Effects of nutrient composition on butterhead lettuce (Lactuca sativa L-cv. Panama) grown in deep flow technique in the tropics

The growth and development of butterhead lettuce (cv. Panama), grown in dee p flow technique, were assessed over two 36-day experimental trials on a ro of-top greenhouse. Plants were subjected to three nutrient compositions: lo w NO3-N (100 mg L-1), high Fe (10 mg L-1) and complete treatment (Cooper's solution). Harvesting and nutrient sampling were conducted at regular inter vals. Data such as fresh head weight, fresh root weight, leaf number, leaf area, NO3-N and Fe levels and mineral composition of tissues were determine d. Low NO3-N treatment produce the lowest head weight, leaf number and leaf area. The second experiment saw an improvement of growth and yield charact eristics for all treatments at crop maturity 36 DAT. Plants grown in high F e levels (10 mg L-1) had notable tipburn incidence but no bolting was obser ved. High Fe levels could be beneficial in producing desired head size. Alt hough low NO3-N levels at 100 mg L-1 is sufficient for plant growth, it res ulted in severe bolting in both experiments. Increasing Fe or reducing NO3- N levels do not have significant influence (P=0.05) on the yield of butterh ead lettuce.