Hossein Sheikhi; Mojtaba Delshad; Sasan Aliniaeifard; Kamahldin Haghbeen; Mesbah Bababalar; Rasool Nasiri
Abstract
Lettuce is one of the most important leafy vegetable crops. Despite lettuce being mostly grown in open fields, its greenhouse production is widely increasing. Lettuce growth comprises two distinct stages known as the seedling and head stages. The effect of supplemental lighting (SL) on lettuce growth ...
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Lettuce is one of the most important leafy vegetable crops. Despite lettuce being mostly grown in open fields, its greenhouse production is widely increasing. Lettuce growth comprises two distinct stages known as the seedling and head stages. The effect of supplemental lighting (SL) on lettuce growth was well studied, but the lighting requirement during the early stage of its growth and head development remained unknown. For this purpose, we evaluated nutritional qualities and growth in lettuce in response to SL in separate seedling and head development stages. The experiment involved SL with different daily light integral (DLI) provided by light-emitting diodes (LEDs). Light treatments included supplemental DLI of 8.64, 11.52, 12.96, and 17.28 mol m-2 d-1. The results revealed that the lighting period was more effective on lettuce biomass increase than the light intensity. Although the SL increased the photosynthetic pigment content of lettuce, its impacts on the two growth stages were not the same. In a way, the chlorophyll a,total chlorophyll, and carotenoid contents decreased under the SL conditions (DLI of 17.28 mol m2 d-1 and light intensity of 300 μmol m-2 s1 for 16 h). Increasing DLI caused a significant increase in the nutritional quality of lettuce, but antioxidant accumulation did not follow a similar trend in seedlings and mature plants. These findings confirmed that SL improves lettuce growth and quality, but optimal lighting requirements may vary depending on the growth stage.
Siamak Kalantari; Mohsen Hatami; Mojtaba Delshad
Abstract
Sensitivity of tomato fruits to chilling injury limits its storage and marketability. This study investigated the effect of hot water treatment (HWT) on reducing the consequences of chilling injury (CI) with respect to quality attributes of tomatoes during storage. Tomatoes were harvested at three ripening ...
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Sensitivity of tomato fruits to chilling injury limits its storage and marketability. This study investigated the effect of hot water treatment (HWT) on reducing the consequences of chilling injury (CI) with respect to quality attributes of tomatoes during storage. Tomatoes were harvested at three ripening stages: mature green, pink, and red; dipped in hot water at 45°C for 15 min; and stored at three storage temperature conditions: 5°C, 13°C, and a simulated condition (SC: 3 days at 25°C and then at 5°C) representing the time between harvest and consumption by consumer. Quality analysis was carried out at the beginning of the experiment and every 10 days of storage 3 days of shelf life evaluation. Fruit color, lycopene content, weight loss, and CI were evaluated during the experiment. HWT reduced CI in mature green tomatoes but had little effect in pink and red fruits. It also caused delay in surface color development and reduced weight loss. During storage, heated mature green fruits often had significantly more lycopene content but low a* compared with unheated ones, whereas in heated red fruits, both a* and lycopene content were lower than unheated ones. This study showed that HWT could be used to reduce CI in mature green tomatoes, but not in pink and red fruits.
