Correlation of biometrical characteristics of fruit and seed with twinning and vigor of Prunus persica rootstocks

This study aimed at determining and correlating the main morphometric characteristics of fruits and seeds with the germination potential and vigor of eight peach rootstocks. The experimental design was completely randomized, with four replications of 50 seeds per treatment. The analyzed variables were: length, width, thickness, fresh mass of fruit and seeds, moisture content of seeds, percentage of seeds attacked by fungi and intact seeds, germination percentage, germination speed index (GSI) and mean germination time (MGT). The Capdeboscq, Aldrighi and Tsukuba 1 cultivars showed higher values of length, width, thickness and fresh mass of seeds compared to other cultivars, presenting a relationship with the later period of fruit ripening. Regardless of the fruit ripening time, the germination percentage was high, ranging between 93% and 100% for all cultivars. In addition, the fresh mass of fruits has showed a high positive correlation with the fresh mass of seeds for the eight evaluated peach rootstocks. The GSI and MGT have a high relationship with the fresh mass of seeds.

Genetic Analysis of Fruit Ripening Time in Japanese Persimmon

Three individuals in progeny from each of 39 crosses and their parents in Japanese persimmon (Diospyros kaki Thunb.) were evaluated for fruit ripening time. Analysis of variance for the progeny, which estimated between- and within-cross variance, and the regression of the mean value in a full-sib family on the mid-parental value (MP) revealed that the genetic differences among crosses could be explained solely by MP. Genotypic values of individuals in progeny from a cross were assumed to be normally distributed around the regression line with within-cross genetic variance. Based on the parental mean performance of 3.5 fruit on a single tree for three years, the coefficient of regression of mean values in a full-sib family on MP was 0.99 ± 0.10, and the proportion of individuals in progeny having genotypic values ripening earlier than early October was estimated as 52%, 24%, and 7% for three sets of mid-parents differing in their ripening time, i.e., early, middle, and late October, respectively. On the basis of the parental mean performance in 10 fruit on a single tree without yearly repetition, the regression coefficient was estimated as 0.91 and the proportion was estimated as 44%, 20%, and 6% for the three sets of mid-parents, respectively.

Optimal Spatial and Temporal Measurement Repetition for Selection in Japanese Persimmon Breeding

Genetic and environmental variances for fruit ripening time (FRT), fruit weight, and soluble solids concentration (SSC) in Japanese persimmon (Diospyros kaki Thunb.) were estimated. The variance among fruit within a tree was the largest among environmental variances. Therefore, using a large sample size per tree and per year effectively increased heritability, but the effect was minimal when more than five fruit were sampled. The variance among years was largest for SSC and smallest for FRT. Generally, the variance associated with the genotype × year interaction was as large as the tree × year interaction. The variance among trees within a genotype was negligible for all traits. Repeating measurements yearly was more efficient than replicating trees.