Ontogenetic changes in growth and net photosynthetic rate of two peanut (Arachis hypogaea L.) cultivars

The ontogenetic changes in growth, and the diurnal changes in net photosynthetic rate (PN) and stomatal conductance were studied in two peanut cultivars of different habit groups. Significant cultivar differences were noticed: the prostrate cv. M 13 was found superior to the erect cv. J 11 in all the parameters studied. Specific leaf mass and the rates of gross photosynthesis and respiration were higher in cv. M 13 than in cv. J 11. In vegetative phase, the maximum PN was in cv. J 11, but in pod filling phase, it was in cv. M 13. The differences in growth and PN of the cultivars were significant after the onset of reproductive sink. Therefore, the screening for higher PN has to be made at the pod-filling phase, and between 09.00 and 10.00 of the day (at optimum temperature).