低磷胁迫下不同根型苜蓿形态及生理响应

Morphological and Physiological Responses of Different Root Types of Alfalfa under Low Phosphorus Stre

采用盆栽试验,比较低磷处理下根茎型、直根型、根蘖型苜蓿形态及生理响应,为不同根型苜蓿低磷胁迫响应策略提供参考。结果表明:低磷胁迫下,供试苜蓿株高、叶长、叶宽、叶面积、根表面积、根体积、根平均直径、叶片相对含水量、根系活力,叶片和根系可溶性蛋白、丙二醛、可溶性糖含量及超氧化物歧化酶(SOD)活性均下降;总根长、主根长,叶片和根系脯氨酸含量、过氧化物酶(POD)、过氧化氢酶(CAT)和酸性磷酸酶(ACP)活性均增加。整个胁迫期间,根蘖型公农4号杂花苜蓿(GN)的株高、叶面积、叶长、根表面积、根体积、根直径、根系活力、叶片相对含水量、叶片和根系SOD活性降幅均小于直根型陇东紫花苜蓿(LD)和根茎型清水紫花苜蓿(QS),叶片和根系CAT、POD活性及根系脯氨酸含量增幅均大于LD和QS,表明根蘖型苜蓿较直根型和根茎型苜蓿耐低磷胁迫能力强。隶属函数综合评价亦证明,GN的耐低磷能力最强,QS最差。回归分析表明,叶长、总根长、根表面积、根平均直径、根体积、可溶性糖含量、丙二醛含量、ACP活性可作为苜蓿耐低磷性鉴定的重要指标。

This study aimed to explore morphological and physiological responses of different root types of alfalfa under low phosphorus stress using pot experiment.Different root types of alfalfa included rhizomatous rooted Medicago sativa‘Qingshui’(QS),tap rooted M.sativa‘Longdong’(LD),creeping rooted M.varia‘Gongnong No.4’(GN).The results showed that under low phosphorus stress conditions,parameters such as plant height,leaf length,leaf width,leaf area,total root surface area,total root volume,average root diameter,root activity,leaf relative water content,and concentrations of soluble sugar,soluble protein,malondialdehyde,as well as the activities of superoxide dismutase in both leaves and roots exhibited a significant decrease.Conversely,parameters including total root length,taproot length,proline content,and the activities of peroxidase,catalase,and acid phosphatase in both leaves and roots displayed an increase in response to low phosphorus stress.Furthermore,it was observed that the reduction in plant height,leaf area,leaf length,total root surface area,total root volume,average root diameter,root activity,leaf relative water content,and superoxide dismutase activities in both leaves and roots were less pronounced in the GN group compared to the LD and QS groups when subjected to low phosphorus stress.Conversely,the increase in catalase,peroxidase activities in both leaves and roots,and proline content in roots was more significant in the GN group compared to the LD and QS groups under low phosphorus stress conditions.Based on above findings,it can be inferred that GN exhibited higher tolerance to low phosphorus stress when compared to LD and QS.Additionally,a comprehensive evaluation using the membership function analysis indicated that GN possessed the highest degree of low phosphorus tolerance,while QS exhibited the lowest level of tolerance among the studied varieties.Regression analysis further identified specific parameters,including leaf length,total root length,total root surface area,average root diameter,total root volume,soluble sugar concentration,malondialdehyde concentration,and acid phosphatase activity,as critical indicators for the assessment of low phosphorus resistance in alfalfa.