Comprehensive Evaluation of Low Temperature Tolerance of Waxy Maize Varieties at Germination Stage.

In order to construct evaluation system of different waxy maize varieties during germination for low temperature tolerance, 48 waxy maize varieties were used as test materials to measure 10 indicators on germination and growth under low temperature stress. And the low temperature tolerances of waxy maize varieties were comprehensively evaluated by principal component analysis, membership function method, cluster analysis and regression analysis. The results showed that 10 measurement indexes were transformed into 2 independent comprehensive indexes by principal component analysis, including root growth factor and seed germination factor. The comprehensive score model of low temperature tolerance of waxy maize was established, Y=0.647 7Y₁+ 0.144 2Y₂, where Y₁ and Y₂ were scores of the two principal components, respectively. Y1 included relative root dry weight, relative root surface area, relative root volume, and relative root length, which could reflect the state of root growth of waxy maize under low temperature stress; and Y₂ included relative seedling dry weight, relative germination rate, relative vitality index, and relative germination potential, which could reflect the germination of waxy maize under low temperature stress. The 48 waxy maize varieties were ranked by affiliation function method for low temperature tolerance, and the five varieties with the strong low temperature resistance were screened, including 'Runcainuo 686' 'Jingpo 82' 'Runnuo 175' 'Runnuo 605' and 'Tianguinuo 932'. The cluster analysis classified 48 waxy maize varieties into 4 groups. The regression analysis showed that the relative root dry weight, relative seedling length, relative germination potential, relative germination rate, relative seedling dry weight and relative root surface area could be used as important indicators for the evaluation of low-temperature tolerance of waxy maize. The comprehensive evaluation of multiple methods could effectively screen and classify waxy maize varieties with different low-temperature tolerances, which provided reference for the evaluation of waxy maize low-temperature tolerance and the screening of low-temperature tolerance germplasm resources. [ABSTRACT FROM AUTHOR]