two days, after which differences became statistically insignificant.The normally irrigated plants (R), whether Megafol®treated or not,did not show statistical differences in their stress index. Daily vari-ations in the stress index were due to variations in the daily solarradiation. This is to be expected as the calculated stress index wasobtained from chlorophyll fluorescence, and variations in the avail-able light would naturally affect the photosynthetic apparatus ofthe plants.