ISHS Acta Horticulturae 314: II International Symposium on Propagation of Ornamental Plants
A PHYSIOLOGICAL ANALYSIS OF THE DIFFERENTIAL ROOTING PERFORMANCE OF CALAMONDIN AND PELARGONIUM CUTTINGS UNDER MIST AND HIGH HUMIDITY |
| Authors: | D. Rosenberg, A. Altman, B. Bravdo |
| Abstract:
It is generally accepted that rooting of leafy cuttings under mist is preferred to other means of air humidity control. This is true in certain plant species and environmental conditions, but not in all. The physiological basis for these differences was analysed in cuttings of Calamondin (C. reticulata var. austera? × Fortunella spp.) and Pelargonium (Pelargonium × hortorum) which were rooted under 4 propagation regimes: intermittent mist (M), intermittent mist with basal heating (MH), and under high humidity in low (LP) and high (HP) polyethylene tunnels. Rooting and performance of Calamondin cuttings was best under polyethylene tunnel (LP and HP) and poorest under mist. Percent rooting of Pelargonium cuttings was similar under all 4 regimes, but many more roots were produced under mist. The differential effects of the environmental conditions on physiological processes in the two plant species explain their different rooting behaviour. Thus, leaf water potential and net photosynthesis of Calamondin cuttings were higher under polyethylene than under mist, and the reverse was true with Pelargonium cuttings. The superior rooting of Calamondin in polyethylene tunnels was possibly due to heavy shading while still maintaining a sufficient radiation level, and to a much lower vapor-pressure gradient in the tunnel. Under these conditions, Calamondin cuttings were less water stressed and maintained higher photosynthetic activity than did Pelargonium cuttings. The different rooting and physiological responses of the two species may reflect different species-dependent ecophysiological adaptations. Thus, conditions for proper rooting should be pre-determined in each case. | |
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