Physiological and Biochemical Modulations upon Root Induction in Rose Cuttings as Affected by Growing Medium

Abstract

Two cut rose (Rosa hybrida) cultivars ‘Sherbet’ (easy-to-root) and ‘Alibaba’ (difficult-to-root) were propagated by single nodal cuttings on preformed media. Four commercial media such as Tosilee, Ellepot, rockwool and phenolic foam RC, and four newly-developed foam media namely Oasis PU 14-S1, Oasis TP-S1, Oasis PU-7B and Oasis PU 15-S1 were employed in this study. All media were manufactured to fit into 50-cell plug trays. The experiment was laid out in a complete randomized block design with three replications on a propagation bench with a plastic tunnel installed in a glasshouse, with (98 ± 2)% relative humidity and over 50% shading of the natural sunlight. After four weeks of experiment, growth parameters, localization of superoxide radicals, and activities of rooting biochemical markers were measured. The results suggested that the newly-developed foam media Oasis TP-S1 and Oasis PU-7B enhanced the growth, density of leaf stomata, and consisted of lesser harmful superoxide radicals in similar manner with the existing commercial media. Moreover, the Oasis TP-S1 and Oasis PU-7B media significantly enhanced the total phenol content and the activities of important enzymes involved in the phenol metabolism which plays a vital role in the formation of roots. Thus, the understanding of both physiological and biochemical changes implicated by the growing medium during the rooting of cuttings would aid in the selection of optimal growing medium for the propagation of rose cuttings. Keywords: foam medium, peroxidase, phenol, phenylalanine ammonia lyase (PAL), superoxide localization