Effects of Low Air Temperature and Light Intensity on Yield and Quality of Tomato at the Early Growth Stage

This study was conducted to the effect of low air temperature and light intensity conditions on yield and quality of tomato at the early stage of growth in Korea.Inplastic greenhouses, low temperature and low temperature with shade treatments were performed from 17 to 42 days after plant.Tomato growing degree days were decreased 5.5% due to cold treatment during the treatment period.Light intensity decreased 74.7% of growing degree days due to shade.After commencing treatments, the plant growth decreased by low temperature and low radiation except for height.Analysis of the yield showed that the first harvest date was the same, but the yield of the control was 3.3 times higher than low temperature with shade treatment.The cumulative yields at 87 days after transplanting were 1734, 1131, and 854 g per plant for control, low temperature, and low temperature with shade, respectively.The sugar and acidity of tomatoes did not differ between treatment and harvesting season.To investigate the photosynthetic characteristics according to the treatment, the carbon dioxide reaction curve was analyzed using the biochemical model of the photosynthetic rate.The results showed that the maximum photosynthetic rate, J (electric transportation rate), TPU (triose phosphate utilization), and Rd (dark respiration rate) did not show any difference with temperature, but were reduced by shading.Vcmax (maximum carboxylation rate) was decreased depending on the low temperature and the shade.Results indicated that low temperature and light intensity at the early growth stage can be inhibited the growth in the early stage but this phenomenon might be recovered afterward.The yield was reduced by low temperature and low intensity and there was no difference in quality.