Identification and Characterization of Physiological Traits Related to Productivity of Maize (Multiple Regression, Leaf Senescence, Inheritance, Green Score)

118 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.Scientists involved in agricultural research need to concentrate research efforts the most important traits related to productivity. Our objectives were to: (a) evaluate genotypic variation and the relationship of a large array of physiological traits to maize (Zea mays L.) grain yield and stalk lodging in a group of 76 hybrids; (b) utilize multiple regression techniques to identify and characterize the combination of traits that accounted for a large proportion of the variation in grain yield and stalk lodging among these hybrids; (c) determine the relationship between visual assessment of leaf senescence following ear removal and leaf green score ratings of eared plants at physiological maturity; and (d) determine the inheritance of leaf senescence following ear removal.Leaf senescence rate of earless plants was negatively correlated with leaf green scores of eared plants at physiological maturity in certain relative maturity groups. This relationship was not significant in relative maturity groups that had a large number of hybrids with an Oh43-type parent. However, hybrids with a slow rate of leaf senescence following ear removal and a high leaf green score on eared plants at physiological maturity generally had a B14 and/or Oh43-type parent and were relatively infrequent in each relative maturity group. In the populations evaluated, leaf senescence score following ear removal was largely controlled by additive gene action involving at least one estimated loci with a minimum of three alleles and had a high heritability estimate. Where leaf senescence is accelerated by ear removal, selection for low leaf senescence score following ear removal may improve hybrids for stalk quality. While hybrids vary for several physiological traits with little or no hybrid by year interaction, few traits show consistent and significant correlations with grain yield or stalk lodging over relative maturity groups. No single physiological trait was associated with grain yield or stalk lodging of these hybrids. Combinations of several physiological traits accounted for a large proportion of the variability in grain yield and stalk lodging. Using multiple regression models (over all groups), combinations of four and five traits accounted for 40 to 93% and 44 to 81% of the variability among hybrids for grain yield and stalk lodging, respectively. Thus, simultaneous use of several physiological traits may be effective for improvement of breeding populations.U of I OnlyRestricted to the U of I community indefinitely during batch ingest of legacy ETD