Excess trace metal effects on cotton: 2. Copper, zinc, cobalt and manganese in Yolo loam soil

Abstract

Abstract Two cultivars of cotton (Gossypium spp.) were grown in Yolo loam soil (soil pH about 6) in pots in a glasshouse to determine phytotoxic effects of excesses of Cu, Zn, Co, and Mn. Leaf yields of cv. Acala SJ‐2 were depressed 35% by 400 μg Cu/g soil, 54% by 400 μg Zn/g soil, 98% by 400 μg Co/g soil, and 84% by 2000 μg Mn/g soil. Leaf metal concentrations at these application levels in μg/g leaf were 12.0 Cu, 520 Zn, 243 Co, and 14780 Ma, respectively. Plants were tolerant of in / dry leaves of 10 Cu, 157 Zn and 444 Mn. The concentration for Co could not be ascertained. Leaf yields of cv. Giza 70 were depressed 53% by 400 μg Cu/g soil, 25% by 400 μg Zn/g soil, 92% by 400 μg Co/g soil and 90% by 2000 μg Mn/g soil. This cv. was more tolerant of Zn than Acala SJ‐2. Leaf metal concentrations at these application levels in μg/g leaf were 11.8 Cu, 312 Zn, 224 Co, and 18300 Mn respectively. Gradients of these four elements existed from leaves to stems. Many interactions with other elements were observed.