Characteristics of seedless berries of triploid hybrid grapes (Vitis vinifera complex) derived from eighteen crosses

Abstract

To evaluate fruit quality of 92 triploid hybrid grapes obtained from 18 interploid crosses between six diploid and five tetraploid cultivars, the flower clusters trimmed and adjusted at about 200 were immersed in a solution of GA3 (100 mg/l) at full bloom and examined at the mature stage. Fruit set in non-treated clusters was observed in 78.3% of the hybrids, whereas GA3 treatment of the clusters resulted in fruit set in all the hybrids. In almost all hybrids that set fruits without GA3 treatment, GA3 treatment to the flower clusters increased not only berry weight but also the berry set rates, especially in those setting small number of berries without GA3 treatment. The mean weight of non-treated berries of hybrids in each cross ranged from 0.8 to 2.7 g, except for the hybrid from a 'Muscat Bailey A'X'Rizamat 4x' cross that produced 6.5 g berry. In the GA 3-treated clusters, the mean berry weight ranged from 2.1 to 16.5 g. Hybrids producing large-sized berries were derived from crosses with 'Rizamat', while those producing small-sized berries were derived from crosses with 'Delaware' and its tetraploid 'Red Pearl'. In the non-treated clusters, fertilized seeds were rarely detected in a few berries with the range of 0-6% per berry, whereas in the GA3-treated clusters the rates of berries with the seeds decreased and ranged from 0 to 1%. The rind color of berries was roughly classified into black, red or white in the 92 hybrids.