This research aimed to study P efficiency of ten maize genotypes (zea mays, L.) under two levels of P in calcareous soil and to quantify the contribution of root growth in P uptake. Plants were grown in potted soil with two levels of available P in soil 40(low P) and 270 (high P) mg P/ kg soil in glasshouse with five replicates in randomized complete block design. The maize genotypes were harvested 4 weeks after transplanting. All plants increased significantly with increasing P level, except code 1, code 3, code 7 and code 8 (single hagen 10, 15, Bshaier 13 and Pioneer 3062 respectively), there was no significant difference between shoot dry matter at low and high P level. Maize genotypes (code1, code 3, code 7, and code 8) attained more than 80% of its maximum yield already at the lower level of available P. In contrast, at low level of available P, maize genotypes code 5 and code 9 (single hagen 123 and 151 respectively) attained only 21.9% and 14.7% respectively of their highest yield. This signified that maize genotypes (code1, code 3, code 7, and code 8) had high P efficiency, whilst maize genotypes (code 5 and code 9) had low P efficiency. Maize genotypes code1, code 3, code 7 and code 8 had longer roots in limited P supply followed by code 2, code 4 and code 6 (single hagen 12, 122 and 129 respectively), and the shorter roots observed in maize genotypes code 5, code 9, and code 10 (single hagen 155). The adaptation of maize genotypes to low level of soil P is closely related to better developed root system and the increase in root length under P stress may be one of the possible mechanisms of P efficiency in maize. At low P level, code 1 and code 7 were the highest P uptake per plant. In contrast, code 5 and code 9 were the lowest maize P uptake. In conclusion, the results of this study suggested that root growth system would be a suitable plant parameter for selecting P efficient maize genotypes especially under limited P supply.