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2022 - 20232
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Author: Shivani × End date: 2023 × Start date: 2022 ×
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    Defense response and source-sink relationship for imazethapyr tolerance in lentil (Lens culinaris L.).
    (Punjab Agricultural University, Ludhiana, 2023) Shivani; Grewal, Satvir Kaur
    Plant growth and yield reduction in lentil crop due to weed infestation is due to poor weed-crop competition. Imazethapyr (IM), controls wide spectrum of weeds as a selective herbicide that targets acetolactate synthase (ALS) which catalyzes the first reaction in biosynthesis of branched chain amino acids (BCAAs), required for plant growth and development. The present investigation was conducted to understand the effect of IM treatment and weed interference on defence mechanism, source-sink relationship and ALS activity along with morpho-physiological traits in IM-tolerant (LL1397 and LL1612) and susceptible (FLIP2004-7L and PL07) lentil genotypes. Lentil genotypes were grown under control (weed free), weedy check (weeds were growing with crop) and sprayed with imazethapyr at 50 days after sowing (DAS). Lower accumulation of methylglyoxal (MG) is due to higher activities of glyoxalase I, II & III enzymes, methylglyoxal reductase (MGR) and lactate dehydrogenase (LDH) in LL1397 and LL1612 after IM treatment as compared to FLIP2004-7L and PL07 along with higher glutathione (GSH) content due to increased γ-Glutamylcysteine synthetase (γ-GCS) help in their recovery post herbicide treatment. Imazethapyr treatment decreased chlorophyll and carotenoid content, plant height and number of pods under IM treatment in FLIP2004-7L and PL07, which resulted in decreased seed yield. Higher activities of ALS, threonine deaminase (TD) with or without any effector molecules and leucine dehydrogenase (LeuDH) was observed in LL1397 and LL1612 for maintaining BCAA pools as compared to FLIP2004-7L and PL07. Expression analysis of ALS gene depicted that 4 days after spray is a critical stage to show its effectiveness at which LL1397 and LL1612 showed higher expression while in PL07 and FLIP2004-7L, expression was highly reduced. Lower H2O2, MDA and DHA content, higher activities of antioxidant and proline metabolizing enzyme activities along with higher ascorbate and proline contents in tolerant (LL1397 and LL1612) might be protecting from herbicide induced oxidative damage thereby improving crop yield. Significantly higher activities of carbon metabolism enzymes in leaves, podwalls and seeds at different developmental stages in tolerant genotypes under herbicide stress as compared to susceptible lentil genotypes might be responsible for maintaining source-sink relationship required for proper growth, grain filling and seed setting. Similarly, enzymes of nitrogen metabolism also showed higher activities in all tissues of tolerant genotypes required for proper nitrogen uptake and better assimilation of inorganic nitrogen into organic nitrogen. Tolerant genotypes had higher total phenolic acid content after imazethapyr treatment as compared to susceptible genotypes with higher content of catechin hydrate, p-coumaric acid, caffeic acid, vanillic acid and rutin that might be contributing towards their better tolerance ability. Soluble protein content was decreased in all tissues of susceptible genotypes as IM treatment affected the protein turnover by accumulating free amino acids. This comprehensive knowledge of mechanisms underlying these metabolic changes after herbicide treatment might provide an efficient way of crop improvement by developing IM-tolerant genotypes.
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    Assessment of biochemical and quality characteristics of C 306 derived mutants
    (Punjab Agricultural University, Ludhiana, 2022) Shivani; Bhardwaj), Rachana D.
    Fifteen lines of C 306 derived mutants along with the check varieties including C 306, PBW 175, UPBW 550, BWL 3498 and PBW 1Zn were evaluated for various agronomic traits, biochemical and physico-chemical characteristics during 2019-20 and 2020-21. The same set of genotypes was also evaluated for baking quality traits and chapatti making characteristics. Mutant 2 showed highest yield and lowest plant height among all the mutants whereas check variety C 306 showed lowest yield within whole set of entries. Plant height of mutants was negatively correlated with yield. Starch content ranged from 53.71 to 66.67 % over the two crop seasons. Phytic acid content varied from 3.8 mg/g to 12.5 mg/g over both the years. Mutants 13 and 7 lied in the higher category of protein and amylose content and lower category of phytic acid and total phenols therefore can be considered as nutritionally good. Mutant 3 showed the minimum phenol reaction score whereas mutant 13 showed the maximum grain appearance score. Mutants 5 and 15 along with the check varieties C 306 and BWL 3498 had higher values of grain hardness, hectoliter weight, protein content and grain appearance score, medium/high values of gluten index, SDS-sedimentation values, puffing height and moisture content. Therefore, mutants 13, 7, 5 and 15 may be considered as promising mutants possessing good grain and chapatti quality traits.