Effect of 4-chlorophenoxyacetic acid on fruit set and nutrient accumulation in Cucurbita moschata (duch.) poir

Squash cultivars, 'Bam' and 'Eunmie', were grown in a greenhouse, and hand pollinated or treated with 4-CPA (4-chlorophenoxyacetic acid) at anthesis. Fruit set in both cultivars was increased more by LF-CPA treatment than by hand pollination, while fruit was enlarged more by hand pollination than by 4-CPA treatment. While protein content of immature fruits was increased by 4-CPA (tomatotone), vitamin C content in placenta part was increased by hand pollination. Calcium (Ca) content of immature fruits was higher by 4-CPA in the flesh part of fruits but higher by hand pollination in the placenta part. Concentrations of nutrients in mature fruits, except for Ca, were higher by hand pollination than by 4-CPA. It appears that both hand pollination and 4-CPA treatment enhance fruit set and growth by inducing synthesis of plant growth regulators and metabolizing enzymes, and it is suggested that hand pollination effects are greater than effects from 4-CPA treatment.