Phosphorus Efficiency and Phosphate-Iron Interaction in Maize1
- George C. Elliott and
- André Læuchli2
Genotypic differences in absorption or utilization of P might be exploited to improve efficiency of fertiliir use or to obtain higher productivity on P-deficient soils. Experiments were conducted to determine rates of P absorption, P accumulation, and P utilization in 15 inbred genotypes of maize (Zea mays L.) at 3 P supply levels. Nutrient solution P concentrations were maintained at approximately 5,25, and 100 mmol m−3 (Pl, F‘2, and P3, respectively) with an alumina-P solid phase buffer. There were significant differences among genotypes for rate of P utilization, but not for rate of P absorption by roots. Utilization of P was negatively correlated with the ratio of inorganic P accumulation rate to total P accumulation rate, indicating that P utilization is limited by partitioning of P between free orthophosphate and organically combined forms. Absorption of P by roots and utilization of P in shoots were positively correlated. Iron deficiency occurred with all genotypes grown in the P2 and P3 treatments, but not in the P1 treatment. Both Fe absorption by roots and partitioning of Fe to shoots decreased with increasing concentration of P in the nutrient solution. Utiliition of Fe (rate of dry matter production per unit of Fe accumulated) in shoots increased in Fe-deficient plants. Phosphate-induced Fe deficiency in maize evidently involves both inhibition of Fe absorption by roots and inhibition of Fe transDort from roots to shoots.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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