Nutrition of new everbearing strawberry cultivars

Annual crops of the everbearing cultivars Calypso, Tango and Evita were used in a three year study investigating their responses to field nutrition, with particular reference to nitrogen requirements. Trials were carried out on a silt loam with moderate to high available water capacity, and a relatively low background level of available mineral N at planting. Adequately fed pot grown plants were spring planted into trickle irrigated polythene mulched raised beds for each trial. Cropping season was extended into early November by the use of walk-in polythene tunnels. In the first year a seasonal total of 40 or 80 kg/ha N applied as fertigation achieved a mean Class 1 yield increase of 40% and 50% respectively over a nil N control. In the subsequent trials, combinations of base and/or fertigation applications were examined. Yield advantages above total applications of 40 kg/ha N, whether applied as a base dressing or fertigation, were small, but there were benefits in early season yields of up to 9% from fertigation commencing shortly after planting, on top of a 40 kg/ha N base dressing. There was no evidence of cultivar differences to nutrition response. Cultivars had a much larger effect than nutrition on fruit flavour and shelf life, but there was an indication that the shelf life of late picked fruit was poorer from the treatment which had received the highest rate of N (40 + 80 kg/ha as base dressing + fertigation). It was concluded that early feeding was most important for maximum yield benefits, and that estimations of available soil mineral N at planting could be valuable in tailoring recommendations to specific sites.