Evaluation of salicylic acid effects on growth, yield and some biochemical characteristics of cumin (Cuminum cyminum L.) under three irrigation regimes

Introduction Cumin of the apiaceae family is a annual plant with thin and aromatic branches that height is variable between 15 -50 cm that depending on the environmental conditions (Kaffi et al., 2002). Drought stress as a factor in reducing plant growth in many regions of the world is that seriously limit crop production and climate changes in the world, the situation is more serious (Anjum et al., 2011). Salicylic acid as a phenolic hormone, within a plant setting performs and its role in the immune system against abiotic (pathogens) and abiotic (drought, salinity, heavy metals and ozone) is well known (Klessig and Malamy, 1994). It has been reported that application of salicylic acid in the tomatoes has helped to improve the growth in drought stress (Senaratna et al., 2000). Materials and methods This research during the crop year 2014 was conducted at the research farm of Zabol university Institute. The experiment was done as a split plot in a randomized complete block with three replications. water availability in three level: 50 mm (control), 100 mm and 150 mm evaporation (high stress) from evaporation pan class A as the main factor and different levels of foliar application of salicylic acid ] 0 (no spraying), 1 and 3 mM) were considered as subplots. Measuring photosynthetic pigments by lichtenthaler (1994), proline by Bates et al (1973) and soluble carbohydrate by Keles and Oncel method (2004) were measured. Harvest, in order to calculate yield cumin seed, was done in ripening stages. Statistical analysis was performed using SAS version 1.9 and averages were compared with Duncan's multiple range test at the 5% level. Results and discussion The results of data analysis showed that the interaction of water availability in salicylic acid on proline of leaf was significant at 1 percent probability level. The highest leaf proline (7.78 micromoles per gram) was obtained by 150 mm evaporation of pan and foliar application 3 mM salicylic acid that compared to control treatment (50 mm evaporation of pan and foliar application 0 mM of salicylic acid) increase 96.96 percent indicated. Drought stress caused a significant increase in carbohydrate of cumin leaves at 1 percent probability level. Results showed that the interaction of water availability in salicylic acid on chlorophyll b at 5% and carotenoids leaves was significant at 1% probability level. Results showed that interaction water availability in salicylic acid on grain yield were significant at the 5% level and the highest grain yield (98.9 grams per square meter) in 50 mm evaporation from pan irrigation and foliar application of 1 mM salicylic acid was obtained. Reduce the rate of growth under drought stress, the compatibilizer state of to survive the adaptation under stress condition, because plant instead of used nutrients and energy for shoot grow, used for the storage molecule leads against stress (Khalid, 2006). In fennel suitable irrigation leads to better growth, more leaf area, followed by the growth gets better (Buchanan-Wollaston et al., 2003). Salicylic acid by increasing the activity of Rubisco enzyme and chlorophyll increases the photosynthetic rate (Sing and Ushs, 2003). Foliar application of salicylic acid was significant effects on yield and yield components of cumin (Asfini Farahani et al., 2013). The salicylic acid by inducing Protection interactions through the hormone abscisic acid leads to the accumulation, osmolytes especially proline in the plant (Yoshiba et al., 2005). Accumulation of organic compounds such as carbohydrates and amino acids in the cytoplasm plays an important role in the regulation of osmotic pressure plant (Flagella et al., 1995). Increase the amount of carbohydrates and proline under drought stress has been reported in in chamomile (Arazmju et al., 2010). Lowering the activity of photosystem ІІ, reduced RuBisCO enzyme activity and inhibits the synthesis of ATP, causes the formation of free oxygen species in chloroplasts increase. In drought stress, lack of water causes decomposition of chlorophyll and glutamate that is chlorophyll and proline precursor the effect of drought has become as a proline and thus reduced chlorophyll content (Lawlor and Cornic, 2002). A significant increase in chlorophyll and carotenoid in the foliar application of salicylic acid has been reported and The results of this affair have considered increasing the photosynthesis rate (El-Tayeb, 2005). Conclusion The results showed that cumin to when faced with drought stress, the osmotic regulation mechanism used by the accumulation of proline and soluble carbohydrates and in this way to tolerate the water shortage conditions.