ERWERBS-OBSTBAU, vol.64, pp.47-53, 2022 (SCI-Expanded)
This article describes pollen formation at various developmental stages, pollen morphology, pollen viability and in vitro germination in 'Cardinal' grapevine (Vitis vinifera L.). Various microscopy techniques were utilized in the study. Formation of pollen grain was observed under stereo zoom and light microscopy using anther squashes and acetocarmine staining. Size of the pollen grains and the development of the nuclei were observed with SEM. TTC test and the "agar in petri dish" method were employed for the assessment of pollen viability and germination, respectively. The pollen development in grapevine (Vitis vinifera L.) may be divided into four basic stages starting from mother cell formation as (1) formation of tetrad, (2) microspore release, (3) germination of microspore, followed by pollen tube growth and elongation, and (4) formation of vegetative and generative cells. The observations and tests showed that the formation of pollen occurred very close to the flowering. The tetrad stage was seen in Mid-May. The exine of the pollen had a striate pattern with long ridges. Pollen had similar size (approximate to 25 mu m) and an elliptical-oval shape. Although the highest pollen viability ratio was 81%, only 31% of the pollenwere germinated. Before germination, the pollen grain contained a nucleus. During pollen tube formation, a defined area in the pollen plasma membrane promoted a directional growth, and the tube cell elongated and formed its own pathway. Before entering the pathway, the generative cell formed two haploid generative cells.