Effects of Phosphorus and Copper on Factors Influencing Nutrient Uptake, Photosynthesis, and Grain Yield of Wheat

Application of large amounts of phosphorus fertilizers is used to enhance early plant growth and yield of wheat (Triticum aestivum L.). This practice can lead to an accumulation of phosphorus in soil and a reduced copper uptake by plants which may result in a reduction of plastocyanin concentrations in chloroplasts. As a result, photosynthetic rates and crop yield can be adversely affected. While copper uptake is sometimes enhanced by vesicular-arbuscular mycorrhizal (VAM) fungi, large accumulations of soil phosphorus can reduce VAM-enhanced copper uptake. Varying amounts of phosphorus and copper were applied to research plots in order to measure their effect on the wheat leaf content of phosphorus, copper, and plastocyanin. VAM spore counts, leaf photosynthesis, and grain yield were also measured. Application of phosphorus to soil increased leaf phosphorus content, but decreased VAM spore count and photosynthesis. Application of copper to soil decreased VAM spore count but had no other effects. The combined effects of soil applied phosphorus and copper increased both photosynthetic rates and grain yield. As expected, photosynthetic rates increased with increasing leaf plastocyanin content, but grain yield could not be related to either plastocyanin content or photosynthetic rates. OHIO J. SCI. 91 (5): 191-194, 199