Comparative Yields and Composition of Eight Tropical Leafy Vegetables Grown at Two Soil Fertility Levels
1971
Schmidt, D. R.
Tropical leafy vegetables including Amaranthus cruentus L., Basella alba L., Brassica chinensis L., Brassica aleracea var. acephala D.C., Corchorus olitorius L., Ipomoea aquatica Forsk, Solarium melanocerasum Allioni, and Talinum triangulare Willd. were grown on plots of medium and high soil fertility at Akure, Nigeria. Average dry matter yields of edible leaves from medium and highfertility soils, respectively, were 1,970 and 3,339 kg/ha from 70 days' growth in 1966, and 2,839 and 5,133 kg from 120 days' growth in 1967. Amaranthus cruentus was the highest-yielding species, in 1966 producing 3,473 kg/ha, compared to an average of 2,383 kg from Brassica chinensis, Corchorus, Solatium, and Talinum. Amaranthus, Basella, and Solatium were most responsive to high fertility. The Brassica spp. and Ipomoea produced relatively high yields with medium fertility. The dry matter of the leaves averaged approximately 5% total N, about three-fourths of this being protein N. Solanum with 5.9% and Ipomoea with 5.4% had the highest total N contents. Leaves from the high-fertility soil averaged 5.4% total N compared to 4.5% for leaves from medium fertility. Calcium contents ranged from 2,045 mg / 100 g dry matter in Amaranthus to 412 mg in Ipomoea. Basella had the highest iron content with 50 mg / 100 g dry matter compared to an average of 34 mg for the other seven species. Leaves from the medium- fertility plots contained an average of 22% more iron than those grown on high-fertility plots. Relationships of the nutrient contents of leafy vegetables to the diets of people in southern Nigeria are discussed.
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