Physiological characteristics in seeds of the common bean under multicollinearity and conditions of salinity

ABSTRACT The objective of this work was evaluate multicollinearity effect and discard the variables which are based on multicollinearity reduction in diversity analysis of common bean genotypes, related to seeds physiological quality, in different salinity levels in germination substrate. The common bean seed germination test for six cultivars and seven landrace genotypes was performed in paper rolls (germitest), imbibed in NaCl solutions on the osmotic potentials of 0.0; -0.3 and - 0.6 MPa, maintained in germinated Mangelsdorff type at temperature of 25 °C, on constant light. The experimental design was completely randomized in factorial arrangement 13 x 3 (genotype x osmotic potential), with four replications with 25 seeds, totaling 100 seeds per treatment. The carried out evaluations were: weight of a thousand seeds, germination mean time, primary root protrusion in five and nine days after seeding, normal seedling percentage, hypocotyl and primary root length and dry matter from aerial part and roots. The multicollinearity diagnosis was carried out on the phenotypic correlation matrix and the characteristic discard was preceded through the canonical variable technique. To evaluate the multicollinearity effect, the Tocher cluster method was used before and after the variables discard. The proposed discard methodology of variables is efficient on the multicollinearity reduction and the number of discarded physiological quality descriptors is higher on the potentials of -0.3 and -0.6 MPa, under salt stress conditions, need to be discarded three characteristics and in the absence of stress only two discarded, to became a weak condition of multicollinearity to follow with the cluster analysis. The common bean genotypes clusters are different on the severe and weak multicollinearity only under salt stress condition.摘要 本研究旨在评估多重共线性的影响，并针对发芽基质不同盐度水平下、与菜豆基因型种子生理品质相关的多样性分析场景，基于多重共线性消减原则剔除冗余变量。本试验以6个栽培品种与7个地方品种基因型的菜豆为材料，采用纸巾卷发芽法（germitest）开展发芽试验：将种子置于浸有氯化钠（NaCl）溶液的纸巾卷中，溶液渗透势分别设置为0.0、-0.3与-0.6 MPa，随后将其置于25℃、持续光照的曼格斯多夫型发芽箱中培养。试验采用完全随机的13×3因子设计（基因型×渗透势），每个处理设置4次重复，每次重复包含25粒种子，单处理总种子数为100粒。本试验测定的指标包括：千粒重、平均发芽时间、播种后第5天与第9天的初生根伸出率、正常幼苗百分率、下胚轴与初生根长度，以及地上部与根系的干物质质量。本研究通过表型相关矩阵开展多重共线性诊断，变量剔除流程则通过典范变量技术完成。为评估多重共线性的影响，本研究在变量剔除前后均采用托彻聚类法（Tocher cluster method）开展聚类分析。本研究提出的变量剔除方法可有效实现多重共线性消减；在盐胁迫条件下，渗透势为-0.3与-0.6 MPa时，需剔除的生理品质描述指标数量更多：盐胁迫下需剔除3项特征，而非胁迫条件下仅需剔除2项，即可使多重共线性减弱至适宜开展后续聚类分析的水平。仅在盐胁迫条件下，菜豆基因型的聚类结果会因多重共线性强弱程度的不同而存在差异。