甘薯苗期耐盐性鉴定及其指标筛选

Identification of Salt Tolerance and Screening for Its Indicators in Sweet Potato Varieties during Seedling Stage

以18个甘薯品种(系)为试验材料,设置对照和200 mmol L^(–1) NaCl浓度处理,通过苗期盐土栽培胁迫方式,对各处理下各品种(系)的茎叶鲜重、根系鲜重、茎叶干重、根系干重、叶片相对电导率、F_v/F_m、SPAD值、SOD酶活性、MDA含量、脯氨酸含量、根系活力、根系Na^+和K^+含量、Na^+/K^+比值等14个生理指标进行测定,通过对各单项指标的耐盐系数进行相关分析、主成分分析、聚类分析和逐步回归等方法对品种(系)耐盐性进行综合评价。通过主成分分析,将盐胁迫处理下甘薯苗期的14个单项指标转换成5个彼此独立的综合指标;通过隶属函数分析,得到不同品种(系)苗期耐盐性综合评价值(D值),并通过聚类分析,将18个甘薯品种(系)划分为4种耐盐类型,其中盐敏感型4个、弱耐盐型3个、中度耐盐型7个和高度耐盐型4个。在此基础上,利用逐步回归方法建立了可用于甘薯苗期耐盐性评价的回归方程,同时筛选出茎叶鲜重、根系鲜重、茎叶干重、叶片SPAD值、SOD酶活性、MDA含量、脯氨酸含量、根系Na^+/K^+比值等8个可用于甘薯苗期耐盐性评价的生理指标。本研究可为甘薯耐盐新品种选育提供种质并为甘薯苗期耐盐性评价及耐盐机制研究提供理论依据。

Eighteen sweet potato varieties were selected as the test material. The control and treatment groups were established via saline soil cultivation in seedling stage. The treatment group received 200 mmol L？1 NaCl. Fourteen physical traits were observed in each treatment, which were fresh stem leaf weight, fresh root weight, dry stem leaf weight, dry root weight, relative leaf con-ductivity, Fv/Fm, SPAD value, superoxide dismutase （SOD） activity, malondialdehyde （MDA） content, proline content, root vigor, root Na＋ content, root K＋ content, and Na＋/K＋ ratio. A comprehensive analysis of the salt tolerance of different varieties was con-ducted via correlation analysis, principal component analysis, clustering analysis, and stepwise regression of the salt tolerance efficiency of each index. Principal component analysis narrowed down the 14 single indexes in the salt-stressed seedling stage of sweet potatoes to five independent comprehensive indexes. Subordinate function analysis was conducted to obtain the compre-hensive assessment value （D-value） of salt tolerance of different varieties in seedling stage. In clustering analysis, the 18 sweet potato varieties were divided into four salt tolerance types, including four salt-sensitive, three weak salt tolerant, seven moderatesalt-tolerant, and four high salt-tolerant. On the basis of this division, stepwise regression method was used to establish a regres-sion equation for salt tolerance assessment of sweet potatoes in seedling stage. Eight physiological indexes were selected （fresh stem leaf weight, fresh root weight, dry stem leaf weight, leaf SPAD value, SOD enzyme activity, MDA content, proline content, and Na＋/K＋ ratio） for the same assessment purpose. This paper presents the germplasm information for selection and breeding of new salt-tolerant sweet potato varieties. The results could serve as a basis for subsequent assessment of seedling stage salt tole-rance of sweet potatoes and further studies on their salt tolerance mechanism.