Effects of net house culture on the plant growth and fruit development of ‘Jen-Ju-Bar’ guava (Psidium guajava ‘Jen-Ju’)

Abstract

Guava (Psidium guajava L.) is a tropical fruit belonging to the family Myrtaceae. It is produced and exported all year round in Taiwan. Since Taiwan is an infestation area of the oriental fruit fly (Bactrocera dorsalis), the conventional solution to this problem involves bagging fruit with polyethylene (PE) bag containing expanded polystyrene net sleeve (EPNS). Previous report showed that the bagging process not only increases labor and material costs, but also generates agricultural wastes. Furthermore, summer fruit produced with this method often results in poor quality, such as flavor change and shortened storage life. The objective of this study was to investigate the potential of non-bagging culture in a net house to replace the conventional PE bag bagging culture in open field. Plants in the net house received 31-37% less photosynthetic active radiation and had lower photosynthetic rate compared to bagging culture in open field, while the transpiration rate, stomatal conductance and intercellular CO2 concentration were higher. After moderate pruning, plants in the net house had higher flowering percentage. The ambient temperature in the net house was 4-8°C, lower than that inside the PE bag used in bagging culture. Non-bagging fruit had lower fruit growth rate compared to the PE + EPNS bagged fruit in the summer season. After low temperature storage, non-bagging fruit had greater performance on the fruit firmness, total soluble solids, and ascorbic acid than the bagged fruit. In addition, non-bagging fruit had lower chilling injury index (core water-soaking) and higher quality during low temperature storage (1°C for 14 days).