Pointed gourd (Trichosanthes dioica Roxb.) (2n = 2x = 22) is a dioecious cucurbit vegetable and green fruit that is edible after cooking. Consumers prefer to consume seedless or less-seeded fruit because seeds are unpalatable due to their hard coats. Therefore, the cross compatibility between the diploid and induced tetraploid will be helpful for seedless or less-seeded fruit production. Thus, the present study was conducted using mature seeds that were immersed in 0.05%, 0.1%, and 0.5% colchicine for 24, 48, and 72 h to induce tetraploids. These tetraploids were used as parents (male or female) in the inter-ploidy and intra-ploidy crosses. A flow cytometric analysis confirmed the induction of three tetraploids at 0.5% colchicine for 48 and 72 h soaking periods. Among these, two (2) females and one (1) male were differentiated after flower initiation. Crossing between the tetraploid’s maternal and diploid paternal parent (4x × 2x), which were revealed to be compatible, resulted in a similar fruit set rate and shape as those of the diploid. In addition, a seed number of 4x × 2x produced fruits that were drastically reduced to 1.8 seeds per fruit, whereas the natural diploid fruits had 26.4 seeds per fruit. These findings suggest that colchicine-induced tetraploid females are important genetic resources for less-seeded fruit production. The genetic stability of tetraploid clones can easily and effectively be maintained by vine cutting for advanced uses.

The method of automatically controlling the CO₂ concentration in a greenhouse depending on ventilation was examined in order to efficiently improve the productivity of strawberries under the weather conditions in the northern part of Kyushu in Japan. The effects of CO₂ enrichment on the yields, fruit Brix, and economic value of the strawberry ‘Sagahonoka’ were investigated. In addition, in order to clarify the physiological response of ‘Sagahonoka’ to the CO₂ concentration, the photosynthetic rate, translocation, and photoassimilate distribution rate were measured. It was found that maintaining the CO₂ concentrations above 800 μmol mol⁻¹ and 400 μmol mol⁻¹ during no ventilation and ventilation, respectively, resulted in 25% increases in marketable fruit yields and a 0.2–1.2% higher fruit Brix compared to control, which was kept in 400 μmol mol⁻¹ CO₂ or above all day regardless of ventilation. Additionally, the economic value of ‘Sagahonoka’ was increased. The photosynthetic rate of ‘Sagahonoka’ increased linearly up to 800 μmol mol⁻¹ CO₂, and high CO₂ concentrations affected the distribution for the primary fruit, the most significant sink. It was clarified that CO₂ enrichment at 800 μmol mol⁻¹ for ‘Sagahonoka’ was effective in increasing the photosynthetic rate and distribution of photoassimilates to fruits, and the yields of strawberries could be increased efficiently by automatically controlling the CO₂ concentration depending on ventilation in a southern region of Japan.

The country bean (Lablab purpureus), is a significant contributor of dietary protein and other essential components in human nutrition. Because of its elevated moisture content, it is susceptible to rapid decay, leading to losses after harvesting. The utilization of solar drying has attracted significant attention as a tactic to minimize nutrient depletion in dried goods and enhance their longevity. This study employed four solar drying techniques, namely long chimney, short chimney, box solar drying and open sun drying, along with pretreatments such as potassium metabisulfite, potassium-sodium tartrate, citric acid and ascorbic acid. The objective was to determine an effective solar drying method, combined with pretreatment, that can maintain the color and nutritional qualities of dried country bean seeds. The treatment combinations were organized in a factorial randomized complete block design (RCBD) with three replications. The data were subjected to a two-way analysis of variance (ANOVA) and a Duncan Multiple Range Test (DMRT) was conducted at a significance level of 5 % (p < 0.05). Results revealed that box solar dryer having the highest drying efficiency, retained the highest β-carotene (82.94 %), vitamin C (90.15 %), protein (96.48 %), fat (11.63 %), and ash (90.50 %) with maximum DPPH radical scavenging activity (lowest IC₅₀ 209.49 μg/ml) compared to other driers. Besides, country bean seeds have noteworthy proximate compositions, antioxidant activity, and bioactive components treated with 1 % potassium metabisulfite. Furthermore, the country bean seeds dehydrated in box solar dryer after 1 % potassium metabisulfite treatment received the highest acceptance score on the five-point Hedonic scale (4.83–4.89 out of 5.00) and color appearance and the similar trend was further supported by principal component analysis. Thus, it can be inferred that using a box solar dryer with a 1 % potassium metabisulfite pretreatment is a feasible method for preserving the color and nutritional value of country bean seeds and reducing postharvest losses.