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20122
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Author: Manpreet Kaur × End date: 2012 × Start date: 2012 × Type: Thesis ×
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    SALICYLIC ACID INDUCED CHANGES IN SOME PHYSIOLOGICAL AND BIOCHEMICAL PARAMETERS IN MASHBEAN (Vigna mungo L. Hepper) GENOTYPES GROWN UNDER SALINITY
    (PAU Ludhiana, 2012) Manpreet Kaur; Navita Ghai
    The present investigation was undertaken to study the effect of salicylic acid on physiological and biochemical parameters in salt sensitive (KUG 363 and KUG 310) and salt tolerant (KUG 529 and KUG 502) mashbean genotypes, along with a check variety (UL 338) grown under NaCl (30mM and 45mM) stress. The plants were grown in plastic pots kept under a rain-out shelter. NaCl was applied in split dose: 50% at the time of sowing and remaining 50% at 15 days after sowing (DAS). Salicylic acid (SA) @ 0.5 mM and 1.0 mM was applied as a foliar spray at 25 DAS. Data on various physiological and biochemical changes was recorded at 35 (vegetative stage), 50 (flowering stage) and 65 (pod setting stage) DAS. Salt stress decreased the leaf area and plant dry biomass of all the genotypes at various stages of development. The decrease in plant dry biomass led to reduction in relative growth rate and crop growth rate. Sensitive as well as tolerant genotypes showed a sharp increase in membrane permeability under saline conditions. NaCl caused a decrease in photosynthetic pigments and increase in levels of hydrogen peroxide and malondialdehyde content. Under saline conditions, all the genotypes showed a higher accumulation of osmotic solute proline, with tolerant genotypes accumulating more amount than sensitive ones. Antioxidant enzymes like catalase and ascorbate peroxidase showed a decrease under saline conditions. However, peroxidase activity was increased under salt stress. Maximum increase was shown in salt sensitive genotypes. Reduction in yield contributing parameters like number of pods plant-1, number of seeds per pod, 100 seed weight and seed yield plant-1 was observed at both the levels of salinity. SA treatments had a pronounced ameliorative as well as, growth promoting effect under saline conditions. The ameliorative effect of SA was observed as increase in leaf area, relative leaf water content, water potential of leaves and photosynthetic pigments in salt-stressed plants. SA treatments increased the biosynthesis of proline under salt stress. Foliar application of SA enhanced the level of antioxidant system (catalase and ascorbate peroxidase) in mashbean plants under NaCl stress and reduced the hydrogen peroxide and malondialdehyde content. The reduction in yield and yield contributing parameters was also less in SA-treated salt-stressed plants as compared to non saline controls. However, tolerant genotypes (KUG 529 and KUG 502) and check variety (UL 338) were able to tolerate high salinity and responded better to the application of SA as compared to sensitive genotypes probably due to improved growth, metabolism and enhanced antioxidant system. Lower concentration of SA (0.5 mM) proved to be more effective to ameliorate the adverse effects of salt stress.
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    ThesisItemOpen Access
    ANALYSIS OF ANTIOXIDANT METABOLISM IN WHEAT SEEDLINGS EXPOSED TO WATER STRESS AND UNDER THE INFLUENCE OF EXOGENOUS ABSCISSIC ACID AND REACTIVE OXYGEN SPECIES
    (Punjab Agricultural University, Ludhiana, 2012) Manpreet Kaur
    The present work was aimed to study the involvement of superoxide anions and ABA biosynthesis in germination, growth and antioxidant response under water stress (WS) and under ABA (A) supply in two wheat cultivars C306 (ABA higher sensitive-cum-drought tolerant) and PBW343 (ABA lesser sensitive-cum-drought susceptible) by using tiron (T) as superoxide scavenger and sodium tungstate (ST) as inhibitor of ABA biosynthesis. Biomass and ascorbate were decreased on scavenging superoxide ions under A in both cultivars. Antioxidant enzymes, H2O2 were decreased in PBW343 but increased in C306 on scavenging superoxide ions under A. ABA inhibitions of shoot length, root length and germination were higher in C306 than in PBW343 and these inhibitions were relieved significantly on scavenging superoxide ions in C306 not in PBW343. Fresh biomasses, antioxidant enzymes, ascorbate/dehydroascorbate ratios were decreased and dehydroascorbate and malondialdehyde contents were increased on inhibiting ABA biosynthesis and on scavenging superoxide anions under water stress in both cultivars but such changes were more significant in C306 than in PBW343. Both cultivars were also compared under H2O2 (H) supply for antioxidant response and for the involvement of ABA biosynthesis under H supply. H2O2 induced antioxidant levels were higher in C306 than in PBW343. On inhibiting ABA biosynthesis under H supply, these H2O2-mediated effects were affected but not completely removed in both cultivars.