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Biocontrol of fusarial wilt of bottle gourd
(Punjab Agricultural University, Ludhiana, 2019) Ruchika, Ruchika; Narinder Singh
The wilt of bottle gourd caused by Fusarium oxysporum is a serious disease in bottle gourd growing areas of Punjab. Rhizosphere soil samples were collected from bottle gourd fields of Ludhiana, Kapurthala and Bathinda districts of Punjab in order to analyze the antagonistic microflora. Five isolates of Trichoderma and three isolates of Pseudomonas were isolated and screened in vitro for their antagonistic activity against Fusarium oxysporum. Among the various isolates, two isolates of Trichoderma (T1 and T2) and one isolate of Pseudomonas (P1) showed good inhibition against Fusarium oxysporum under lab conditions. Trichoderma isolate T2 showed maximum inhibition of Fusarium oxysporum (76.33 % and 65.83%) in dual culture and volatile assay, respectively. On Molecular characterization the selected isolates T1 and T2 were identified as Trichoderma asperellum and isolate P1 was identified as Pseudomonas aeruginosa. The selected isolates were then applied as seed, soil and seed + soil treatments using 10g and 15g formulation of each antagonist to check their efficacy against Fusarium oxysporum in two different seasons (March and June) under field conditions. Maximum germination (91.67% and 87.50%) and maximum disease inhibition (92.31% and 86.67%) was found in case of chemical treatment followed by Trichoderma asperellum isolate T2 with a germination of 87.50 per cent and a disease reduction of 84.62 and 80.00 per cent in March and June, respectively. Maximum yield (235.99q/acre and 229.00q/acre) along with maximum total length (5.43 m and 4.83 m) was obtained in case of Trichoderma asperellum isolate T2 in March and June, respectively due to disease control and the plant growth promoting behaviour of the antagonist. The results of rhizospheric competence showed that enough propagules of the antagonists were present throughout the growing season to effectively manage the wilt pathogen. Talc based bioformulation of the selected antagonists showed maximum shelf life on storing at 0°C and packing in polythene bags.
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Characterization, population dynamics of Streptomyces spp. and management of potato scab
(Punjab Agricultural University, Ludhiana, 2019) Sabhikhi, Hardeep Singh; Hunjan, Mandeep
Scab of potato caused by various Streptomyces spp. has assumed serious proportions in certain potato growing regions of Punjab. A total of 2060 acres were surveyed during this study, out of which 490 acres were having scab infection. Maximum disease severity was observed in Kapurthala (7.9%), followed by Ludhiana (6.3%) and Jalandhar (6.2%) districts. During the surveys, it was observed that common scab type of symptoms were the most prevalent (89.7%), however disease induced by multiple type symptoms was viz., pitted or raised corky lesions was more severe. One hundred seven isolates of Streptomyces were collected, and characterized biochemically, pathotypically and genetically. All the Streptomyces spp. isolates could utilize hexose sugars, but not pentose sugars and most of the isolates produced melanoid pigment, an important virulence factor of this bacterium. Multiple antibiotic resistance was observed in 20 isolates. Pathotypic bioassay of Streptomyces spp. isolates revealed that Kufri Pukhraj had the highest virulence frequency (81.3%) while K. Himsona had the least (40.2%). Ninety six isolates were confirmed pathogenic. The 16srDNA amplification confirmed the identity of the genus, whereas sequence analysis of nine representative isolates revealed that Strep101 belonged to Streptomyces acidiscabies, Strep102 to reticuliscabiei, while Strep131, Strep137, Strep143, Strep145, Strep154, Strep170 and Strep173 to scabiei. All isolates were further characterized on the basis of pathogenicity genes, txtA and nec1.The txtA gene from Punjab isolates either matched with S. scabiei or S. turgidiscabies No txtA amplification was observed in S. acidiscabies, Strep101 and S. reticuliscabiei, Strep102. The nec1 gene was amplified in 84 out of 96 isolates and no nec1 was detected in S. reticuliscabiei, Strep102. Genetic fingerprinting carried out by using 17 RAPD primers clustered these into eight genetic groups. Many genetic groups had multiple virulence groups and vice-versa. To identify resistant donors, 41 potato germplasm lines were screened using representative isolates of different virulence groups. Most of the lines were susceptible to moderately susceptible. Three crop rotations viz., fallow-rice-potato, summer moong-rice-potato and sunhemp-rice-potato showed maximum per cent decrease in the population of Streptomyces spp. in soil and scab severity on potato tubers. Using disease free seed tuber or early harvesting of potato from scab sick field also observed that to reduce scab effectively. In vitro and in vivo evaluation of different chemicals against S. scabies showed that Streptocycline, streptomycin, boric acid and copper sulphate were effective. However, tuber seed treatment with chemicals viz., Kocide@0.2% and Streptocycline@100 ppm and antagonist Streptomyces spp. strain S25 and S27 had negative impact on the germination of potato seed tuber. For the management of scab, complete package involving use of tolerant cultivars, disease free seed or seed treatment, and cultural practices have to be followed.
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BIOCHEMICAL AND HISTOPATHOLOGICAL STUDIES IN BARLEY FOR COVERED SMUT (Ustilago hordei) RESISTANCE
(Punjab Agricultural University, Ludhiana, 2019) Jashandeep Singh; Vineet Kumar
Covered smut caused by Ustilago hordei is an important disease of barley in India. In present study, biochemical basis of resistance, histopathological & ultrastructural changes and identification of sources of resistance to U. hordei were undertaken. The biochemical basis of resistance was studied on a set of three barley cultivars viz. PL 426 (resistant), PL 891 (moderately susceptible) and VJM 201 (susceptible). Maximum level of total phenols (0.64 units min-1 g-1 fresh weight) and activity of peroxidase (POD) (86.70 units min-1 g-1 fresh weight) was recorded in PL 426 whereas maximum activity of polyphenoloxidase (PPO) (89.30 units min-1 g-1 fresh weight) and phenylalanine ammonia lyase (PAL) (1.39 units min-1 g-1 fresh weight) was recorded in PL 426 and PL 891, respectively. The aqueous extract of seedlings of PL 426 (resistant variety) inhibited 98% of teliospores at 100% concentration. Ultrastructural comparison of compatible and incompatible Hordeum vulgare-Ustilago hordei, host-pathogen interaction done with scanning electron microscope showed germinated teliospores and trailing hyphae all over the host surface in the compatible interaction. Whereas, in incompatible interaction the teliospores were intact and extracellular polysaccharides were present completely adjacent to teliospores which might be involved in hindering the germination of teliospores. Eighty three germplasm accessions comprising of 74 germplasm lines and 9 varieties were evaluated against covered smut disease. Among the 9 varieties, 5 varieties namely HBL 113, HBL 391, HBL 316, DWRUB 92 and DWRUB 123 were found to be completely free from covered smut disease under field conditions at two locations viz. Ludhiana and Faridkot. PL 172 and PL 891 were categorized as moderately resistant and moderately susceptible, respectively. Among 74 germplasm lines tested at both locations, 41 showed high level of resistance and were found free from disease. BL 1562, BL 1656, BL 1627 and BL 1562, BL 1652 lines were found to be resistant at PAU, Ludhiana and RRS, Faridkot, respectively. 17 germplasm lines showed moderate resistance against covered smut.
Open Access
Etiology of charcoal rot of maize caused by Macrophomina phaseolina (Tassi.) Goid. in Punjab
(Punjab Agricultural University, Ludhiana, 2019) Ahmadi, Khalilullah; Harleen Kaur
Five different stages (55, 65, 75, 85 and 95 days old plants) of three maize hybrids viz. PMH 10, DKC 9108 and PMH 2 were evaluated for determination of most susceptible growth stage against charcoal rot during spring season. The data revealed that 75 days old plant was the most susceptible growth stage for charcoal rot. At this particular stage, mean disease severity (60.83 %) was maximum, resulting in minimum mean grain yield (55.27 q/ha).This stage also coincides with tasseling and silking stage of the plant. The effect of five different sowing dates on disease severity of charcoal rot of five maize hybrids during spring 2018 and 2019 revealed that crop sown on 20th January suffered minimum disease severity (40.91 and 36.3 %) resulting in maximum grain yield (74.27 and 77.89 q/ha) during spring 2018 and 2019 respectively. The plant height and cob height was found maximum on this date. As sowing date was delayed, severity of charcoal rot increased, thus decreasing grain yield, plant height and cob height. Among meteorological factors, disease severity was found positively correlated with mean temperature (+0.98) and negatively correlated with mean relative humidity (-0.92) and total rainfall (-0.90). The effect of three irrigation schedules (additional irrigation at tasseling and silking stage, local practice and stress at tasseling and silking stage) on the development of charcoal rot showed that application of an additional irrigation at tasseling and silking stage had least mean disease severity (36.28%) compared to other irrigation schedules and resulted in highest mean grain yield (72.61 q/ha). Water stress at tasseling and silking stage of the crop aggravated the disease development. Fifty four maize germplasm lines were evaluated artificially against charcoal rot, out of which five germplasm lines (PML-81, LTY 9808, JCY 13-1-1, SNL 172470 and SNL 172475) were found resistant, thirty moderately resistant, seventeen moderately susceptible and two of them were found highly susceptible. The maize hybrids sown in month of January and February coupled with additional irrigation at tasseling and silking stage resulted in low disease severity of charcoal rot, thus maximizing the grain yield. The germplasm lines found resistant after artificial screening of charcoal rot at the most susceptible growth stage (75 - 85 days old plants) during spring season could be successfully utilized in future breeding programme for maize improvement.
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Integrated management of Meloidogyne incognita and Rhizoctonia bataticola in root rot disease complex in mungbean
(Punjab Agricultural University, Ludhiana, 2019) Rohit Kumar; Dhillon, Narpinderjit Kaur
Mungbean crop is attacked by number of soil and air borne pathogens. Of the different soil borne pathogens; root-knot nematode (Meloidogyne spp.) is an important pathogen affecting growth and production of mungbean. Another soil and seed borne pathogen, Rhizoctonia bataticola causes root rot disease of mungbean. Meloidogyne incognita and R. batalicola being soil borne organisms may affect each other activity besides influencing the responses in their common host mungbean. Studies were conducted on the build-up of root knot nematode in nine different genotypes in summer and kharif season. The reaction of different genotypes was varied in two seasons. Eight of the nine genotypes were found to support multiplication of root knot nematode while decrease in nematode population was observed in only one genotype ML 2056. M. incognita populations in soil were observed to be significantly higher in kharif season in four genotypes viz., SML 1906, TMB 37, SML 1827, SML 1900 in comparison to summer season while in the other five genotypes there was no significant difference in the nematode population in two seasons. The interaction of M. incognita and R. bataticola revealed that higher incidence of root rot disease and maximum decrease in plant growth parameters was recorded in simultaneous inoculation of Meloidogyne incognita and R. bataticola. Of the one hundred two genotypes screened against M. incognita in summer and kharif mungbean; only ten genotypes were found to be moderately resistant. Of the eighty eight mungbean genotypes screened against Rhizoctonia bataticola only ten were moderately resistant. In multiple disease resistance studies, four genotypes which were moderately resistant against both pathogens were evaluated. Breakdown of resistance was observed in ML2581 and ML2560, while ML 2056 showed moderately susceptible reaction and ML2607 was observed to be moderately resistant against both pathogens. Integrated management of root knot nematode and R. bataticola in mungbean revealed that combined application of Bionematon@4l/ha + neem cake@1 t/ha + Captan (seed Treatment) was more effective than the individual application of chemical, bioformulation or cakes.
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Genetic diversity and pathogenicity of Fusarium oxysporum f.sp. melonis in Punjab
(Punjab Agricultural University, Ludhiana, 2019) Gurjot Singh; Buttar, Daljeet Sigh
Muskmelon wilt caused by Fusarium oxysporum f.sp. melonis caused serious damage in muskmelon growing districts of Punjab. Random surveys were conducted for the collection of diseased samples in different muskmelon growing districts viz. Jalandhar, Kapurthala, Patiala and Sangrur of Punjab during the year 2017-18 and 2018-19. During surveys the maximum disease incidence was reported in Sangrur (18.5%) followed by Jalandhar (12.8%) and Patiala (12 %) districts, whereas minimum disease incidence (11.3%) was reported in Kapurthala. Out of total 57 diseased samples, 20 isolates were purified and identified based on cultural and morphological characters as F. oxysporum f.sp. melonis. Set of five differentials namely Charentais T, Charentais FOM-1, Charentais FOM-2, Margot and Isabelle were grown under pot house conditions for the evaluation of prevalent races of F. oxysporum f.sp. melonis under Punjab conditions. After 2-3 leaf stage these set of differentials were artificially inoculated with spore suspension @ 1×106 /ml of twenty isolates of F. oxysporum f.sp. melonis. Results indicated that out of total 20 isolates, 8 isolates belonged to race 1, 8 isolates belonged to race 1.2, 3 isolates belonged to race 2 and remaining 1 belonged to race 0. Race 1 and 1.2 were mainly prevalent in Punjab. Genetic diversity among the twenty isolates of F. oxysporum f.sp. melonis was analyzed with the Random Amplified Polymorphic DNA (RAPD) markers. Based on cluster analysis J2 and J4 isolates of Jalandhar district were outliers and they were genetically different from other isolates of different districts of Punjab. Maximum genetic diversity was found between isolates P2 and J4 with coefficient value of 0.131. Twenty isolates of F. oxysporum f.sp. melonis from different muskmelon growing districts of Punjab were divided in to six groups. Group 1 had two isolates (J2 and J4) belonged to Jalandhar district. Group 2 had one isolate (P2) belonged to Patiala district and one (K5) belonged to Kapurthala district. Group 3 had one isolate (K6) belonged to Kapurthala district and one (J1) belonged to Jalandhar district. Group 4 had two isolates (P3 and P4) belonged to Patiala district. Group 5 had three isolates (S2, S3 and S4) belonged to Sangrur district. Group 6 had highest number of isolates i.e. seven. In this group four isolates (K1, K2, K3 and K4) belonged to Kapurthala district, two (S4 and S5) belonged to Sangrur district and one isolate (P1) belonged to Patiala. Based on the findings, it is suggested that this study could be considerably important for selection and integration of muskmelon wilt resistance gene into muskmelon breeding programmes for Fusarium wilt management.
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Etiology and comparative aggressiveness of Ascochyta complex associated with pea blight
(Punjab Agricultural University, Ludhiana, 2019) Anjali; Jain, Sandeep
Pea (Pisum sativum L.) has wide adaptation to almost all the agro-ecological zones of India and is 2ndmost widely cultivated crop in Punjab after potato. Three distinct syndromes viz., leaf spot; leaf blight and pod spot and foot rot were recognized and distinguished in pea field and their primary pathogenic causes were established. All the three symptom-types were more prevalent in Western plain zones with incidence and severity of 56.90 and 23.35 per cent followed by sub-mountainous zone i.e. 49.12 and 21.48 per cent, respectively. The overall mean disease incidence of Punjab state was recorded to be 33.99 and 37.46 per cent during the year 2017-18 and 2018-19, whereas disease severity was 13.78 and 5.78 per cent respectively during the same years. Among the different varieties grown in field, maximum mean disease incidence (58.20%) and severity (25.28%) recorded on AP-3 followed by MA-7 i.e. 55.24 and 23.22 per cent, respectively. Pathogenicity tests were conducted to prove the Koch‟s postulate and identification of species associated with distinct symptom-types was done through morphological and molecular studies. All the isolates of pea blight were significantly variable from each other with respect to colony colour, colony texture, colony form and margin, mean radial growth (mm), spore size and sporulation intensity. Average conidial size ranged from 4.12-12.30 (L) x 2.09- 4.37(B) μm with mean average size of conidia 6.19- 6.49 (L) x 3.27-3.66 (B) μm. Smallest conidia length (4.02 μm) was observed in isolate PB-11 and the longest conidia were recorded in isolate PB-1(11.03 μm). All the isolate cultured on PDA medium produced average sporulation of 6.21 x106 pycniospores/ml. The pathogen associated with leaf blight and pod spot type of symptoms was identified as Didymella pinodes which was found to be the most prevalent pathogen species. This was followed by foot rot type of symptoms caused by Phoma pinodella. The pathogen associated with leaf spot type of symptom was identified as Ascochyta pisi. This pathogenic species was least prevalent among the three identified species of pea blight. Thirty isolates of pea blight were categorized on the basis of pathological aggressiveness of different components viz., area under disease progress curve (AUDPC), incubation period (IP50), latent period (LP), lesion size (LS), percentage of stem girdling (%HTM) and number of girdled internodes (NOI) using seven pea cultivars. Hierarchical cluster analysis of these aggressiveness components categorized isolates into three distinct groups. Isolate PB-27 was found to be highly aggressive followed by PB-30 whereas isolate PB-1 was the least aggressive. Logistic model gave the best fit for disease progress of pea blight. Out of 100 genotypes evaluated, only 5 genotypes namely Eddy, PS-24, Arya Veer, CHPMR-2 and PS-19 showed resistant reaction against pea blight complex and can be used as a donor in pea blight resistance breeding programme. This is the first systematic study on etiology and comparative aggressiveness pathogen associated with pea blight complex in Punjab.
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Integrated management of Meloidogyne incognita and Rhizoctonia bataticola in root rot disease complex in mungbean
(Punjab Agricultural University, Ludhiana, 2019) Rohit Kumar; Dhillon, Narpinderjit Kaur
Mungbean crop is attacked by number of soil and air borne pathogens. Of the different soil borne pathogens; root-knot nematode (Meloidogyne spp.) is an important pathogen affecting growth and production of mungbean. Another soil and seed borne pathogen, Rhizoctonia bataticola causes root rot disease of mungbean. Meloidogyne incognita and R. batalicola being soil borne organisms may affect each other activity besides influencing the responses in their common host mungbean. Studies were conducted on the build-up of root knot nematode in nine different genotypes in summer and kharif season. The reaction of different genotypes was varied in two seasons. Eight of the nine genotypes were found to support multiplication of root knot nematode while decrease in nematode population was observed in only one genotype ML 2056. M. incognita populations in soil were observed to be significantly higher in kharif season in four genotypes viz., SML 1906, TMB 37, SML 1827, SML 1900 in comparison to summer season while in the other five genotypes there was no significant difference in the nematode population in two seasons. The interaction of M. incognita and R. bataticola revealed that higher incidence of root rot disease and maximum decrease in plant growth parameters was recorded in simultaneous inoculation of Meloidogyne incognita and R. bataticola. Of the one hundred two genotypes screened against M. incognita in summer and kharif mungbean; only ten genotypes were found to be moderately resistant. Of the eighty eight mungbean genotypes screened against Rhizoctonia bataticola only ten were moderately resistant. In multiple disease resistance studies, four genotypes which were moderately resistant against both pathogens were evaluated. Breakdown of resistance was observed in ML2581 and ML2560, while ML 2056 showed moderately susceptible reaction and ML2607 was observed to be moderately resistant against both pathogens. Integrated management of root knot nematode and R. bataticola in mungbean revealed that combined application of Bionematon@4l/ha + neem cake@1 t/ha + Captan (seed Treatment) was more effective than the individual application of chemical, bioformulation or cakes.
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Over summering behaviour of Puccinia striiformis f. sp. tritici Erikss., the incitant of yellow rust of wheat and its management
(Punjab Agricultural University, Ludhiana, 2019) Tak, Parminder Singh; Pannu, P.P.S.
Yellow rust of wheat was found to survive in off season on main crop, self grown plants, ratooned plants and abandoned un-harvested plants/ fields in nine regions viz. Janjehli and Rohanda (Mandi), Bhalyani and Pulga (Kullu), Galu (Shimla), Haripurdhar (Sirmaur), Keylong in H.P. and Kargil and Leh in J&K from April to October. Aeciospores of rust from barberry caused chlorotic specks on susceptible wheat cultivar PBW 343, but no further sporulation was observed even after one month. Average minimum temperature influenced incubation period, latent period and disease severity. Incubation period increased to 19 days and 14 days with minimum average temperature above 12˚C and below 6˚C, respectively even when RH was around 90%. Minimum temperature in the range of 7-13˚C, relative humidity ≥ 90%, frequent rains during Feb-March along with winds are congenial for development and spread of yellow rust. No infection developed on barberry under in situ conditions when inoculated with teliospores from wheat. Twenty nine polymorphic SSR primers revealed polyphyletic origin of the races of Pst. Bhutti and Bhalyani (Kullu) isolates grouped together with Pst 46S119 isolate from Santokhgarh adjoining Punjab. Isolates from Sundarnagar (H.P.) grouped with Pst isolate from Fatehgarh Sahib (Punjab). Primer pair Scaffold233-153774 and Scaffold904-62635 were found to differentiate Pst 46S119 and 110S119, respectively. Barberry rust isolates were not amplified by any SSR primers specific to Pst, indicating them to be different from Pst. Early sowing (October) of wheat resulted in highest disease severity and highest area under disease progress curve as compared to November sowings. Out of four wheat varieties tested, PBW 343 was found to give highest AUDPC of upto 2041.7. Fungicides viz. Amistar top 325SC, Amistar xtra 280SC, Custodia 320SC, Opera 175SE and Tilt 25EC @ 0.1%, Nativo 75WG @ 0.6% and Taqat 75WP @ 0.3% were found to give almost complete control of yellow rust along with significant increase in thousand grain weight (26.0 to 30.3 %) and increase in yield varying from 33.3 to 40.2 per cent. Amistar top 325SC reduced the average plant height, but recorded maximum tillers in both the years without any adverse effect on yield. Maximum activity of PAL, PPO and POX was observed in resistant variety PBW 725 as compared to susceptible cultivar HD 2967. Enzyme expression under challenged conditions was more than un-challenged. Highest PAL activity was observed in Nativo, PPO in fermented butter milk and POX activity in Opera, where elevation of 10.8, 1.8 and 5.6 fold, respectively was observed as compared to unchallenged conditions. Timely sowing, varietal diversity, cultivation of resistant/ tolerant varieties, monitoring of crop during December – January, management of initial foci of infection in disease prone areas and timely advisories based on weather forecasting has been found the best strategy for management of yellow rust in Punjab.

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