Foliar Application of Moringa and Mint Leaf Extracts Enhances Carnation Growth and Flower Yield Under Saline Conditions by Improving Plant Defense Mechanism

Carnation (Dianthus caryophyllus L.) plant is native to the Mediterranean region. However, it is cultivated throughout the world for its beautiful flowers. In Pakistan, its flower yield and quality is very poor due to numerous abiotic stresses including salt stress, which drastically decreases plant growth, flower yield and quality. The aim of the present study was to evaluate foliar application of moringa and mint leaf extracts (0.03% each, separately) to mitigate negative effects of irrigation water salinity (0, 30 and 60 mM NaCl) on carnation plants. Salinity treatments reduced plant height, plant fresh and dry weights, leaf number, root length, number of flower buds, number of flowers, fresh and dry weights of flowers, photosynthetic pigments, i.e. chlorophyll a, chlorophyll b and total chlorophyll, and carotenoid content as well as ascorbic acid content. However, number of branches increased at 30 mM irrigation water salinity level and then decreased at 60 mM, while hydrogen peroxide (H2O2), malondialdehyde (MDA), peroxidase (POD) and catalase (CAT) activities increased with an increase in salinity level. Leaf length, root fresh weight, total phenolic content and superoxide dismutase (SOD) activity in leaves remained unaffected due to the salinity treatments. Over all, performance of mint leaf extract was better that of moringa; however, moringa leaf extract was more effective in improving leaf carotenoids content than mint leaf extract. Both, extracts reduced H2O2 and MDA contents. Leaf length, root length, root fresh weight, fresh weight of flowers and total phenolic content remained unaffected due to foliar application of extracts. Present study revealed that plant extracts especially mint leaf extract had good potential to mitigate negative effects of salt stress in carnation through regulation of metabolic and biochemical capabilities.