Alleviation of Temperature Stress in Ornamental Plants by Salicylic Acid
Date Issued
2011
Date
2011
Author(s)
Lin, Ling-Na
Abstract
The ornamental plants often suffer from hot summer and cold winter in Taiwan. How to alleviate temperature stresses in plants has been an important topic nowadays. Since salicylic acid (SA) has proved to enhance temperature stress tolerance in many plants, this study evaluates the potential of salicylic acid on alleviation of high- and low-temperature stresses.
The treatments of SA at 25, 100 and 400 μM for 2 hours prior to heat shock (35/30℃, 16 days) enhanced thermoprotection of wax begonia ‘Super Olympia’ with higher Fv/Fm and lower F0 values, especially 100 μM drench treatment on the plants without flowers. Both medium drench and foliar spray treatments improved heat tolerance of wax begonias. SA treatments by medium drench enhanced more thermoprotection than those by foliar spray, based on the higher Fm and Fv/Fm value. SA treatment prior to heat stress was more effective than that after heat stress. Plant leaf temperature arose significantly while 4 and 24 hours after SA treatment, especially drench treatment did. We assume that SA treatments could induce thermotolerance, decrease leaf temperature and initiate series metabolism involved in overcoming high temperature injury.
Wax begonia ‘Super Olympia’ plug seedlings were treated with 25, 100, 400, 800, or 1600 μM SA before 55℃heat stress for 2 hours. Results indicated that 25- 400 μM SA enhanced heat tolerance of plants by reducing the values of relative injury (RI) and malondialdehyde (MDA), whereas 800, 1600 μM SA had adverse effects. The thermoprotection period of 100 μM SA maintained significantly 5 days long, based on the lower values of F0, RI and MDA, and the higher values of Fm and Fv/Fm. Applying times up to 2 or 3 times extended significantly protective effect, based on the fact of reducing the values RI and MDA, increasing plant height and number of flowers.
For rapid assessment of the SA effective concentration, we established the system of using plug seedlings treated with short heat stress (55℃, 2 h) instead of using mature plants treated with long heat stress (35/30℃, 3 weeks). Results showed that two systems had similar SA effective concentration in both wax begonia and impatient plant.Therefoe it proved that the rapid assessment system is feasible.
Coleus treated with 0, 200, 400, 800, 1600 μM SA before heat stress (45/40℃, 1 days). Results indicated that 200 μM SA treatment had maximum Fv/Fm value, minimum RI value and none heat damage, but 1600 μM SA treatment showed adverse effects, lower Fv/Fm value and higher RI and MDA values significantly. Before treatment of SA, the solution should be adjusted to about pH 6, because plants treated with SA at pH 3.7 showed significantly lower Fv/Fm value and higher RI value than those at pH 6.4. Coleus ‘Wizard Sunset’ treated with 200 μM SA could effectively maintain the initial 1-2 days of high Fv/Fm values, but then heat damage appeared irreversibly. Coleus ‘Defiance’ applied with 200 μM SA had higher Fv/Fm values and improved heat tolerance. Addition of CaCl2 and SA did not prove additive effect. SA pre-heat-stressed treatment improved more effectively heat tolerance of coleus as when compared with the post-heat-stressed treatment. The leaf temperature of coleus ‘Wizard Jade’ plants reduced after they were sprayed with 100, 200 μΜ SA or drenched with 200 μΜ SA. Especially treatments drenched with SA 200 μΜ showed the lowest leaf temperature. But SA treatment of the other cultivar ‘Wizard Sunset’ had not the same significant cooling effect. The result may coincide with that 200 μΜ SA treatment on coleus ‘Wizard Sunset’ improved heat tolerance insignificantly.
Heat-stressed anthurium ‘Essencia’ pre-treated with SA (100, 200,400 μM), CaCl2 (4, 8, 12 mM), and 200 μΜ SA+ 8 mM CaCl2, results showed pre-treated with 100, 200 μM SA, 12 mM CaCl2, and 200 μΜ SA+ 8 mM CaCl2 had higher Fv/Fm value and quantum yield, especially SA 200 μΜ alone treatment. Addition of CaCl2 and SA showed no additive effect. Heat-stressed anthurium ‘Rosa’ treated with 200μM SA, and 100 μΜ SA+ 8 mM CaCl2. The results also showed 200μM SA treatment had higher Fv/Fm value.
SA also could enhance cold-stressed tolerances in begonia and anthurium. Begonia ‘Super Olympia’ plug seedlings were sprayed with 400, 800, 1000, and 1600 μM SA before low temperature stress (0℃, 2 h), all treatments showed lower RI values than the control, especially the concentration of 1000 μM. On the contrary, the treatment with 1600 μM SA had adverse effect. Anthurium ‘Pistache’ plants were treated with SA (500, 1000, 2000 μM), CaCl2 (4, 8, 12 mM), and 1000 μM SA+ 8 mM CaCl2 before low-temperature stress (15/13℃), the Fv/Fm values of all treatments decreased in the 3 weeks initially. Based on the results of Fv/Fm values, net photosynthesis, leaf damage ratio values, 500 μM SA had more effective cold tolerance, but SA at a concentration at or above 1000 μM had adverse effect. Addition of CaCl2 and SA showed no additive effect. Anthurium ‘Tropical’ plants were treated with SA (400, 800, 1600 μM), CaCl2 (4, 8, 12 mM), and 800μΜ SA+ 8 mM CaCl2 treatments, all treatments showed the higher Fv/Fm and quantum yield values than the control. Compared the improvement of cold tolerance, the treatment of 8 mM CaCl2 is the most effective, and then the treatments of 4 mM CaCl2, 12 mM CaCl2, 1600 μM SA, 800 μM SA, 400 μM SA and 800 μM SA+ 8 mM CaCl2. Addition of CaCl2 and SA proved non-additive effect. Advanced test showed that: the treatment of 1000 μM SA+ 8 mM CaCl2+ 0.3% KH2PO4 show highest Fv/Fm value, and higher chlorophyll meter readings and lower RI value as compared to the other treatments and the control.
Subjects
Salicylic Acid
Ornamental Plants
Temperature Stress
Type
thesis
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