Zinc Accumulation by Corn Seedlings as Influenced by Phosphorus, Temperature, and Light Intensity1

Abstract

AbstractZinc deficiencies of corn (Zea mays L.) are often associated with cool, cloudy weather and appear to be intensified with high P fertilization. Experiments were conducted under controlled conditions to determine the effect of light intensity, temperature, and P on the uptake and translocation of Zn.Corn seedlings were grown at 30,000 lux light intensity for 6 days in nutrient solutions containing either 0 or 0.1 mM P and at 18/14C or 30/26C day‐night temperatures. The seedlings were then exposed to Zn solutions of 0, 0.4, and 0.8 μM Zn for 48 hours with the same temperatures being maintained as during the initial growth period. Phosphorus pretreatment had no effect on Zn accumulation or translocation. At the low temperature there was very little uptake of Zn from an external solution.In a second experiment, corn seedlings were grown for 6 days in a complete nutrient solution at light intensities of 19,300, 25,800 and 30,000 lux and temperatures of 18/14C or 30/26C. The seedlings were then exposed for 48 hours to treatments of 0, 0.4, and 0.8 μM Zn containing either 0 or 0.1 mM P. The initial temperature and light intensities were maintained during the uptake period. Phosphorus treatments did not affect Zn translocation to the shoots. Temperature influenced the translocation of Zn. More Zn accumulated in the roots at the lower temperature than at the higher temperature. Also, total Zn accumulation was reduced markedly as light intensity was decreased from 30,000 to 19,300 lux. At low light intensity Zn contained in the seed was the main source of Zn for young corn seedlings.The shoot‐to‐root ratio increased with a high supply of P. With decreasing light intensity, root growth decreased and shoot.to‐root ratio increased. The effect of low light intensity in reducing root growth more than shoot growth appears to be an important reason for the occurrence of early season Zn deficiencies.