Journal of Applied Horticulture. 2005: 7(2): 87-89

Effect of different nutrient levels on anthocyanin and nitrate-N contents in turnip grown in hydroponics

Asao, T; Kitazawa, H; Washizu, K; Ban, T; Pramanik, M H R

Faculty of Life and Environmental Science, Shimane University, 2059 Kamihonjo, Matsue, Shimane, 690-1102, Japan.

Seedlings of Japanese turnip (Brassica rapa [B. campestris var. rapa] cv. 'Tsudakabu') that were in the first-leaf stage were grown hydroponically in plastic containers containing 25, 50 and 75% of Enshi nutrient solution with either full or half dose of NO3-N. The nutrient solutions were renewed at 2-week intervals until harvest. The experiment was conducted from 19 September (transplanting in containers) to 21 November 2002 (harvesting). The size and colour of roots from hydroponic culture were similar to that of turnip grown in soil culture, while the size of leaves was larger in the former than that in the latter. Leaf number, leaf length and width, and leaf dry and fresh weights all decreased significantly at the lowest concentration of the nutrient solution. The presence of full and half dose of NO3-N in the 75 and 50% nutrient solution did not show significant difference in growth. Root dry and fresh weights also significantly decreased at the lowest concentration of the nutrient solution. Anthocyanin content in roots significantly increased with decreasing concentration of the nutrient solution irrespective of NO3-N dose. NO3-N dose in the nutrient solutions had no marked effects on NO3-N content of turnip. In general, 50% nutrient solution with half-dose of NO3-N was optimum for the production of quality turnips in hydroponic cultures.