Role of copper in improving the seed quality of sunflower (Helianthus annuus)

'Morden' sunflower (Helianthus annuus L.) was grown in refined sand at a co pper supply ranging from acute deficiency (0.00065 mg/litre) to excess (6.5 mg/litre) to study the effect of variable copper on growth, biomass, oil y ield, etc. The oil content in seeds was highest at 0.065 mg Cu/litre and co mpared to this, it decreased more in deficiency (<0.065 mg/litre) than in e xcess of copper (6.5 mg/litre). High copper also reduced the biomass, total seed weight and the activities of polyphenol oxidase, ascorbic acid oxidas e and cytochrome C oxidase in leaves. In sunflower, low copper (<0.065 mg C u/litre) induced the characteristic visible deficiency symptoms and drastic ally reduced the growth, biomass and seed yield accompanied by low sugar co ncentration and lowered activities of polyphenol oxidase, ascorbic acid oxi dase and cytochrome C oxidase in leaves.