Parthenocarpy induced by N-(2-chloro-4-pyridyl)- N′-phenylurea (CPPU) prevents flower abortion in Chinese white-flowered gourd ( Lagenaria leucantha)

Abstract

Flower abortion under unfavorable weather conditions is a serious problem in commercial production of cucurbitaceous crops in spite of artificial pollination. The effects of naphthaleneacetic acid (NAA), gibberellic acid (GA 3), N-(2-chloro-4-pyridyl)- N′-phenylurea (CPPU), 6-benzylaminopurine (BA), N, N′-diphenylurea (DPU) and N-(4-pyridyl)- N′-phenylurea (4-PU) on fruit set in unpollinated and pollinated ovaries of Chinese white-flowered gourd ( Lagenaria leucantha) were studied with the aim of increasing fruit set. Among the tested compounds, only CPPU showed high activity in inducing parthenocarpy and all the parthenocarpic fruit developed to normal size. The parthenocapy percentage induced by CPPU was as high as 100% within the tested concentration (10–100 mg l −1) and was not significantly altered by application time from 2 days before anthesis to two days after anthesis. NAA and GA 3 induced parthenocarpic fruit set in 37.5% and 45.5% of treated ovaries respectively, however, they could not induce parthenocarpic fruits of normal size. DPU, 4-PU and BA treatments had little effects on unpollinated ovaries. NAA, however, improved fruit set of pollinated ovaries but did not accelerate fruit growth. A contrary trend was observed in GA 3 treatment. CPPU also increased fruit set and fruit growth of pollinated ovaries. Treating all ovaries on a plant or alternate ovaries increased fruit yield by 91.3% and 83.3%, respectively, but reduced fruit size.