著者

Yosuke Isoyama Atomu Sugimura Kazuyoshi Nada Hideki Kato Hatsuyoshi Kitamura

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-029, (Released:2023-03-09)

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Supplemental interlighting is a technique to improve horticultural light conditions. However, optimal methods for energy-efficient supplemental lighting are not yet established. Therefore, this study investigated the influence of supplemental light canopy position during the tomato fruit enlargement stage on photosynthetic function and aboveground dry-matter weight. A supplementary interlighting module was fixed at the initial irradiation position, then the irradiation position for three other modules were raised to 10 cm above each fruit truss at different developmental stages. These stages were the early enlargement stage (ES), from flowering until the first fruit reached a diameter of 10 mm, then the vigorously enlarging stage (VES), with tomato fruit diameter from 10 to 30 mm, and the late enlargement stage (LS) with a tomato fruit diameter greater than 30 mm. Cultivation was carried out using a D-tray system with a planting density of 5.5 plants·m−2. The LED supplemental interlighting reduced specific leaf area (SLA), altering the plant canopy structure. This increased the canopy light transmittance from 40% to 70% at 20 cm from the canopy and from 20% to 40% at 40 cm from the canopy, especially during the ES. The total chlorophyll (Chl) content of leaves was higher under all irradiated treatments compared to the untreated control. However, Chl a/b ratios decreased for all treatments except in leaves under continuous LED irradiation. The maximum photosynthetic rate was higher in leaves closer to the supplemental interlighting exposure, but was lower in the 17th and 13th leaves at 6 μmol·m2·s−1 and 4 μmol·m2·s−1, respectively. Fruit dry-matter weight increased significantly to 143.2–156.5 g in all supplemental interlighting treatments compared with 119.6 g for the control. Interlighting treatment during VES achieved the highest yield and the greatest increase in fruit and total dry-matter weight. Therefore, VES-irradiation is most efficient to increase dry-matter weight.

著者

Taishi Hayashida Kazuyoshi Nada Shin Hiratsuka

出版者

一般社団法人 園芸学会

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.MI-067, (Released:2015-12-19)

被引用文献数

1

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Since both artificial pollination and fruit thinning are necessary for marketable fruit production of Japanese pears (Pyrus pyrifolia (burm. f.) Nakai) in Japan, about a 20% fruit set is ideal without pollination because only 5% of flowers are actually subjected to fruit production. In this study, copper (Cu2+) and ferrous (Fe2+) ions were shown to be effective for inducing a nearly-ideal fruit set of the Japanese pear ‘Kosui’. Fruit induced by ferrous sulfate (FeSO4) solution or a Bordeaux mixture, which is a combination of copper sulfate (CuSO4), lime, and water, were parthenocarpic, because 1) self-pollen tube growth was not promoted by Cu2+ and Fe2+, 2) almost no perfect seeds were observed at harvest, and 3) Cu2+ and Fe2+ acted as strong inhibitors of pollen tube growth in vitro. The effective stage for inducing parthenocarpy was sprouting time to 4 days after anthesis in the Bordeaux mixture, and sprouting time to 4 days before anthesis in the FeSO4 solution. Annual changes in the effectiveness were found in both chemicals, and the Bordeaux mixture showed no inhibitory effect on the fruit set of cross-pollinated flowers. The growth of Bordeaux mixture-induced fruit was improved by gibberellin (GA) paste or GA paste mixed with N-(N-(2-chloro-4-pyridy1)-N'-phenylurea (CPPU) treatment of the fruit stalk; the treated fruit was about 100 g heavier than the untreated fruit. The GA paste treatment is currently conducted to promote fruit growth and maturation in ‘Kosui’ fruit production in Japan, and the Bordeaux mixture can be substituted for chemical fungicide generally used before anthesis to control scab and black spot disease. Accordingly, the Bordeaux mixture is a promising chemical for great labor-saving in ‘Kosui’ cultivation.