Seasonal changes in some physiological and biochemical responses of six groundcover plants

Landscape groundcover plants are a diverse group of trailing or spreading species that naturally form continuous soil coverage.Ground cover plants that were used in this study consisted of vegetative propagules of: Vinca minor L. ٬Variegatum’, Vinca minor L. ٬Green’, Oxalis brasiliensis G. Lodd, Trifolium repens L., Phyla nodiflora L. and Frankenia thymifolia Desf. The aim of this study was to compare some physiological and biochemical responses of each species used under seasonal changes in Shiraz climatic conditions. Several factors including chlorophyll and relative water content (RWC), electrolyte leakage (EL), proline content, soluble sugars and starch levels and antioxidant enzyme activities of these ground covers were investigated. Results showed that chlorophyll and RWC content were decreased in all ground cover plants during summer time. Furthermore, considerable seasonal variations in antioxidant enzyme activities were detected in all of the studied plants. The highest activity of CAT was obtained in summer, while SOD, POD and APX had their highest activities in autumn and winter seasons. Proline concentration in F. thymifolia was higher than the other species, especially in mid-winter. According to the results of this research, it appears that plants show different mechanisms against natural adverse environmental conditions. It can be concluded that F. thymifolia and P. nodiflora are well-matched with warm season and T. repens and V. minor are well-matched with cool season environmental conditions. Therefore, these plants can be recommended for cultivation in Shiraz green space and the same conditions elsewhere.