UPPER CRITICAL-LEVEL OF COPPER IN WHEAT (TRITICUM-AESTIVUM) RAISED ONTYPIC USTIPSAMMENT SOIL

Effect of different levels of copper (0, 5, 10, 20, 40, 80, 160, 320 a nd 640 mg/kg soil) was studied on 'WL 1562' wheat (Triticum aestivwn L . emend. Fiori & Paol.), grown on a Fatehpur loamy sand soil under gre enhouse conditions. Mean dry-matter yield of wheat decreased significa ntly with the application of Cu @ > 20 mg/kg soil. Copper-toxicity sym ptoms in plants were observed with 40 mg Cu/kg soil treatment, and the y became severe at its higher levels. Copper content > 15.5 mug/g in f lag-leaf of wheat and 8 mg/kg in soil indicated the threshold values a bove which plants would suffer from its toxicity. A significant declin e was observed in iron and boron content of flag leaf with increase in Cu rate.