Investigating some characteristics of ‘Red Sultana’ autotetraploid grapes

Abstract

Polyploidization in seedless grapes is an important technique to produce new cultivars in order to increase the quality and yield of grapes in the world. Seedless grapevines with increased ploidy can gain better quality than their original diploids in some characteristics. With the aim of creating an autotetraploid cultivar of seedless red grape in the Urmia region, an experiment was carried out for 9 years (2014-2022). In this study, which was carried out to obtain polyploid genotypes in vineyard conditions, the effects of two (9, 11 g L^-1) doses of colchicine were applied to the meristem regions in the bud burst stage of seedless grapevine ‘Red Sultana’, for two times (72 and 96 h) were investigated. The effects of mutagen were evaluated by following the treated buds. Mutant individuals were compared with the ‘Red Sultana’ (2x) cultivar by Karyotyping analysis. Stomatal characteristics, chloroplast numbers and karyotypes differed to varying degrees from their original diploids, and stomatal density decreased inversely with the increase in stomatal size in polyploid genotypes. To examine morphological changes, tetraploid shoots were rooted and planted in the vineyard. It was observed that the genotypes examined showed some differences in their morpho-physiological characteristics. In terms of autotetraploid performance, the result of colchicine concentration of 11 g L^-1/96 h with 18.250 kg vine^-1 was superior to other treatments. Quantitative characteristics of clusters in terms of width, length and cluster weight, berry length, width and weight, this treatment was superior. In the autotetraploid genotype, the highest TSS (Total Soluble Solids) amount was obtained from the 9 g L^-1/72-h colchicine treatment (23 °Brix), while the lowest TSS amount was obtained from the 11 g L^-1/96-h colchicine treatment (18 °Brix), and the opposite result was obtained in terms of acidity (TA, titratable acidity). In terms of maturity index (TSS/TA), the tetraploid genotype obtained from colchicine treatment 9 g L^-1/72 h of bud treatment was superior to others. In the cluster analysis, two groups including the control, tetraploid genotypes 1, 2 and 3 were in one group and tetraploid genotype 4 was located in the second group.