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ThesisItem Open Access Biochemical defense response and genetic basis of resistance against Ascochyta blight (Ascochyta rabiei (Pass.) Labr.) in chickpea (Cicer arietinum L.)(Punjab Agricultural University, 2024) Abassy, Omer; Dr Upasana RaniChickpea (Cicer arietinum L.), the second-largest global pulse crop, is under threat from highly variable nature of Ascochyta rabiei, causing widespread disease damage under favourable environmental conditions. This disease, Ascochyta blight is a major concern worldwide, with insufficient resistant sources and frequent breakdowns due to rapid pathogen evolution. This study evaluated 238 kabuli chickpea genotypes for resistance to Ascochyta blight (AB) over the growing seasons from 2019-2022 at Punjab Agricultural University under artificial epiphytotic conditions, identifying 18 resistant lines (GLK 10-40, GLK 20054, GLK 20055, FLIP 10-298C-IFC-S2, FLIP 10298C-IFC-S1, CS-3-E-24, FLIP 09 256C-55, FLIP 07-314C-57, FLIP 10-243C, FLIP 09-194C, FLIP 08-104C, FLIP 04-219C, ICCV 55233, ICCV 55215, ICCV 55135, ICCV 55108 and ICCV 155141) belonging to different genetic backgrounds with disease scores of 1.0 to 3.0, whereas seventy-three (73) lines demonstrated a moderate level of disease resistance with a disease rating of 3.1-5.0. The activities of defense-related enzymes (PAL, TAL, PPO, POD) associated with phenol metabolism along with lignin and total phenol content were compared among six kabuli chickpea lines, viz., five resistant (GLK 10-40, GLK 20055, FLIP-09-194C, FLIP-04-219C, ICCV 55215) and one susceptible (GLK 17301) treated lines that exhibited differential responses to Ascochyta blight at tested time intervals of 48, 96, 144 and 240 hr post-inoculation respectively. The perusal of data showed increased activity of all enzymes (PAL, TAL, PPO, POD) till 96 hr after inoculation, whereas the non-enzymatic contents such as lignin and total phenols showed the maximum enzyme activity till 144 hr after inoculation. However, enzyme and non-enzymatic activity remained almost constant with no significant difference in all control/untreated resistant and susceptible line(s) at different time intervals. For understanding the genetic basis of resistance, the F2 population comprising of 162 plants derived from the cross, GLK 24096 (resistant) and L 556 (susceptible) was assessed under artificially epiphytotic conditions against local isolate of Ascochyta rabiei. Of 162 plants evaluated, 39 plants were grouped in resistant (R ) category (disease score ≤ 5.0 ) and 123 were classified as susceptible (S) with score of five and above. Consequently, the F2 plants exhibited a segregation ratio of 1R:3S, suggesting that a monogenic recessive gene governed resistance to Ascochyta blight. Of thirty four SSR markers associated with Quantitative Trait Loci (QTLs)/genes were used for confirmation of resistance in identified eighteen resistant and six susceptible lines, only 19 SSR markers depicted polymorphism. Notably, SSR markers, STMS11, TA194, TS12, TA146, and TA2 exhibiting significant polymorphism, indicated tight linkage to Ascochyta blight resistance. Phylogenetic analysis showcased distinct clustering based on resistance, offering insights into the genetic basis of resistance. These findings informed about targeted resistance breeding and sustainable disease management with defence-related enzymes/identified markers holding promise for developing superior, resistant and resilient chickpea varieties contributing to crop sustainability and productivity.ThesisItem Embargo Understanding sunflower - Macrophomina phaseolina interaction under water stress conditions(Punjab Agricultural University, 2023) Navkiran Kaur; Sharma,PankajA total of 35 isolates of Macrophomina phaseolina causing charcoal rot were collected from eleven kharif and rabi crops from different districts of Punjab and adjoining states. Macrophomina phaseolina isolated from sunflower field, Ludhiana was characterized on cultural and morphological and molecular basis. The isolates infecting sunflower showed highest sequence homology of ITS genomic region with M. phaseolina isolate from Indore, Madhya Pradesh NCBI accession no. MT127404. This isolate was further used to standardize the inoculation techniques under field and polyhouse conditions. Tooth pick inoculation technique was found most effective for large scale screening while sorghum grain inoculation method was proficient under polyhouse conditions. A set of 71 sunflower genotypes were evaluated using tooth pick inoculation technique against charcoal rot under irrigated and restricted irrigation conditions. Four genotypes viz; 75B, EC6078261, OPH137, and OPH 172 were found moderately resistant under irrigated conditions whereas only two genotypes 75B and EC6078261 showed moderately resistant reaction in restricted irrigated conditions. The present study was first attempt to investigate the water stress-Macrophomina phaseolina interaction on different components of physiological, plant growth and yield parameters along with disease incidence. A significant reduction in total chlorophyll content (54.78 %), relative water content (47.06 %), membrane stability (51.75 %), sugar (69.00 %), protein (13.90 %) and proline (56.66 %) content was observed with inoculum density of 4 g/kg soil at soil moisture levels of 40 % and 60 %. The inoculum density of 4 g/kg of dry soil resulted in maximum mortality during seedling stage and growth period. Thus, varied inoculum density and water stress conditions made the sunflower plants more prone to dismissive physiological alterations. It led to biomass reduction viz; root length (41.27 %), root width (76.74 %), root weight (85.37 %), shoot length (56.71 %) and shoot weight (79.06 %). Thus it resulted in per plant seed yield reduction (95.45 %) at 52.62 to 100 % disease severity at higher inoculum density (4g, 6g, and 8g/kg dry soil). The expression levels of the defense related genes LOX, ACCO1, PAL, SOD, and APX were also modified under varying degree of water stress and inoculum density. The strong correlation between low soil moisture and disease severity implies that the proper irrigation of the field can be suggested as cultural management practices for the farmers.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 Embargo Detection, variability and translocation of Potato virus Y (PVY) infecting potato in Punjab and identification of host plant resistance(Punjab Agricultural University, 2023) Belludi, Rakesh; Sharma, AbhishekThis study aimed to investigate the variability of Potato virus Y (PVY) infecting potato crop of Rabi season in Punjab, encompassing symptomatology, serology and molecular aspects. The study revealed prevalent symptoms, such as mild mosaic, chlorotic patches, interveinal chlorosis, puckering, veinal necrosis and stem necrosis, on potato plants caused by various potato viruses including PVY. ELISA tests confirmed the presence of six out of seven viruses in potato samples. Among them, PVX exhibited the highest incidence (78.08%), followed by PVYN (51.37%), PVM (20.55%), PVYO/C and PVS (13.01%). PLRV exhibited a lower incidence (2.74%) and no samples tested positive for PVA. Notable regional variations noticed, with Ludhiana showing high incidences of PVYN (78.43%), PVYO/C (31.37%), PVM (33.3%) and PVS (35.29%). Conversely, Kapurthala displayed a 100% PVX incidence, while Jalandhar had the highest PLRV (19.05%) incidence. In nucleic acid-based detection through RT-PCR, the primer NIb2F/3R effectively amplified the desired ~350bp amplicon in all PVYN and PVYO/C seropositive samples. Whereas, the qPVY NIb F2/CP R2 primer generated the ~1.5kb fragment in only 24 out of 67 samples, further confirmed via BLASTn sequence analysis as PVYO, PVYNTN and PVYN-Wi strains. Further virus translocation studies revealed a wide range of carryover rates, spanning from 40% to 92.46%, from infected mother plants to daughter tubers, exhibiting significant variation in viral titre across genotypes and among tubers. Spatial translocation within the tuber's root zone revealed that the bottommost tuber displayed a relatively lower PVY titre. Interestingly, freshly harvested tubers exhibited a higher viral titre at the heel end (stem end) compared to the rose end eyes in all examined tubers. After storage, a contrasting trend emerged in sprouted tubers, where the highest PVY titre was found in rose end eyes and the lowest in heel end eyes. In germplasm screening against resistance to PVY, one germplasm (KP -16-19-14) displayed high resistance (HR), while 16 exhibited resistant (R), 20 moderately resistant (MR), 22 moderately susceptible (MS), 10 susceptible (S) and two were highly susceptible (HS) to PVY. Following PVY inoculation, significant reduction was observed in chlorophyll fluorescence parameters, viz., Fv/Fm, Y(II), qP, and qL values in susceptible cultivars, accompanied by notable increases in NPQ, Y(NO) and qN values. Susceptible genotypes displayed yield losses ranging from 13.64 to 58.84% with viral titre ranging from 0.014 mc to 419.673 mc. Finally, a farmer-friendly and cost-effective vertical flow assay (VFA) was developed for rapid PVY detection in potato leaf samples. The sensitivity of the developed assay was equivalent to commercially utilized ELISA. Specificity test confirmed assays precision for prevalent PVY strains and its non-specificity to other potato viruses. Developed assay exhibited 95% accuracy compared to RT-PCR.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 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 Restricted 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 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.
