OVERWINTERING STRAWBERRY PLANTS UNDER ROWCOVERS: EFFECTS ON DEVELOPMENT OF YIELD COMPONENTS
Strawberry production in some temperature climates may be limited by low temperatures in autumn, winter and spring. Each season affects a different phase of fruit production. Under the short photoperiods and low temperatures of autumn, floral buds are initiated (Austin et. al., 1960, Darrow, 1966, Moore and Hough, 19621). As temperatures decrease floral bud initiation eventually ceases. Low temperatures in winter can damage crowns resulting in poor growth in spring. Low temperatures in spring can damage flowers and delay anthesis and fruit ripening. Rowcovers may overcome some low temperature effects, as suggested by Pollard and Cundari (1988), who found higher yields and earlier maturity for strawberries grown under rowcovers compared to non-rowcovered controls. Their work did not investigate the effect of rowcovers on yield components.
Yield components can be divided into those which directly affect yield, the reproductive yield components, and those which indirectly affect yield, the vegetative yield components. Reproductive yield components include achenes per receptable, total flowers per truss, number of higher order flowers per truss, and size and number of trusses per crown (Robertson and Wood, 1954; Strik and Proctor, 1988). Vegetative yield components include crown diameter, crown dry mass, crown number, leaves per crown and per plant, leaf dry mass and area (Hancock et. al., 1984; Strik and Proctor, 1988). In light of the findings of Pollard and Cundari (1988), and the importance of yield components to production, the objective of this study was to examine how yield components of strawberry were affected by a rowcover and a conventional date of mulch removal.
Dormant crowns of the short day cultuvars 'Earliglow' were planted in June 1986, in Durham, NH, USA. Floating type rowcovers (Beghin Say, Inc., Kayersberg, France) were applied on 11 September 1986 and were removed at anthesis on 12 May 1987. A winter protective mulch of straw was applied to both treatments on 22 December 1986 and wa.