Variation in Growth and Flowering Habits of Junebearing and Everbearing Strawberries

Abstract

Variation in vegetative and reproductive growth patterns leading to summer flowering and fruiting was evaluated in everbearing and in representative Junebearing strawberry ( Fragaria × ananassa Duch) clones under simulated summer conditions in the greenhouse and in growth chambers. Summer flowering intensity, periodicity, fruit set, and maturation were related to plant architectural parameters such as crown, leaf and runner production, number of meristems produced and differentiated, leaf areas and petiole length, plant volume, and dry weight allocation patterns. A continuum of growth habits and flowering behavior precluded rigid classification of summer flowering response, but useful arbitrary distinctions were made on the bases of: photoperiod reaction into short-day (Junebearing) vs. weak, intermediate, or strong day-neutrals; or summer fruit expectation into essentially none (Junebearing) vs. sporadic or consistent everbearers. Critical criteria for separating Junebearers from everbearers include degree of summer flowering and fruiting (fresh or dry weight basis), plant volume (and its components, petiole length, and average leaf area), and the dry weight allocation ratios—root : shoot and reproductive : vegetative. Everbearing (or day-neutral) types could be distinguished by plant volume and composition differences (size, number, and percentage of developed meristems, leaf area ratio, reproductive dry weight, etc.) and continuity of individual plant flowering. Three basic models of shoot growth and inflorescence positioning are proposed from evidence for alternative modes of flowering site generation in everbearing strawberries.