Inheritance of sugar and acid contents in the ripe berries of a tetraploid x diploid grape cross population

Inheritance patterns of sugar and organic acid contents of ripe berries in a tetraploid x diploid table grape cross population were investigated in two successive years. The population segregated for three different ploid levels: dipolids, triploids, and tetraploids. Sugar content in tetraploid progeny was significantly higher than that in the diploid progeny. Transgressive segregation for sugar content was observed in all the three ploid levels in the progeny population. The broad sense heritabilities (H(2)) of glucose, fructose and total sugar contents ranged from 0.68 to 0.79. The tetraploid progeny had the highest H(2), followed by the diploid and triploid progeny. The sugar contents appeared additive as the ploid level increased. All the sugar contents were highly and positively correlated with each other. Malic acid in the diploid progeny population was significantly higher than that in the polyploid progeny populations, and the tartaric acid in the triploid progeny was significantly higher than that in diploid and tetraploid progenies. H(2) of organic acids ranged from 0.71 to 0.91, with the tetraploids having the highest mean H(2). In contrast with the sugar content, the total acid content was decreased as the ploid level increased. Positive correlations were also observed among the contents of various acids, but the correlation coefficient was low between tartaric acid and malic acid and moderate between tartaric acid and the total acids. A large range of variation was observed for both sugars and acids in the triploid and tetraploid progenies than in the diploid progeny.