Effects of Adjusted Light Levels on Plant Growth and Flowering Characteristics of Oncidesa Cultivars

The aim of this study was to evaluate the growth and flowering characteristics of three Oncidesa cultivars under four distinct canopy treatments in a greenhouse environment. The control canopy treatment (canopy D) involved covering the greenhouse with black shade nets to reduce natural light penetration. Canopy B included black shade nets in combination with a transparent plastic screen on the sides to further modify the light conditions. Additionally, two other treatments were applied: black shade nets with (canopy A) or without (canopy C) plastic sheeting, supplemented with daily lighting from high-pressure sodium lamps. Ten horticultural traits were measured to assess the impact of these canopy treatments on different cultivars at various growth stages. The results show that canopy treatments significantly affected all the measured traits of the Oncidesa cultivars, except for leaf width. Apollo plants treated under canopy A exhibited longer and thicker pseudobulbs, wider leaves, higher chlorophyll content, and a greater number of branches and florets compared to Honey Angel and Golden Star. Plants under canopy C showed superior growth traits across all cultivars, while those under canopies A and D exhibited better flowering quality. These findings suggest that different canopy treatments had varying effects on the growth and flowering traits of Oncidesa cultivars, with each cultivar showing distinct adaptability to specific canopy conditions.