Effects of Temperature and Photoperiod on the Flower Potential in Everbearing Strawberry as Evaluated by Meristem Dissection

Abstract

The growing interest in using everbearing (EB) strawberry cultivars to extend the cultivation period has faced some challenges. These include poor runner production due to its perpetual flowering nature; irregular flowering behavior and extended periods of high temperature have caused floral inhibition and reduced yield. As flowering is an interplay between temperature and photoperiod, it is important to investigate the effects of this interaction on the cultivation. Therefore, this study used meristem dissection as a tool to study the effect of temperature and photoperiod on meristem development. Tray plants of two EB strawberry cultivars ‘Florentina’ and ‘Favori’ were grown at 20 °C, 25 °C, and 30 °C under short day (SD) conditions, and subsequently at 20 °C under long day (LD) conditions. The meristem development was analysed every 6 weeks for a 15-week period in SD and for 14 weeks in LD conditions using meristem dissection. The plants showed similar flowering patterns to previously studied everbearing cultivars, which was qualitative LD plants at high temperatures and quantitative LD plants at lower temperatures. Our results show that meristem dissection can be used to determine the temperature and photoperiodic effect on meristem development, and for the occurrence of cropping peaks, and can therefore be used to decide the environmental input and to evaluate yield potential.

Effect of Temperature and Photoperiod Preconditioning on Flowering and Yield Performance of Three Everbearing Strawberry Cultivars

“…On the other hand, runner formation was enhanced by SD over the same intermediate to high temperature range. All these results concur with previous results for EB cultivars in general [8,9] as well as for 'Favori' and other modern EB cultivars [2,4,10,11]. Furthermore, a new flush of flowers emerged after a time span of approximately seven weeks, which had apparently been initiated after the plants had been transferred to the LD and relatively high temperature forcing conditions.…”

“…A rather short exposure to varying temperature and photoperiod conditions during the raising of the plants in one year had a remarkable effect on the flowering and fruiting pattern in the following year. The highest yields were generally obtained in plants exposed to LD at intermediate temperatures of 15-21 • C. This temperature range has previously been reported as highly effective for LD-induced flower bud formation in EB cultivars [2,[8][9][10] and was also found to be optimal for photosynthesis in these cultivars [12]. As previously reported by Melis [6], treatments that produced a large first fruiting flush were generally associated with a long off period with little flowering and fruiting.…”

Characterization of environmental effects on flowering and plant architecture in an everbearing strawberry F1-hybrid by meristem dissection and gene expression analysis

“…Specifically, we investigated meristem development in both stages and correlated it to changes in the expression of known flowering genes. To ensure that the starting material in these studies had no prehistory of being induced [4,12], we used seed propagated F1-hybrids. This enabled us to compare the reliability of flower mapping and molecular analysis as practical tools for strawberry growers and breeders, and to determine how genes shape the flowering phenotype.…”

“…Furthermore, in commercial production, strawberry plants are raised under inducing conditions and then transferred to a greenhouse for flowering and fruiting when floral initiation is complete. However, several studies have shown that environmental factors can influence flower bud differentiation and subsequent development even in plants that have been induced and initiated flower buds [4,[10][11][12][13][14][15][16]. This must be taken into account because initiating adequate numbers of inflorescences is of similar economic importance to producing runners for clonal propagation [11].…”

“…Although the physiology of flowering in the cultivated strawberry has been widely studied [2][3][4][5][8][9][10][11][12][13][14][15], there have been comparatively few genetic studies on this topic [17,[24][25][26][27][28][29]. The Arabidopsis photoperiodic pathway is conserved in the octoploid strawberry, but because the genetics of the cultivated strawberry are complex, most functional studies on this topic have been conducted in the closely related diploid wild strawberry Fragaria vesca [30][31][32][33][34].…”