Can auxin be used to cultivate seedless watermelon?

Hormone seedless watermelon is a seedless fruit produced by treating the female flowers of common diploid watermelon with plant hormones. Professor Huang Changxian, a famous scholar in China, was the first to create contemporary seedless watermelon with exogenous hormone treatment. During studying in the United States from 65438 to 0938, the stigma of cut diploid watermelon was treated with acennphthene and NAA lanolin ointment, and 7.2 1% seedless watermelon was obtained, which was the first hormone seedless watermelon in the world. Cantliffe( 1977) sprayed the unfertilized ovary of watermelon Mibao variety with indoleacetic acid, naphthylacetic acid and chlorohydroxy fluorenic acid. The stimulation of the first two hormones can form fruits with similar size and weight as the control, but the fruit shape is not straight. Unless chlorohydroxy fluorenic acid is added, it can be seen that the latter plays a role in shaping and makes the effect of stimulating parthenocarpy more perfect [8, 9]. Yang Xiangcheng et al. of Tianshui Agricultural College (1979) mixed 100 ppm NAA, 25 ppm GA3 and 25 ppm 2,4-D with the same amount of watermelon male flower extract, smeared the stigma and ovary of bagged watermelon female flower, and smeared the mixed solution of the above three solutions and young fruit on watermelon young fruit four days later. The seedless rate was 87.4%. Lindpe et al. (1983) treated the stigma, ovary and fruit stalk of female flowers of watermelon varieties "330 1" and "Mibao" with sodium naphthylacetate, gibberellin, 2,4-d, IAA, male flower extract and spreading agent, all of which induced seedless watermelon fruits, and the fruit yield reached 50%.

Yasuyoshi( 1955) treated unpollinated watermelon ovary with CPPU (a new type of phenylurea cytokinin) to induce parthenocarpy and produce seedless fruit. 200ppmCPPU did not affect watermelon fruit shape and soluble solid content, so it can be applied in production. There are also reports in China. Tan et al. (1995) treated the ovary of unpollinated watermelon female flower with strong cucurbitacin, and also produced seedless watermelon fruit [1 1]. However, Kawaguchi Gongyu et al. (2000) reported that CPPU increased the number of small cells, thickened the pericarp, reduced the fruit, and was easy to deform, which affected the commodity.

The above-mentioned treatment with exogenous hormones to obtain seedless watermelon is time-consuming and laborious, which requires strict control of chemical concentration and treatment time and strict cultivation technical measures, but the fruit setting rate is still low and unstable, causing thick skin, deformity and light taste. This method is also prone to food safety problems, so it is difficult to use in production.