MANAGEMENT PRACTICES TO IMPROVE LOWLAND SUBTROPICAL SUMMER TOMATO PRODUCTION: YIELDS, ECONOMIC RETURNS AND RISK
Four experiments were conducted in southern Taiwan to evaluate the yield and economic benefits of management practices aimed at alleviating the effects of high temperature and heavy rain on tomato production. Following tropical storms, waterlogging caused wilting which was more evident in tomatoes grown in beds 20 cm in height than in those grown in raised beds 40 cm in height. This indication of crop water stress induced by flooding was quantified by measurement of the difference between canopy surface and air temperature at a specified saturation vapour pressure deficit. Canopy heating was less on the raised beds, especially when straddled by rain shelters. Nevertheless, waterlogging stress for the low-bed treatment did not result in loss of stand. In crops which experienced heavy rain, application of a synthetic fruit-set hormone enhanced fruit numbers as did the simple transparent polyethylene rain shelters. While planting on raised beds was without yield benefit the use of fruit-set hormone improved yield by at least 10 t ha−1. A further 4–6 t ha−1 yield was gained through the additional use of rain shelters. Partial budget analysis showed positive returns to the use of fruit-set hormone (US$6600 ha−1) but, unless rain shelters could be constructed with cheaper frame material or used for two tomato crops throughout the summer, their use would be uneconomical. Using existing frame material, net returns to rainshelters reached US$8000 ha−1. The likelihood of high temperatures, tropical storms and typhoons will influence economic returns to summer tomato production. Data from this study may be subjected to economic analyses using values for inputs and tomato prices from other countries with similar climatic conditions.(Accepted June 27 1996)
p1 Present address: Biology Department, Central Queensland University, Rockhampton, Queensland 4702, Australia.