Water Absorption of Cucumber Plants Based on Diurnal Variation in Plant Weight with Solar Radiation and Fruit Load

The effects of solar radiation and presence or absence of fruit on transpiration and the moisture retained by the growing plant itself were investigated at the individual level using pot-grown cucumber plants. Plants with 5 to 12 fruits were used to assess transpiration over time by measuring the pot weight on an electronic scale for 3 days. Fruits were removed on the second day of the study to determine whether the presence of fruits caused differences in transpiration and water content in the same plants. Most of the water retained by the plants was in the fruits, and about half of the water absorbed during the night was accumulated in the fruits. The variation in water uptake of cucumber plants with fruit enlargement was greater at night than during the day. Transpiration tended to be higher in the presence of fruit when solar radiation was high. The average solar radiation and transpiration per leaf area could be regressed by a quadratic equation, and the coefficient of the square of the solar radiation term was negative.