Physiological and Morphological Responses of Five Tropical Flowering Shrubs to Drought and Waterlogging Stress and Their Landscape Utilization

PurposeThe physiological and morphological changes of five tropical flowering shrubs under different water stress treatments were studied to reveal the response of plants to drought and waterlogging stress.

MethodAllemanda schottii, Gardenia jasminoides, Schefflera arboricola ‘Variegata’, Syzygium campanulatum and Tabernaemontana divaricate were used as experimental materials to conduct four water stress treatments, including normal water supply (CK), continuous drought (CD), continuous flooding (CF), drought and flooding alternation (FD). The morphological changes and the physiological indexes of plants under different water stress treatments were respectively observed and measured. And the stress resistance of plants was comprehensively evaluated by fuzzy membership function method.

ResultUnder drought stress, the leaf damage of S. campanulatum suffered the most, which performed grade VI. The SOD activity of five flowering shrubs decreased, malondialdehyde content increased, and chlorophyll content of S. arboricola ‘Variegata’ decreased significantly (P<0.05). Flooding stress has a significant impact on the external morphology of plants. G. jasminoides growed new roots, A. schottii formed hypertrophic lenticels and growed a lot of new roots and leaves, a large number of leaves of S. arboricola ‘Variegata’ withered and its root rotted seriously, lots of leaves of T. divaricata fell. Under waterlogging stress, the chlorophyll content of five flowering shrubs decreased significantly (P<0.05), soluble protein content also decreased, however the malondialdehyde content increased, the SOD activity of S. arboricola ‘Variegata’ and T. divaricate decreased significantly (P<0.05). Under alternate stress of drought and flooding, the leaf morphologies of A. schottii and S. campanulatum were performed as grade I and II respectively, the chlorophyll content of five flowering shrubs decreased, and the SOD activity of T. divaricate increased, while the other four plants decreased.

ConclusionCombining subordinate function and plant morphology, the tolerance of five flowering shrubs to drought from strong to weak was S. arboricola ‘Variegata’, T. divaricate, A. schottii, G. jasminoides, S. campanulatum, the tolerance of five flowering shrubs to waterlogging from strong to weak was G. jasminoides, S. campanulatum, A. schottii, S. arboricola ‘Variegata’, T. divaricate, and the adaptability to alternate stress of drought and flooding from strong to weak was A. schottii, S. campanulatum, S. arboricola ‘Variegata’, T. divaricate, G. jasminoides. A. schottii can be arranged in rain garden and waterfront riverbank zone, S. arboricola ‘Variegata’ and T. divaricate are excellent plant materials for building roof garden and water-saving green space, G. jasminoides and S. campanulatum can be arranged in waterfront green space, freshwater wetland or humid soil environment.