© 1991 Heron Publishing—Victoria, Canada
Family variation in gas exchange, growth and leaf traits of black locust half-sib families
Tesfai Mebrahtu and James W. Hanover
Department of Forestry, Michigan State University, East Lansing, Michigan 48824-1222, USA / Received November 22, 1988
Summary
Variations in several growth, gas exchange and leaf traits among greenhouse-grown black locust (Robinia pseudoacacia L.) seedlings from 11 half-sib families were investigated. Three weeks after germination, early growth rates ranged from
a minimum of 1 cm d–1 in the slowest growing family, to a maximum of 3 cm d–1 in the fastest growing family. Significant family variation in net photosynthetic rate per unit leaf area (PN), stomatal conductance, chlorophyll content, height, diameter, stem dry weight and total dry weight was observed. Net photosynthetic
rate declined with seedling age. Net photosynthetic rate per unit leaf area was significantly correlated (r < 0.4) with specific leaf area, total chlorophyll, root dry weight, foliage dry weight and total dry weight. The correlation
coefficients were higher (r ≥ 0.55) between PN × total leaf area and growth traits (height, stem dry weight, foliage dry weight and total dry weight). The study indicated
that variation in leaf area among the families was one reason for the lack of a strong relationship between PN and growth.
