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ThesisItem Restricted Epidemiological studies on Alternaria blight of marigold(Punjab Agricultural University, Ludhiana, 2018) Mailem, Y.S; Amarjit SinghMarigold (Tagetes erecta L.) is an important multipurpose flower crop grown throughout India. Its production is affected by various biotic and abiotic factors of which Alternaria blight caused by Alternaria tagetica plays an important role in economic production. The pathogen affects almost all parts of the crop under severe condition. It was found that the disease affects plant at all stages of growth with increased severity in older plants compared to younger plants. The optimum inoculum load of the fungus for disease development was 4 x 104 conidia/ml of water, although incidence and severity increased with increased inoculum load. Leaf wetness duration and temperature were also found to play a role in disease development. Temperature of 25± 1oC and wetness period of 12 h was found to be optimum creating high disease pressure. Marigold seeds were found to play role in the transmission of the disease when naturally and artificially infected by the pathogen. The pathogen also showed survivability under different conditions. Maximum survival was observed under room conditions where there were no soils during storage. Progression of disease was more towards South-eastern and North-western direction due to flowing of North-westerly and South-easterly winds during the two crop seasons. Among twenty-one marigold cultivars evaluated, four cultivars viz. Pusa Arpita, Double Dwarf Lemon, Harmony Boy and French Banita were found to be resistant under field conditions. All other remaining cultivars, except Pusa Narangi Gainda were found to be moderately susceptible. Morphological characters of marigold plant were found to show non-significant role in disease development. Biochemical analysis of defense related enzymes viz. peroxidise, polyphenol oxidase and phenylalanine ammonia lyase among eight cultivars showed that these enzyme activities were greatly reduced in susceptible marigold cultivar in comparison to resistant and moderately susceptible cultivars.ThesisItem Restricted Identification, characterization and management of major virus(es) associated with cucurbits in Punjab(Punjab Agricultural University, Ludhiana, 2018) Dhkal, Manmohan; Sharma, . AbhishekViral disease was reported to be major constraint in the cucurbits cultivation under Punjab conditions. Disease survey conducted during February-August 2017 and 2018 in different cucurbits growing areas of Punjab revealed maximum viral disease incidence in district Pathankot (100%) during 2017 and Ludhiana (36.5%) during 2018. During survey blistering, yellows, leaf curl, mosaic, puckering and necrosis were observed as common viral symptoms on cucurbits. Among these, yellows and leaf curl were most prevalent symptoms on cucurbits in different districts of Punjab, whereas watermelon showed necrotic symptoms. Musk melon samples with yellows and leaf curl symptoms showed seronegative reaction against antisera of commonly occurring viruses and was found positive in PCR for whitefly transmitted begomovirus infection. Musk melon and tinda were identified as new host of begomovirus in India. Tomato leaf curl New Delhi virus (ToLNDV), Tomato leaf curl Palampur virus (ToLCPMV) and Seena leaf curl virus were characterized from musk melon showing yellows and leaf curl symptoms. ToLNDV infection was found to be associated with tinda and cucumber causing yellows and leaf curl symptoms. In watermelon, Groundnut bud necrosis virus (GBNV) was serologically detected with samples showing necrosis symptoms. Among different methods of transmission ToLCPMV associated with yellows and leaf curl symptoms was found to be transmitted only by whitefly, whereas one percent seed transmission of necrosis symptoms caused by GBNV was observed in watermelon. Out of 75 melon accessions SM/IC-267375 and WM-11 showed high resistance response against ToLCPMV in artificial screening as no symptom observed even after 45 days of sowing as compared to susceptible checks. Three watermelon accessions viz., WM-6-2-2-1-1-2, WM-36 and WM-829833 produced mild necrotic symptom during natural screening. Among different natural products used for management of viral disease in musk melon, buttermilk was found to be highly effective at 20% concentration with least per cent disease incidence (50.8%) as compared to 10 % (64.2 %) and 5 % (71.1%) concentrations. Besides buttermilk, kaolin was also found to be effective in the management of viral diseases of musk melon. Among different dates of sowing least incidence of viral disease was observed on late sown or transplanted musk melon crop 15 March (38.96%) followed by the 5 March (46.7%) sown crop. Among different methods of planting, tray transplanted musk melon crop showed less incidence (48.3%) compared to directly sown crop (50.4%) whereas, normally transplanted crop showed maximum disease incidence of 55.7 per cent.ThesisItem Open Access Gene scouting for rust(s) resistance in wheat germplasm(Punjab Agricultural University, Ludhiana, 2018) Sandeep Singh; Jaspal KaurDuring the Rabi crop season of the year 2016-17, six hundred and seven (607) wheat germplasm lines were evaluated in the field and found sixty six lines resistant to stripe rust, three hundred thirty six lines resistant to leaf rust and thirty four lines resistant to both stripe rust and leaf rust. In the second year (2017-18), the wheat germplasm was evaluated against different pathotypes of Puccinia striiformis tritici (Pst) (238S119, 110S119, 46S119 and 78S84) and P. triticina (Pt) (77-5 and 77-9) at seedling stage. From seedling reaction test it was observed that fifty six (56) lines and one hundred and ten lines (110) possess resistance against all the pathotypes of Pst and Pt tested respectively. All the test wheat lines were categorized into different clusters based on final rust severity (FRS), area under disease progress curve (AUDPC), relative area under disease progress curve (rAUDPC) and coefficient of infection (CI). Fifty two (52) lines were highly resistant to stripe rust and one hundred seventy one (171) lines were highly resistant to leaf rust and remaining lines showed different reaction based on the particular range of slow rusting parameters. Genotypes which showed resistance either to stripe rust or to leaf rust were further evaluated against mixture of Pst pathotypes (238S119, 110S119, 46S119 and 78S84) and individually against 110S119 and 46S119. For leaf rust evaluation was done by using mixture of Pt pathotypes (77-5, 77-9, 104-2 and 12-2) and 77-5 and 77-9 in isolation. NILs carrying known APR genes and susceptible checks for also used for comparison purpose under the field conditions. The results of the present study revealed that fifty two lines has resistance against most prevalent pathotypes of stripe rust in Punjab (238S119, 110S119, 46S119 and 78S84) and one hundred seventy one (171) lines have resistance to mixture (77-5, 77-9, 104-2 and 12-2) pathotypes of Pt. Reaction on NILs showed that Yr1, Yr5, Yr10, Yr15, Yr24, Yr26, Yrsp, Yr31, Yr51, Yr47, Yr57, Yr63 are effective against most prevalent pathotypes of stripe rust in Punjab and Lr2a, Lr2b, Lr8, Lr19, Lr22a, Lr23, Lr(27+31), Lr45, Lr51, Lr53, Lr57, Lr58, Lr76 are effective against leaf rust pathotypes. For deployment of resistance sources, total 40 crosses were made. Eleven lines resistant to stripe rust were crossed with PBW621 and twenty nine lines resistant to leaf rust were crossed with HD3086. F1 and F2 plants obtained were tested separately against stripe rust and leaf rust. From the disease reaction of majority of F1 and F2 populations it was concluded that resistance in these lines is controlled by single dominant gene against both stripe and leaf rust.ThesisItem Restricted Epidemiology and management of Stemphylium blight of garlic(Punjab Agricultural University, Ludhiana, 2018) Salaria, Pooja; Amarjit SinghStemphylium blight of garlic caused by Stemphylium vesicarium (Wallr.) Simmons is commonly found in garlic growing areas of Punjab. The lesions colonized by S. vesicarium was round to elliptical. The most effective media for growth and sporulation of S. vesicarium was V8 juice agar media. Maximum disease severity was recorded in Moga district whereas minimum in Ludhiana. Leaf wetness duration of minimum 8 hrs is necessary for the infection but maximum disease developed at 24 hrs of leaf wetness duration. The optimum temperature for the disease development was 25ºC whereas it was nil at 15ºC. The disease severity increases with the increase in age of the plant and it was found maximum on 105 days old plants. The garlic plants sown on 6-16 November exhibited minimum disease severity. No genotype exhibited resistance to disease under natural and artificial epiphytotic conditions. The performance of PG-17 and PG-18 was better in comparison to other genotypes tested against Stemphylium blight under artificial epiphytotic conditions. Neem oil and Neem extract can be used as an alternative to Mancozeb 75% WP for eco-friendly management of the disease. These can be useful in devising integrated management strategy for Stemphylium blight of garlic.ThesisItem Open Access Etiology and management of root rot complex of groundnut (Arachis hypogaea L.)(Punjab Agricultural University, Ludhiana, 2018) Sekhon, Amritpal Singh; Sandhu, P.S.Isolations made from root rot complex samples of groundnut collected from groundnut growing areas of Punjab revealed that the five fungal genera namely Aspergillus niger, A. flavus, Mcarophomina phaseolina, Rhizoctonia solani and Sclerotium rolfsii were found associated with the root rot complex disease. Among the species associated with root rot complex, the incidence of A. niger was highest. The maximum incidence of root rot complex was found in Hoshiarpur district (21.52 %), followed by Sangrur (21.35 %). Among the five cultivars found on the farmer’s field, only SG-99 showed moderately resistance reaction to the disease while other four cultivars namely M-522, Malika, TAG-24 and TG 37A showed moderately susceptible reaction. Among the 29 isolates of A. niger, 18 isolates were with light yellow, 6 isolates white and 5 isolates with pale yellow colour of mycelium. Effect of sowing date on the disease development was studied at three locations namely PAU, Ludhiana, RRS Ballowal Saunkhri and KVK, Kheri. Among the total seven sowing dates, 15th March was most suitable for SG-99 and 30th March for M-522. The early sowing of virginia type groundnut (M-522) was more sensitive to the temperature compared to spanish type (SG-99). Among the fungicides tested using poisoned food tehcnique, tebuconazole gave maximum inhibition of mycelial growth of A. niger followed by azoxystrobin and Sprint (carbendaim + mancozeb). In paper towel method, the seed treatment with Sprint (carbendazim 25 + mancozeb 50) gave maximum seed germination and seedling vigour followed by Vitavax power (carboxin 37.5 + thiram 37.5). Total six fungicides were evaluated for their effectiveness against root rot complex disease under field conditions with 13 treatments. Among them, seed treatment with tebuconazole plus two sprays of tebuconazole found to be highly effective in controlling the disease followed by seed treatment with azoxystrobin plus two sprays of azoxystrobin and seed treatment with Vitavax power plus two sprays of tebuconazole. The seed treatment with tebuconazole plus two sprays of tebuconazole (0.15 %) gave maximum pod yield (3267 kg/ ha in SG-99 and 2811 kg/ ha in M-522) followed by seed treatment with azoxystrobin plus two sprays of azoxystrobin (0.1 %).ThesisItem Restricted Prevalence and management of leaf spots of sorghum(Punjab Agricultural University, Ludhiana, 2018) Lambay, Gursimran Kaur; Upasana RaniThe present investigation was conducted at Forage Research Farm and Pathology Laboratory of Department of Plant Breeding and Genetics, PAU, Ludhiana during Kharif 2012. Leaf spots were prevalent in Ropar, Hoshiarpur, Jalandhar, Ludhiana, Moga and Faridkot but intensity was more in Hoshiarpur and Ropar. Grey leaf spot was widely and severely distributed than zonate leaf spot and anthracnose. Fungi associated with leaf spots were identified as Cercospora sorghi causing grey leaf spot, Gloeocercospora sorghi causing zonate leaf spot and Colletotrichum graminicola causing anthracnose of sorghum. The fungi associated with these leaf spots has also been detected as part of seed mycoflora and might play role in primary infection. Development of leaf spots revealed that grey leaf spot appeared in first week of July, whereas zonate leaf spot and anthracnose appeared in field in second week of August and end of July respectively with maximum per cent disease index (PDI) of 39.67 (grey leaf spot), 20.42 (zonate leaf spot) and 11.75 (anthracnose) towards the end of the season. Relative humidity and rainfall were positively correlated, whereas temperature was significantly and negatively correlated with develoopment of leaf spots. Grey leaf spot was predominant on all dates of sowing but intensity of all the leaf spots was high in timely and the late sown. Of 119 germplasm accessions, 7 (94001 A, NS 1008-A, SSG 226, SSG 241, SSG 253, SGL 244 and SGL 98-12) showed multiple disease resistance against these leaf spots. Under in vitro conditions, Emisan @ 2.5g/kg seed showed the lowest infection by different mycoflora, whereas under in vivo conditions seed treatment with Emisan @ 2.5g/kg seed and Bavistin @ 3g/kg seed recorded minimum leaf spot intensity in both forage and grain crops. These treatments also showed increase in yield.ThesisItem Open Access Etiology of stem gummosis and leaf blight of bottle gourd (Lagenaria siceraria) in Punjab(Punjab Agricultural University, Ludhiana, 2018) Gurpreet Singh; Jain, SandeepThree simultaneously occurring syndromes viz. stem gummosis and slow vine decline; quick wilting and leaf blight were deciphered in the bottle gourd fields and their primary pathogenic causes were established. All the three types of syndromes were more prevalent in south-western districts of Punjab. The incidence of stem gummosis and slow vine decline varied from 0 to 68.30 per cent and 20.57 to 67.89 per cent, whereas the severity varied from 0 to 51.22 per cent and 11.77 to 39.33 per cent in the years 2015 and 2016 respectively. The incidence of quick wilt varied from 2.33 to 57.00 per cent and 5.15 to 27.78 per cent in the years 2015 and 2016 respectively. The incidence of leaf blight varied from 35.57 to 85.15 per cent and 28.88 to 80.15 per cent whereas the severity from 11.55 to 53.33 per cent and 20.44 to 59.67 per cent in the year 2015 and 2016, respectively. Pathogenicity tests were conducted to prove Koch’s postulates and identification of organisms was done through morphological as well as molecular studies. The causal organism of stem gummosis and slow vine decline was identified as Fusarium verticillioides (Sacc.) Nirenberg. The pathogen associated with quick wilting was identified as Fusarium oxysporum Schltdl. and the pathogen associated with leaf blight was identified as Lasiodiplodia theobromae (Pat.) Griffon & Maubl. Best medium for vegetative growth of F. verticillioides was observed to be potato dextrose agar followed by czapek’s dox agar and richard’s agar while for F. oxysporium it was czapek’s dox agar followed by potato dextrose agar and richard’s agar and for L. theobromae it was observed to be potato dextrose agar followed by V8 juice agar and rye agar. None of the test genotypes showed the resistant or moderately resistant reaction against stem gummosis and slow vine decline or quick wilting whereas two bottle gourd genotypes were adjudged as the moderately resistant against leaf blight. Under in vitro evaluation of fungitoxicants, carbendazim 50 WP was found to be the most effective fungicide against Fusarium verticillioides and Fusarium oxysporum. Trifloxystrobin + tebuconazole 75% WG was found to be the most effective fungicide against Lasiodiplodia theobromae. Soil drench with carbendazim 50 WP @ 0.2 per cent along with foliar application of tebuconazole 25 EC @ 0.1 per cent three times at fortnightly interval starting from end of July proved to be the most effective against stem gummosis and slow vine decline. Against leaf blight, three foliar sprays of propiconazole 25 EC @ 0.1 % were found to be most effective against leaf blight of bottle gourd under field conditions. This is the first systematic study on stem gummosis in Punjab.ThesisItem Open Access Pathotyping of Pyricularia oryzae causing neck blast of basmati rice in Punjab(Punjab Agricultural University, Ludhiana, 2018) Jasvir Singh; Jain, JyotiThe neck blast disease was prevalent throughout the Punjab state with disease intensity ranging from 5 to 65 per cent on different basmati varieties. The highest disease incidence was observed in south western districts of the state on variety Pusa basmati 1401 followed by the Pusa basmati 1121, Pusa basmati 1509, CSR 30 and PB 3 respectively. The neck blast isolates of Pyricularia oryzae were significantly variable from each other with respect to colony colour, colony texture, colony form, colony margin, mean radial growth (mm), spore size and sporulation intensity. Eighteen isolates were designated as medium growers with Kr value of 6-8mm/24 hours and only three isolates (NB-1, NB-4 and NB-33) as fast growers having Kr > 8mm/24 hours. All the isolates cultured on oatmeal agar medium (OMA) produced higher conidia per ml (7.49×106) than on paspalum grass medium (6.74×106). Seventeen isolates were pathotypically characterized based on different components of aggressiveness viz. area under disease progress curve (AUDPC), lesion length, incubation period (IP 50), disease incidence (%) and sporulation intensity using near isogenic lines (NILs). Hierarchical cluster analysis of these aggressiveness components categorized the isolates into three distinct groups. Isolate NB-7 was found to be the most virulent followed by NB-51whereas isolate NB-6 was the least virulent. None of the single blast resistance gene was effective against different isolates of neck blast. Out of 69 genotypes evaluated, none was found to be resistant against neck blast disease. Only 4 entries viz. Tetep, Pusa basmati 1637, INGR 15001 and INGR 15002 showed moderately resistant reaction to most virulent isolate NB-7 and can be used as donors in neck blast resistance breeding programme. This is the first systematic study on pathotyping of neck blast isolates in Punjab suggesting the occurrence of three distinct pathotypes in the state.ThesisItem Restricted Molecular and biochemical bases for resistance to sclerotinia stem rot in introgressed Brassica juncea lines(Punjab Agricultural University, Ludhiana, 2018) Gill, Rupeet; Sandhu, Prabhjodh SinghSclerotinia rot caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary is one of the most serious and damaging diseases of oilseed Brassicas and there is keen interest worldwide to identify Brassica genotypes with resistance to this pathogen. In this study, introgression lines derived from hybridization of wild crucifers with Brassica juncea were evaluated for response to stem rot. These were challenged against local Sclerotinia sclerotiorum isolate and 24 lines giving variable reaction were selected. Apart from this a total of 58 isolates of S. sclerotiorum were collected from different Brassica growing states (Punjab and adjoining states). These were evaluated for their pathogenicity on susceptible B. juncea cultivar RL1359 and based on disease progression; they were divided into five groups. Further 24 isolates were chosen from these groups and analysed for biochemical parameters. It was found that oxalic acid production significantly correlated with the pathogenicity of the isolates and lesser/no correlation was observed for pectinase enzymes. These 24 isolates were then used to further evaluate the selected 24 introgression lines. The observation on progression of lesion length revealed a variable response of lines to different isolates. Disease scoring was done and thus lines were categorised as resistant, moderately resistant and susceptible. Qualitative analysis was carried out on lines from different categories for genes NPR1, COI1 and EIN2. Upregulation in COI1 gene after fungal infection in resistant lines indicates the possible induction of jasmonic acid mediated defence response. Four lines from each category were selected for biochemical analysis involving SOD, POX, PAL, total phenols and lignin. All of these had a negative correlation with disease and the genotype with a greater level of resistance was superior to the susceptible one in regard to phenol and lignin production and the activities of defence enzymes. These results suggest that a combination of these defence responses in Brassica may contribute to greater plant resistance to S. sclerotiorum and that these enzymes have potential use in selection of resistant genotypes.