Effect of salicylic acid pretreatment and various planting depths on emergence and some morpho-physiological characteristics of lentil

Introduction Lentil is one of the major legume with protein content about 28% where is cultivated in different regions of Iran, especially in arid and semi-arid regions with low or variable rainfall. In these regions abiotic stresses such as heat of the around the end of growing season, drought stress in early and late within the season and salt stress alone or together have a large negative impact on germination, emergence, seedling growth and ultimately yield. Germination and seedling establishment are sensitive and crucial stages in the life cycle of plants, and determine density, uniformity as well as final yield of the crops. On the one hand, optimal germination and plant establishment and also planting depth due to the significant effect on seedling emergence and plant establishment is very important. So, selecting appropriate treatments with the combination of time and suitable planting depth are necessary for successful crop production. Seed priming as one of the strategy for increasing the rate and percentage of the germination, increasing in quality of seedling productivity, plant suitable establishment and increasing crop yield in the area is favorable. Materials and Methods This experiment was conducted in the form of factorial based on completely randomized block design in three replications in the research greenhouse of Gonbad Kavous University, College of Agriculture and Natural Resources in November of 2013. Factors included salicylic acid pretreatment in four concentrations (0, 50, 100 and 150 mg/kg) and various planting depths in five levels (2.5, 5, 7.5, 10 and 12.5 cm). In the present experiment, lentil seeds before planting were kept in the solution of salicylic acid hormone for 6 hours at room temperature and then they were removed from solution and dried on paper towels for 24 hr at room temperature. Then 30 primed lentil seeds of Kimia cultivar were planted in pots with 20 cm diameter and 30 cm height. Soil of the pots was prepared from research field of Gonbad Kavous University. The physicochemical characteristics of the soil included loam silt texture, pH 7.9, 13.4 mg/kg resorb able phosphorus, 68% carbon, 0.07 total nitrogen, 356 mg/kg resorb able potassium. Then some of the emergence traits such as rate, percentage and seed vigor as well as some morpho-physiological traits such as seedling dry weight, shoot length, number of primary branches, leaf area, leaf area ratio, specific leaf area, leaf weight ratio, chlorophyll Index and proline content were measured 60 days after planting. Results and Discussion Results showed that whole study traits except leaf weight ratio were affected by various priming and planting depths. The treatment of 100 mg/Kg salicylic acid in 2.5 cm planting depth increased traits such as percentage of emergence (98.89), emergence rate (1.80 seedlings per day), seedling dry weight (1.13 g), leaf area (70.64 cm2), number of primary branches (4.7), leaf dry weight (0.69 g) and chlorophyll index (2.13). While proline content, leaf area ratio and specific leaf area decreased. It was also observed that priming treatment with 150 mg/kg salicylic acid increased proline content and shoot length, while leaf area and seedling dry weight inversely decreased. In this study, the treatment of 100 mg/kg of salicylic acid + 2.5 cm of planting depth due to additive effects on the most of the traits was suitable treatment. Salicylic acid treatments increased lentil emergence, while proline content decreased using various concentrations of study treatment. It may be due to some physiological and morphological changes resulting from them. Under rainfed conditions, cultivation depth is more considerable. It may be prevented from seed germination, seed emergence and subsequent growth. Seed priming to reduce the risk of poor establishment is useful in a wide range of environmental conditions. Results of this experiment also showed that priming is a simple and useful method to enhance the rate and percentage of the emergence of lentil. The beneficial effects of priming can cause optimal seedling establishment, creating a uniform density and increasing of legumes yield which are important food. The results showed that priming with 50 mg/kg of salicylic acid had a weak effect on emergence and growth traits of lentil over higher concentrations. However, priming with 150 mg/kg salicylic had a negative effect on the studied traits. In other words, the effects are not ideal. Under normal conditions by increasing cultivation depth the emergence and vegetative lentil traits had a declining trend. However, the trend in plant depth of 2.5 to 7.5 cm was less sensitive; but in the more than 7.5 cm of plant depth, the mentioned traits were influenced considerably. Conclusions In the present experiment the most effective and ideal combination treatment was 100 mg/kg of salicylic acid in low cultivation depth especially in 2.5 cm. Therefore, the study treatment had an additive effect on most of the measured traits.