EXTENDING STRAWBERRY PRODUCTION SEASON IN LATVIA

Strawberry production season in open field conditions is quite short in Latvia. It starts approximately in the middle of June and lasts till the end of July for June bearing cultivars. Several experiments with the aim to extend the production season were conducted at the Pūre Horticultural Research Centre during 2008-2009. Three cultivars grown on beds with or without mulch in small tunnels covered by transparent polyethylene foil or Agronet (Agryl 17) were tested for early production. Day-neutral ‘Brighton’ grown on beds mulched with double colored plastic (with white upper and black lower side) and without mulch was tested for late production. Both transparent film and Agronet covers increased earliness of production respectively 16 and 7 days compared to uncovered plants. The earliest yield was obtained from ‘Zefyr’ grown in small tunnels covered by transparent film on beds without soil mulching. Black plastic mulch gave earlier production start in 2008 compared to unmulched treatment, but did not influence the production time in 2009. It increased the yield in both study years and reduced the amount of rotted fruits. Strawberry harvesting season was significantly prolonged by growing day-neutral ‘Brighton’- till the first autumn frosts. Unfortunately the yield and fruit quality of this cultivar was unsatisfactory. White/black plastic mulch did not influence the produc¬tion time for this cultivar. In average of two production years, the best results were obtained when M0 generation from tissue culture plants were grown on beds mulched with white/black plastic.