Examples of improved production techniques for major vegetable crops, tomato, cabbage, rape, onion, okra and cucurbits were discussed. The techniques covered were:-
· Land/site selection: To take into account crop adaptation to soils, climate and market considerations.
· Seed/cultivar choice: Sources of seed, characteristics of good seed, advantages of using high quality seed, adaptability, market suitability, seasonal adaptation, resistance to diseases, disadvantages of using recycled seeds.
· Nursery Management: Nursery as an intensive care unit, nursery requirements - site selection, rotation, good sanitation, irrigation, fertilizer needs, pest and disease management.
· Land preparation for vegetables: Importance of good tilth, different tillage systems raised beds, farrows, flat beds, basics. Suitability of tillage systems according to season, soil types, irrigation methods respectively.
· Fertilisers: Sources of nutrients - organic (compost, green and cattle manures) and inorganic fertilizers. Nutrient requirements of vegetables to determine yields and quality. The importance of following fertiliser recommendations in relation to amounts, timing and placement. Options for improving soil fertility using green manure crops, compost and livestock manure. Handling manure and application of manure. The concept of Integrated Plant Nutrition Systems was introduced. The concept aims at maintaining or adjusting of soil fertility and plant nutrient supply to sustain a desired level of crop production. This is to be achieved through the following:a. Balanced use of mineral fertilisers combined with organic and biological sources of plant nutrients.
b. Improving and maintaing the stock of plant nutrients in the soils.
c. Improving efficiency use of plant nutrients by avoiding losses to the environment.
· Seed rates: The implications of using recommended seed rates were discussed.
· Spacing: The importance of using optimum spacings for high yields were emphasised.
· Crop rotation: The implications of good crop rotations to minimise pests and disease build up and to enhance soil fertility were discussed.
· Irrigation: The functions of water in horticultural crops were reviewed. Moisture requirements for different crops and critical growth stages to avoid moisture stress were discussed. Soil moisture management in the nursery and direct seeded crops such as okra, beans and peas. Use of mulch to conserve soil moisture.
· Staking: The importance if staking tomatoes to avoid diseases was discussed.
· Pruning: Essential to enhance fruit quality in indeterminate tomato cultivars.
· Pest and disease management: This is the biggest problem in vegetable production. Proper pest and disease identification was emphasised. A list of the major vegetable pests and diseases was presented and discussed. The concept of integrated pest management was reviewed. Integrated approach to pest/disease management involving cultural, biological, cultivar resistance and use of pesticides. Effects of cultural techniques on pests and diseases were discussed. Chemical control of vegetable pests and diseases. Judicious use of pesticide, effects of pesticides on environment and humans.
· Weeding: The importance of weeding was emphasised avoid competition for space, nutrients, water. Certain weeds like Nicandra are alternate hosts for red spidermites.
· Post harvest handling: The following were discussed: proper harvesting methods, time of harvest, care in handling of produce, use of field storage sheds, proper packaging materials, treatment of produce and grading of produce.
· Marketing of horticultural crops: Marketing decisions should be made before planting the crop. Some marketing strategies discussed include; knowing the market requirements, when to sale, timing, off-season production, formation of association for better bargaining, formation of marketing days to create awareness, market research and crop diversification.