VALIDITY OF THERMAL UNIT SUMMATIONS FOR PURPOSES OF PREDICTION IN PHASEOLUS VULGARIS L. CROPPED IN MEDITERRANEAN ENVIRONMENT.
Thermal unit summations calculated with different formulas, except the "Standard" one (TMAX + TMIN)/2)-10), predicted the dates of flowering and of commercial ripening of the first pods more accurately than time expressed in calendar days. The formulas with the maximum temperature adjusted gave better results expecially in the cold non ventilated greenhouse which can be explained by the particular thermometric trend in the mediterranean climate. The formula with base temperature of 4.5°C and the subtracting of the degrees above 30°C in the maximum temperature, was the most reliable in the Blue Lake and Borlotto running varieties. The formula named "Daily heat stress" with base 10°C was more effective in the Provider and Borlotto bush varieties, but even more so was the same formula with base of 4.5°C.