Effect of sodium nitroprusside on morphological characters under chilling stress in chickpea (Cicer arietinum L.).

An experiment was conducted with chilling tolerant (IC-424234) and sensitive (PBG-1) chickpea (Cicer arietinum L.) genotypes to study the effect of sodium nitroprusside (SNP) – nitric oxide donor applied as foliar spray of 150 and 300 µM concentrations at 45 DAS (vegetative stage), 85 DAS (flowering stage) and 125 DAS (post flowering stage). Both the concentrations of SNP (150 and 300 µM) resulted in significant increase in all the morphological characters viz. plant height, number of leaves plant-1, leaf area plant-1 and leaf area index (LAI) over the control at all the stages, though lower concentration (150 µM) was more effective. Chilling sensitive (CS) genotype PBG-1 responded more effectively to SNP treatment. Electrolyte leakage percentage was effectively reduced by SNP treatments in both the genotypes at low temperature (15 DAA). Chilling sensitive genotype PBG-1 treated with SNP (150 µM) recorded significantly higher yield contributing characters viz. number of pods plant-1, number of seeds pod-1, seed yield plant-1(g), pod setting percentage (%), 100 seed weight (g) and yield (kg ha-1) over the chilling tolerant (IC-424234).

Comparative studies on morphological and biochemical characters of chickpea genotypes under chilling stress.

Comparison of chickpea (Cicer arietinum L.) genotypes for morphological and biochemical attributes was done. Morphological characters viz. Plant height, number of branches and number of leaves were recorded highest in chilling tolerant genotypes at early stages of development (30 and 60 DAS) whereas at later stages (90 and 120 DAS) these characters were recorded highest in chilling sensitive genotypes. Pollen viability percentage at 5 and 10oC temperatures were recorded highest in chilling tolerant genotypes as compared to sensitive genotypes. Biochemical characters viz. electrolyte leakage (%), total soluble sugars and total free amino acids were recorded highest in chilling tolerant genotypes as compared to sensitive genotypes.

Effect of exogenous H2O2 on antioxidant enzymes of Brassica juncea L. seedlings in relation to 24-epibrassinolide under chilling stress.

Hydrogen peroxide is most stable molecule among reactive oxygen species, which play a vital role in growth and development of plant as signaling molecule at low concentration in response to various abiotic and biotic stresses. Exogenous application of H2O2 is known to induce chilling tolerance in plants. Brassinosteroids are plant steroid hormones known for their anti-stress properties. In this study, effect of exogenous H2O2 on antioxidant defense system of Brassica juncea L. seedlings was investigated in 24-epibrassinolide (24-EBL) treated and untreated seedlings under chilling stress. The surface sterilized seeds of B. juncea L. were germinated in petriplates containing different concentrations of H2O2 alone and in combination with 10-8 M 24-EBL. Chilling treatment (4 ºC) was given to 10-days old seedlings grown in different treatments for 6 h daily up to 3 days. 24 h recovery period was given to chilling treated seedlings by placing at 25ºC ± 2ºC and harvested for antioxidant enzymes on 14th day after sowing (DAS). Treatment of 24-EBL in combination with H2O2 (15 and 20 mM) helped in reducing the toxicity of seed and seedlings due to H2O2 exposure on their germination rate, shoot and root length respectively. 24-EBL treatment at seed and seedling stage helped in alleviating the toxic effect of H2O2 through antioxidant defense system by increasing the activities of various enzymes involved in antioxidant defense system such as catalase (CAT, E.C. 1.11.1.6), ascorbate peroxidase (APOX, E.C. 1.11.1.11), and superoxide dismutase (SOD, E.C. 1.15.1.1). In conclusion, exogenous pretreatment of H2O2 to seeds of B. juncea L. adapted the seedlings to tolerate chilling stress, which was further ameliorated in combination of H2O2 with 24-EBL.