低磷胁迫对雷公藤幼苗叶片生理生化特性的影响

为研究雷公藤的耐磷胁迫性,对雷公藤（Tripterygium wilfordii Hook.f.）一年生和三年生同一无性系扦插苗采用土培的方法进行了控制条件下的低磷胁迫实验,以KH2PO4为磷源,土壤中P2O5浓度为0、5、10、15、20、25（CK）mg/kg,低磷胁迫3个月和6个月后取叶片测定其丙二醛（MDA）、脯氨酸（Pro）含量以及超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性和酸性磷酸酶（APA）活性的变化。实验结果表明：低磷胁迫下一年生和三年生雷公藤叶片SOD、APA活性升高,MDA、Pro含量增加,并呈现随低磷胁迫加重和胁迫时间延长而上升趋势,低磷胁迫下各处理的一年生和三年生雷公藤叶片CAT、POD活性普遍低于对照,并随着低磷胁迫程度的加重而呈下降趋势。低磷胁迫下雷公藤幼苗叶片的几种保护酶活性、MDA、Pro含量以及APA活性响应都较为灵敏,保护酶系统在15、20 mg/kg处理下能够起到较好保护作用,表明雷公藤能通过自身生理调节来适应中度和轻度缺磷环境;综合各项生理指标,三年生雷公藤相对于一年生雷公藤显示了较强的抗氧化能力和渗透调节能力,具有较强的耐低磷能力,对磷较为缺乏的林地下套种雷公藤的苗龄选择有参考价值。

Effects of Low Phosphorus Stress on Leaf Physiological and Biochemical Characteristics of Tripterygium wilfordii Hook.f.Seedlings

Phosphorus（P） is a very important element that controls the processes of plant life,especially during its growth phase.Low-P in the soil usually leads to adaptive changes in plants in aspects such as photosynthesis,respiration and biosynthesis,and low available P is one of the major limitations to plant production.Tripterygium wilfordii Hook.f.is an important traditional Chinese medicine,widely used in medical treatment of diabetes,rheumatism,and nephropathy.Tripterygium wilfordii is distributed in southeastern China in poor P and available P red soil.Low-P in the soil may lead to reduced T.wilfordii production.Usually,chemical fertilization and soil improvement are the primary measures used to meet the P demands of crops in traditional agriculture and trees in forestry management,but these measures still fail to increase T.wilfordii yield to meet good manufacturing practice（GAP） standards.Recently,plants with high P use efficiency have been discovered and used to replace traditional measures for improving P use efficiency of plants.Therefore,studying the effect of different P stresses on T.wilfordii will help to reveal the mechanism of low-P adaptation,and breed T.wilfordii with high-P use efficiency.Therefore,we analyzed the physiological and biochemical responses（such as peroxidase（POD）,catalase（CAT）,malondialdehyde（MDA）,superoxide dismutase（SOD）,acid phosphatase（APA）,and proline（Pro）） during one growing season of one-year-old and three-year-old seedlings（T.wilfordii clones） to six P stresses under soil culture：normal P supply（25 mg/kg,CK）,slight P deficiency（20 mg/kg）,medium P deficiency（15 mg/kg,10 mg/kg）,and heavy P deficiency（5 mg/kg,0 mg/kg）.The results indicated that under low phosphorus stress,the leaves of both seedling types were higher in SOD,MDA,Pro,APA than in CK,and these values increased with concentration and time of stress.In contrast,CAT and POD values were lower than CK values in the leaves of both seedling types,and decreased with the concentration of low P stress.The protective enzymes,MDA,Pro and APA of seedling leaves were sensitive to low-P stress and worked well,especially at the treatments of 15 and 20 mg/kg.As mentioned above,T.wilfordii was adapted well in the environments of slight and medium P deficiency by self physiological regulation.The adaptability of three-year-old T.wilfordii seedlings was better than that of one-year-old seedlings in oxidation resistance,osmoregulation and low-P tolerance.Consequently,the three-year-old seedlings were preferred for interplantation in low P conditions.The APA levels can serve as a reference to the breeding of T.wilfordii with low P tolerance,but more research is needed to determine whether APA levels are an important index for evaluating and selecting T.wilfordii clones with high P use efficiency.