EFFECT OF HYDROGEN CYANAMIDE (HC) ON FRUIT RIPENING AND YIELD OF SOUTHERN HIGHBUSH BLUEBERRIES IN NORTHWESTERN OF ARGENTINA

The effect of timing and rates of HC applications was evaluated during spring of 2006 and 2007. Climatic conditions were very different in both years, 2006 being warmer than 2007. The year 2006 had 50 chilling hours and 2007, 1,000 chilling hours. Treatments included a randomized complete block design with two blocks and two replications. HC applications were made with a high volume of water (1,000 L/ha) and using 0.05 % (v/v) of a nonionic surfactant (silicon coadjutants). Rates were 0.5, 1.0, 1.5, 2.0 and 2.5% (v/v). One year plants of Emerald, Jewel and Star were studied. Fruit ripening and yield were evaluated and compared with the control (no HC). The results showed that there was an increase in total yield and harvest concentration in all the cultivars that were evaluated. Best rate was different for each cultivar. Increments between 10 to 60% were observed in total yield in the first year, and 10 to 30% in the second. Better results were obtained in the year with less chilling hours comparing with the colder year.