Abstract
The effects of air temperature and light intensity on β-carotene concentration in spinach and lettuce leaves were investigated to seek means of enhancing β-carotene concentration in these crops. β-carotene concentrations in these crops decreased with increasing fresh weight, independent of air temperature and light intensity treatments. During a certain period of growth, the effects of air temperature and/or light intensity were not clear because there were differences in growth among the treatments. On a fresh weight basis, β-carotene concentration increased in plants exposed to low air temperature and/or high light intensity. Low air temperature and/or high light intensity are valuable factors for increasing β-carotene concentration in leafy vegetables because they are nutritions and are sold fresh. Though the β-carotene concentration in spinach and lettuce are different, the effects of air temperature and light intensity on β-carotene concentration are the same. These results indicate that the principle for increasing β-carotene concentration is applicable to other leafy vegetables.
