Behaviour of everbearers 'Portola' and 'Verity' in response to treatment with Prohexadione-Calcium
Gibberellin biosynthesis inhibitor Prohexadione-Calcium (Pro-Ca) has with widespread success been used to influence the vegetative development of short-day strawberry crops and consequently determine the fate of viable apical and axillary buds where eventual floral induction takes place. In this trial the effect of treatment with Pro-Ca on everbearing cultivars Verity and Portola was explored. In an initial trial with Verity, Pro-Ca was applied 3 weeks after planting at 125 mg L‑1. This resulted in a yield increase of 41% without affecting fruit size. In a second trial Pro-Ca was applied to Portola early after planting, in a single treatment at two rates: 62.5 and 150 mg L‑1. Twenty five days later, a repeat dose of the two rates was applied on a third and fourth group. In all Pro-Ca treatments stolon development was significantly reduced (17-37%). Repeated treatment at 150 mg L‑1 gave a significantly higher yield (20%). There were again no differences in fruit size grading between treated and untreated plants. Further trials on Verity explored the effect of timing of Pro-Ca application both on plant yield and runner development. The highest yield and runner reduction occurred when Pro-Ca was applied 5 weeks after planting. Variation in the timing outside this window gave suboptimal results. In Portola a waiting period of 42 days was needed before fruit residues for Pro-Ca fell below allowable levels. This research indicates that the early application of Pro-Ca in everbearers is an interesting means to improve yield and reduce runner development leading to higher profitability.
Gallace, N. and Lieten, P. (2021). Behaviour of everbearers 'Portola' and 'Verity' in response to treatment with Prohexadione-Calcium. Acta Hortic. 1309, 367-372
Fragaria × ananassa, growth regulator, Regalis Plus®, runners, side branching, perpetual flowering, gibberellin synthesis inhibitor