Photosynthetic rate per leaf area (P_A) was positively correlated with transpiration rate, dark resipration rate, nitrogen content per leaf area and specific leaf weight. Optimum air flow rate for P_A differed according to leaf size. Diploid species with smaller leaves showed the highest P_A at lower air flow rate. In warmer season P_A was higher in spring types while in cold season it was in winter types. Wild types generally showed high nitrogen content per leaf area and high P_A as compared with cultivated types. Light saturation was not observed up to 80 klx for any of 20 strains investigated.