508 Studies on the Effects of Zinc Supply on Growth, Development, and Nutrient Uptake of Pecan Seedlings from Different Seedstocks

Abstract

Zinc deficiency is a nutrient disorder that is observed in pecan production areas. In the field it is characterized by a rosette shoot habit and interveinal leaf chlorosis. Up to now, the induction of zinc deficiency has not been accomplishable in the field or greenhouse. Thus any critical evaluations of effects of zinc nutrition on tree growth and development have been lacking. A hydroponic culture system was developed where zinc deficiency was induced. Seedstocks collected from `Stuart', `Curtis', and `Wichita' trees were grown with and without zinc supply. Biomass, leaf area, node number, and visual symptoms were assessed. Foliar deficiency symptoms were rated 4 and structural evaluations were conducted using light and electron microscopy. Significant differences in visual symptoms were observed between treatments and among cultivars. Leaf area significantly decreased in `Stuart' and `Curtis' under zinc deficient conditions. Zinc had no significant effect on biomass and internodal length. Foliar nutrient contents were compared between cultivars. Our data suggest that genotypic differences in sensitivity to zinc deficiency exists and improving pecan production through genetic selection for zinc efficiency appears promising.