Photoperiod and Temperature Effects on Flower and Runner Development in Day-Neutral, Junebearing, and Everbearing Strawberries

Abstract

Abstract Strawberries (Fragaria Xananassa Duch.) classified as day-neutrals (‘Hecker’ and ‘Tristar’), Junebearers (‘Redchief’ and ‘Guardian’), and everbearers (‘Ourown’ and ‘Ozark Beauty’) were grown at a constant 21°C under 16 hour long days (LD), 9 hour short days (SD), or 9 hours with the dark period interrupted by 3 hours of low-level incandescent radiation [night interruption (NI)]. Flowering of day-neutrals was unaffected by photoperiod; Junebearer flowering was inhibited under NI and LD compared to SD; flowering of everbearers was promoted by LD compared to SD. Runner production was greatest for all types under LD, followed by NI then SD. Everbearers produced more runners than the other types. Effects of photoperiod on total, nonstructural carbohydrates varied with photoperiodic type and tissue sampled. The 3 types of strawberries were grown also under SD and NI under day/night temperature regimes of 18°/14°, 22°/18°, 26°/22°, and 30°/26°C. With number of inflorescences and runners and total dry weight per plant, significant photoperiod × temperature × type interactions were found. Results indicate that current classification of strawberry cultivars into photoperiodic type is inadequate.