Research article EFFECT OF SHADING AND VARIETY ON THE GROWTH AND YIELD OF BROCCOLI DURING THE DRY SEASON IN SOUTHERN THAILAND

The effects of shadings and varieties on the broccoli (Brassica oleracea L. var. italica Plenck.) growth and yield were studied at Prince of Songkla University, Hat Yai, Songkhla, Thailand. The study was conducted in split-plot in a randomized complete block design with four replications. The broccoli can be adapted to shading by increasing seedling survival rate, plant height and plant width. Consequently, the broccoli under the shading had the highest in head diameter, head weight and yield which was significantly better than full sunlight. There was a positive impact of the shading on yield and yield attribute of the three varieties. The highest total yield was obtained from the Yok Kheo under the both full sunlight and shading (10.92 and 8.29 t . ha -1 , respectively), followed by the Green Queen under the shading (6.21 t . ha -1 ). The appropriate broccoli variety on growing during dry season in southern Thailand was the Yok Kheo and Green Queen because their growth rate and yield per hectare were higher than of the Top Green and they also had the bigger size and higher quality of head. Particularly, those grown under the shading because of the decreasing light intensive and maximum temperature and the increasing relative humidity compared to the full sunlight. These factors would support the increasing growth and yield of broccoli.