DESIGN AND DEVELOPMENT OF NATURALLY VENTILATED TROPICAL CROP PROTECTION STRUCTURES AND HYDROPONICS SYSTEMS
Conventional crop production in the open field is high risk against environmental stress such as extreme solar radiation, high rainfall, high surface wind, weed competition, crucial insects and diseases. Moreover, the inputs of fertilizer, pesticides and labor are necessary to produce high yield and quality horticultural crops. Naturally ventilated tropical crop protection structures and hydroponics systems have been developed to address these constraints. The structures are rain shelter and netted rain shelter. Rain shelter has simple structural frames, transparent roofing and open sidewall, while the netted rain shelter has an extra insect screen at the side wall. Rain shelter protects cultivation area against rain, transmits photosynthetically active radiation (PAR) for photosynthesis, without sidewall provides ventilation and insects pollination. However, the netted rain shelter has an extra insect-screen side wall that excludes the target insects. Generally, the advantages of the naturally ventilated tropical crop protection structures are to avoid fertilizer loss by surface runoff, reduce weed growth, keep cultivation area dry for easy working conditions and less soil borne disease. The structures were found durable, reliable, low-maintenance and cost-effective. Several types of hydroponics systems suitable in tropical conditions were also developed. The systems are nutrient flow technique, deep flow technique, aerated static technique and micro drip fertigation system. The main functions of the systems are to supply the right amount of water and nutrient solution direct to the crop root zone according to their growth requirements. Basically, the systems consist of water source, nutrient solution tank, water pump, automatic irrigation controller, distribution pipes and growing through or growth media. The advantages of the systems are to supply efficient water and nutrient solution according to the crop growth, to reduce soil borne disease, keep root temperature low, reduce labor in watering and save operational time. The systems were found durable, reliable and cost-effective. High value temperate and tropical crops such as tomato, capsicum, cabbage, musk melon, Japanese cucumber, chili, brinjal, kalian and brassica were successfully grown under the structure using hydroponics systems in the lowlands. The yields of the crops were found higher to 2-4 times, premium quality and all year round production as compared to open field production. In addition, it reduces labor requirements and saves operational time. This paper highlights some scientific information on the design criteria, construction and performances of crop protection structures, hydroponics systems and crop production in the tropical lowlands.
Kamaruddin, R. (2007). DESIGN AND DEVELOPMENT OF NATURALLY VENTILATED TROPICAL CROP PROTECTION STRUCTURES AND HYDROPONICS SYSTEMS. Acta Hortic. 742, 139-154
design and construction, tropical crop protection structures, hydroponics systems, natural ventilation system, crop production