Abstract:

Lodging is one of the main factors affecting oat yield and quality. Screening to identify the morphological traits related to the lodging resistance of oats and the construction of an evaluation system are important steps towards identifying and utilizing superior oat germplasm. In this study， we evaluated and compared 18 morphological characters of the root， stem， and ear of 20 oat genotypes. The morphological indexes closely related to lodging resistance were screened by correlation analysis and principal component analysis （PCA）. An evaluation system for lodging resistance based on morphological indexes of oat was constructed by a step linear regression method. This system provides the basis for breeding lodging-resistant oat varieties. Some traits varied widely among the different oat genotypes. Morphological traits showed extremely significant differences among genotypes （P<0.01）. The root， stem， and ear morphological traits of the same oat genotypes differed significantly between the two test sites （P<0.05） and there was a significant interaction effect between the genotype of each morphological character and the test environment （P<0.05）. The average coefficient of variation of the actual lodging rate was 81.17%， and there was a large amount of genetic variation. Among all of the morphological traits， barycenter height had the smallest coefficient of variation （7.91%）. Stem strength， center of gravity height， basal internode stem length， and root volume were closely related to lodging resistance， and were the key indexes affecting oat lodging resistance. The PCA identified three key factors representing 85.082% of the information provided by 11 morphological traits. Systematic clustering was carried out based on 11 traits including root volume， stem base length （1st and 2nd internode lengths）， stem strength， and ear morphology. Three morphological trait cluster groups， seven cluster subgroups， and three genotype cluster groups were obtained. The scores from the cluster heat map， two-dimensional PCA map， and function model were basically consistent with the degree of lodging of different genotypes and the actual lodging rate， and these relationships were mutually verified. A linear regression model based on the relationship between morphological indexes and the lodging resistance of various cultivars was developed to predict the lodging resistance of oat varieties. A small root system， high center of gravity， long internodes at the base， and a slim stem were identified as factors related to lodging. A large root volume， short and thick base segments， thick stalk walls， and high stalk strength were identified as factors related to lodging resistance. Our results show that the actual lodging rate， root volume， center of gravity height， stem base length （1st and 2nd internode lengths）， stem diameter， and stem strength are useful characters for evaluating the lodging resistance of oats. The lodging resistance evaluation system is relatively reliable and can be used to evaluate the lodging resistance of oat varieties and lines in the field.

Key words: oats, lodging resistance, morphological traits, linear regression, evaluation system