Correlation between floral morphology and microspore developmental stages in local grapevine cultivars ‘Ekşi Kara’ and ‘Gök Üzüm’

The developmental stage of microspore cultivars plays a crucial role in the success of anther and microspore cultures in grapevines. External floral characteristics, particularly flower bud and anther size, can be used as practical indicators to estimate cytological status. Cultivar-specific differences necessitate precise determination of these threshold values. This study was conducted on the genetically and economically important local grape cultivars ‘Ekşi Kara’ and ‘Gök Üzüm’ to evaluate differences in microspore development at various inflorescence developmental stages. In the ‘Ekşi Kara’ cultivar, the tetrad stage was observed at stage 2. At this stage, flower buds measured 848.64 µm wide and 1020.17 µm long, while anthers measured 351.78 µm wide and 475.96 µm long. In the third stage, the uninucleate flower dimensions reached 1396.82 µm wide and 1765.17 µm long, while the anthers reached 441.82 µm wide and 709.44 µm long. In’ Gök Üzüm’, the uninucleate stage was detected earlier, in the 1st and 2nd stages. Bud sizes ranged from 1066.51 to 1222.13 µm wide and 979.75 to 1524.53 µm long, while anthers ranged from 483.28 to 521.19 µm wide and 516.37 to 606.54 µm long. In the fourth stage, the flower buds exceeded 1500 µm wide and 1780 µm long, marking the transition to the multinucleate stage. The uninucleate stage is preferred for androgenesis induction. Cultivars differed in the timing of uninucleate stages. In ‘Ekşi Kara’, stage 3 bud sizes were larger, while in ‘Gök Üzüm’, bud sizes appeared earlier and in smaller size ranges. These results highlight the importance of cultivar-specific morphometric criteria in selecting suitable explants and provide a practical framework for improving haploid plant production in grapevine breeding.