Pollen quality and performance in strawberry plants exposed to high-temperature stress

• Published in: Journal of the American Society for Horticultural Science Vol. 130; no. 3; pp. 341 - 347
• Main Authors: Ledesma, N, Sugiyama, N
• Format: Journal Article
• Language: English
• Published: 01.05.2005
• Subjects: air temperature; cultivars; Fragaria ananassa; fruit crops; heat; heat stress; heat tolerance; in vitro studies; in vivo studies; plant fertility; pollen; pollen germination; pollen tubes; strawberries
• ISSN: 0003-1062; 2327-9788
• DOI: 10.21273/jashs.130.3.341

The effects of high-temperature stress on pollen viability and in vitro and in vivo germinability were studied in two facultative, short-day strawberries (Fragaria xananassa Duch.), 'Nyoho' and 'Toyonoka.' Plants were exposed to two day/night temperature regimes of either 23 degrees C/18 degrees C (control) or 30 degrees C/25 degrees C (high temperature) from when the first inflorescence became visible until anthesis. Pollen viability in 'Nyoho' was only slightly affected at 30 degrees C/25 degrees C when compared with pollen from plants grown at 23 degrees C/18 degrees C. In 'Toyonoka', however, pollen viability was significantly lower at 30 degrees C/25 degrees C than at 23 degrees C/18 degrees C. The in vitro germination percentages were significantly lower in pollen from plants grown at 30 degrees C/25 degrees C and germinated at 30 degrees C than from plants grown at 23 degrees C/18 degrees C and germinated at 23 degrees C in both cultivars. But the percentages were much lower in 'Toyonoka' than in 'Nyoho', particularly at the 30 degrees C germination temperature. Pollen from plants grown at 23 degrees C/18 degrees C also extended longer pollen tubes than pollen grown at 30 degrees C/25 degrees C in both cultivars, but 'Nyoho' had longer pollen tubes than 'Toyonoka' at 30 degrees C/25 degrees C. Fluorescence microscopy revealed that most of the 'Nyoho' pollen germinated on the stamen, elongated through the style and reached the ovule regardless of temperature treatment. In 'Toyonoka', pollen germination and elongation were greatly inhibited at 30 degrees C/25 degrees C, resulting in unfertilized ovules. These results suggest that certain strawberry cultivars produce heat-tolerant pollen, which in turn could result in higher fruit set.