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  • Author or Editor: Marc-J. Trudel x
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Abstract

An increase in soil temperature from 14.0 to 21.8°C increased total yield of greenhouse tomatoes (Lycopersicon esculentum L. cv. Vendor) by 47% in the spring under warm air temperature conditions, but a rise in soil temperature from 13.8 to 20.5° increased tomato yield by only 5% in the fall. Under plastic tunnel conditions (low air temperature), heating soil increased total yields by 36% in the spring and 42% in the fall.

Open Access

Abstract

Tomato plants (Lycopersicon esculentum Mill. cv. Carmello) seeded on 3 Dec. 1984 and 17 Jan. and 8 Mar. 1985 were grown under natural or supplementary lighting (high-pressure sodium) of 100 μ·mol·s−1·m−2 (photosynthetically active radiation) from pricking out to transplanting. Plants of the first, second, and third seeding dates grown under supplementary lighting had at transplanting dry weights 6.6, 3.5, and 2.5 times higher, respectively, than plants grown under natural light. The number of leaves formed below the first inflorescences was reduced significantly with supplementary lighting, which also reduced the incidence of flower abortion. Supplementary lighting increased early marketable yields for the 3 Dec. seeding by 100% (from 0.77 to 1.55 kg/plant) and total yields by 10% (from 3.55 to 3.91 kg/plant). No significant differences between lighting treatments could be observed in early and total yields of plants from the last seeding date.

Open Access

Abstract

Four cultivars of greenhouse cucumber (Cucumis sativus L. ‘Corona’, ‘Far-biola’, ‘Pandex’, and ‘Sandra’) were grown under four lighting conditions: natural light and natural light supplemented by 100, 200, or 300 μmol·s−1·m−2 provided by high-pressure sodium lamps for a photoperiod of 18 hr. For this purpose, transplants were first seeded on 24 Sept. 1984, transplanted on 23 Oct., and grown according to the successive cropping method. Supplemental lighting enhanced plant growth and increased yield. Our data indicate that a marketable yield of 240 fruit/m2 per year of greenhouse cucumbers could be obtained with supplementary lighting of 300 μmol·s−1·m−2.

Open Access