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ThesisItem Restricted Physiological traits associated with grain weight in 5U/5A wheat chromosomal segment substitution lines under waterstress conditions(Punjab Agricultural University, 2024) Kulveer Kaur; Dr. Navita GhaiThe scarcity of water is a severe environmental constraint to plant productivity. Water-stress affects wheat growth and development at various stages in its life cycle. The present investigation, entitled "Physiological traits associated with grain weight in 5U/5A wheat chromosomal segment substitution lines under water-stress conditions", was carried out during the Rabi seasons 2020-21 and 2021-22 in the experimental area and laboratories of the Department of Botany, Punjab Agricultural University, Ludhiana. The plant material used for the experiment was a disomic substitution line DS5Ut(5A), wheat cultivar Pavon Ph1b mutant, hexaploid wheat cultivar WL711 and 91 chromosomal segment substitution lines (CSSLs) derived from their three-way cross. 91 CSSLs along with parents and relevant checks were sown at the recommended time of sowing under two irrigation regimes (irrigated conditions and rain-fed conditions). The CSSLs, parents and checks varied significantly and were negatively affected by water-stress for traits viz., days to booting, days to heading, days to flowering, days to physiological maturity, awn length, spike length, peduncle length, plant height, spikelets per spike, thousand grain weight, grain weight per spike and grain yield under rain-fed conditions. Genome wide association studies were carried out to detect genomic regions responsible for water-stress tolerance CSSLs which revealed fifty-five highconfident markers associated with stress tolerance for traits studied. The current study suggested that 5U-24, 5U-26 and 5U-27 are water-stress tolerant and also CSSL 5U-26 outperformed check variety PBW725, parent DS5Ut(5A) and other CSSLs by maintaining grain yield besides exhibiting an increase in thousand grain weight under water-stress conditions. In 5U-26, maintenance of water content, canopy temperature depression, increased amounts of compatible solutes (proline, glycine betaine and soluble sugars), decreased cell damage (in terms of malondialdehyde and hydrogen peroxide contents), lower reduction in photosynthetic activity (chlorophyll content, quantum yield of PSII and nonphotochemical quenching) and enhanced stem reserve mobilization might have contributed towards maintenance of grain yield along with increased thousand grain weight under waterstress conditions. Therefore, 5U-26 may act as a potent germplasm donor in future breeding programs to enhance water-stress tolerance in wheat.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 Embargo Variation in grain filling and dry matter partitioning in synthetic derived wheat (Triticum aestivum L.) introgression lines under heat stress(Punjab Agricultural University, 2023) Tavisha Singh; Bedi, SeemaWheat crop has specific temperature requirements and a shift in sowing dates impose temperature stress at different crop growth stages. The present study was conducted on introgression lines derived from two synthetic hexaploid wheats (SHW14102 and SHW3761) and two hexaploid bread wheats (BWL4444 and BWL3531) with an aim to identify heat tolerant lines. The SHW14102 was crossed with two bread wheat lines BWL4444 and BWL3531, while SHW3761 was crossed with BWL4444, to develop BC1F1s. About 100 BC1F1 seeds from each cross were developed into doubled haploids (DH). These lines were assessed for phenological, physiological and yield traits under both early and late sown conditions. Based on the results of genetic variability analysis, 100 doubled haploids out of 390 population were selected for further multivariate analysis. These 100 DH were screened for yield traits by principal component analysis (PCA) and differentiated into three clusters by hierarchical clustering. Cluster 1 had maximum value for grain yield, biomass and thousand grain weight under both early and terminal heat stress conditions, thus, suggesting these as a potential germplasm to withstand heat stress. Source-sink manipulation was done in order to study the dry matter partitioning in high grain weight introgression lines. Grain yield per plant was reduced by 9.2% in sink manipulation (spikelets removal) while in source manipulation (flag leaf removal) this caused the reduction in plant yield by 1.95%. Thus, source was not a limiting factor for grain yield in introgression lines, whereas sink appeared to be a limiting factor. Further, these 15 high grain weight introgression lines were evaluated on the basis of biochemical attributes viz., water soluble sugars, proline content, malondialdehyde (MDA) content, hydrogen peroxide content and α-amylase activity under three different sowing regimes i.e., early, timely and late. The results showed that the doubled haploids that outperformed on the basis of both agronomic and biochemical attributes were DH3, DH12, DH30, DH31, DH41, DH45 and DH121. These lines could be considered as a potential candidate for utilizing in future breeding programmes aimed at early and terminal heat stress tolerance.ThesisItem Restricted Effect of growth retardant to hasten maturity in groundnut (Arachis hypogaea L.) and utilization of phosphorous solubilizing bacteria to enhance its phosphorous uptake(Punjab Agricultural University, 2023) Bajya, Mamta; Sharma, PushpThe preliminary field experiment was conducted on SG99 to test the efficacy of growth retardant mepiquat chloride at five concentrations (100,300,500,700 and 900ppm) keeping check as control. Single foliar spray of mepiquat chloride was given at 40, 60 and 80 DAS. Results of preliminary field experiment revealed the effective concentration of growth retardant was 700 ppm and the time of foliar spray selected was between 45-50 days after sowing. Therefore two foliar sprays were given first at 50 DAS followed by second spray 10 days thereafter (60 DAS) on three released varieties of groundnut (SG99, TG37A and J87) during the two consecutive kharif seasons (2020 and 2021) significantly reduced days to maturity days, plant height but increased number of branches, nodule number and weight with mobilization of assimilates to the developing sinks as per source sink relationship .Overall, mepiquat chloride@700 ppm improved physiological and biochemical traits along with an increased number of mature pods and decreased immature pods, resulting in enhanced pod (14.6%) and kernel yield(21.4%) in kharif .Similarly an increase of 19.6% in pod yield and 24.3% in kernel yield was witnessed in spring season. Kernel treated with different microbial inoculants showed differential responses to RWC, membrane stability, leghaemoglobin content, nodulation, however with Azotobacter increase in enzymatic activity was almost similar over control at two doses of P2O5 i.e.16.5% for nitrite reductase and almost 5.0% .for nitrate reductase. Strong relationship between source-sink existed with Azotobacter inoculations for two phosphorous doses at 100DAS. Pod yield improved by 19.7 % with Azotobacter double dose and P uptake in kernels. Pod yield improved by 17.4%, shelling percentage by (6.6%), kernel yield by 25.2 % and 100 kernel weight by 11.9% with combined treatment of Azotobacter + mepiquat@700 ppm over control. The photosynthetic pigments and enzymatic activities enhanced with this beneficial treatment.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 Embargo Impact of heat stress on germination and growth in wheat (Triticum aestivum L.): Physiological and biochemical mechanisms(Punjab Agricultural University, 2023) Mandeep Kaur; Bedi, SeemaThe present study was conducted with the objectives to screen a diverse set of wheat genotypes for thermo-tolerance and to investigate morpho-physiological and biochemical basis of thermo-tolerance under early sown conditions in Punjab. 467 wheat genotypes (winter wheat x spring wheat) were screened for high temperature tolerance at three temperatures viz., 25oC, 30oC and 35oC under laboratory conditions. Sixty genotypes showing maximum coleoptile length at 30oC were selected and grown in the field at three dates of sowing viz., early (20th October), timely (14th November) and late (5th December) in the years 2019-20 and 2020-21 respectively. Under early sown conditions (ambient temperature ranging between 25 to 28oC), the selected genotypes showed higher percentage of emergence, early growth vigor, root length (at 25 DAS), plant biomass (at 25 DAS), leaf area (at 90 DAS), chlorophyll content in flag leaf (at 90 DAS), tiller numbers, number of spikelets per spike, spike length, 100 seed weight and grain yield per plot as compared to timely and late sown conditions. From these, ten high yielding and two low yielding genotypes were identified. Biochemical estimations and root architecture studies were performed on these ten high yielding genotypes (heat tolerant) and two low yielding genotypes (heat sensitive) at seedling stage. The heat tolerant genotypes showed higher sugar, protein, proline and α-tocopherol content. Higher activity of antioxidant enzymes was observed in heat tolerant genotypes as compared to heat sensitive genotypes. Also, the tolerant genotypes showed more number of seminal roots, nodal roots, root branches and root length as compared to heat sensitive genotypes.
