Development of an integrated production system for african indigenous leafy vegetables in Taita district

Abstract

In Kenya, the consumption of African indigenous leafy vegetables (AlLY's) is increasing due to the public awareness on these vegetable's contribution to nutritional and economic values. However, several factors limit their production. The objective of this study was to improve the productivity of these vegetables by addressing their nutritional requirements and the insect pests problem The study which was carried out in Wundanyi location, Taita district, sought to establish major AlLY's production constraints and to develop strategies to deal with the major constraints. This was done through Participatory Rural Appraisal (PRA) and a structured questionnaire. A total of 70 AlLY's producing farmers participated in the PRA and were also interviewed using the structured questionnaire. On farm studies were carried out in farmers' fields. Amaranthus hybridus and Solanum scabrum were selected based on preference by the community. Four plantings were done between May 2008 and February 2009. Farm yard manure levels at rates of 2Ot/ha. 40t/ha, 60t/ha, poultry manure at rate of 40t/ha, 2Ot/ha, 40t/ha, 60t/ha farm yard manure each top dressed with CAN- 1030kg/ha, DAP-200kglha top dressed with CAN-l 030kg/ha, farmer practice and a control, were evaluated for yield improvement. This was carried out in replicated field experiments. A study was also carried out to identify and quantify the pest complex in the selected study site. In addition, experiments to establish an action threshold for the major insect pest and assessment of different IPM components (Azadiractin, Dimethoate, Lambda-Cyhalothrin) were also carried out in farmer's fields. Results of the PRA and questionnaire showed that the area had several resources such as rivers and streams, which if well utilized could assure farmers of good AlLY's yields. However, it was revealed that AlLY's are allocated very small portion ofthe farmers' total land. Though, most of the farmers used farmyard manures, they were not aware of the recommended rates. Several production constraints were highlighted. These included low soil fertility, low yields due to lack of information on AIL V's agrononuc packages, insect pests and diseases, poor market organization and lack of capital. Others were, lack of quality seed, lack of irrigation facilities and lack of information on whether their cooking procedures preserve nutrients in the vegetables. The on farm study on production packages indicated that, incorporation of farmyard manure (20, 40, 60tlha), poultry manure (40tlha) and inorganic nitrogen (N), significantly increased plant growth parameters (plant height, canopy width, number of branches, stem diameter) and yields. Yields obtained from plants which were grown with organic manures top dressed with inorganic Nwere higher than those from plants with manures alone. There were a variety of insect pests on both vegetables occurring at different stages of plant growth. Insects belonging to six insect orders (Coleoptera, Lepidoptera, Orthoptera, Homoptera, Heteroptera and Diptera) were identified as pests on the two vegetables. Aphids were identified as a major pest of both vegetables. However, red spider mites were a major pest of Solanum scabrum occurring during the dry hot weather. 10 aphids/ young leaf was established as an action threshold, a point after which the leaf begins to curl making the produce unmarketable. The management studies revealed that Azadiractin, Dimethoate and Lambda -Cyhalothrin significantly reduced aphids and red spider mites populations and maintained the quality of the produce for marketing. Cattle manure levels at the rates of 20tlha, 40tlha, 60tlha either alone or top dressed with C.A.N-I030kglha and 40tlha poultry manure are recommended for use by small scale farmers to improve yields of AILV's, thus their incomes, health and livelihoods. The information on the pest complex and their damages can be used in designing management strategies for insect and mite pests, which have been identified as a major AILV's production constraint in many parts of the country. The action threshold could be adopted by AIL V's producers to encourage rational pesticide use in AILV's production as components of Integrated Pest Management