Effect of Regulated Deficit Irrigation on Photosynthesis, Photosynthetic Active Radiation on Yield of Sorghum Cultivar

The effects of regulated deficit irrigation technique on photosynthesis, photosynthetic active radiation and yield of sorghum grown on Rhu Tapai and Rengam series soil were examined in a Control Environment House at the Faculty of Agrotechnology and Food Science, University Malaysia Terengganu. The experiments regulated deficit irrigation consisted of a factorial combination of irrigation regimes and soil types laid in a randomized complete block design with eight treatments for. Irrigation regimes were at four levels namely: I 100 , I 75 , I 50 and I 25 and the soil types were at two levels namely: Rhu Tapai and Rengam series soil.  The treatments were randomly assigned to experimental pots and replicated four times. All agronomic practices starting from planting of sorghum to harvesting were adhered to and photosynthesis, photosynthetic active radiation and yield parameters were recorded for the experiment. The result of the study shows that sorghum performed better under regulated deficit irrigation technique. The results further revealed that, irrigation regimes I 100 and I 75 performed better in terms of photosynthesis, photosynthetic active radiation and yield parameters compared to I 50 and I 25 irrigation regimes. The study also revealed that there was no significant different between the two types of soil used for the study. The study, therefore, recommended the use of I 75 percent regulated deficit irrigation for optimizing sorghum yield production in semi-arid regions. Keywords : Regulated deficit Irrigation, photosynthesis, photosynthetic active radiation, yield, sorghum