The Effect of Foliar Application of Salicylic Acid, Spermidine and Sodium Nitroprusside on some Growth and Flowering Characteristics, Photosynthetic Pigments and Vase Life of Lisianthus ‘Mariachi Blue’

Introduction Lisianthus (Eustoma grandiflorum) from Gentianaceae family is from wild flowers of north and west America. Lisianthus, a relatively new floral crop to the international market, quickly ranked in the top ten cut flowers worldwide due to its rose-like and blue flowers. It is also widely used as a flowering potted and bedding plant. Lisianthus ‘Mariachi Blue’ is cultivated as a cut flower. Salicylates have very beneficial effects on plant growth and development. The effect of phenolic compounds in many biochemical and physiological processes including photosynthesis, ion adsorption, membrane permeability, enzyme activity, flowering, stimulation of plant resistance systems, heat production and plant development has been proven. The most famous member of this group is salicylic acid, which as a simple phenolic compound, is naturally produced by plants. Salicylic acid (SA) is considered to be plant signal molecule that plays a key role in plant growth, development, and defense responses. Polyamines (PAs) are ubiquitous and biogenic amines that have been implicated in cellular functions in living organisms. In plants they have been implicated in a wide range of biological processes including cell division, cell elongation, senescence, embryogenesis, root formation, floral initiation and development, fruit development and ripening, pollen tube growth and plant responses to biotic and abiotic stress. Sodium nitroprusside is a nitric oxide releasing agent. Nitric oxide is a gaseous free radical that can disperse very rapidly through cell membranes due to its gaseous nature and medium shelf life, without a carrier. Nitric oxide (NO) is an unstable environmentally-friendly gas radical that is used to protect the postharvest longevity of different horticultural crops. In addition to controlling harvested crop senescence, NO is involved in many plant processes, e.g., germination, growth and development, photosynthesis, pigment synthesis, defensive system, and many others. In the present study, we investigated the effects of foliar application of salicylic acid, spermidine and sodium nitroprusside on some morpho-physiological characteristics and vase life of lisianthus flowers ‘Mariachi Blue’.Materials and Methods This study was conducted based on a completely randomized design with 10 treatments, 4 replications which each replication containing 2 pots. The treatments were included spermidine at concentrations of 0.5, 1 and 2 mM, salicylic acid at concentrations of 0.5, 1 and 1.5 mM, sodium nitroprusside at concentrations of 50, 100 and 200 μM and control (without any application of growth regulators) as foliar application at intervals of 15 days for 2 months. Plant characteristics including leaf area, stem length, fresh and dry weight of leaves and flower, number of buds, flowers’ length and diameter, photosynthetic pigments and vase life were assayed. To perform analysis of variance and compare the mean of the studied traits, SAS software version 9.1 was used. The means were compared using the Tukey multi-domain method at a probability level of 1%. Also, Excel (2016) software was used to draw the chart. Results and Discussion The results obtained from analysis of variance in this study showed that the effect of growth regulators used in the study was significant at the level of 1% probability on all morphological traits measured, photosynthetic pigments and vase life of lisianthus flowers. Mean comparison graphs showed that salicylic acid, spermidine and sodium nitroprusside had a positive effect on some morphological traits, photosynthetic pigments and vase life compared to control. It can be concluded that, salicylic acid caused to increase all parameters except the flowers’ fresh weight compared to control. Spermidine increase stem length, leaf fresh weight, flowers’ fresh and dry weight, length, and diameter, chlorophyll index, chlorophyll b, and carotenoid and vase life of flowers. Also, sodium nitroprusside had beneficial effects on all parameters in this research except leaf area, leaf dry weight, chlorophyll a and vase life of flowers. Salicylic acid plays an important role in regulating some physiological processes of plants such as growth and development, ion uptake and transport, stomatal conductivity, and membrane permeability, which is effective in plant photosynthesis and with increasing photosynthesis, plant growth rate increases. Polyamines such as spermidine are involved in a wide range of developmental stages including cell division, embryogenesis, root growth, and flowering. Sodium nitroprusside is involved in the most important plant processes such as photosynthesis, respiration, growth and cell division. Probably, these growth regulators, due to their effect on plant growth, flowering, as well as photosynthetic pigments, have caused the increment of plant biomass and vase life.Conclusion In the present study, the effect of salicylic acid, spermidine and sodium nitroprusside on some growth and flowering characteristics, photosynthetic pigment and vase life of Eustoma grandiflorum ‘Mariachi Blue’ was assayed. According to the results of the present study, it can be concluded that these growth regulators improved growth indices, flowering parameters, photosynthetic pigment and vase life of flowers. According to the results, the appropriate concentrations for salicylic acid were 1 mM, for spermidine, 1 mM and for sodium nitroprusside were also 50 and 100 μM.