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ThesisItem Restricted Effect of foliar application of humic acid against terminal heat stress in wheat (Triticum aestivum L.) genotypes(Punjab Agricultural University, 2023) Aishwarya Rawal; Aparjot KaurTerminal heat stress in wheat (Triticum aestivum L.) is a major threat on account of global climate change that significantly affects the yield. To investigate the present study, wheat varieties viz PBW 725 (timely sown) and PBW 752 (late sown) were sown in randomised block design as per PAU‟s package and practice in PVC cylinders (PAU) and field (RRS, Bathinda) conditions. Foliar application of two concentration of humic acid (2000 ppm and 4000 ppm) was done ten days prior to tillering, booting and flowering stage. The treatment without any spray served as control. At all stages morpho- physiological and biochemical parameters were recorded whereas yield and yield attributes were recorded at maturity. The present study found that foliar spray of 2000 ppm and 4000 ppm humic acid significantly increased plant height in flowering and grain filling stages. The booting stage exhibited the maximum dry weight (0.089 g) in PBW 752 at 4000 ppm dosage. The 4000 ppm foliar spray significantly increased the relative growth rate of PBW 725 (15 %) at Bathinda. Humic acid reduced electrolyte leakage in PBW 725 and PBW 752 plants at Bathinda, and increased cellular viability (72 %) along with leaf relative water content (99 %) at 4000 ppm foliar spray The chlorophyll a (25.84 mg g-1 FW), chlorophyll b (10.96 mg g-1 FW), total chlorophyll content (33.5 mg g-1 FW) and carotenoids (10.46 mg g-1 FW) spiked after 4000 ppm foliar spray of humic acid. The flowering stage showed an unprecedented value of total soluble sugars for PBW 725 (49.8 mg g-1 FW) on 4000 ppm treatment of humic acid. The study found that starch content (52.9 mg g-1 FW) increased significantly PBW 752 after 4000 ppm of foliar spray of humic acid. The highest α-amylase activity (133.1 nanomoles of glucose formed min-1 g-1 FW) was observed in PBW 752 at booting stage after 4000 ppm of foliar spray of humic acid. On the other hand, foliar spray of humic acid did not depict any significant effect on yield components.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 Morpho-anatomical and biochemical characterization of interspecific cotton (Gossypium spp.) derivatives for jassid tolerance(Punjab Agricultural University, 2023) Garg, Nitika; Gupta, NehaThe present investigation entitled “Morpho-anatomical and biochemical characterization of interspecific cotton (Gossypium spp.) derivatives for jassid tolerance” was undertaken to evaluate the performance of backcross derivatives carrying genomic introgressions of G. arboreum in G. hirsutum background for jassid tolerance. Various leaf morpho-anatomical characteristics such as gossypol glands, trichome density on both young and mature leaves, extrafloral nectaries, distance between lower epidermis to phloem, leaf thickness in stelar and extra-stelar region were studied in parents G. arboreum LD 491, G. hirsutum LH 2107 and their BC1F2 derivatives find out their relationship with jassid (Amrasca biguttula) tolerance on cotton. Present research revealed non-significant differences for gossypol glands and extrafloral nectaries among the parents. The backcross derivatives exhibited a wide genetic variation for gossypol glands, trichome density and other studied morpho- anatomical traits. Trichome density was significantly higher in G. arboreum (156.02±4.36) than G. hirsutum cv. LH 2107 (92.24±2.03). However, trichome counts on young and mature leaves depicted a significant decline in trichome density with maturity among parents and backcross derivatives. The backcross derivatives exhibited wide range of leaf thickness from 0.25 mm to 0.82 mm in stelar region whereas in extra-stelar regions, the BC1F2 individuals had leaf thickness from 0.09 mm to 0.30 mm. The distance between lower epidermis to phloem was highest in G. arboreum (0.26 mm) than G. hirsutum (0.23 mm). The backcross population had a range of 0.13 mm - 0.36 mm for distance of lower epidermis to phloem among the individuals. No direct relationship between above mentioned morpho-anatomical traits and jassid nymph count on was depicted in our study. In addition, various biochemicals such as chlorophyll and carotenoid, sugars, starch, gossypol, phenolic, tannins, flavonoids, lignin and salicylic acid contents of leaf tissue were also determined in G. arboreum and G. hirsutum parents and backcross population at maximum jassid infestation. Tolerant entries (belonging to Grade I and II) had significantly higher contents of chlorophyll and carotenoid, soluble sugars, total phenols, tannins, and flavonoids than susceptible group of entries (with grade IV). Starch and salicylic acid content was significantly lower in the tolerant group of genotypes than susceptible ones. Our study concluded that higher levels of the secondary metabolites (phenols, tannins, flavonoids) and maintained production of sugar assimilates might contribute towards jassid tolerance of interspecific derivatives belonging to Grade I and Grade II.ThesisItem Restricted Physiological and histological changes induced by Xanthomonas citri pv. punicae in pomegranate (Punica granatum L.)(Punjab Agricultural University, 2023) Komal; Nirmaljit KaurIn Pomegranate, bacterial blight is a major disease caused by Xanthomonas citri pv. punicae which leads to enormous economical losses. The objective of the present research was to analyze five pomegranate varieties against bacterial blight under field conditions; and to evaluate biochemical, physiological and histological characteristics in relation to reaction of the pomegranate varieties to the disease. Varieties of pomegranate were rated on the basis of Percent disease Index (PDI) worked out in the leaves and fruit peels and the varieties Bhagwa, Mridula and Jyoti were rated as susceptible and Jodhpur Red and Ganesh are rated as highly susceptible varieties, respectively. The stomatal frequency, stomatal size and stomatal index were significantly high in the most susceptible varieties Ganesh and Jodhpur Red. The chlorophyll a, chlorophyll b, total chlorophyll content, total carotenoid content, total soluble proteins, total soluble sugars, free amino acids, total phenols, ascorbic acid, proline and hydrogen peroxide, MDA and mineral content; and peroxidase and polyphenoloxidase were quantified from healthy and diseased leaves and fruit peels of the pomegranate varieties. The chlorophyll a, chlorophyll b, total chlorophylls and total carotenoid content were higher in the healthy leaves as compared to the diseased counterparts. These metabolites were higher in the less susceptible varieties as compared to the highly susceptible ones. Total soluble proteins, total soluble sugars, free amino acids, total phenols, ascorbic acids, total proline content and minerals were significantly higher in the susceptible variety Bhagwa and lower in the highly susceptible varieties Ganesh and Jodhpur red. The hydrogen peroxide and malondialdehyde (MDA) content was higher in the varieties Ganesh and Jodhpur Red and lower in the varieties Bhagwa. The activity of the peroxidase was high in the susceptible varieties (Bhagwa, Jyoti) and lower in the highly susceptible varieties (Ganesh), while polyphenoloxidase activity was higher in the highly susceptible varieties and lower in the susceptible varieties of pomegranate. Hence, it may be concluded that the variety Ganesh was highly susceptible to blight disease on the basis of studies conducted.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 Constitutive Defence Response In Cucumber (Cucumis Sativus L.) Against Downy Mildew(Punjab Agricultural University, 2023) Samarveer Kaur; Ghai, NavitaThe present study was conducted to assess the constitutive defence response in cucumber (Cucumis sativus L.) against downy mildew. Plants of two varieties Kheera No.1 and Punjab Naveen were artificially inoculated at three leaf stage using conidial suspension by spray inoculation method. On the basis of disease severity index (Jenkins scale), variety Kheera No.1 was found to be moderately resistant while Punjab Naveen as moderately susceptible. Stomatal and trichome characteristics were conducted to determine the structural variation on 8th day after inoculation and stomatal characteristics were found to be higher in variety Punjab Naveen on both adaxial and abaxial surface of leaf, but trichome size and frequency was higher in variety Kheera No. 1 as compared to variety Punjab Naveen. A decrease in total chlorophyll content and electrolyte leakage was recorded in inoculated plants of both the varieties from 2 to 12 days after inoculation, but there was more decrease in variety Punjab Naveen as compared to Kheera No.1. Post infection, a decrease in total soluble sugar content was recorded in both the varieties. However, an increase in total soluble proteins, total phenols, total flavonoids, ascorbic acid was exhibited with more enhancement in Kheera No.1 in contrast to Punjab Naveen. The activities of various enzymes viz., Polyphenol oxidase (PPO), Peroxidase (POD), Phenylalanine ammonia lyase (PAL) and Superoxide Dismutase (SOD) was found to increase in inoculated plants of both the varieties as compared to their respective uninoculated plants. Based on anatomical studies, there was more increment in total leaf thickness, spongy and palisade tissues in cultivar Punjab Naveen in contrast to Kheera No.1. However, phylloplane morphology, enhanced level of antioxidants (enzymatic and non-enzymatic), total soluble proteins and decline in level of total soluble sugars, post infection, helped in conferring moderate resistance to the pathogen infection in variety Kheera No.1.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.
