International Research Journal of Applied and Basic Sciences. Vol., 2 (9), 366-370, 2011 Available online at http://www. irjabs.com 2011 THE EFFECTS OF FOLIAR APPLICATION OF SALICYLIC ACID ON QUALITATIVE AND QUALITATIVE YIELD OF WHEAT UNDER SALINE CONDITIONS MARVI HAMID 1* ARMIN MOHAMMAD 2 AND BORHANI NAVID REZA 1, 2,3- Department of Agronomy and Plant Breeding Sabzevar Branch, Islamic Azad University, Sabzevar, Iran *Corresponding author: E-mail: moh_armin@yahoo.com Abstract: Salicylic acid is an important phenolic compound which can reduce the effects of saline condition on the plant through regulating it growth processes. In order to study the effects of time and amount of the application of salicylic acid on qualitative and quantitative yield of wheat, a factorial combination was conducted in an experimental farm in a randomized complete block design with 3 replicates in Islamic Azad University, Sabzevar Branch, in 2011. The aforementioned factors were investigated with respect to the time of application which entailed three stages (Tillering, stem elongation, and flowering) and with respect to the amount of salicylic acid application which encompassed four levels (0, 50, 100, and 150 mg/l). The findings reveal that the time of salicylic acid application exerts a significant effect on the economic and biologic yields, the number of seeds per spike as well as sodium, potassium, and protein percentages. The highest economic yield and the number of seeds per spike were observed in the stem elongation period. The amount of salicylic acid application had a significant effect on qualitative and qualitative yields of wheat as well. Most of the parameters studied at the time of application of 150 mg/l of salicylic acid were at the highest. The application of salicylic acid led to higher resistance to salinity by changing the way sodium and chlorine ions are absorbed. All in all, the findings show that application of 150 mg/l of salicylic acid at tillering stage is the most appropriate time of application for ensuring the optimum economic yield. Key words: Salinity, Wheat, Salicylic acid, Protein. INTRODUCTION World population will rise up to eight billion by 2050, and accordingly by that time the need for food will be doubled. This growth will affect food supplies in many countries including Iran. Wheat yield, as the main food source, is threatened by plenty of dangers particularly that of salinity (Satorre & Slafer, 1999). There are a number of methods suggested to enhance or stabilize the yield in saline conditions among which those developing resistance by osmosis are particularly emphasized (Kafee et al, 2009). Salicylic acid plays an important role in how the plant reacts to undesirable environmental issues such as salinity or aridity (Hayat & Ahmed, 2007). External application of SA through foliar application decreased the adverse NACL effects on wheat, and application of 100 mg/l of salicylic acid exerted more effect on reducing the adverse effects of salinity on wheat. The destructive effects of salinity on wheat were reduced by applying 0.5 and 1 mm of salicylic acid. Moreover, wheat seed germination increased in saline conditions upon using 200 mg of salicylic acid (Arfan et al, 2007). Treating wheat using 0.5 mm of salicylic acid helped cell development in epical meristem in the root of the wheat resulting an increase in wheat growth and yield (Shakirova et al, 2003). The study showed that application of
SA increased both Abscisic acid and Auxins in wheat seedlings; yet, it did not affect Cytokinins. The application of SA lessened the harmful effects on the growth of the seedlings and speeded up the growth processes. Dolatabadian et al (2009) studied the seed priming with SA in wheat and have reported that in saline conditions with 200 mm of slat, the sprouting of wheat decreased by 17 compared with the control. Applying SA in both saline conditions and controlled condition boosted sprouting. Salicylic acid increased cell division in root and stem which led to a better growth in seedlings. Salinity significantly increased catalase, superoxide dismutase, and polyphenol oxidase antioxidant enzyme activities in wheat seedlings; yet, SA decreased these activities. It was observed that SA prevented the active oxygen which lead to a reduction in damage to the membrane. Arfan (2009) has studied the application of salicylic acid in different hydroponic and saline conditions with 7- day old seedlings taken to hydroponic condition with salinity of 0 or 150 mm for 30 days. The study entailed 0.25, 0.5, 0.75, and 1 mm of salicylic acid which were added to Hogland cultivation environment. Applying salicylic acid increased the activity of antioxiditive enzymes and accumulation of proline in medium salinity resistant cultivar while no change was traced in tolerant cultivar. The proper application of salicylic acid in saline and non-saline conditions were respectively 0.75 and 0.25 mm, and it was found that an increase in resistance to salinity as a result of applying salicylic acid was due to an increase in absorption and oxidized activities. Shakiro et al (2007) posit that when wheat treated with the same amount of salicylic acid as plant hormones (0.5 mm), it brings about growth and protection against environmental actions. Salicylic acid causes a change in hormonal balance leading to an accumulation of Oxin and ABA without affecting the level of Cytokinins. The effect remains the same in pre-treatment of the seeds and treatment of the seedlings. The effect of SA promotes growth as a result of an increase in cell division rate and growth of the cells. MATERIALS AND METHOD This study was conducted as a factorial combination based on a randomized complete block design with 3 replicates in Islamic Azad University, Sabzevar Branch. The factors studied were application of 0, 50, 100, 150 mg of salicylic acid and application time at three stages of wheat growth stage(beginning of tillering, beginning of stem elongation, and beginning of flowering). Each plot involved 4 rows each 30 cm apart, and both sides of the rows were planted. The growth of broad leaf weeds was controlled using a 2-4-D herbicide as much as 1.5 liters per hectare before tillering and grass weeds controlled by hand in the plots. Ghods wheat seeds were planted linearly on the rows with lines 15 cm apart on Dec 6, 2009. The plant density was 400 plants per square meter, and there were 6 rows in each plot each 15 cm apart. The depth of seeding was 3-4 cm. based on soil analysis guide, the required amount of Nitrogen (as urea) fertilizer was added as 30 at the time of seeding and the rest in the middle of tillering stage. Phosphorous was also added to the farm based on soil analysis at the time of seeding. For the assessment of the experiment, 30 spikes were randomly selected and the number of fertile spikelet and the number of seeds in each spike were counted, and the thousand seed weight was estimated. To assess the biological and economic yields, an area of 1 square meter was harvested and its biological and economic yields were estimated. sodium and potassium in leaf were measure using flame photometer method, and the percentage of protein in each seed was calculated through Kjeldahl method (in which the percentage of nitrogen is calculated and then multiplied by 5.3 to estimate the amount of protein. All required conversions were carried out according to the type of variables and the data were analyzed by SAS statistical software. A comparison of the means appertaining to both characteristics in their significant levels was drawn by Duncan's multiple range test. All the graphs and tables were drawn using Microsoft Office Excel software. 367
Table 1 the charactristics of the soil PH EC Ds.m - 1 Organic matters Nitrogen Mg/kg Phosphorous Mg/kg Sand Loam Clay Saturation Percentage 7.26 11.7 0.262 0.022 2.6 110 58 27 15 31.24 12.25 Lime RESULTS AND DISCUSSION The Time of Foliar Application Analysis of variance showed that the time of applying SA had significant effect on biological yield, economic yield, harvest index, seeds per spike, amount of sodium, and the level of potassium, while the weight of 1000 seeds was not affected by the application time (Table 2). Table 2 Analysis of variance of application and wheat yield' Source of economic biological seeds per Sodium Protein Variation yield yield spike Replicate * ns ** ** * ns Time of ** * ** ** ** ** Application The Amount ** ** ** ** ** ** of Application Time*Amount * ns ** ** ** ** Variation Index 14.15 10.19 3.83 7.55 3.19 2.79 **: p<0.01 *: p<0..5 ns: not significant Means comparison of the treatment showed that the highest economic yield is achieved at stem elongation stage SA application which showed a significant difference with other treatments. There was not a significant difference between foliar applications at tillering and flowering stages regarding economic yield seemingly because the early application in the former and late application in the latter could not aid the plant with tolerating salinity (Table 3). The highest biological yield as a result of salicylic acid application was achieved at tillering stage which did not have a significant difference from its application at stem elongation stage (Table 3). It seems that due to the application of salicylic acid at this stage, an increase in the plant height or in the tillers raises the biological yield. Furthermore, the highest number of seeds was observed at stem elongation stage for foliar application and lowest at tillering stage (Table 3). It seems that at stem elongation stage, due to formation of spike primordial and the vulnerability of the plant to salinity at this stage, application of salicylic acid increases the tolerance of the plant to salinity stress and biologically more primordial seeds are formed in the spike which results in a higher number of seeds in the spike. The highest amount of sodium was observed at flowering stage SA application and the lowest at tillering stage which was not significantly different from the application at stem elongation stage (Table 3). It seems that a higher percentage of sodium at flowering stage application is due to the completion of the plant growth processes for by that time the plant has already absorbed sodium in saline conditions, and because of a decrease in the growth of the plant, the application of salicylic acid does not affect the amount of sodium absorbed. A means comparison of the applications show that the highest amount of potassium resulted at stem elongation stage SA application which had a significant difference with the application at tillering stage; yet, the application at flowering stage could not affect the level of potassium (Table 3). There is also a significant difference in application time at stem elongation and tillering stages with respect to the levels of protein. However, application at flowering stage yielded more protein compared with other stages (Table 3). It seems that the higher level of protein at this stage is due to more salinity stress in the plant since at this stage the application of salicylic acid does not have a positive influence on the 368
plant s resistance to salinity. So, stress promotes the quality of the plant. Table 3 the effect of application time on economic yield, biological yield, seeds per spike, sodium, potassium, and protein Application Time Economic Biological Seeds per Spike Sodium Protein per Hectare) per Hectare) Tillering 2.3b 8.4a 31.72b 2.15b 4.31b 26.29b Stem 3.49a 7.77ab 35.58a 2.24b 4.59a 26.81b Elongation Flowering 2.8b 7.36b 30.96b 2.62a 3.55a 3.88a The means which enjoy the same letter do not have significant difference in any of the characteristics (Duncan =0.01). The Amount of Application Economic yield, biological yield, harvest index, seeds per spike, 1000 seeds weight, sodium percentage, potassium percentage, and protein percentage were affected by the amount of salicylic acid application at 1 probability (table 2). The means comparison showed that the highest economic yield was achieved with 150 ml/l of salicylic acid which was not significantly different from its application of 100 mg/l. Although application of 50 mg/l could not offer resistance to salinity in wheat and produced a lower economic yield in comparison with application of 150 mg/l of salicylic acid, the application yielded more product (Table 4). The highest biological yield was produced by applying 150 mg/l of salicylic acid which did not show a significant difference with those of 50 and 100 mg/l; however, it had a significant difference with the control (Table 4). It seems that the main cause for an increase in the biological yield is an increase in the height of the plant which raises biomass. There was not a significant difference between applications of 50 and 100 mg/l of salicylic acid with respect to the number of seeds formed in the spike; however, application of these two amounts had formed less seeds compared to application of 150 mg/l of salicylic acid (Table 4). It seems that application of 150 mg/l of salicylic acid had a positive effect on biochemical processes which lead to the fulfillment of potentials in the seed in the spike. The lower number of seeds in the spike in application of 50 mg/l, compared that of 100 mg/l, is due to low dosage of application. A means comparison indicates that there was no significant difference between applications of 100 and 150 mg/l with respect to thousand seed weight (Table 4). The lowest thousand seed weight came from control because of the salinity stress of the seeding area in which plants were affected by salinity and hence had provided the seeds with less photosynthetic materials. The means comparison revealed the highest level of sodium could be found in control and its lowest level was with application of 100 mg/l. Although there was no significant difference between 100 and 150 mg/l applications, increasing the application to 150 mg/l resulted in an increase of 5.75 in sodium level (Table 4); it seems that this application decreases the activity of enzymes affecting the transformation or a decrease in the amount of the absorbed sodium which ultimately affects the absorbed level of sodium. Moreover, the highest level of potassium came from application of 100 mg/l of salicylic acid which did not show a significant difference from 150 mg/l application (Table 4). Also the lowest level of potassium was observed in the control. It seems that lack of significant difference between applications of 100 and 150 mg/l is due to the adverse effects of salicylic acid in higher densities which reduces its positive effects to that of 100 mg/l. Since application of 100 mg/l was a proper density, it yielded the highest level of potassium. In the control, a lower level of potassium was observed owing to higher absorption of sodium. A means comparison indicates that application of 50 mg/l of salicylic acid produced more protein in the seeds than others. There was not a significant difference between 0 and 150 mg/l applications of salicylic acid (Table 4). It seems that better growth conditions and higher levels of carbohydrates in these applications for the seeds are the main causes of having lower levels of protein in these applications. 369
Table 4 the effect of the amount of application on economic yield, biological yield, seeds per spike, sodium, potassium, and protein Amount of Time Economic Biological Seeds per Spike Sodium Protein per Hectare) per Hectare) 0 2.04b 6.01b 27.83c 2.89a 3.19c 27.72b 50 2.79bc 8.03a 31.64b 3.5b 30.78a 100 3.05ab 8.58a 32.56b 2.05c 4.89a 28.16b 150 3.58a 8.75a 38.06a 2.11bc 4.93a 25.31c The means which enjoy the same letter do not have significant difference in any of the characteristics (Duncan =0.01). By and large, the findings of the study showed that different application times for salicylic acid can affect the economic yield of wheat. The positive effect of application time mainly is due to an increase in hormonal and biochemical changes of the plant which raises the production of carbohydrates which is evident in thousand seed weight and the number of seeds per spike. The amount of salicylic acid applied also exerted a positive influence on the economic yield of the wheat which was in part affected by the time of application, too. The most appropriate time and amount of application of salicylic acid were 150 mg/l and at stem elongation stage. Although analysis regarding only the amount of application revealed that applications of 100 and 150 mg/l of salicylic acid did not have a significant difference, the qualitative yield of the wheat reacted to the time of the application differently. The highest level of protein as the result of application was achieved at flowering stage; application of 50 mg/l yielded the highest protein which corresponded negatively to the quantitative trend. Overall, the findings suggest that the best economic yield of application of salicylic acid was with 150 mg/l at stem elongation stage. ACKNOWLEDGEMENT The present article is part of a research project conducted in the Islamic Azad University, Sabzevar Branch, which was financially supported by the research center at the university. Hereby, the authors express their gratitude to the research center committee for their support. Arfan M (2009) Exogenous application of salicylic acid through rooting medium modulates ion accumulation and antioxidant activity in spring wheat under salt stress. Int. J. Agric. Biol., 11: 437 442 Arfan M, Athar HR, Ashraf M (2007) Does exogenous application of salicylic acid through the rooting medium modulate growth and photosynthetic capacity in two differently adapted spring wheat cultivars under salt stress? Journal of Plant Physiology 164. 685 694. Dolatabadian A, Sanavy SA, Sharifi M (2009) Effect of salicylic acid and salt on wheat seed germination. Acta Agriculture Scandinavica. Section B, Plant Soil Science. 59(5):456-464. Hayat S, Ahmad A (2007) Salicylic Acid a Plant Hormone. Springer Publishers, Dordrecht, The Netherlands. Kafi M, Borzoei A, Kamandi A Massomi A, Nabati j (2009) Plant Stress Physiology. Jahad Daneshgahi Mashhad Press.(In Persian). Satorre EH, Slafer GH (1999) Wheat: Ecology and Physiology of Yield Determination. CRC Press Shakirova FM, S Hayat, Ahmad A (2007) Role of hormonal system in the manifestation of growth promoting and anti stress action of salicylic acid. plant hormone: 69-89. REFERENCES 370