Phosphorus-zinc interactions in two barley cultivars differing in phosphorus and zinc efficiencies

Phosphorus (P)–zinc (Zn) interactions in two barley cultivars (Clipper and Sahara) differing in P and Zn efficiencies were investigated in a pot experiment carried out in a growth chamber. A highly calcareous field soil from a semi-arid region of South Australia was used. Five levels of P addition and three levels of Zn addition were used. Plants were harvested five weeks after emergence. Increase in P supply significantly increased plant shoot biomass and tissue P concentrations in both cultivars, indicating that the soil used is P deficient. Zinc additions with low P additions caused slight decreases in plant biomass. However, Zn addition did increase plant growth when higher levels of P were applied demonstrating the importance of the balance Zn and P supply. Results showed that the genotypic difference between the two cultivars in P uptake efficiency (specific P uptake, SPU) can be altered by Zn–P interactions, and that total Zn uptake by Sahara was higher than Clipper irrespective of P supply. Tissue Zn concentrations decreased significantly with an increase in P supply in both cultivars. Increase in P supply drastically reduced the molar ratio of Zn to P in shoots (MRZP), and addition of Zn compensated for the reduction in MRZP due to P addition. The role of P–Zn interactions in the context of nutritional quality of plant food is also discussed.H.-Y. Li, Y.-G. Zhu, S. E. Smith, and F. A. Smit