The efficiency of C4 plants is more than those of C3 plants because (i) C4 plants are more efficient in picking up CO2 even when it is found in low concentration because of the high affinity of PEP, (ii) concentric arrangement of mesophyll cells produces a smaller area in relation to volume for better utilization of available water and reduce the intensity of solar radiations, (iii) they can tolerate excess salts because of the presence of organic acids, (iv) normal oxygen concentration is not inhibitory for the growth in contrast to C3 plants, (v) they are adapted to high temperature and intense radiation of tropics.