Effect of salicylic acid spraying and application of biofertilizers on the physiological characteristics and yield of chickpea (Cicer arietinum L.) cultivars under rainfed conditions

Chickpea is one of the valuable pulses and rich source of protein. In most years, in west of Iran, the amount of rainfall is low and the distribution of rainfall is not suitable. In many cases, rainfed lands are affected by drought stress. On the other hand, most rainfed lands have low fertility, especially in nitrogen and phosphorus nutrients. In higher plants, salicylic acid applied to reduce the dangerous effects of drought stress. Different varieties of chickpeas show different responses to environmental changes. This experiment was carried out in order to investigate the effect of salicylic acid and biofertilizers on the physiological characteristics of two chickpea cultivars. 

This experiment was done in factorial based on randomized complete block design with three replications in Kermanshah under rainfed conditions in the 2016. Kermanshah is located at an altitude of 1319 m of sea level (Latitude: 34°21′ N and Longitude: 47°9′ E). Experimental treatments included two chickpea cultivars (Bivanij and Azad), foliar spraying of salicylic acid (non-application, 0.5 and 1 mill molar concentrations) and biological fertilizer (non-application of biofertilizers, bio-superphosphate bacteria (Pseudomonas+Enterobacter), biosulfur bacteria (Thiobacillus spp.), a rhizobium bacterium (Mesorhizobium ciceri), and mycorrhiza fungus (Rhizophagus irregularis). Each plot was six m2 (four meters long and 1.5 meters wide) with 6 lines (density= 40 plants per m2, sowing line spacing= 25 cm, sowing distance on each line= 10 cm and sowing depth= 7 cm). The sowing date was March 19. The studied traits were relative water content, relative water loss, chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/b ratio, carotenoids, hydrogen peroxide, catalase and peroxidase enzyme activity and grain yield.

Foliar spraying of salicylic acid and the application of biofertilizers increased the production of hydrogen peroxide and decreased the activity of catalase and peroxidase enzymes. The highest catalase activity were obtained in Bivanij cultivar×non-application of salicylic acid, Bivanij cultivar×non-use of biofertilizer, non-application of salicylic acid and the lowest catalase activity were obtained in Azad cultivar×one mM salicylic acid, Bivanij cultivar×bio-superphosphate and one mM salicylic acid×biosulfur application. The highest and lowest peroxidase activity were obtained under non-application of salicylic acid×non-application of biofertilizer and one mM salicylic acid×rhizobium application, respectively. The highest relative water loss (RWL) was obtained in Bivanij cultivar×non-application of biofertilizer, while the lowest RWL was observed in Azad cultivar×biosulfur application biofertilizer. Relatively, the content of chlorophyll a, chlorophyll a/b, total chlorophyll and carotenoids increased with the application of biofertilizers. Bivanij cultivar had a higher grain yield than Azad cultivar. In both Bivanij and Azad varieties, the highest grain yield was obtained from the use of rhizobium and mycorrhiza biofertilizers. The highest grain yield (1626 kg.ha-1) was observed from the application of the concentration of 0.5 mM of salicylic acid and rhizobium biofertilizer. In both Bivanij and Azad varieties, the highest catalase activity was observed due to non-use of salicylic acid and non-application of biofertilizer. 

In general, at all three levels of salicylic acid, the highest peroxidase activity was observed in the absence of biofertilizer application. It is possible that biofertilizers reduce both nutrient deficiencies and drought stress, thus reducing peroxidase activity. In general, in this experiment, in terms of grain yield and physiological traits affecting grain yield, between the cultivars, native Bivanij cultivar, among the salicylic acid levels, the concentration of 0.5 mmol and among the biofertilizers, rhizobium biofertilizer were superior treatments.