EFFECT OF ROOTSTOCKS ON POLLEN PRODUCTION, VIABILITY AND GERMINATION IN GRAFTED TETRAPLOID AND DIPLOID WATERMELON

Abstract

The two years study was conducted to investigate the effects of graft combinations on pollen production, pollen germination, pollen viability and normal pollen development in grafted tetraploid and diploid watermelons. Two scions (tetraploid watermelon line ‘ST 101’ and diploid watermelon line ‘WL 92’) were grafted onto three rootstocks (Cucurbita interspecific hybrid ‘Nun-9075’; Lagenaria siceraria ‘Argentario’ and citron watermelon ‘PI 296341’) and non-grafted ST 101 and WL 92 were used as control.  Cultivation was conducted in spring seasons of 2016 and 2017 at horticultural experimental fields; flower and pollen analysis were done at the cytological laboratory of the Department of Horticulture, Cukurova University in Turkey. All graft combinations were grown and received the same management practices and flowers for analysis were collected randomly from every plot. There was a significant difference in pollen germination among graft combinations. In 2016, the highest pollen germination percentages were 94.13% and 89.85% obtained in non-grafted ST 101 and PI 269342/WL 92. In 2017, the highest pollen germination percentage value (79.75%) was obtained in Nun-9075/ST 101. No significant difference was found among graft combinations in percentage of pollen viability and normal pollen development in both years. Although no significant difference was observed in 2016 in number of pollen, the highest value was recorded in Argentario/WL 92 (509719.61 pollen per staminate flower) and the lowest value was obtained in Nun-9075/ST 101 (279494.76 pollen per staminate flower). In 2017, Nun-9075/WL 92 graft combination resulted in the highest number (260682.61 pollen per staminate flower) of pollen compared to other graft combinations. WL 92 diploid scion resulted in a higher number of pollen compared to tetraploid ST 101 scion. This study indicates that grafting increases production and development of normal pollen and improve pollen germination and viability.