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Four tropical leaf vegetables commonly used as pot herbs for “kallaloo,” a local West Indian dish, were grown in replicated plots during the fall season of 1996 to determine growth and productivity. Leaf vegetables included green malabar spinach (Basella alba L.), red malabar spinach (Basella rubra L.), sweetpotato (Ipomoea batatas L.), and bush okra or jute mallow (Corchorus olitorius L.). Plants were harvested periodically and data on number of stems or vines, fresh weight of stems and leaves, leaf area, and leaf area index (LAI) were recorded. Except for leaf fresh weight, cultivars or species did not differ significantly in all parameters measured. Leaf fresh weight ranged from 27 g for jute mallow to 198 g for red malabar spinach. LAI was highest for sweetpotato (2.90) and lowest for jute mallow (0.86). Among the species, productivity (fresh weight) was highest (6.78 g/m2 per day) for green malabar spinach and lowest (3.22 g/m2 per day) for jute mallow.
Small-scale herb growers in the U.S. Virgin Islands traditionally water their crops with sprinkler cans and garden hoses. This method is inefficient and consumes large amounts of water, a scarce resource in the islands. Introduction of drip irrigation has reduced water use in vegetable production. Integrating this system with mulches may further cut water use, making herb production more profitable. Basil (Ocimum basilicum) was grown in plots with organic (compost or straw) and synthetic (black plastic or weed barrier) mulches. A no mulch control plot was also included. All plots were drip irrigated to maintain soil moisture at -30 kPa. Total plant fresh weight and leaf fresh and dry weights were highest in the compost mulch treatment. Fresh and dry basil yields in black plastic mulched plots were almost identical with those in compost mulch, but did not differ from other treatments. Black plastic mulch reduced water use 46% compared with 27% for compost or straw mulch. All mulch treatments resulted in increased water use efficiency. Organic mulches reduced surface soil temperature, while synthetic mulches increased soil temperature 2-5°C.
Using fish culture waste water may benefit vegetable production by reducing the need for high quality irrigation water. Fish waste water also contains nutrients, reducing the need for chemical fertilizers. A study was conducted to integrate fish (tilapia) culture with field production of bell pepper (Capsicum annuum L.). Waste water from low and high fish stocking densities and variable water exchange rates were applied to bell peppers 2 to 3 times weekly. These treatments were compared with fish sludge. cow manure and commercial N fertilizer. Fish waste water and sludge were applied by hand in the first year. A modified irrigation system was used in the second year. All other treatments were drip irrigated. In 1992 marketable yield was highest (9.0 t/ha) in plots with N fertilizer (drip fertigation) followed by plots applied with sludge (5.0 c/ha). Lowest yield (2.0 t/ha) was obtained from plots applied with fish waste water. In 1993 plots applied with fish waste water had a slightly higher yield (7.0 t/ha) than N-fertigated plots. Marketable yield was highest (10.4 t/ha) in plots treated with sludge.