不同紫花苜蓿品种对低磷环境的形态与生理响应分析

【目的】筛选耐低磷苜蓿品种及与耐低磷密切相关的性状指标,进一步为紫花苜蓿耐低磷机制研究和生产应用提供理论依据。【方法】在溶液培养条件下,对20个紫花苜蓿品种的24 d龄的幼苗分别进行常磷(500μmol·L~(-1) KH2PO4)和低磷(5μmol·L~(-1) KH_2PO_4)处理,30 d后检测各品种的茎叶干重(SLW)、株高(PH)、根干重(RW)、根冠比(RS)、总根长(TRL)、根表面积(RSA)、全磷含量(TP)、磷利用率(PUE)、酸性磷酸酶活性(ACPA),并计算各指标的耐低磷系数。进一步对各指标的耐低磷系数进行相关性分析,并运用主成分分析、隶属函数分析、回归分析及聚类分析方法,综合评价不同品种耐低磷性及筛选与耐低磷密切相关的指标,同时建立耐低磷评价模型。【结果】低磷胁迫下,各品种紫花苜蓿的地上部分生长受到抑制,地下根系增大,全磷含量显著下降(P0.01)。通过主成分分析可将9个单项指标转化为4个新的相互独立的综合指标。进一步利用隶属函数对4个新的综合指标进行耐低磷综合评价,结合聚类分析结果,可将20个紫花苜蓿品种可分为三类,其中耐低磷较强的品种包括敖汉、新牧1号、耐盐之星、皇冠;中度耐低磷品种包括骑士T、驯鹿、牧歌37CR、龙牧801等9个品种;耐低磷较弱的品种包括巨能Ⅱ、中苜2号、康赛等7个品种。进一步利用逐步回归分析方法建立了紫花苜蓿耐低磷性评价数学模型D=-0.7997+0.3856SLW+0.2025PH+0.3789RW+0.1051TRL+0.4188TP+0.1347ACPA,方程的决定系数R~2=0.9982.【结论】通过分析紫花苜蓿不同品种的耐低磷能力,得出耐低磷较强的品种为敖汉、新牧1号、耐盐之星、皇冠,与耐低磷性最相关的指标有茎叶干重、株高、根干重、总根长、全磷含量和酸性磷酸酶活性,可用于紫花苜蓿耐低磷性的评价筛选。

Analysis of Morphological and Physiological Responses to Low Pi Stress in Different Alfalfas

【Objective】 The objective of this study is to screen low Pi (inorganic phosphate) tolerant alfalfa and related characters, and to provide the theoretical basis for deficient Pi tolerance mechanism and then for application in production. 【Method】 In the condition of nutrient solution, twenty 24-day-old alfalfa seedlings were cultured in nutrient solution with sufficient phosphate (500 μmol·L^﹣1 KH₂PO₄) and deficient phosphate (5 μmol·L^﹣1 KH₂PO₄). After 30 days of treatment, a variety of physiological indexes, including dry weight of stems and leaves (SLW), plant height (PH), dry weight of root (RW), ratio of root to shoot (RS), total root length (TRL), root square area (RSA), total Pi content (TP), phosphate utilization efficiency (PUE), acid phosphatase activity (ACPA), were measured, and coefficients of resistance to deficient-Pi of each index were calculated. Furthermore, the correlation was carried out on the deficient-Pi coefficient of each index. Based on principal component analysis, subordinate function analysis, regression analysis and cluster analysis, deficient-Pi tolerance of different varieties were evaluated, and the indexes closely related to deficient-Pi tolerance were screened. At the same time, the evaluation model of deficient-Pi tolerance was established. 【Result】 Under deficient-Pi stress, the aboveground growth of all varieties were inhibited. However, the root system and the content of total Pi were decreased (P＜0.01). Through principal component analysis, nine primary indexes could be transformed into four new mutual independent comprehensive indexes, which covered 92.04% of information. Then four new indexes were used to comprehensively assess the characters of deficient-Pi tolerance by subordinate function analysis. Combined with the clusters result, 20 alfalfa varieties were divided into three clusters. The varieties resistant to deficient-Pi include Aohan, Xinmu NO.1, Magnum Salt, Phabulous; varieties moderate resistant to deficient-Pi include nine varieties, such as Knight T, Caribou, Amerigraze 37CR, Longmu 801 and so on; varieties sensitive to deficient-Pi include seven varieties, such as Magnum II, Zhongmu NO. 2, Concept and so on. Furthermore, the mathematic evaluation model of resistance to deficient-Pi, D=﹣0.7997+0.3856 SLW+0.2025 PH+0.3789 RW+0.1051 TRL+0.4188 TP+0.1347 ACPA (R² = 0.9982).【Conclusion】The analysis of the ability of deficient-Pi tolerance in different alfalfa varieties showed Aohan, Xinmu NO.1, Magnum Salt and Phabulous have strong resistance to deficient-Pi stress. And the dry weight of stems and leaves, plant height, root dry weight, total root length, total Pi content and acid phosphatase activity were the most suitable indicators for the tolerance to deficient-Pi.