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  • ThesisItemOpen Access
    VARIABILITY PRESENT AMONG THE ISOLATES OF Pseudomonas spp. IN SAURASHTRA REGION OF GUJARAT 3748
    (JAU JUNAGADH, 2023-08) SAVITA PATIL; Dr. U. M. VYAS; 2010121085
    Management of plant diseases is very important to attain a significant output in a crop production system. There is a great threat to the environment and crop ecosystem due to use of chemical pesticides even though they manage plant diseases effectively. Furthermore, many chemicals are suspected to harm non-targeted organisms and degradation of the environment especially soils. Biological control of plant pathogens by microorganisms and improvement of plant growth by enhancing nutrient uptake by roots is a potential non-chemical eco friendly tool. Members of the genus Pseudomonas have long been known for their potential to reduce the plant disease caused by fungal pathogens and they have gained considerable importance as potential antagonistic microorganisms. A survey was carried out from seven districts of Saurashtra region viz., Bhavanagar, Jamnagar, Rajkot, Porbandar, Junagadh, Gir Somnath and Amreli to collect soil samples from different fields of groundnut. Isolation and maintainance of isolates of Pseudomonas spp. was done by applying dilution plate technique. The colonies developed were yellowish with fluorescence under UV light. To study cultural variability the bacteria were grown on different media viz., Aleksandrow agar, King's B, Potato dextrose agar, Pikovaskay's agar, Pseudomonas agar, MacConkey Agar, and Nutrient agar medium. There was a difference in characteristics of colonies viz., bacterial growth, appearance, pigmentation, colony colour and fluorescence under UV light on seven different culture media. All the isolates of Pseudomonas spp. were screened for siderophore production by the CAS assay. Among thirty isolates tested, 27 isolates of Pseudomonas spp. were positive for siderophore production. Isolates Pf1, Pf5 and Pf12 were negative for siderophore production. Biochemical tests of the Pseudomonas isolates were done by using KB002 Hi Assorted Biochemical test kit (Himedia). The isolates Pf1, Pf10, Pf22 and Pf23 are identified as P. aeruginosa and isolates Pf3, Pf5, Pf9, Pf17, Pf18 and Pf30 are identified as P. putida and all the remaining isolates are characterized as P. fluorescens. Among the isolates of Pseudomonas spp. tested for their efficacy against the four soil borne fungal plant pathogens under in vitro condition, five isolates of Pf were effective in variable degrees against Aspergillus niger, Sclerotium rolfsii, Macrophomina phaseolina and Fusarium sp. Isolate Pf12 was most effective in inhibiting A. niger, whereas isolate Pf30 was less effective. Isolate Pf26 was most effective in inhibiting S. rolfsii, whereas, isolate Pf3 was less effective. Isolate Pf2 was most effective in inhibiting M. phaseolina, whereas, isolate Pf17 was less effective. Isolate Pf21 was most effective in inhibiting Fusarium sp. whereas, isolate Pf9 was less effective. Isolate Pf24 was found common among five highly antagonistic isolates in inhibiting mycelial growth of all four soil borne pathogens. Highly antagonistic Pseudomonas isolate i.e., Pf24 was tested for compatibility with fungicides, insecticides and weedicides at different concentrations. Among fungicides tested, the isolate was highly compatible with carbendazim followed by carbendazim 25% + mancozeb 50% WS. Whereas, hexaconazole was least compatible with isolate Pf24. Among insecticides tested, the isolate was highly compatible with fipronil followed by carbosulfan. Whereas, chlorpyriphos was least compatible with isolate Pf24. Among insecticides tested, the isolate was highly compatible with pendimethalin followed by quizalofop ethyl. Whereas, propaquizafop was least compatible with isolate Pf24. In pot culture studies the isolate Pf24 showed lowest disease incidence percentage of 45% compared to control in case of collar rot of groundnut. The isolates Pf2, Pf15 and Pf24 showed lowest disease incidence of 40% compared to control in case of root rot of chickpea. The isolates Pf4, Pf21 and Pf24 showed lowest disease incidence percentage of 50% compared to control in case of wilt of cumin
  • ThesisItemOpen Access
    CHARACTERIZATION OF PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) AGAINST SOIL BORNE FUNGAL PATHOGENS INFECTING CHILLI 3679
    (JAU,JUNAGADH, 2023-05) GHADIYA ROMIT HEMANTBHAI; Dr. J. R. Talaviya; 2010121020
    Chilli (Capsicum annuum L.) is one of the most important vegetable as well as spice and a cash crop of India which is priced for its pungency. Chilli is consider as one of the major crop of Saurashtra and major soil borne diseases viz., wilt and collar rot attack at different stages of crop growth and reduced the yield significantly. Therefore, a systematic study was undertaken to isolate native strains of rhizobacteria from major chilli growing areas of Saurashtra regions in order to test their efficacy, their mechanisms of bio control and assessment of plant growth promotion. The experiments were carried out from 2022-23 at the Department of Plant Pathology, College of Agriculture, Junagadh Agricultural University, Junagadh. A total 42 rhizosphere soil samples along with chilli roots were collected from the chilli fields of Saurashtra regions for the isolation of efficient PGPR strains. Total 60 PGPR isolates were isolated by serial dilution method on Bacillus medium, Pseudomonas Agar (For Fluorescein), Actinomycetes Agar and Nutrient Agar media. Further identification based on gram staining, morphological and cultural characteristics and then biochemical characterization were done by using HiAssorted Biochemical test kit for gram positive bacteria (KB013) and HiAssorted Biochemical test kit for gram negative bacteria (KB002) were used for identification. Based on morphological and biochemical charcterization, 13 isolates of Pseudomonas spp., 28 isolates of Bacillus spp. and 19 isolates of Actinomycetes spp., which belongs to genera Streptomyces were identified.
  • ThesisItemOpen Access
    ALTERNARIA LEAF SPOT [Alternaria alternata (Fr.) Keissler] OF BRINJAL AND ITS MANAGEMENT 3678
    (JAU,JUNAGADH, 2023-05) SUDANI DAX PRAVINKUMAR; Dr. K. K. Kanzaria; 2010121058
    Brinjal (Solanum melongena L.) is an important vegetable crop of Saurashtra belongs to the Family: Solanaceae. In India, it is grown throughout the country. It is known to affect by many parasitic diseases. Among them, Alternaria leaf spot caused by Alternaria alternata is an important disease of brinjal, which diminish the quality and yield under field condition. Considering the economic importance and regular occurrence of the disease in moderate to severe form in Saurashtra region, the present study on "Alternaria leaf spot [Alternaria alternata (Fr.) Keissler] of brinjal and its management" was carried out at the Department of Plant Pathology, Junagadh Agricultural University, Junagadh using fungicides and also to identify the available genotypes/varieties resistant against the disease under field condition. Naturally infected leaf sample of brinjal showing the typical characteristics symptoms of Alternaria leaf spot disease were collected from the Vegetable Research Station, JAU, Junagadh. Isolation of the fungus was made by using tissue isolation method and purified by single spore isolation technique on PDA medium. The symptoms initially characterized by small, necrotic, scattered, brown, circular spots with varying size. Later on, it becomes irregular in shape with typical concentric rings, which coalesced to form big irregular patches on leaves exhibited blighted appearance and eventually, results into withering and shedding of the leaves. Pathogenicity of A. alternata was proved by adopting four distinct artificial inoculation techniques on brinjal leaves viz., pin prick, tooth brush injury, injury by carborundum powder and spray without injury. Each inoculation techniques effectively proved the pathogenicity. However, pin prick inoculation method was more effective than other techniques.
  • ThesisItemOpen Access
    PATHOLOGICAL ASPECTS OF WILT AND ROOT ROT COMPLEX IN CHICKPEA (Cicer arietinum L.) AND THEIR MANAGEMENT 3653
    (JAU JUNAGADH, 2023-02) BHALIYA CHIRAGKUMAR MANSUKHBHAI; Dr. H. J. Kapadiya; 1010119030
    Globally, pulses are considered as the second most common food source after cereal crops with high protein, vitamins and minerals content. The significance of pulses is much more in countries like India, where the majority of the people are vegetarians. Among the pulses, chickpea (Cicer arietinum L.) popularly known as bengal gram or chana is one of the important pulse crop grown in temperate, sub-tropical and tropical climate throughout the world. The several biotic and abiotic stresses become the prime reason for its low productivity. Among the different biotic stresses, wilt and root rot complex is considered the most important, devastating and challenging disease that becomes major limiting factor in successful cultivation of chickpea crop in Saurashtra region of Gujarat state. The management of chickpea wilt and root rot complex is quite difficult to achieve, as pathogens are soil borne in nature and survive in the soil for many years even in the absence of host by producing resistant structures i.e. chlamydospores and sclerotia. The effective control measures against this disease are not available till date. Considering the importance of this disease, the present investigation was performed to develop the most effective and eco-friendly management strategies to manage this soil borne complex disease. The pathogens can infect the crop at any stage of its growth. The disease characterized by shrinking of the collar region, drooping and chlorosis of petioles and leaves, internal discolouration of xylem vessels followed by rotting of tap roots with shredding of bark and lateral roots. The isolations were made from infected chickpea plant roots showing characteristic symptoms, revealed the association of Fusarium oxysporum f. sp. ciceri, Fusarium solani and Macrophomina phaseolina. Based on cultural and morphological characters, chickpea wilt and root rot complex pathogens were identified as F. oxysporum f. sp. ciceri, F. solani and M. phaseolina and further confirmed with molecular identification based on 18s rDNA ITS sequencing with NCBI accession number OP107270.1 (F. oxysporum f. sp. ciceri), OP102548.1 (F. solani) and OP094831.1 (M. phaseolina). The ITS rDNA region-based sequencing of M. phaseolina proved accurate for species-level identification of the pathogen, whereas Fusarium spp. were identified based on the multilocus analysis of the ITS region, TEF1-α and β-TUB gene. The phylogenetic trees were also constructed and compared with other similar worldwide fungal isolates available in the NCBI database. Out of sixty-five fungal isolates collected, thirty isolates of F. oxysporum f. sp. ciceri, twenty-five isolates of F. solani and ten isolates of M. phaseolina were observed that were designated as Foc, Fs and Mp, respectively. The frequency of occurrence of F. oxysporum f. sp. ciceri was high (46.15%) among all the samples collected followed by F. solani (38.46%) and M. phaseolina (15.39%). All the representative fungal pathogens isolated from infected plants were found pathogenic in pathogenicity test employed by soil and seed inoculation method. Abstract The survey was conducted to identify wilt and root rot complex hot spots and disease free areas in major chickpea growing tracts of Anand, Amreli, Bhavnagar, Jamnagar, Junagadh, Porbandar and Rajkot districts of Gujarat state. Out of ninety fields surveyed, eighteen fields were noted free from disease or near about negligible disease incidence (less than 5 per cent) whereas, seventy two fields were recorded as infected with the disease in a range of 1.25-52.78 per cent.The villages of Porbandar district viz, Madhavpur (52.78%), Kadegi (47.50%), Amipur (45.93%) and Ratia (40.65%) were identified as highly prone areas to wilt and root rot complex. The Fusarium spp. produce dense to sparse, fluffy to flat, white to pale yellow, pale violet, orange or pink colour colony with regular to irregular margin. It also produced hyaline, septate or aseptate, oval/ellipsoid to reniform/oblong, slightly curved/straight microconidia and 2-5 septate, sickle shape with pointed or blunt end macroconidia as well as globose/spherical to oval/pear, terminal or intercalary chlamydospores. M. phaseolina produced aerial, fluffy, compact, partial submerged, greyish white to blackish/brownish grey mycelium with spherical/circular to oval/oblong black microsclerotia. All the isolates of F. oxysporum f. sp. ciceri, F. solani and M. phaseolina exhibited tremendous variability in their cultural and morphological characters. The colonies of different isolates differed considerably with regard to their colony colour, texture, pigmentation and sporulation. The glaring differences in the size and shape of conidia/chlamydospore/sclerotia were also noticed among the isolates. The twelve isolates of F. solani and fifteen isolates of F. oxysporum f. sp. ciceri demonstrated the fast growth rate. Among 105 varieties/germplasm screened, none showed immune response against the wilt and root rot complex disease, whereas nine varieties/germplasm viz., WR-315 (6.26%), Phule G-08108 (6.33%), AKG-1303 (7.49%), JG 315 (7.89%), GJG 1713 (9.17%), GJG 2002 (9.44%), GJG 2015 (9.49%), GJG 1820 (9.69%), PUSA-256 (9.88%) were found as resistant, thirty seven were moderately resistant, thirty six were moderately susceptible, seventeen were susceptible and six were highly susceptible. The biochemical alteration in infected roots as compared to healthy roots revealed that sugar and protein content were maximum in healthy root of chickpea, while phenol content was maximum in infected root. The minimum decreased in protein (32.48%) and sugar (24.48%) content and maximum increase in phenol content (30.69%) was recorded in resistant germplasm (WR 315). Out of nine antagonists evaluated in vitro against wilt and root rot complex causing pathogens by dual culture technique, T. harzianum showed strongest antagonistic activity against F. oxysporum f. sp. ciceri (87.28%), while B. subtilis found to be the best antagonist against F. solani (84.62%). With respect to M. phaseolina, the maximum per cent growth inhibition was observed in T. virens (70.98%). In field condition, seed biopriming treatment for 10 hrs with the suspension of talc-based formulation of B. subtilis (1x108 CFU/g) @ 50 g in 250 ml of water/kg of seed remained the best treatment with minimum disease incidence (4.79%), maximum seed yield (2339 kg/ha), seed germination (97.10%), root (12.62 cm) and shoot (25.05 cm) length as well as vigour index (3021). The chickpea wilt and root rot complex disease was effectively managed under irrigated field conditions by soil application of B. subtilis (1x108 CFU/g) @ 5 kg/ha enriched in 500 kg FYM/ha as it recorded minimum disease incidence (15.24%) and highest seed germination (96.55%) and seed yield (2228 kg/ha). While, soil application of T. harzianum (2x106 cfu/g) @ 5 kg/ha enriched in 500 kg FYM/ha was found most effective under unirrigated field condition with 96.87 per cent seed germination, 7.60 per cent disease incidence and 1383 kg/ha seed yield.
  • ThesisItemOpen Access
    COWPEA STEM ROT [Sclerotium rolfsii Sacc.] AND ITS MANAGEMENT 3565
    (JAU,JUNAGADH, 2022-09) BAVALIYA MEENABEN MANSANGBHAI; Dr. I. B. Kapadiya
    Cowpea [Vigna unguiculata (L.) Walp] is an important food legume belonging to the family Fabaceae and growing across the world many tropical and subtropical regions. Cowpea is considered as a nutrient dense food and also known as “poor man’s meat”. Stem rot is common disease of cowpea caused by Sclerotium rolfsii and is epidemic which had been reported in worldwide warm moist climate condition. The disease appears at any growth stage of plant and causes severe damage with great yield loss.
  • ThesisItemOpen Access
    LEAF BLIGHT (Alternaria macrospora Zimm.) OF COTTON AND ITS MANAGEMENT 3634
    (JAU JUNAGADH, 2022-10) CHAUDHARI RAMESHKUMAR JETHABHAI; Dr. D. S. Kelaiya
    The present investigation was undertaken to manage cotton (Gossypium spp.) leaf blight disease caused by pathogenic Alternaria macrospora Zimm., which is quite destructive in all the cotton growing areas. During last few decades, the area and production of this crop has shown a positive trend and it’s a most important commercial crops of the world. Cotton is attacted by many fungal diseases among them, leaf blight is most destructive in Saurashtra region of Gujarat. Cotton plants showing typical symptoms of leaf blight were collected from Cotton Research Station, Junagadh Agricultural University, Junagadh and pathogen was isolated on Potato dextrose agar medium. On the basis of cultural and morphological characters, it was identified as Alternaria macrospora. Conidiophores were short or long dark brown bearing single but some time two conidia in chain at the tip and 40-110 × 6.2-12.4 µm in size with 1 to 6 septa. Conidia were dark to reddish brown with usually 4 to 6 transverse and 2 longitudinal septa and size measured 16.2-51.4 × 6.8-18.3 µm. Impact of different meteorological parameters on development of leaf blight on cotton, first leaf blight symptoms were appeared on 37th and 39th standard meteorological week during 2020-21 and 2021-22, respectively. In correlation study, maximum temperature was non-significant with negative effect on leaf blight disease development in year 2020-21, while maximum temperature was also non-significant but positive effect leaf blight disease development in year 2021-22. Minimum temperature was non-significant with negative effect in year 2020-21 and 2021-22, respectively. Morning and evening relative humidity was significant and highly significant in both years, respectively and wind speed opposite to RH. Regression study, in year 2020-21 reflect that one per cent increase in morning relative humidity and wind speed led to corresponding decrease in per cent disease index of Alternaria blight in 2020-21 and 2021-22. Maximum seed cotton yield of 2269 kg/ha was recorded in treatment plot of hexaconazole + captan (0.1%) at 55, 75, 95 and 115 DAS with maximum percent disease control (61.10% PDC) and maximum avoidable yield loss (29.44%). Hexaconazole + captan (0.1%) at 55, 75, 95 and 115 DAS proved the most effective in controlling the disease in field condition for two seasons with higher yield. Among different varieties/genotypes were screened against A. macrospora under natural conditions, none of the entries was found immune at 90 DAS, 31 entries showed resistant reaction, 18 showed moderately resistance or tolerant reaction and only one entries GBHV 241 was found moderately susceptible. Thirteen entries were showed resistant reaction, 25 entries showed moderately resistance or tolerant reaction and 12 entries found moderately susceptible. None of the entries was found highly susceptible at 120 DAS. Various fungicides were evaluated under laboratory conditions at different four concentrations. Among them, maximum mean spore germination inhibition (90.83%) was found in the treatment of hexaconazole 5% + captan 70% WP which was at par with propiconazole 25% EC (88.89%). Among nine plant extracts @ 5, 10 and 15% tested against A. macrospora under in vitro, growth inhibition ranged from 34.32 to 51.97 per cent. Maximum radial growth inhibition was found by Datura stramonium (Daturo) (51.97%), followed by Cascabela thevetia (Karen) (48.27%). Minimum growth inhibition recorded in Calotropis gigantea (Ankado) (34.32%). Field evaluation of nine fungicides carried out during Kharif 2020-21 and 2021-22. Among them, hexaconazole 5% + captan 70% WP (0.1%) was found the most effective fungicide with 16.58 per cent disease intensity and maximum disease control of 55.42 per cent. Maximum seed cotton yield (2346 kg/ha) and maximum avoidable yield loss (36.49%) was also recorded in treatment of hexaconazole 5% + captan 70% WP at 0.1%. Biochemical analysis of healthy and diseased plant of cotton revealed decreased amount of total chlorophyll and total phenol content in diseased leaves as compare to healthy leaves. While in the case of gossypol, increase in diseased leaves compared to healthy leaves. All the biochemical parameters decrease with increase the age of plant except phenol
  • ThesisItemOpen Access
    GREEN GRAM DRY ROOT ROT [Macrophomina phaseolina (Tassi) Goid.] AND ITS MANAGEMENT 35
    (JAU,JUNAGADH, 2022-09) MATHUKIYA HARIYALI VIJAYB; Dr. I. B. Kapadi; 2010120057
    Green gram [Vigna radiata (L.) Wilczek] is one of the important pulse crop of India and also known as mungbean. It belongs to the family Fabaceae and it is an excellent source of high-quality protein. Dry root rot disease caused by the soil and seed borne fungus M. phaseolina is a major limiting factor in the green gram production. Dry root rot also known as charcoal rot. It is economically more important in the tropical and sub-tropical areas of the world having arid climate. The causative organism isolated from the infected root of green gram plant was cultured and the isolated pathogen was identified as M. phaseolina (Tassi) Goid. based on cultural and morphological characters, young mycelium was white in colour and it turned into dark at maturity. The fungus produced sclerotia, pycnidia and pycnidiospores. The microscopic observation revealed that mycelium was hyaline, thin walled, light brown to dark brown in colour and having more septa with branching of hyphae was at right angle and constrictions observed at point of branching. The sclerotia were irregular in shape and size with measuring form 95-130 x 70-150 µm with an average of 95 to 112 µm in size. Pycnidia were ostiolate, globose, dark brown and opening by apical having multicellular wall with heavily pigmented thick-walled cells on the outer surface of host tissue and measured 100-169 µm in diameter. Pycnidiospore were hyline, ellipsoid to ovoid in shape measurin
  • ThesisItemOpen Access
    VARIABILITY PRESENT AMONG THE ISOLATES OF Macrophomina phaseolina (Tassi) Goid. CAUSING ROOT ROT OF CASTOR AND ITS MANAGEMENT 3556
    (JAU,JUNAGADH, 2022-09) PIPROTAR JIGNESHKUMAR GOVINDBHAI; Dr. K. K. KANZARIA
    Groundnut (Arachis hypogaea L.) is a leguminous oilseed crop belonging to the family Fabaceae and referred to as “King of oilseeds”. The word Arachis hypogaea derived from two Greek words Arachis meaning a legume and hypogaea meaning below ground. It is originally native of Brazil and was expanded world-wide from its main centre West Africa, from where it was introduced into French colonial possessions and thereafter overflowed into other parts of the world. The groundnut crop is reported to affect by many biotic and abiotic factors and causes considerable loss in pod and haulm yield. Among the different diseases of groundnut, root rot caused by Aspergillus niger is an economically important in India. It is emerging as a major and widespread problem in the Saurashtra region since last few years causing pre-emergence seed rot and post-emergence seedling rot. Considering the importance of disease in Saurashtra region, the present study on “Collar rot (Aspergillus niger van Tieghem) of groundnut and its management” was undertaken at Research Farm of the Department of Plant Pathology, Junagadh Agricultural University, Junagadh.
  • ThesisItemOpen Access
    VARIABILITY PRESENT AMONG THE ISOLATES OF Macrophomina phaseolina (Tassi) Goid. CAUSING ROOT ROT OF CASTOR AND ITS MANAGEMENT 3555
    (JAU,JUNAGADH, 2022-09) LAVANYA N; Dr. D. S. KELAIYA; 2010120050
    Castor (Ricinus communis L.) is one of the most important non-edible oilseed crop in the world. It is a species of flowering plant in the spurge family, Euphorbiaceae. The Ricinus communis plant’s seeds contain more than 45 per cent oil that is rich in triglycerides, primarily ricinolein oil. Castor oil and its derivatives have long been used as a lubricant, and as a result, they have wide range of commercial applications. Though castor is seriously affected by many diseases, root rot caused by Macrophomina phaseolina (Tassi) Goid. is one of the devastating serious disease of castor. More or lessregular occurrence of this disease in moderate to severe form causes considerable yield losses in many pockets of Saurashtra region of Gujarat.