THE EFFECTS OF LIFTING DATE, CHILLING DURATION AND FORCING TEMPERATURE ON VEGETATIVE GROWTH AND FRUIT PRODUCTION IN THE JUNE BEARING STRAWBERRY CULTIVAR ELSANTA

The effects of different durations of cold storage (0, 2, 4, 6, 8, 10 and 12 weeks at -2 degrees C and +3 degrees C) on strawberry plants cv . Elsanta from two different lifting dates (6 November and 6 December) were investigated, to determine the chilling required for optimum gro wth and development. With greater durations of chilling, the petiole l ength, leaf weight and runner production of plants were increased. The chilling requirement for optimum vegetative growth was saturated afte r 6-8 weeks. For chilling durations up to six weeks there was no diffe rence between the two cold storage temperatures, but with larger durat ions subsequent vegetative growth of the plants stored at -2 degrees C was reduced compared with plants stored at +3 degrees C. The vegetati ve growth after cold storage of plants lifted on 6 December was greate r than that of plants lifted on 6 November. Cold storage temperature d id not affect the number of flowers produced per plant, fruit number o r fruit weight. However fruit number and fruit weight were both greate r in plants lifted on 6 November than in those lifted on 6 December. I n a second experiment, the effects of chilling duration on growth and fruiting at three forcing temperatures were studied. There was no sign ificant interaction between chilling duration and temperature during f orcing, and while eight weeks chilling was optimum for vegetative grow th, in terms of fruit production four weeks chilling was optimum. Over all, these results indicate that there may be an important interaction between fruit set and vegetative vigour and that field chilling is mo re effective than cold store chilling in promoting vegetative growth. The results also show that the optimum chilling requirements for veget ative vigour and fruit production are different, and that chilling bec omes more important when the temperature during forcing is low.