These studies were undertaken to identify photosynthetic traits of the cultivated peanut (Arachis hypogaea L.) that might be used in breeding programs designed to increase yield. Net photosynthesis (Pn), CO2 compensation point (), stomatal diffusion resistance to water vapor and stomatal frequency were measured on 32 diverse genotypes. Pn was measured on 3 and 4 week old plants in a semi-closed compensating system, by initial introduction of CO2-free air and equilibration thereof, and stomatal resistance with a diffusion porometer; photorespiration and mesophyll diffusion resistance to CO2 were calculated. At high light (1400 E m2s1PAR) eight genotypes had Pn rates of 20 to 30, seventeen 31 to 40 and seven 41 to 43 mg CO2 dm2h1. At any given light level tested Pn rates of a given genotype were significantly different from other genotypes. Only three genotypes showed any tendency toward photosaturation at 1400 E m2s1PAR. Photosynthetic rate and photorespiration were positively correlated (r = 0.92, P<.001). Stomatal density for the 32 genotypes averaged 168 and 154 mm2on adaxial and abaxial surfaces. Neither stomatal density nor stomatal resistance to water vapor diffusion was correlated with Pn. In all instances, resistance to water vapor diffusion of the adaxial surface was less than that of the abaxial surface. Pn was negatively correlated (r = 0.98, P<.001) with mesophyll resistance which suggests that somewhere within the residual resistance system lies the reason(s) for differences in Pn amongst the genotypes tested.
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Keywords: Carbon Dioxide Exchange Rate, photorespiration, Mesophyll resistance, Leaf resistance, Stomatal resistance and density, Groundnut, Arachis hypogaea L
How to Cite:
(1982) “Photosynthetic Traits of Selected Peanut Genotypes1,2”,
Peanut Science 9(1),
01 Jan 1982