CULTURAL PRACTICES AND PHYSIOLOGY OF SOME VALUABLE TROPICAL FRUITS IN THAILAND

Cultural practices and physiology of durian (Durio zibethinus Murr.), mangosteen (Garcinia mangostana L.) and rambutan (Nephelium lappaceum L.) in Thailand are discussed. Chanthaburi Horticultural Research Center (CHRC), Department of Agriculture has developed an appropriate package of technologies to improve production and quality of durian, mangosteen and rambutan, and has transferred the information to extension staff and growers. The flowering process of these crops is broken down into several stages. The process begins with trees being manipulated to produce maximal photosynthates and assimilates through cultural practices such as pruning, fertilization, irrigation, and crop protection, and ends when the floral buds swell and develop sequentially until bloom. A dry period is needed to trigger flowering. After exposure to an optimum level of water deficit, the leaves exhibit symptom of water stress and proper water management is necessary to promote flower bud emergence. Cross pollination by hand using pollen from different varieties and inducing viable pollen using plant growth regulators are recommended to increase fruit set in durian and rambutan, respectively. Mangosteen has no problem on fruit set since the fruit is formed parthenocarpically. According to a source-sink theory, fruit thinning and enlarge source capacity are important cultural techniques to promote growth, good shape and quality of fruits.