Effect of Light Intensity and Temperature on the PhotoSynthesis of Shaded and Unshaded Native Sorghum

Abstract

AflSTHi\Cr Seed of an indigenous variety of sorghum from Jizun were grown in plastic pots. After gcnrrination and thinning half of the pots were transferred to 30% shade and the other half continued to be in the ope n sun . Apparent photosynthesis (A P) was measured at heading on both gr oups of plants at five light intensities (12.22.27.30 and 40 K Lux) and Three temp­ crature levels (25 . 35 and 4SOC). Total dry weight and grain yield were high er for the open sun plants, while harvest index (III) was lower than shade plants, Leaf area. however. was almost equal for both groups. APde­ dined with the increase in temperature . while it increased with th e increase of light intensity. AI' of shade plants remained alwa ys lower than open sun plants. Thi s explains the reduction in biomass and grain yield of shade plants. Apparent photosynthesis (A P) could be taken as criteria for evaluating the adaptation of crop plants to environmental str esses such as temperature a nd light to be used lor breeding adapt ed varieties.