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- Author or Editor: Teresa K. Howe x
Bell pepper (Capsicum annuum L.) cultivars were grown in nine Florida environments to evaluate phenotypic stability of marketable fruit yield (t-ha-') and mean fruit size (g/fruit). A stable cultivar excelled for a particular trait when grown in either favorable or unfavorable environments. A stable cultivar for a given trait was defined as one with an individual mean greater than the grand mean (mean of all cultivars) (x > X), a regression coefficient (b1) ≤ 1 (individual genotypic mean regressed against environmental means), nonsignificant deviation mean squares from regression (S2d), coefficient of linear determination (R2) > 0.50, and coefficient of variation (cv) < the pooled cv. `Ssupersweet 860', `Whopper Improved', and `Ranger' were stable for mean marketable fruit weights and fruit size, and `Ssupersweet 860' and `Whopper Improved' were stable for mean fruit size. Bell pepper cultivars were differentiated for phenotypic stability of yield and fruit size or adaptability to diverse environments. Therefore, through stability analyses, bell pepper plant breeders can identify cultivars or select advanced breeding lines that express adaptability for fruit yields or size to diverse environmental conditions or cultural practices.
‘Horizon’, a small shoot-mass tomato (Lycopersicon esculentum Mill) cultivar, and ‘Sunny’, a large shoot-mass cultivar were planted at 30.5-, 61-, and 91-cm within-row spacings at five locations in Florida during Spring 1985 to determine if yields differed between these cultivars and among plant densities. Marketable weight and number of fruit per plant, mean fruit size (g/fruit), and shoot weight increased linearly with an increase in within-row spacing. Marketable weight of fruit/ha decreased linearly with wider within-row spacings. Responses of both cultivars to within-row spacing were similar for each measured trait, except for marketable fruit number per plant. A larger increase in marketable number of fruit per plant occurred between 61- and 91-cm within-row spacings for ‘Sunny’ than for ‘Horizon’. Fruit : shoot ratio (w/w) was not influenced by within-row spacings or cultivars. Each measure variable differed among locations. These results suggest that ‘Sunny’, with a larger inherent shoot growth, sufficiently compensated for smaller shoot growth when grown at higher plant densities to maintain marketable fruit yields comparable to ‘Horizon’.
Ten fresh market tomato (Lycopersicon esculentum Mill.) genotypes were evaluated for yield stability in 7 environments within Florida. Genotype × environment interaction was significant for yield of marketable fruit. Linear relationships between mean yields of individual genotypes and environmental mean yields were evaluated to determine genotype stability. Mean square deviations from linear regression (s2d), regression coefficients (b1) and coefficient of linear determination (R 2) were used to evaluate phenotypic stability. ‘Sunny’, Castlehy 1035’, ‘Burgis’, ‘FTE 12’, and ‘Duke’ were considered stable and high yielding. An advanced breeding line, 827015-IBK, was considered stable but low yielding. ‘Hayslip’, D76127, ‘Flora-Dade’, and ‘Walter PF’ were considered unstable. This study suggests that yield stability differences occur among fresh market tomato genotypes. Therefore, selection of tomato genotypes for improved adaptability should be considered in tomato breeding programs.
Ten fresh-market tomato (Lycopersicon esculentum Mill.) genotypes were evaluated for stability of fruit firmness, citric acid, soluble solids, β-carotene and ascorbic acid concentrations, sugar : acid ratio, color, N content, and dry weight when grown in nine environments. Linear relationships between the genotype means for a given trait and the mean for the trait in each environment were used as an indicator of stability. A stable genotype for a given trait was considered to possess a regression coefficient (b1) ⩽ a coefficient of linear determination (r2) > 0.50, a genotype mean above the grand mean (mean of all genotypes), and a nonsignificant deviation from regression mean square (S2d). Using these criteria, stability in the nine environments was shown by the fruits of the various cultivars as follows: ‘Flora-Dade’, ‘FTE-12’, and D76I27 for firmness; ‘Castlehy 1035’ and ‘Sunny’ for citric acid; ‘Walter’ for soluble solids concentration; ‘FTE-12’ for ascorbic acid concentration; ‘Hayslip’, ‘Walter’, and ‘Burgis’ for sugar : acid ratio; ‘FTE-12’ and ‘Hayslip’ for β-carotene concentration: ‘Flora-Dade’ and 827115-IBK for color a/b; ‘Castlehy 1035’ and ‘Hayslip’ for dry weight; and ‘Walter’ for N content. Stable genotypes are less sensitive to environmental changes and are more adapted to favorable and unfavorable conditions than unstable genotypes. No genotype was found to be stable for every fruit quality trait in the nine environments. Stability of fruit quality characteristics should be considered in tomato breeding programs to develop genotypes adapted to diverse environmental and management conditions.