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ThesisItem Restricted Management Of Sclerotinia Stem Rot Of Rapeseed-Mustard Incited By Sclerotinia Sclerotiorum (Lib.) De Bary(Punjab Agricultural University, 2023) Yadav, Monika; Sandhu, P.S.Sclerotinia stem rot caused by Sclerotinia sclerotiorum, is an important fungal disease of rapeseed and mustard crop because of its destructive nature. In the present study, 112 genotypes of rapeseed-mustard screened against stem rot disease. Ten genotypes (EC223400, EC765482, IC268306, IC296703, IC491169, IC491178, IC491197, IC491290, IC531377 and IC538699) were found moderately resistant to the pathogen. Early sowing of brassica during first week of October results in lower incidence of the disease and higher yield compare to the late sowings. Poison food technique was used to evaluate botanicals and fungicides under in vitro condition. Among the botanicals maximum per cent inhibition in mycelial growth was observed in case of Chenopodium album at 20 per cent concentration. Whereas, in case of fungicides complete inhibition (100%) was observed in combination fungicides picoxystrobin 7.05%+ propiconazole 11.7% w/w SC, azoxystrobin18.2% w/w + difenoconazole 11.4% w/w SC and fluopyrum 17.7% w/w + tebuconazole 17.7% w/w SC at a concentration of 5, 10 and 25 ppm, respectively. Under in vitro conditions, combination fungicides were more effective against S. sclerotiorum compared to contact fungicide mancozeb 75 % WP which resulted in lower inhibition of pathogen growth even at higher concentrations. The same set of botanicals and fungicides were used under in vivo conditions as a foliar spray application. Chenopodium album at 40 % concentration was observed most effective in reducing the per cent lesion length as compared to the control. Combination fungicide picoxystrobin7.05%+ propiconazole 11.7% w/w SC resulted in lower lesion length development and highest yield as compare to the control in Brassica juncea var. RLC 3.ThesisItem Embargo Biodiversity of seed-borne pathogenic mycoflora of wheat (Triticum aestivum L.) in Punjab(Punjab Agricultural University, 2023) Rubleen Kaur; Tak, Parminder SinghA total 105 grain markets of 23 districts of Punjab were surveyed for study of seed-borne mycoflora during 2021-22 and 654 grain samples were collected. Grains were visually inspected for incidence of Karnal bunt (KB), Black point (BP) and shrivelling. Prevalence of Karnal bunt, Black point and shrivelled grains was 10.24%, 55.20% and 79.51 per cent, respectively. Grain samples from Patiala and Mansa were found to have statistically lowest KB, black point and shrivelled seeds while highest incidence was observed in Pathankot followed by Hoshiarpur and Mohali. Three pathogenic and nine opportunistic fungi were isolated from these samples. Fungal diversity in Sarhali Kalan samples (66.67%) was highest, followed by Sirhind-1, Jalandhar, Rajpura (58.3% each). Bikhi, Nabha, Dadehra, Bucho mandi, Panjgrain (16.67%) carried low mycoflora load. All the samples collected met the minimum seed certification standards for germination. Maximum vigour index I and II of 3327.6 and 26.46 was observed in grain samples collected from Doraha-1 and Shahkot, respectively. Prevalence of Alternaria spp. (94%) was highest followed by Fusarium spp. (64%), Aspergillus flavus (48%) whereas, low prevalence was observed for Exserohilum sp. and Leohumicola sp. (2% each). The fungal isolates were characterized on the basis of morphology and cultural characteristics into 11 fungal genera belonging to 7 families which included Alternaria alternata, Bipolaris sorokiniana, Curvularia verrucosa, Curvularia spicifera and Exserohilum rostratum from Pleosporaceae family (34%); Aspergillus flavus, A. japonicus and Penicillium digitatum, from Aspergillaceae (17%); Fusarium equiseti from Nectriaceae (8%); Epicoccum purpurascens from Didymellaceae (8%); Leohumicola sp. from Incertae sedis (8%), Chaetomium globosum and Pseudothielavia terricola from Chaetomiaceae (17%) and Rhizopus stolonifer from Rhizopodiaceae (8%). Sequencing of Curvularia verrucosa, Bipolaris sorokiniana, Curvularia spicifera, Aspergillus japonicus, Pseudothielavia terricola, Alternaria alternata and Fusarium equiseti was done and cultures have been deposited in MTCC repository, Chandigarh. Thirty nine fungal isolates were inoculated on three wheat varieties and determined for seed health, foliar blights and carryover studies. Opportunistic fungi such as Curvularia sp. (isolate CUS-1), Aspergillus sp. (isolates AF-1, AF-7), Rhizopus sp. (RIZO-1), Penicillium sp. were found to reduce germination under field conditions. Highest average foliar blight severity was observed in Gurdaspur (26.98%) as compared to 20.60 per cent in Ludhiana. Bipolaris isolate BIS-1, Aspergillus flavus AF-1, Curvularia CUT-1, Alternaria ALT-6 and ALT-10 resulted high severity in Ludhiana while Fusarium FUS-1, Rhizopus RIZO-1, Drechslera DRH-3, Aspergillus flavus AF-7 and Alternaria ALT-8 were highly pathogenic in Gurdaspur. The seed inoculated with these fungi induced foliar blight, affected the germination as well as severity of foliar blight however, they could not be re-isolated in all the cases indicating their primary role only up to seedling stage. Overall, Alternaria spp. had the highest frequency in grain market samples as well as carryover studies.ThesisItem Restricted 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 Restricted Characterization of Fusarium species associated with pokkah boeng disease of sugarcane(Punjab Agricultural University, 2023) Meena, Manisha; AnuradhaSugarcane (Saccharum spp. hybrid complex) is an important cash crop of India. Among the various fungal diseases, pokkah boeng caused by Fusarium spp. has emerged as an important disease in this crop. As the occurrence of this disease has been reported from Punjab till date the cultural, morphological and molecular aspects of this disease are not studied. Keeping in view, the present research was carried to characterize the Fusarium spp. associated with pokkah boeng disease of sugarcane. Survey was conducted in the sugarcane growing command area of sugar mills (nine co-operative and seven private) of Punjab during the year 2021-22. The maximum average incidence of pokkah boeng was reported on commercially grown variety Co 0238 (17.70 %) which depicted that the said variety is highly susceptible for pokkah boeng disease. Thirty isolates of Fusarium were obtained after isolation and purification from diseased samples collected during the survey. On the basis of pathogenicity tests, all the test isolates of Fusarium found to be virulent by producing necrotic lesion in detached leaf assay and typical symptoms of pokkah boeng in syringe method. Among all the isolates, Fs23 and Fs25 were highly pathogenic. The isolates showed significant variations on basis of their cultural and morphological characteristics and were categorized into various groups. Molecular study of isolates revealed that isolates Fs7, Fs20, Fs27, Fs29 showed 100 per cent similarity with the ITS, RPB2 and TEF-1α gene sequences of F. sacchari available in GenBank whereas isolates Fs13 and Fs17 showed 99 per cent similarity with F. proliferatum. Hence, the two species of Fusarium namely F. sacchari and F. proliferatum were identified as causal pathogens associated with pokkah boeng disease of sugarcane in Punjab. Genetic diversity estimate by seven ISSR primers showed high degree of polymorphism. Two isolates Fs16 (Jalandhar) and Fs18 (SBS Nagar) were found to be highly diverse among all test isolates. Sugarcane clones along with commercially released varieties were screened against pokkah boeng to identify the resistance sources in which 23, 18 and four clones/varieties showed resistant, moderately resistant and moderately susceptible disease reaction, respectively.ThesisItem Restricted Characterization of blast and bacterial blight resistance genes in basmati rice(Punjab Agricultural University, 2022) Vashisth, Tanvi; Jain, JyotiThe present study was conducted to evaluate MCF1 populations of basmati rice developed from complex crosses (designated as cross A and cross B). Phenotypic evaluation of cross A was done for resistance to neck blast (Pyricularia oryzae) using highly virulent isolate NB-7 under artificial inoculation conditions. Cross B was evaluated against neck blast (NB-7) as well as bacterial blight (Xanthomonas oryzae pv. oryzae) using two pathotypes PbXo-7 and PbXo-8 under artificial inoculation conditions. Among the MCF1 population comprising of 421 plants from cross A, 12 plants were immune, 6 were highly resistant, 30 were resistant and 59 were moderately resistant to neck blast isolate NB-7. A population of 103 plants from cross B showed immune response to neck blast in 9 plants, while 12 plants were resistant to pathotype PbXo-7 and 27 plants were resistant to PbXo-8. Both the crosses were also analyzed for known blast resistance genes (Pi54, Pi2, Pi9 and Pi68) and bacterial blight resistance genes (xa13 and Xa21). A total of 200 plants were tested in cross A, and 199 were found to have the Pi54 gene, while 155 had the Pi2 gene. Only 4 plants showed the presence of Pi9 gene in cross A. The combination of two blast resistance genes was found in 149 plants (Pi54 + Pi2) and in four plants there was a combination of three genes (Pi2 + Pi54 + Pi9). In the cross B, only two plants showed the presence of blast resistance gene (Pi9) and 40 plants showed the presence of Xa4 gene. Two plants were heterozygous for bacterial blight resistance gene (xa13) and four were heterozygous for Xa21. There were only two plants identified as having blast + BB resistance genes (Pi9+Xa4) and one plant showing two BB resistance genes (Xa21+Xa4). The assay of biochemical parameters indicated a significant increase in activity of peroxidase, PPO, PAL, catalase and hydrogen peroxide among resistant/moderately resistant genotypes as compared to the susceptible genotypes at 10 days after inoculation with P. oryzae. Out of 35 genotypes screened against leaf and neck blast phases under artificial inoculation conditions, none was found to be resistant to both the phases. Only two entries viz., Tetep and Pusa Basmati 1637 showed moderately resistant reaction to both neck and leaf blast with susceptibility index (Sx) value <3. Three genotype namely JJ92, UPR3519-18-1-1 and IET 15392 exhibited moderately resistant reaction to leaf blast but were moderately susceptible to neck blast under artificial inoculation conditions. Under natural epiphytotic conditions (hotspot location), five entries namely JJ92, UPR3519-18-1-1, IET 15392, Tetep and Pusa Basmati 1637 showed moderately resistant reaction to neck blast and resistant reaction to leaf blast. The current study has the potential to contribute towards strengthening ongoing blast and bacterial blight resistance breeding program by utilizing the identified donors harbouring single as well as multiple resistance genes to both the diseases.ThesisItem Restricted Efficacy of Ty genes against begomovirus species causing tomato leaf curl disease in Punjab(Punjab Agricultural University, 2023) Nayak, Lopamudra; Sharma, AbhishekTomato leaf curl disease (ToLCD) transmitted by vector whitefly (Bemisia tabaci) is major constraint in tomato production in the Indian subcontinent. During 2021-22 symptoms noticed on leaf curl disease infected tomato were yellowing, mild to severe curling of leaves, mosaic, puckering, stunting, excessive flowering and rudimentary leaves. Symptom variability was more in rainy season compared to winter season. Infected plants showed the association of tomato leaf curl NewDelhi virus (ToLCNDV), tomato leaf curl Palampur virus (ToLCPalV) and tomato leaf curl Karnatka virus (ToLCKV) along with associated satellites by PCR assay. Partial genome characterization of begomovirus from infected samples confirmed the association of ToLCNDV, ToLPalV, ToLKV from these samples. Apart from these chilli leaf curl India virus (ChiLCV), tomato leaf curl Joydebpur virus (ToLCJoV), croton yellow mosaic virus (CYVMV) along with a new species of papaya leaf crumple virus were (PLCrV) were recorded for the first time from tomato in Punjab. Plant age 20 to 40 days after sowing was found to be most susceptible stage to begomovirus infection as considerable yield loss (up to 90.4 %) was observed during inoculation of predominant begomovirus. ToLCNDV along with beta satellites was found to cause maximum yield loss compared to helper virus alone. The kinetics of virus multiplication in tomato genotype with different Ty gene(s) combinations showed accumulation of viral genomic unit and symptom severity were lower in tomato genotypes (PVB-4-1, NLLR-1) carrying Ty-1+Ty-2+Ty-3 and genotype CA-4 carrying ty-5+Ty-6 gene combination as compared to susceptible genotype Punjab Chuhhara (1179.18 x106) when inoculated with ToLCNDV+beta satellite.ThesisItem Embargo Etiology And Management Of Fruit Drop In Kinnow Mandarin(Punjab Agricultural University, 2023) Damanpreet Kaur; Amrinder KaurFruit drop in Kinnow mandarin is a major problem causing quantitative and qualitative losses, globally to the growers. Among the 33 diseased samples collected during the survey from different Kinnow growing orchards of Punjab, Colletotrichum spp. was found to be associated with all the isolates. Morphological characterization of 33 isolates (C-1 to C-33) revealed that the fungus produced creamy white to light grey colony with orange conidial mass in centre. The conidia were non-septate, cylindrical with round apex having oil droplets, ranging in size from 10.26 x 2.77 to 15.70 x 4.82 µm. An irregular shaped brown to black acervuli was produced in isolate C-1, C-4, C-5, C-10, C-19, C-24, C-25, C-29 and C-30 ranging from 130.00-164.30 µm in length and 145.50-168.40 µm in breadth having erect and septate, brown to black setae. Molecular characterization of all the 33 isolates done by amplification of ITS region, ACT and TUB2 genes revealed that all the isolates were of Colletotrichum, whereas amplification of species-specific primer CgInt/ITS4 confirmed that all the isolates belong to Colletotrichum gloeosporioides complex and no amplicon was observed in any of the isolates with primer pair CaInt2/ITS4 (C. acutatum). The phylogenetic analysis of two isolates C-4 and C-19, selected on the basis of high virulence and growth rate proved that Colletotrichum siamense (belonging to gloeosporioides complex) is associated with fruit drop in Kinnow mandarin under Punjab conditions. For management of the disease, different fungicides, botanicals, bio-control agents and nanoformulations were evaluated both under in vitro and field conditions, among the systemic fungicides, azoxystrobin 18.2% + difenoconazole 11.4% SC and propiconazole 25% EC proved to be the most effective by inhibiting 100 % and 88.33% mycelial growth at 25 ppm concentration, respectively. Among, non-systemic fungicides copper oxychloride 50% WP exhibited 100% mycelial growth inhibition at 1000 ppm concentration. In case of botanicals and bio-control agents, maximum mycelial growth inhibition was shown by neem extract (47.96%) and T. harzianum (55.12%), respectively. Nano-particles were not much effective and showed only (22.03-22.77%) growth inhibition of the pathogen. Under field conditions, the fungicides treatment of azoxystrobin 18.2% + difenoconazole 11.4% SC (61.19% and 63.81%) and propiconazole 25% EC (56.95% and 59.12%) were significantly effective in reducing fruit drop over control while neem extract (32.91% and 33.61%) was at par with T. harzianum with (30.92% and 33.41%) reduction in fruit drop over control during 2021 and 2022, respectively. Thus, the disease management strategies could be further incorporated in the IDM programmes for effective management of fruit drop in Kinnow mandarin.ThesisItem Embargo Impact of arbuscular mycorrhizal fungi on fusarium wilt of pea(Punjab Agricultural University, 2023) Monga, Vishal; Buttar, Daljeet SinghIn the survey of pea growing districts of Punjab, the highest mycorrhizal colonization and spore population of mycorrhiza was observed in Hoshiarpur district while lowest was found in Fazilka district. Among the three types of Arbuscular mycorrhizal fungi (AMF), Gigaspora margarita showed the highest colonization and spore population, leading to its selection for further experimental purposes. Comparatively, the mycorrhizal colonization in root samples collected from 20-day-old pea crops was lower than that of crops at 40, 60, and 80 days. The presence of 80 mg 'P'/kg soil did not significantly increased AMF colonization. Inoculation of G. margarita resulted in increased root and shoot length, along with an increase in the number of leaves and pods in all four observations. The influence of the pea wilt causing pathogen Fusarium oxysporum f.sp. pisi (Fop) on mycorrhizal colonization was observed in the presence of G. margarita, as the colonization of G. margarita was reduced by the pathogen. The 'P' level also significantly affected AMF colonization, as well as the abundance of mycelium, arbuscules, vesicles, and spore population in the presence of the pathogen. The overall effect of G. margarita on Fusarium wilt of pea was observed during the crop season at three 'P' levels: 0, 40, and 80 mg P'/kg soil in Ludhiana and Abohar. At Ludhiana, at 40 mg „P‟/ kg soil level in the presence of both AM fungi and the pea wilt pathogen, a considerably higher average percentage of plants (93.34% and 85.00%) were found to be healthy, while a lower average percentage (5.00% and 10.00%) exhibited yellowing and wilting (1.67% and 5.00%). Similarly, at Abohar, at 40 mg „P‟/ kg soil level the average percentages of healthy plants (84.17% and 76.67%), yellowed plants (10.00% and 15.00%) and wilted plants (5.83% and 8.33%) were observed. All 'P' levels showed 100 percent infected plants in the presence of only the pathogen and 100 percent healthy plants in the presence of only AMF treatment. Similar trends were observed in other observations at both locations. The presence of G. margarita significantly reduced the development of Fusarium wilt in pea, with infected plants showing yellowness surviving throughout the entire crop season. Plant growth parameters were significantly higher at 40 mg 'P'/kg soil in all four observations in both locations. Based on these findings, it was suggested that the AM fungus Gigaspora margarita effectively managed Fusarium wilt in pea and enhanced crop yield.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.
