EFFECT OF ULTRAVIOLET-A IRRADIATION ON PLANT GROWTH AND NUTRITIONAL CONTENT OF BRASSICA RAPA
Solar irradiation affects photosynthesis and the composition of vegetative tissue. Previous research on light irradiation drying of harvested agricultural products has demonstrated greater increases in amino acid content and antioxidant activity with ultraviolet-A (UV-A) irradiation than with irradiation in the visible blue, green and red wavelengths. Here, the effects of UV-A irradiation on growth, and amino acid and vitamin content were investigated in Brassica rapa. B. rapa seeds were planted in soil in pots saturated with nutrient solution under four light irradiation regimes: natural light plus red light, blue light, visible light or UV-A light. Experiments were conducted in an air-conditioned room with constant irradiation. Growth rate and dry weight, and nitrate (NO3-), amino acid, ascorbic acid and chlorophyll concentrations were measured in the dried leaves. Natural light plus UV-A irradiation resulted in increased ascorbic acid but 0.4-fold lower dry weight, 0.21-fold lower ascorbic acid concentration and greater NO3- accumulation compared with visible light irradiation alone. Chlorophyll content did not differ significantly among treatments. The results show that the stress of UV-A irradiation slowed foliage growth and the decreased rate of photosynthesis. In the present research, we examine the effects of UV-A irradiation and the timing of its application on plant growth and the quality of postharvest vegetables.
Aoki , H. and Hirano, K. (2011). EFFECT OF ULTRAVIOLET-A IRRADIATION ON PLANT GROWTH AND NUTRITIONAL CONTENT OF BRASSICA RAPA . Acta Hortic. 907, 259-262
amino acid, ascorbic acid, growth rate, nitrate ion, photosynthesis