ASSOCIATION OF WEATHER DATA AND THE INCIDENCE OF BLOTCHY RIPENING OF GREENHOUSE TOMATOES IN BRITISH COLUMBIA

Abstract

Blotchy ripening (BR) of greenhouse tomatoes (Lycopersicon esculentum Mill.) appears irregularly in the spring crop in British Columbia. Variation in BR incidence among seasons and also within a season does not appear correlated with any changes in cultural conditions; therefore, an examination of meteorological data for an association with incidence of BR was undertaken. Light as hours of bright sunshine was studied in the cases where BR was reported in the commercial crop. Daily meteorological records were examined for weekly periods, and the correlation of BR with conditions at week of harvest and each of the 7 wk preceding harvest, and combinations of 2–8 of those weeks studied. Some 180 models were examined, and the highest r2 value occurred in the regression equation of Y = 1.51 − 0.0167 X, where Y is the severity rating (0–3) of the BR incidence, and X is the total hours of bright sunshine from the combination in which these hours were the difference between the sums for alternate weeks from harvest and the remaining weeks of the 8-wk period. In other words, the incidence of BR will be severe when the total hours of bright sunshine of even-numbered weeks were smaller than that of odd-numbered weeks, or when even-numbered weeks were cloudy and odd-numbered weeks were sunny. The emphasis is placed on a cumulative, cyclical effect that previous workers appear to have overlooked. The hypothesis is being used to plan regimes in controlled environment to study blotchy ripening.