Copper Deficiency in Chrysanthemum: Critical Level and Symptoms1

Abstract

A series of experiments was conducted with chrysanthemum cv. Giant Betsy Ross grown in acid-washed quartz sand. The nutrient solution was buffered at pH 7.8 to induce Cu deficiency while Fe, Mn and Zn were supplied in high quantities to avoid simultaneous deficiencies. Nutrient levels in the tissues were monitered by atomic absorption analyses. The critical range of Cu was established at 6.7 to 7.4 ppm for the first fully expanded leaves of the plant. The deficiency first appeared on the terminal leaves as chlorosis most intensely developed at the leaf blade base. As the leaf became more chlorotic the margin, and particularly the lobes toward the leaf apex, retained a normal green color. Tissues over and adjacent to the vascular tissue did not become as chlorotic as the leaf lamella giving rise to the second symptom which was interveinal chlorosis. At that stage the green pigmentation associated with the vascular tissue occurred in a broader pattern than in Fe deficiency. In the third stage of deficiency veinal chlorosis appeared, followed by necrosis of leaves located immediately below the first fully expanded leaf. There was a concomitant regreening of foliage at the terminal end of the shoot which lasted for a short time. In the final stage the shoot apex died.