Effects of Hormonal Treatment and Shading on Occurrence of Lusterless Fruit in Summer-Autumn Cultivation of Cherry Tomato

Abstract

We investigated the effect of hormonal treatment with 4-chlorophenoxyacetic acid (4-CPA) and shading on the occurrence of lusterless fruit in order to suppress its production during the summer-autumn cultivation of cherry tomato. The occurrence of lusterless fruit on 4-CPA spraying was 5–12%, which was significantly lower than that on no spraying with 4-CPA (22–39%). Therefore, 4-CPA is an effective plant hormone for suppressing the occurrence of lusterless fruit produced by cherry tomato plants. In addition, the incidence rates of lusterless fruit in the continuously shaded area and the area only shaded during strong light where the temperature rise in the greenhouse was suppressed by shading treatment were 7 and 9%, respectively, being significantly lower than 15% in the unshaded area. As a result, the fruit yield in September with the highest incidence of lusterless fruit was 0.8 and 1.0 kg per plant in the continuously shaded area and the area only shaded during strong light, respectively, and 0.4 kg in the unshaded area. Furthermore, the suppression of temperature rise due to light shielding was considered to be effective as a technique for suppressing lusterless fruit. In addition to the effect of suppressing the production of such fruit, the method of shading only during the incidence of strong solar radiation temporarily increased the fruit yield as compared with the method of continuous shading, while suppressing the production of lusterless fruit. It is considered that this is an effective shading method to avoid a decrease in yield.