Effect of Plant Growth Regulators on Leaf Biochemical Characters and Fruit Yield Components of Bittergourd (Momordica charantia L.) Cvs. MHBI-15 and Chaman Plus

Effect of plant growth regulators on leaf biochemical parameters (chlorophyll pigments, sugars, nitrate reductase activity, total phenols) and fruit yield bitter gourd (Momordica charantia L.) was studied. The experiment consisted of foliar treatment with three plant growth regulators, GA3 (20, 40 and 60ppm), NAA (50ppm) and CCC (100 and 200ppm) in two bittergourd varieties, MHBI-15 and Chaman Plus at 45 days after sowing (DAS). Results revealed significant difference between treatments on chlorophyll, sugar, total phenol content as also on nitrate reductase activity. Foliar application of CCC (200ppm) recorded maximum amount of total sugars (18.03% over Control), total phenol content (10.93%) as also nitrate reductase activity (16.12%). Among the treatments, application of GA3 (20ppm) recorded maximum chlorophyll content (18.03% over Control). Highest increase in mean fruit yield over Control was recorded with application of GA3 (20ppm) (39.88%), followed by CCC (200ppm) (34.15%) in both the cultivars

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Not AvailableFrench bean, being a cool season legume crop, with a requirement of 17-28°C optimum temperature requirement, is grown mainly during Kharif and Rabi seasons. But its cultivations is severely constrained during summer months due to prevailing high temperatures. Further, under climate change conditions high temperature episodes are likely increase and considerably affect pod yield. The identification of suitable cultivars is a prerequisite for adaptation to high temperature situations.Thus, the temperature induction response (TIR) technique, which involves exposure ofseedlings to sub lethal temperatures to induce inherent cellular tolerance and consequent exposure to challenging temperatureswas standardized and employed for screening French bean genotypes for high temperature stress tolerance. Two day old French bean seedlingswere subjected to various challenging temperatures from 43 to 50°C for 3 hoursand were allowed to recover at room temperature for 72 hours. Based on the least survival (11%) and highest growth reduction (92%) during recovery, 45°C for 3hours was identified as challenging temperature. Consequently the induction temperature was identified by subjecting French bean seedlings to different induction temperature regimes. The gradual induction temperature from 30 to 40°C for 3 hours at which 60% of the seedlings survival was observed during recovery was identified as the optimum induction temperature. Subsequently, ten French bean genotype were screened by subjecting them to the standardized induction temperature of 30-40°C for 3 hours followed by challenging temperature of 45°C for 3 hours. The genotypes showed differences in percent seedling growth reduction during recovery period over control. The genotypes, (IC-525224 x IC-525239) IPS-1, (IC-525224 x IC-525239) 1-12and Arka Anoop, with 60%, 65.27 %, 66.30% reduction in seedling growth showed tolerance to high temperature stress. In this study we standardized the TIR technique as a screening method to evaluate and identify temperature tolerant French bean genotypesIndian Institute of Horticultural Researc

Evaluation of Solanum lycopersicum L. genotypes for high temperature stress tolerance employing temperature induction response technique

680-689Solanum lycopersicum L., an important vegetable crop (Tomato) in most regions of the world, is affected by high temperature stress at various stages of its growth. Likely increase in periodicity of high temperature episodes under climate change conditions would further affect the tomato production. To sustain productivity and yields under climate change situations, there is an urgent need to develop suitable cultivars as an adaptation strategy. For this endeavour, identification of high temperature tolerant lines for crop improvement is a prerequisite. Hence in the present study, temperature induction response (TIR) technique was employed to evaluate thermotolerance in 52 tomato genotypes. Two day old seedlings were subjected to an initial induction treatment i.e., gradual temperature increase from 33-43°C for 3 h followed by 50°C for 3 h as challenging temperature. Wide variability was seen for seedling survival and vigour. In genotypes IIHR-2202, IIHR-2836 and IIHR-2841 seedling survival was as high as 90%, while H-329, H-371, IIHR-2745 and H-335 showed least reduction in growth and also had better seedling vigour index. Of the 52 genotypes, 21 were identified as tolerant, 12 moderately tolerant and 19 susceptible. This TIR technique is simple, quick and less expensive than whole plant screening. Hence, it could be used by plant physiologists and plant breeders for screening seedlings at an early stage in the phenotyping and crop improvement programmes

Antioxidant enzymes activity and physiological response of tomato (Lycopersicon esculentum M.) genotypes under mild temperature stress

Not AvailableTomato being sensitive to high temperature experiences mild to high temperature stresses under climate change conditions. To understand the response of tomato genotypes to mild temperature stress, a study was conducted in temperature gradient tunnel facility. The results revealed that across the genotypes studied, specific activity of antioxidant enzymes viz., superoxide dismutase (SOD), peroxidase (POX) and glutathione reductase (GR) increased significantly. Among the genotypes, increase in SOD activity was highest in cv. Arka Vikas, followed by IIHR 2195 and least in Abhinava. The GR activity was highest in Abhinava, followed by IIHR 2195 and least in cv. Arka Vikas. The mild temperature stress caused reduction in catalase (CAT) activity. The decrease in CAT activity and concomitant increase in POX activity was observed in cv. Arka Vikas. Low leaf water potential (Wleaf) and higher electrolyte leakage indicated that the membrane integrity was affected across the tomato genotypes even under mild temperature stress. Among the genotypes studied, cv. Arka Vikas showed greater activity of SOD and POX, higher membrane stability and least reduction in water potential under mild temperature stress.ICAR under NICRA projec