight organic acids and amino acids of enriched Zn cultivar Fengyuan 1 were higher than that of Gongguan 2. The different quantities and species of root exudates, especially the different quantities and species of the low-molecular-weight organic acids seemed to play an important role in differences of Zn uptake in two cultivars of Chinese cabbage.