A study on initial establishment of multi-purpose Moringa (Moringa oleifera.Lam) with focus on stand densities, Nitrogen, Phosphorus, pH, media type and Seed priming

Abstract

Moringa is a multi-purpose tree which has gained a lot of publicity because of its many varied uses, which range from the medicinal applications, industrial, sanitary to the nutritional. Moringa has very high nutritional properties that would be useful as a food supplement, especially in those marginalized communities. As regards Moringa nutrition, much research has been documented, as opposed to research on agronomic needs of the plant. Hence, studies were carried out studies to determine whether initial establishment of Moringa is affected by stand densities, nitrogen, phosphorus and pH, and whether media type and seed priming influences the germination, emergence and initial seedling establishment. These studies were conducted as four separate experiments. The first experiment tested five population densities. The second experiment was a 5 x 3 x 3 factorial experiment with five pH levels (3.2, 6.2, 7.6, 8.2, 8.7) three phosphorus levels (0 g/plant, 8 g/plant, 16 g/plant) and three nitrogen levels (0 g/plant, 4 g/plant, 8 g/plant), and was carried out in the greenhouse. The third experiment was a 4 x 3 x 2 factorial with four pre-treatment methods, three organic sources and two soil texture sources, and also carried out in the greenhouse. The fourth experiment was a 4 x 3 x 2 factorial with four nitrogen levels (0 g/pot, 2 g/pot, 4 g/pot, 8 g/pot), three organic sources (pine bark, sawdust, none) and two textures (clay, sand). All these experiments were carried out at the University of Zimbabwe, Crop Science Department site. The results obtained indicated that high plant density produced high biomass yields and longer stems, but with smaller stem diameters, while low density produced higher individual growth of the plants as evidenced by the thicker stem diameters produced. The results further indicated that use of 1% potassium nitrate and water as seed primers best improves the germination, emergence and initial seedling establishment of Moringa compared to dehulling or heating. Clay proved more suitable than sand for Moringa seedling establishment. pH and phosphorus interaction had an effect on biomass and growth of Moringa. The most ideal pH for initial seedling establishment and growth was indicated as 7.6 (CaCl2 scale), while P and N with the highest growth results was 4 g/plant P and 4 g/plant N.