INFLUENCE OF SOME ATMOSPHERIC FACTORS AFFECTING YIELD AND SINGLE FRUIT WEIGHT IN STRAWBERRY

In 1975-1987, experiments evaluated mean, maximum and minimum temperatures, precipitation, air humidity, saturation deficit and sunshine on the plant yield and single fruit weight in six strawberry genotypes. The vegetative period of the harvest year and the preceding autumn were divided into ten-day periods and for each period and every genotype simple correlation coefficients were computed. Temperature was most highly and positively correlated with yield and fruit weight and this in the first ten-day period of May. In the second and third periods of this month and in June, lower temperatures and humidity were needed for high productivity. The reaction of genotypes differed: cv. Paula and clone 547/5 showed few relationships with atmospheric factors, and were better adapted to local conditions than 'Senga Sengana' and clone B-302. In the autumn of the previous year, lower temperatures were suitable for inflorescence initiation in the third ten-day period of September and in October. In late August, early September and November, high temperatures, water-deficit and sunshine were beneficial. The single fruit weight showed fewer correlations with atmospheric factors, but tendencies were similar to those for the whole yield.