Phosphorus deficiency is one of the principal yield limiting factors for crop
production in Egyptian soils. The objectives of this study were to evaluate P-use
efficiency in 17 corn cultivars under P-deficient soil and to elucidate some of the
putative mechanisms governing P-use efficiency. To achieve this goal, two pot
experiments were carried out; in the first experiment the corn cultivars were grown in
P-deficient soil at three levels of P (0, 50 and 75 mg P kg-1) for 30 days after planting.
Shoot, root dry matter production, P uptake and P-use efficiency of corn cultivars were
investigated. The results showed that shoot and root dry matter production and P
uptake were significantly affected by P treatments and corn cultivars. Based on dry
matter production and P-use efficiency, corn cultivars were classified as efficient and
responsive (ER), efficient and non responsive (ENR), non efficient and responsive
(NER), and non efficient and non responsive (NENR). In the second experiment, four
corn cultivars differing in P-efficiency were selected from previous screening. These
were as follows; T.w.C.320 (ER), T.w.C. 324 (ENR), T.W.C. 351 (NER) and S.C. 12
(NENR). The corn cultivars were grown in the same P-deficient soil for 18 days after
planting with and without P application. Dry matter production of shoot and root, root-
shoot ratio, root length and organic acids concentrations in rhizosphere soil were
investigated under P-deficient and P-sufficient treatments. The results of this
experiment showed that dry matter production of shoot and root, root-shoot ratio, root
length and organic acids concentrations were increased in all corn cultivars under P-
deficient treatment. The effects on root dry weight, root-shoot ratio, root length and
organic acids concentrations in rhizosphere soil were greater for efficient cultivars
(T.W.C 320and T.W.C 324) than for non-efficient, (T.w.C 351 and S.C 12).