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ThesisItem Embargo Effect of biochar and bacterial endophytes on salinity tolerance in oats (Avena sativa L.)(Punjab Agricultural University, 2023) Arshdeep Kaur; Gupta, NamartaThe present investigation was carried out to study the effect of biochar and plant growth-promoting bacterial endophytes for salt tolerance in oats (Avena sativa L.). Forty four morphologically distinct salinity-tolerant endophytic bacteria were isolated from the leaf, stem and root samples of oats on nutrient agar with 2.5% NaCl and screened for the production of ammonia, auxins, siderophore and HCN; solubilization of Ca3(PO4)2, ZnO, Zn3(PO4) and ZnCO3 and salt tolerance up to 12% NaCl. Bacterial isolates showing high salt-tolerance and plant growth-promoting traits were selected and tested for growth promotion of oats on 1% H2O agar plates. Three potential isolates were identified based on polyphasic approach as Enterobacter quasiroggenkampii O1SE4, Bacillus inaquosorum O3SE2 and Bacillus safensis O4SE1. The SEM analysis showed the colonization of the plant tissues by all the three bacterial strains. Total 25 genotypes were screened for germination parameters viz. percent germination, shoot length, root length, seedling length, fresh weight, dry weight, vigour index I and II, proline, SOD, POD and CAT under salt stress conditions and were grouped into highly salt tolerant, moderately salt tolerant, moderatly salt sensitive and highly salt sensitive. Among seed treatments, the combination of biochar (2%) and Bacillus safensis maximally improved the above parameters as compared to the other treatments of Enterobacter quasiroggenkampii, Bacillus inaquosorum and biochar (1%). The evaluation of biochar and bacterial strains was done in two salt tolerant and two salt sensitive genotypes grown in the pots. The highest plant height, SLW, NAR were observed with the bacterial treatment (Bacillus safensis) + biochar (2%). Among biochemical parameters chlorophyll, carotenoid, total soluble sugar, starch, total soluble protein and free amino acids along with activities of antioxidant enzymes SOD, POD and CAT were enhanced by the application of Bacillus safensis and biochar (2%). Na+/K+/Ca2+/Mg2+ homeostasis was maintained by biochar and bacteria application. In conclusion, it is stated that the combined use of biochar and halotolerant endophytic bacteria can be used for improving the crop growth under salt stress in oats.ThesisItem Embargo Evaluation of morpho-physiological and metal accumulation potential of Salix alba L. and Toona ciliata M. Roemer grown on heavy metal contaminated soils(Punjab Agricultural University, 2022) Ravneet Kaur; Sharma, RajniThe present investigations were carried out to study the effect of lead (Pb), cadmium (Cd) and their combinations (Pb+Cd) on morpho-physiological and metal accumulation potential of Salix alba and Toona ciliata during 2020 and 2021. Heavy metals induce negative effect on morphological and biomass attributes of both species, but Toona showed better survival percentage (>95%) than Salix (<55%) even at higher concentrations of Pb300 and Cd25. The accumulation of proline, total soluble sugars, total soluble proteins along with increased antioxidant enzyme activities are responsible to enhance tolerance in both species. On the basis of phytoremediation efficiency evaluation factors such as bioconcentration factor (BCF) and translocation factor (TF), Salix alba can be categorized as excluder plant for Pb and Cd with higher metal accumulation in roots than shoots (BCF>1, TF<1), while Toona ciliata can be categorized as hyperaccumulator with more Pb and Cd accumulation in the shoots than roots (BCF>1 and TF>1). Further, heavy metal translocation and accumulation decreased in combinations as compared to single element application suggesting the antagonistic relationship among both metals. Pb and Cd negatively affect the plant nutrient content either by affecting their translocation or by decreasing nutrient availability in soils. Anatomical studies showed significant alterations in stomatal pore size, stomatal density and trichome density due to heavy metal toxicity in both Salix and Toona. Field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FESEM-EDS) results confirmed the Pb and Cd accumulation sites in the leaves and root tissues of plants. Fourier transformed infrared (FTIR) spectroscopy analysis revealed that Pb and Cd accumulation in plants induced changes in carboxy, amino, hydroxyl and phosphate groups that ultimately caused alteration in physiological functioning in plants. Conclusively, both Salix alba and Toona ciliata have potential to be used as remediation species for Pb and Cd contaminated soils.ThesisItem Open Access EVALUATION OF MORPHO-PHYSIOLOGICAL AND METAL ACCUMULATION POTENTIAL OF Salix alba L. AND Toona ciliata M. Roemer GROWN ON HEAVY METAL CONTAMINATED SOILS(Punjab Agricultural University, Ludhiana, 2022) Ravneet Kaur; Sharma, RajniThe present investigations were carried out to study the effect of lead (Pb), cadmium (Cd) and their combinations (Pb+Cd) on morpho-physiological and metal ccumulation potential of Salix alba and Toona ciliata during 2020 and 2021. Heavy metals induce negative effect on morphological and biomass attributes of both species, but Toona showed better survival percentage (>95%) than Salix (1, TF1 and TF>1). Further, heavy metal translocation and accumulation decreased in combinations as compared to single element application suggesting the antagonistic relationship among both metals. Pb and Cd negatively affect the plant nutrient content either by affecting their translocation or by decreasing nutrient availability in soils. Anatomical studies showed significant alterations in stomatal pore size, stomatal density and trichome density due to heavy metal toxicity in both Salix and Toona. Field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FESEM-EDS) results confirmed the Pb and Cd accumulation sites in the leaves and root tissues of plants. Fourier transformed infrared (FTIR) spectroscopy analysis revealed that Pb and Cd accumulation in plants induced changes in carboxy, amino, hydroxyl and phosphate groups that ultimately caused alteration in physiological functioning in plants. Conclusively, both Salix alba and Toona ciliata have potential to be used as remediation species for Pb and Cd contaminated soils.ThesisItem Restricted Effect of micronutrients on carbohydrate metabolism and grain quality in sweet corn (Zea mays L.)(Punjab Agricultural University, 2023) Harmanjot Kaur; Gupta, NamartaThe present research was performed to study the ―Effect of micronutrients on carbohydrate metabolism and grain quality in sweet corn (Zea mays L.)‖. The investigations were carried out in two experiments. The first experiment was carried out under laboratory conditions and second one is field experiment. In the laboratory experiment, seeds of sweet corn were soaked in different concentration of micronutrients and allowed to germinate according to cigar roll method. Total twenty treatments were given with different combinations of iron sulphate, zinc sulphate and manganese sulphate. The observations on physiological and biochemical parameters of seedling were recorded after seven days of treatment. All the seed treatments with micronutrients significantly improved vigour parameters with respect to control. Percent germination, shoot length, root length and vigour index was higher in seeds treated with T9 (0.2% FeSO4 and 0.5% ZnSO4) and T7 (0.2% FeSO4 and 0.2% ZnSO4). The biochemical parameters viz. total soluble sugars, starch content and amylase activity was enhanced maximally by the T7 (0.2% FeSO4 + 0.2% ZnSO4), followed by T9 (0.2% FeSO4 and 0.5% ZnSO4), T8 (0.5% FeSO4 and 0.2% ZnSO4) and T10 (0.5% FeSO4 + 0.5% ZnSO4 micronutrient treatments. In Field experiment, for morpho-physiological parameters, data was collected after 30DAS, 60DAS and 90 DAS in year 2020 and 2021. Foliar spray of micronutrient treatments enhanced vegetative and reproductive growth parameters. Increased plant height, leaf area index, leaf weight ratio, leaf area ratio, specific leaf weight, specific leaf area, crop growth rate, relative growth rate, net assimilation rate were observed after foliar spray with micronutrients. Maximum increase was recorded in T9 (0.2% FeSO4 + 0.5% ZnSO4) followed by T7 (0.2% FeSO4 + 0.2% ZnSO4) and T8 (0.5% FeSO4 and 0.2% ZnSO4). Cob length, cob girth, grain weight and grain yield, it was observed that higher increase was recorded in treatment T9 (0.2% FeSO4 + 0.5% ZnSO4) and T7 (0.2% FeSO4 + 0.2% ZnSO4). Biochemical estimations in grains exhibited strong correlation among micronutrients and grain quality. Among biochemical parameters, T9 (0.2% FeSO4 + 0.5% ZnSO4) and T7 (0.2% FeSO4 + 0.2% ZnSO4), increased chl a, chl b, carotenoids, total chlorophyll and carotenoid content along with higher sucrose synthase and sucrose-6-phosphate synthase activities as compared to other treatments and control. Total soluble sugars, total starch content, and free amino acids were significantly higher in T9 (0.2% FeSO4 + 0.5% ZnSO4), followed by T7 (0.2% FeSO4 + 0.2% ZnSO4). Total soluble proteins, proline content and free amino acids were maximum in treatment T8 (0.5% FeSO4 and 0.2% ZnSO4), followed by T7 (0.2% FeSO4 + 0.2% ZnSO4) and T9 (0.2% FeSO4 + 0.5% ZnSO4). Overall, T9 (0.2% FeSO4 + 0.5% ZnSO4), followed by T7 (0.2% FeSO4 + 0.2% ZnSO4) and T8(0.5% FeSO4 and 0.2% ZnSO4) recorded better results as compared to other micronutrient treatments for improving growth, yield and grain quality in sweet corn. Seed treatment with T20 (0.5% FeSO4, 0.5% ZnSO4 and 0.5% MnSO4) and T19 (0.2% FeSO4, 0.2% ZnSO4 and 0.2% MnSO4) recorded less improvement in growth than other treatments as compared to control.ThesisItem Embargo Physiological and biochemical variability in Brassicas under conservation tillage(Punjab Agricultural University, 2023) Mamta Pal; Sharma, PushpDrought is a multifarious stress affecting almost all the growth stages and yield in Brassicas. Present investigation was carried out to assess germination and tolerance to moisture stress induced by different concentration of PEG in laboratory. Comparative germination studies for drought tolerance using distilled water as control and six osmotic potentials (-0.2, -0.4, -0.6, -0.8, 1.0 and -1.2 MPa) induced by PEG 6000 were carried out under controlled condition. All the germination traits suffered a decline over control with increased stress levels except to mean germination time. The three varieties GSC-7 (B.napus), Giriraj (B. juncea) and PC-6 (B. carinata) exhibited better performance for germination and related traits in the induced six stress levels over the control which was further endorsed by PCA and HCA. Field trials were conducted for 2 years to study the morpho-physiological and biochemical variability in Brassicas under conservation tillage. Twelve varieties/strains of the three Brassica species: B.napus (GSC-7, GSC-6, GSC-21, GSC-22 and I-75), B. juncea (JC-210-325, CJRD-1261, PBR-357, Giriraj and RLC-3) and B. carianata (PC-5 and PC-6) were selected for field evaluation under split-split plot design with 3 irrigation regimes: moisture stress, restricted stress and normal irrigation along with two tillage treatment: conventional (CT) and zero tillage (ZT). ZT delayed the phenophases over CT irrespective of irrigation regimes. Flowering duration, siliquing duration and reproductive phase were longer under ZT over CT. At studied 3 crop stages physiological parameters, i.e. SPAD, NDVI, photosynthetic pigments, hill reaction activity increased with ZT. Similar increased trend was noticed in RWC, LWR however RSD and WSD declined. Membrane stability in the varieties/ strains was higher under ZT with lowered membrane injury. Antioxdative enzymes and biomolecules were upregulated under stress, but were more in CT relative to ZT. Total carbohydrate were more under ZT and reached maximum at flowering stage whereas proteins under CT and were highest at siliquing stage. Assimilation improved with irrigation regimes. ZT was also beneficial in improving oil content (≤1%), seed N content and N in stem and chaff. Overall, GSC-7, a canola variety of B.napus, non-canola varieties (PBR-357 and Giriraj), canola variety (RLC-3) of B. juncea and non-canola determinate variety PC-6 of B. carianata registered more siliqua length, seed/siliqua, more developed and lesser shriveled seed/siliqua with ZT. The elite varieties possessed higher tolerance indices viz. DTI≥ 0.8, YSI≥0.79 and DTE≥ 70% under both the tillage treatments.ThesisItem Restricted Mechanism of salinity tolerance in elite wheat (Triticum aestivum L.) germplasm(Punjab Agricultural University, Ludhiana, 2023) Choudhary, Anuj; Nirmaljit KaurThe current research work on “Mechanism of salinity tolerance in elite wheat (Triticum aestivum L.) germplasm” was conducted to illuminate the genetic potential of wheat lines for salt stress tolerance. The study was undertaken at the laboratory and experimental area of Department of Botany and Department of Plant Breeding & Genetics, Punjab Agricultural University, Ludhiana during 2018-19 and 2019-20. A set of 278 wheat lines was procured from Department of Plant Breeding & Genetics was initially screened under lab condition. Selected lines were subjected to various salt stress concentrations viz. 0 mM, 30 mM, 60 mM, 90 mM, 120 mM, 150 mM and 180 mM NaCl. It was followed by screening of all wheat lines at standardized 150 mM salt stress condition for shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight and vigor index. They were grouped as 11 highly salt tolerant, 57 salt tolerant, 89 moderately salt tolerant, 116 salt sensitive and 5 highly salt sensitive. Twenty lines were selected for precise evaluation under the naturally salt affected field conditions and the controlled condition on the basis of morphological, physiological and yield attributes. The EC value of the controlled plots ranged between 0.41 to 0.81 m mhos cm-1 whereas the EC value of saline plots was between 0.79 and 1.71 m mhos cm-1. Among the 20 wheat lines, the LTP 187 (linked top cross population), LTP 210, and LTP 221 performed better for all the traits under field conditions and therefore, these are suggested for the future wheat breeding improvement programs for salt stress. Three SNPs (SNP_986175, SNP_ 2264905 and SNP_4910157) were found significantly associated with salt stress. Significantly associated SNPs were mainly observed on chromosomes 1A, 1B, 3A, 3B, 5A, 5B, 6B, 7A and 7D and therefore these SNPs can be used in marker assisted breeding programs for improving thousand grain weight in wheat.
