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ThesisItem Open Access Interaction of Meloidogyne spp., Fusarium spp. and Begomovirus(es) infecting muskmelon and identification of resistant source(s)(Punjab Agricultural University, Ludhiana, 2021) Dalvir Singh; Sukhjeet KaurSurvey conducted in major muskmelon growing areas of Punjab in districts, Jalandhar, Kapurthala, Ludhiana, Fatehgarh Sahib, Sangrur and S.A.S. Nagar revealed maximum incidence of begomovirus(es) (51.14%) from Sangrur district followed by S.A.S. Nagar (32.33%), Kapurthala (32.00%), Fatehgarh Sahib (26.00%), Jalandhar (25.79%) and Ludhiana (24.00%). Root knot nematode incidence was maximum in Ludhiana (29.25%) followed by Sangrur (23.14%), Jalandhar (12.63%) and Kapurthala (10.56%). Fusarium wilt incidence was highest in Sangrur (41.14%) followed by Ludhiana (39.00%), Fatehgarh Sahib (29.67%), S.A.S. Nagar (25.67%), Jalandhar (22.74%) and Kapurthala (17.11%). Symptomatic, morphological and molecular marker based detection revealed the association of three begomoviruses viz., Tomato leaf curl New Delhi Virus (ToLCNDV), Tomato leaf curl Palampur virus (ToLCPaV) and Squash leaf curl virus (SqLCV), Root knot nematode, Meloidogyne incognita and wilt causing fungus Fusarium oxysporum f.sp. melonis with the muskmelon crop under Punjab conditions. During the interaction studies of root knot nematode, Fusarium and Tomato leaf curl Palampur virus in muskmelon, it was observed that maximum reduction in growth parameters was recorded where all the three pathogens were inoculated simultaneously. Root gall index was more severe in treatments with prior inoculation of root knot nematode (T2=4.5 and 4.28; T3=4.41 and 4.42) or with simultaneously inoculation of RKN with other pathogen (T5=4.56 and 4.50) in comparison to treatments where root knot nematode was inoculated ten days after other pathogen (T7=3.0 and 2.67; T11=3.11 and 2.06; T12 =2.83 and 2.0) in both the years. Severity of fusarium wilt was more where F. oxysporum f.sp. melonis was inoculated along with M. incognita either simultaneously or in sequence as compared to treatment with F. oxysporum f.sp. melonis alone. Tomato leaf curl Palampur virus severity grade was maximum (4.3 and 4.5) during simultaneous inoculation of all the three pathogens followed by treatment with virus alone (4.1 and 4.3) compared to treatments where virus was inoculated 10 days after nematode (2.8 and 2.3) or virus was inoculated 10 days after Fusarium (2.3 and 3.0) during both the years, respectively. Out of total sixty four muskmelon genotypes screened for resistance against root knot nematode, F. oxysporum f.sp. melonis and Tomato leaf curl Palampur virus, two genotypes, MCPS and SM2012-1 were found moderately resistant to M. incognita. Eight genotypes (SM2013-2, MM-KP15103, WM11, MM121103, KP4HM15, SM2012-1, MM Sel.-103 and SM2013-9) were found resistant to F. oxysporum f.sp. melonis. For Tomato leaf curl Palampur virus, genotypes, SM2013-2, WM11, SM2013-9 and SM2012-1 showed highly resistant reaction, while genotypes, MH-41, MM-KP15103, KP4HM15 and MM Sel.-103 showed resistant reaction and genotypes viz., MM120103, MH-51, Pusa Madhuras and MM121103 were found moderately resistant against the virus.ThesisItem Open Access Histopathological and Biochemical alterations due to Meloidogyne incognita and Fusarium oxysporum Sch f. sp. melonis and their management in Muskmelon wilt disease complex(Punjab Agricultural University, Ludhiana, 2021) Harkanwal Pal Singh; Dhillon, Narpinderjeet KaurHistopathological studies of twenty-day old roots revealed few galls which were smaller in size while the number of galls increased in the forty-day old samples. Forty-day old samples showed the giant cells as well as dikaryotic condition of nuclei along with egg masses of root knot nematodes. Whereas in histopathology of root tissues in fungus inoculated samples clearly showed cell-wall distortions. Biochemical studies revealed that in susceptible variety (Punjab sunehri) all the enzymes viz., Phenylalanine ammonia lyase (PAL), Superoxidase (SOD), Tyrosine ammonia lyase (TAL), and Peroxidase (POD) showed decrease in their activity as the disease incidence increased. In-vitro efficacy of Brassica cultivars (canola and non-canola) was evaluated against M. incognita. Brassica varieties (Canola: GSC7 & RLC3 and Non-canola: PBR357 & TMLC 2) on egg hatching and mortality of Meloidogyne incognita revealed that per cent egg hatch inhibition of canola and non-canola extracts was found to be dose as well as duration dependent and extracts of TMLC2 (non-canola) and RLC3(canola) brassica variety inhibited the egg hatching and mortality most effectively. The per cent mortality was found to be maximum (100%) when J2 of root knot nematode were exposed to TMLC 2 and RLC3 (most effective varities) extracts after 240 hours at maximum concentration(S). Screening of ninety-nine brassica genotypes against root knot nematode was done against Meloidogyne incognita. 75 germplasm lines were found to be resistant to Meloidogyne incognita, as most of these showed negligible galling (RGI=0-1) and soil nematode population was also found to be minimum. Management of muskmelon wilt disease complex was experimented to evaluate the efficacy of different botanicals, organic amendments, chemicals and their combinations against Fusarium oxysporum f.sp. melonis and root knot nematode in both pot house and field conditions and revealed that integrated management with Mustard Cake @10t/ha + Velum @5.12 µL/sqm. were found most effective i.e., 89.03 per cent decrease in nematode population.ThesisItem Open Access Sheath rot and its association with discolouration of rice(Punjab Agricultural University, Ludhiana, 2021) Sarbjit Kaur; Anju BalaThe present investigation was undertaken with the objective to find out the association of pathogens causing grain discolouration and sheath rot of rice and to identify the resistance sources against sheath rot in rice germplasm. Four pathogens viz., Sarocladium oryzae, Fusarium verticillioides, Fusarium fujikuroi and Albifimbria terrestris were found associated with sheath rot and grain discoloration of rice. The fungal pathogens were inoculated on plants using syringe inoculation, grain insertion method and spray inoculation on 2 varieties, PR 114 and PR 121. The variety PR 114 was more susceptible to fungal disease as compared to PR 121. Plants inoculated with grain insertion method showed high disease incidence followed by syringe inoculation method. Among all the pathogens, S. oryzae caused maximum per cent disease incidence and severity followed by F. verticillioides, F. fujikuroi and A. terrestris. The highest disease progress was also observed in plants inoculated with S. oryzae. All the pathogens produced similar disease symptoms in rice. All the pathogens caused chaffiness of panicles, significant reduction in seed germination, seedling length and vigor index was observed in highly infected seeds. The seed quality deterioration was directly proportional to the intensity of seed infection. Further, the effect of fungal metabolites extracted from discoloured grains was observed on physiological and biochemical parameters by dipping seeds in these metabolites for different durations. The seed quality losses were increased with the increase in duration of seed dipping in fungal metabolites. Significant reduction in total sugars and total proteins along with an increase in defense related enzymes, amino acids, proline, total phenols and malondialdehyde content was recorded. Fifty advanced breeding lines of promising rice germplasm were screened against sheath rot by inoculating three pathogens S. oryzae, F. verticillioides and F. fujikuroi using two inoculation techniques (syringe inoculation and grain insertion). Among all the lines evaluated against sheath rot, RYT 3886 was found to be resistant and RYT 3836 was moderately resistant to all the three pathogens.ThesisItem Open Access Epidemiology and Management of Post harvest diseases of Kinnow mandarin(Punjab Agricultural University, Ludhiana, 2021) Gurwinder Kaur; Raheja, SandeepSurveys were conducted periodically (twice in a month) from January to March during 2019 and 2020 to record the incidence and prevalence of major post-harvest rots of Kinnow mandarin and pathogens associated with it in South-western Punjab. Highest incidence of post-harvest rot of Kinnow mandarin 20.21 and 12.59 percent was observed in the month of March during the year 2019 and 2020, respectively. Penicillium digitatum and Penicillium italicum causing green and blue mould rots were found to be two most prevalent post-harvest pathogens with their prevalence of 30.88 and 26.44 percent, respectively during 2019 and 32.44 and 24.88 percent, respectively, during 2020. Temperature of 25˚C favoured maximum radial growth (84.67 mm) of both test pathogens also, maximum percent disease index of green (95.00 percent) and blue mould rot (90.00 percent) was recorded at 25˚C. The pH 5.5 and 6.0 supported maximum radial growth of P. italicum by 90.00 & 88.66 mm and of P. digitatum by 88.67 & 87.67 mm, respectively and were found to be at par with each other. Among different GRAS chemicals and botanicals evaluated against test pathogens, copper sulphate, boric acid, sodium bicarbonate and sodium carbonate at 100mM and above concentrations among chemicals and garlic extract at 10 per cent and above concentration among botanicals showed complete inhibition (100.0 percent) of both test pathogens under in vitro, whereas, under in vivo garlic extract at the concentration of 15 percent showed complete inhibition of green (100.0 percent) and of blue mold rot (92.22 percent). Boric acid at the concentration of 4 percent showed complete inhibition (100.0 percent) of both the test pathogens.ThesisItem Open Access DIVERSITY ANALYSIS OF Drechslera maydis, THE INCITANT OF MAYDIS LEAF BLIGHT OF MAIZE AND ITS MANAGEMENT(Punjab Agricultural University, Ludhiana, 2022) Bagaria, Pravin Kumar; Vineet KumarThe investigation entitled “Diversity analysis of Drechslera maydis, the incitant of maydis leaf blight of maize and its management” was carried out at PAU Ludhiana and ICAR-IIMR, Ludhiana during 2019-2021. The sixty-nine isolates of D. maydis were collected from Punjab and other states showed significant variation in terms of cultural, morphological, and pathological characteristics. The majority of isolates (31) were having greyish black growth of the mycelium on the PDA medium, while 10, 11 and 17 isolates were black, grey and whitish grey, respectively. Most of the isolates (37) showed rough appressed type growth pattern, whereas sectoring and irregular margins were present in 36 isolates. The twenty isolates recorded slow growth (6.0 mm/day). The isolates Dm_8, Dm_46, Dm_58, and Dm_69 showed minimum number septa (3-5 septa/conidium) whereas maximum number of septa (8-12) were observed in isolate Dm_22. Similarly, maximum and minimum spore count (×104/ml) were recorded in isolates, Dm_29 (58) and Dm_51 (11), respectively. Isolate Dm_25 (Ladhowal) recorded minimum incubation (2 days), maximum average lesion numbers (15.03), and highest PDI (94.07%) on susceptible genotype, CM 600, while Dm_26 (Gujarat), the least aggressive isolate, showed maximum incubation period of 4 days with minimum average lesions (11.73) and minimum PDI (61.85%). The isolates were clustered into four groups based on the PDI and representative isolates, viz., Dm_25, Dm_27, Dm_44, Dm_49, and Dm_61 were selected from these groups which were further tested on 10 maize genotypes. The isolate Dm_25 showed maximum average PDI (63.9%), number of lesions (11.1) and AUDPC (846.6), while Dm_27 exhibited minimum average PDI (50.7%), number of lesions (9.1) and AUDPC (668.8). Forty-eight unique polymorphic SSRs were obtained through in-silico analysis of D. maydis strains and filtered to 15 SSRs for further amplification and validation. Six markers (SSR1, SSR4, SSR5, SSR10, SSR13, and SSR15) exhibited high polymorphism with PIC values ranging from 0.81-0.92. Among the 69 isolates, maximum melanin production at 25ºC was recorded in the isolate Dm_25 (2.62 μg/g) while minimum production of melanin (0.37 μg/g) was recorded in Dm_62 isolate. The majority of isolates showed maximum melanin production at temperature range of 25-30°C. Out of 234 maize inbred lines screened under artificial epiphytotic conditions, thirteen genotypes (HKI 42050, V-373, IML66-1, HKI 484-5, LM 13, HKI 163, UMI 112, DQL- 2017, DQL- 2030, DQL- 2231, DQL- 2300-1-1, DQL-2294, and DQL-2105) were found resistant to MLB pathogen. The evaluation of SAR chemicals revealed that maximum disease control (36.72%) and highest yield (29.59 q/ha) were recorded in foliar application of BABA at 200 mg/L followed by ASM (28.66% and 28.34 q/ha) and SA (25.73% and 28.06 q/ha) at 200 mg/L, respectively, as compared to the inoculated control (24.62 q/ha). An overall trend of an upsurge in defensive enzymes (PAL, β-1,3 glucanase and chitinase), antioxidative enzymes (POX and PPO), total phenols and flavonoids was found in inoculated plants of Punjab Sweet Corn 1 treated with SAR chemicals up to 6 days after treatment. Thus, these resistant genotypes may serve as an important source in resistance breeding program against maydis leaf blight and SAR chemicals could be applied for disease management in maize.ThesisItem Open Access Mapping of stripe rust resistance gene(s) in recombinant inbred lines of Triticum aestivum L.(Punjab Agricultural University, Ludhiana, 2022) Waris, Mohammad; Jaspal KaurStripe rust caused by Puccinia striiformis f.sp. tritici (Pst) has been identified as the most devastating wheat rust disease and is considered one of the major constraints on wheat (Triticum aestivum L.). The pathogen's polycyclic and airborne nature causes the emergence of novel pathotypes, resulting in the breakdown of many resistance genes and considerable losses in grain yield and quality. To combat the emergence of novel pathotypes, breeders and plant pathologists are constantly on the lookout for stable and long-lasting sources of resistance. Thus, this research work was designed to find novel sources of resistance. A 441 germplasm entries were evaluated, first for their seedling response against the most prevalent pathotypes of Puccinia striiformis f.sp. tritici (238S119, 110S119, and 46S119). Based on infection-type data, out of the 441 lines, 30 lines were found highly resistant to all three pathotypes tested, and 27 lines were highly susceptible. The same entries were also tested for adult plant resistance against stripe rust under field conditions at Ludhiana and Gurdaspur during 2019-21. From the field response against stripe rust infection, i.e., based on final rust severity (FRS) and area under disease progress curve (AUDPC) for all three years at Ludhiana and Gurdaspur, the lines were categorized into highly resistant, resistant, moderately resistant, moderately susceptible, and susceptible. To see the performance of genotypes in multi-environments the data was subjected to GGE biplot analysis. Wheat genotypes were inconsistent in terms of stripe rust reaction at the tested locations. IC111939 (G1) was found to be the "ideal" genotype in both environments. Gene postulation in the 45 lines which shows both all-stage resistance as well as adult plant resistance was done by using 13 known YR geneassociated markers pertaining to 5 Yr genes (Yr5, Yr10, Yr15, Yr24, and Yr26). Yr5 presence was detected in sixteen lines with two linked markers, i.e., Xwmc175 and Xgwm120; Yr10 was detected in ten lines linked with the marker Xpsp3000; Yr15 was detected in fourteen lines with two linked markers, i.e., Xgwm413 and Xgwm273; Yr24/26 was detected in 15 lines with two linked markers, namely Xbarc181 and Xbarc187. For mapping of stripe rust resistance genes in RILs of bread whe at, four F5:6 RIL populations (IC530087 x PBW621, IC530078 x PBW621, IC553914 x PBW621, and IC529094 x PBW621) were tested with stripe rust pathotypes at the seedling stage (238S119, 46S119, and 110S119) as well as at the adult plant stage against a mixture of pathotypes. The same amounts of DNA from ten resistant (R) and ten susceptible (S) lines from each of the four populations were used to make the R and S bulks. A BSA-based 90K SNP array was performed, and 81,423 SNPs were reduced to 71,991 KASP SNPs. The polymorphic SNPs were then used for the mapping of stripe rust resistance genes in all the RILs. A total of 66 KASP markers were developed from the sequencing data. Out of 66 KASP markers, 35 were found to be polymorphic between the parents, and 19 were validated on RIL populations. Mapping using these 19 markers led to the identification of five major QTLs, qYr-pau1A_P5, qYr-pau-5B_P5At, qYr-pau-5A-p11, qYr-pau-6A, qYr-pau-2B_P7, and one minor QTL, qYrpau-P9-3b, on chromosomes 1A, 5B, 5A, 6A, 2B, and 3B, respectively. KASP markers associated with these genes can be directly utilized for marker-assisted breeding in wheat.ThesisItem Open Access Mapping quantitative trait loci and biochemical analysis of sheath blight resistance in rice (Oryza sativa L.)(Punjab Agricultural University, 2023) Thesiya Mayur Rajeshbhai; Lore, Jagjeet SinghSheath blight caused by Rhizoctonia solani Kühn, is one of the most prevalent diseases of rice in South East Asia. Use of resistant sources is an eco- and farmer friendly and more economically approach to mitigate yield losses due to this disease. The aim of the present study was to identify potential quantitative trait loci (QTLs) linked with resistance to sheath blight and associated with temporal spike in defense related enzymes as well as histopathological patterns during infection process of R. solani. Next generation sequencing (NGS) assisted bulk segregant analysis (BSA) was integrated with R package i.e. QTLseqr to map QTLs associated with sheath blight resistance in F3 mapping population derived from the cross between susceptible rice cultivar PR121 and resistant parent ShB1. The five QTLs namely qShB1, qShB3, qShB5.1, qShB5.2 and qShB6 were identified on chromosome 1, 3, 5 and 6, respectively. Activity of defense related enzymes such as phenylalanine ammonia lyase, polyphenol oxidase and peroxidase were estimated in parental lines along with three sets of progeny lines which showed significantly high activity in resistant parent as compared to the susceptible parent after R. solani inoculation. The moderately resistant (MR) lines expressed maximum enzyme activity than the highly susceptible (HS) lines. The pathogen R. solani exhibited more profuse and dense hyphal growth with close contact to surface grooves, lobate appressoria-like structures, higher number of microsclerotial development and longer lesion length on HS line as compared to the MR line. The present results provided better understanding of host-pathogen interaction and novel QTLs identified may be used in rice breeding program for the development of durable resistance to sheath blight in rice cultivars.ThesisItem Embargo Factors affecting aggressiveness of Sclerotinia sclerotiorum (Lib.) de Bary inciting stem rot of rapeseedmustard(Punjab Agricultural University, Ludhiana, 2022) Chetan V. N.; Sandhu, P SThe stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the major diseases of rapeseed-mustard. In this study, factors affecting aggressiveness of the pathogen were evaluated using isolates collected from various rapeseed-mustard growing regions of India. These isolates were estimated for development of the disease, oxalic acid production, total cellulase and cutinase activity. These isolates were significantly different w.r.t. their aggressiveness which highly correlated with oxalic acid production and cutinase activity and moderately with total cellulase activity. Low and high aggressive isolates were sequenced to detect variation in genes Sscut and Ssoah1. No variation was seen in Sscut while Ssoah1 showed 7 synonymous SNPs. Further study was conducted to test the efficacy of alkali salts such as sodium carbonate (SC), potassium silicate (PS), sodium propionate (SP) and calcium propionate (CP) against Sclerotinia stem rot. Under in vitro conditions, the PDA media amended with SC (0.6-1 per cent), PS (0.8-1.2 per cent), CP and SP (1.6-1.8 per cent) showed complete mycelial growth inhibition when compared with un-amended PDA medium. In case of detached leaf assay, SC @ 1 per cent, PS @ 1.4 per cent, SP @ 1.8 per cent and CP @1.8 per cent were effective in inhibiting lesion development of pathogen when compared to untreated leaves. Effective treatments were tested under field conditions at two locationswhere different treatments were sprayed with different alkali salts 2 days before the inoculation. The pooled data of both the locations revealed that CP @ 1.8 per cent showed highest percent reduction in mean lesion length (63.35 per cent) followed by SP @1.8 per cent with 57.77 per cent reduction. The yield data showed negative correlation with lesion length which implies significant reduction in yield of control as compared to treatments.ThesisItem Embargo Web blight of mungbean (Vigna radiata L.) and its management(Punjab Agricultural University, Ludhiana, 2022) Raghveer Singh; Sharma, Krishan KumarWeb blight of mungbean, caused by Rhizoctonia solani, has a significant impact on grain yield and quality. The pathogen is soil-borne and has a broad host range. Field surveys were conducted in different districts of Punjab during the year 2019-20. The survey concluded that Ludhiana district had the lowest prevalence and severity of web blight, while Ballowal Saunkhri (SBS Nagar) had the most. Pathogen variability was investigated at morphological and molecular level. On the basis of morphological characterization viz. colour, mycelial abundance, shape and size of sclerotia, the pathogen was identified as Rhizoctonia solani. Of all the five isolates, BS (Ballowal Saunkhri) and NS (Nawanshahr) were found to be the fast-growing isolates with a 0.88 mm/hr growth rate followed by RO(Ropar) and L1(Ludhiana 1) and L2 (Ludhiana) 0.68 mm/hr. Among all the isolates, L1-L2, BS-L1, RO-L1, NS-L1, and NS-BS were vegetatively compatible, whereas BS-L2, NS-L2, BS-RO, RO-NS, RO-L2 were vegetatively incompatible. The isolates were characterized on the basis of ITS region sequence homology and confirmed as R. solani. The sequences have been registered with NCBI as accession numbers ON17668, ON176686, ON084814, ON084815 and ON084816. Further, Among the three inoculation techniques viz. soil inoculation, foliar spray and field screening at hotspot location, the foliar spray technique was found to be the most precise inoculation technique. Among the four biocontrol agents viz. recommended consortium (LSMR 1+RB3), a new consortium (Bacillus subtilis +RB1), Trichoderma viride, and Pseudomonas flourescens, the new consortium (Bacillus subtilis +RB1) was found most effective against web blight under both in vitro and in vivo conditions. Further, a set of 58 elite mungbean genotypes was screened for web blight resistance by field screening technique at hotspot location. Out of 58 genotypes, seven namely, SML 2061, SML 2056, SML 2064, SML 2055, SML 2073, SML 2065 and SML 2070 showed resistant reaction to web blight.
