The influence of low temperature treatment on dormancy release, growth and flowering of strawberry (fragaria x ananasa. Duch.

Abstract

This study was conducted to investigate the effects of artificial low temperature treatment in overcoming bud dormancy and promoting vegetative growth, runner production and flowering in two strawberry cultivars 'Pajaro' and 'Douglas·. In the first study, cultivar 'Douglas' was grown both in Thika and Limuru whereas cultivar 'Pajaro' and ~Douglas' in the second study were grown only in Limuru. Low temperature treatment at 3-50 C promoted dormancy release and vegetative growth. 'Pajaro' showed better growth response to chilling than -Douglas' in Limuru. The number of runners, runner plants, runner series, petiole length and leaf area increased with increasing duration of cold treatment. Branch crown development and flower production was lower with increasing duration of cold treatment. Vegetative growth was more vigorous in Thika than in Limuru. Cold treated -Douglas' plants produced significantly more runner plants in Thika than in Limuru. In contrast, the number of branch crowns produced was higher in Limuru than in Thika. Cold treatment resulted in early and increased production of runners and runner plants. Those plants which received no chilling or one month of low temperature treatment produced few runners which produced very few runner plants or failed to produce any. Runner elongation This study was conducted to investigate the effects of artificial low temperature treatment in overcoming bud dormancy and promoting vegetative growth, runner production and flowering in two strawberry cultivars 'Pajaro' and 'Douglas·. In the first study, cultivar ~Douglas' was grown both in Thika and Limuru whereas cultivar 'Pajaro' and 'Douglas' in the second study were grown only in Limuru. Low temperature treatment at 3-50 C promoted dormancy release and vegetative growth. 'Pajaro' showed better growth response to chilling than 'Douglas' in Limuru. The number of runners, runner plants, runner series, petiole length and leaf area increased with increasing duration of cold treatment. Branch crown development and flower production was lower with increasing duration of cold treatment. Vegetative growth was more vigorous in Thika than in Limuru. Cold treated Douglas' plants produced significantly more runner plants in Thika than in Limuru. In contrast, the number of branch crowns produced was higher in Limuru than in Thika. Cold treatment resulted in early and increased production of runners and runner plants. Those plants which received no chilling or one month of low temperature treatment produced few runners which produced very few runner plants or failed to produce any. Runner elongation and production of runner series were also stimulated by chilling. Petiole length and leaf area increased with increasing duration of cold treatment. Unchilled plants produced small leaves with short petioles. The petiole length and leaf area increased reaching a maximum at 120 days from transplanting and then started decreasing. There were no significant differences among treatments in petiole length and leaf area at 50 days and after from transplanting. The number of branch crowns produced were inversely proportional to the duration of cold treatment. Unchilled plants and those which received one month of chilling were characterized by increased branch crown development. The number of branch crowns increased rapidly after 150 days from transplanting in all treatments. 'Low temperature treatment increased early flower production from the terminal bud and vigorous flower development upto 30 days from transplanting. Unchilled plants flowered profusely in the field all the time. The number of flower clusters produced after 30 days from transplanting were less with increasing duration of cold treatment. Unchilled plants and those which received one month of low temperature treatment produced more flower clusters than those plants which were chilled for two and three months. Flower production also increased rapidly after 150 days from transplanting in all the treatments due to dormancy resumption. Many flower clusters were initiated from the many branch crowns formed in plants in both sites.