YIELD AND QUALITY OF STRAWBERRY UNDER A LOW-COST PLASTIC HOUSE IN TROPICAL CLIMATE

King Mongkut’s University of Technology Thonburi (KMUTT) is in collaboration with the National Center for Genetic Engineering and Biotechnology (BIOTEC) to grow and develop strawberry as an alternative job for farmers in Naheaw District, Loei Province in the Northeast of Thailand. This area has a period of 6 months for a suitable temperature and rain volumes for strawberry growth (between November-March and a range of average temperature of 15-25°C). Farmers could grow strawberries outside this period of time; however, the strawberry yield decreases lower than the break-even point. Plastic house is a new innovation preventing strawberries from rainfall. This project designed and constructed a low-cost plastic house with a width of 2 m, a length of 20 m, and a height of 2.5 m. The yield and quality of strawberries were monitored to evaluate the quality of the design and the heat accumulation inside the house. Each plastic house was designed to have two grooves, while each groove has two rows with a spacing of 25-30 cm. Strawberry 329 (‘Yael’) was selected. The comparison between strawberry growing inside and outside the plastic house showed that the sizes of strawberry fruits were insignificantly different during the early growing period (1-90 days). After 90 days, a strawberry tree inside the plastic house had a bush size of 588.99 cm², which was larger than a strawberry tree outside the plastic house (with a bush size of 577.14 cm²). Strawberry products in the plastic house had a diameter product greater than 2.5 cm. Inside the plastic house, the productivity (fruit number) per plant was 4.6, while outside the plastic house the productivity per plant was 6.1 due to the heat accumulation inside the plastic house. However, the number and the overall weight of the strawberry product outside the plastic house were higher than the strawberry inside the plastic house (60.1 g/plant, 70.8 g/plant). Further, the firmness of strawberry product inside the plastic house was still lower than the strawberry product outside the plastic house. The temperature inside the plastic house was higher than outside 2°C affecting the growth of a flower bud that is in a direct effect to reduce the amount of the strawberry product. Therefore, further research is needed to be conducted to reduce the heat accumulation inside the plastic house.