Comparison of Photosynthetic Efficiency and Growth in Vanilla tahitensis ‘Haapape’Plantlet under Two Greenhouse Conditions

Abstract

The study of growth and photosynthetic parameters of one-year-old Vanilla tahitensis ‘Haapape’ plantlets after transplantation from tissue culture were compared under two greenhouses types, including a 50% net shading greenhouse (net shading greenhouse) and environment control semi-open greenhouse (plastic greenhouse). This study was conducted at Thai Orchids Co., Ltd., Damnoen Saduak district, Ratchaburi province from January 2017 to January 2018. The results showed that a number of leaves and internodes of V. tahitensis ‘Haapape’ plantlets were higher under the plastic greenhouse than net shading greenhouse, whereas other growth parameters did not differ among the treatments. The different types of greenhouse were unaffected in the photosynthetic pattern of vanilla plantlet that demonstrated the positive values of CO₂ exchange rate (CER) in both day and night times, namely, the C3-CAM photosynthetic pattern. Nevertheless, vanilla plantlet cultivated under the net shading greenhouse showed higher CER, stomatal conductance (gs) and transpiration rate (E) than the plastic greenhouse. In addition, the environmental factors such as temperature and relative humidity inside the greenhouses were not different between net shading and plastic greenhouse, while the light intensity, the light reception period, which higher than light saturation point, and precipitation were higher under net shading greenhouse than the plastic greenhouse.