Postharvest Longevity of Cut-flower Gerbera. II. Heritability of Vase Life

Intensive selection to improve vase life was performed on a sample population of Gerbera ×hybrida Hort. from a broad source of germplasm. Progeny of a 5 × 5 diallel cross yielded estimates of narrow sense heritability (h 2 = 0.28) and broad sense heritability (H2 = 0.28) for vase life based on a mean of 1.96 measurements per plant. Additive gene action is postulated to control this character since the difference between total genotypic variance and additive genetic variance components was small. Repeatability (r = 0.57) based on a single measurement per plant was moderately high. Heritability estimates were also determined based on 1, 2, 3, 5, and ∞ measurements per plant. Heritability ranged from 22% to 39%. Gerbera ×hybrida is a popular cut flower, but its postharvest performance is often less than desirable. Postharvest treatments (i.e., floral preservatives) are used to enhance the vase life of gerbera (Accati, 1989) but developing cultivars with genetically superior postharvest longevity may provide the consumer with a reliable expectation for postharvest quality. Therefore, research to evaluate the potential of plant breeding as a method to improve vase life in gerbera is important. Estimates for heritability of vase life have been previously reported. However, estimates can vary based on the population of plants evaluated, selection intensity, mating design, and environ- ment (Simmonds, 1979). Serini and De Leo (1978) concluded that selection should be based more on families than individual plants, since their estimate of narrow sense heritability was higher among full-sib families (h 2 = 0.67) than among plants (h 2 = 0.17). Tesi (1978), using clones from a population of Gerbera jamesonii with semi-double flowers, concluded that vase life is strongly influ- enced by environmental factors. He observed only 15% of the phenotypic variation in vase life was due to genotype (h 2 = 0.15). Harding et al. (1981) based their results on a nonrandom sample population of gerbera genotypes from their Davis population, which consisted of half-sib families and clonal parents. They concluded that since narrow sense heritability (h 2 = 0.24 and 0.38) and broad sense heritability (H 2 = 0.36 and 0.46) were moderately low for two successive generations, either intense selection or selection over a large number of generations would be required to increase mean vase life. Harding et al. (1987) compared their earlier average estimate of narrow sense heritability (21%) to a new average of narrow sense heritability (18.5%). Both averages were calculated using data from three generations of half-sib family mating. Realized heritability estimated from the ratio of the selection response to the selection differential was about 30%. The objectives of this study were to determine narrow sense heritability and broad sense heritability of vase life by diallel analysis using a broad based source of germplasm.