The relationship of leaf area and stem weight, with stem length at different times during the year, was studied on 5 apple (Malus domestica Borkh.) cultivars. Leaf area was related linearly to stem length, but the slope differed by up to 2-times between cultivars. Stem dry weight increased curvilinearly with respect to stem length and showed less variation among cultivars than did leaf area. These 2 relationships combined indicated that the stem constitutes an increasing proportion of the total shoot weight with increasing stem length. Dormant stems had a greater weight per unit length than stems of growing shoots. Both stem length and leaf area showed strong fitting linear relationships with accumulated growing degree-days, but the stem length relationship showed less variability among cultivars than did leaf area.
Present address: Univ. of California Kearney Agr. Center, Parlier, CA 93648.
Received for publication 28 Oct. 1983. Approved by the Director of the New York State Agr. Expt. Sta. for publication as Journal Paper No. 3555. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.