The influence of leaf area on the rooting physiology of leafy stem cuttings of Terminalia spinosa Engl
Abstract
The effect of different leaf areas on the rooting of Terminalia spinosa Engl. cuttings in an non-mist propagation system in glasshouses at Edinburgh was investigated by trimming the leaves to 0, 7.5, 15 and 30 cm<sup>2</sup> before cuttings were severed from stockplants. Cuttings were taken to a standard length of 5 cm from the lateral shoots of previously pruned stockplants grown in a tropicalised glasshouse. During the rooting period, photosynthetic rate, stomatal conductance, water potential and relative water content of the cuttings were assessed at regular intervals. It was found that (i) removal of the entire leaf area prevented rooting; (ii) cuttings with a 7.5 cm<sup>2</sup>, 15 cm<sup>2</sup> and 30 cm<sup>2</sup> leaf all achieved 80% rooting after 3 weeks; (iii) an increase in leaf area from 7.5 cm<sup>2</sup> to 30 cm2 increased the rate of rooting and the length of the longest root after 2 weeks, but also increased the number of original leaves abscised after 6 weeks; and (iv) the greatest number of new leaves were produced by cuttings with 7.5 cm<sup>2</sup> and 15 cm<sup>2</sup> leaf area per cutting. All leafy cuttings actively photosynthesized during the propagation period, with a mean rate of 2 µ mol CO2 m<sup>-2</sup> s<sup>-1</sup> with an irradiance of 100 µ mol m<sup>-2</sup> s<sup>-1</sup>. Cuttings with 30 cm<sup>2</sup> leaf area had lower relative water contents, lower stomatal conductances and lower photosynthetic rates per unit leaf area than those with a 7.5 cm<sup>2</sup> and 15 cm<sup>2</sup> leaf. It was concluded that T. spinosa cuttings are easy to root, provided the cuttings have leaves to produce current assimilates.
Citation
Trees - Structure and Function (1992) 6 (4) 210-215 [DOI: 10.1007/BF00224338]