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Subject: Microbiology × End date: 2019 × Start date: 2019 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Evaluation of plant growth promoting actinomycetes on chickpea (Cicer arietinum L.)
    (CCSHAU, 2019) Kavita Rani; Leela Wati
    Chickpea is the second most important cold season food legume grown globally on a very wide area. However, global yields of chickpea have been relatively stagnant for the last two decades due to unpredictable climatic changes, incidence of diseases and extensive application of chemical fertilizers and pesticides. Actinomycetes are one of the major components of rhizosphere microbial population and are useful in soil nutrient cycling as well as plant growth-promotion. Since last few years, studies on beneficial traits of actinomycetes regarding plant growth promotion and biocontrol activities had opened new avenues for their applications in sustainable agriculture. In the present investigation, total 40 (AK1-AK40) actinomycete isolates were retrieved from different soil samples and chickpea nodules collected from CCS Haryana Agricultural University, Hisar farms. All the isolates were assessed for different plant growth promoting traits including IAA production, P solubilization (P-SI), Zn solubilization (Zn-SI), siderophore production, HCN production, salt tolerance, biocontrol potential against F. oxysporum, ACC utilization and ammonia excretion. Based on the results of various PGP traits, isolate AK3 with high P-SI (2.78) and Zn-SI (3.92); AK6 with high HCN production; AK11 with good P-SI (2.70) and Zn-SI (3.27) and AK34 with high IAA production (20.95μg ml-1) were evaluated for growth promotion of chickpea under pot culture conditions. Isolate AK3 found promising in terms of nodulation, growth and yield parameters under pot culture conditions was evaluated on chickpea variety HC-5 under field conditions (during 2017-2018). Coinoculation of AK3 along with Mesorhizobium 1233 was beneficial for plant growth and yield of chickpea. The promising actinomycete isolate AK3, identified as Streptomyces griseoruber on the basis of partial 16S rDNA sequencing, can be further tested on different locations for use as biofertilizer.
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    ThesisItemOpen Access
    Effect of conservational practices on physico-chemical and microbiological properties of soil under different cropping systems
    (CCSHAU, 2019) Yadav, Dhinu; Leela Wati
    Tillage is the mechanical disturbance of soil through plowing, cultivation or digging and has been used by the farmers since ancient time that influence physical, chemical and biological properties of soil. Conventional tillage practices may adversely affect long-term soil productivity due to erosion and loss of organic matter in soils. Conservation tillage is the practice in which at least 30% of crop residues are left in the field during sowing, thus reduce soil erosion. The advantages of conservation tillage practices over conventional tillage include reducing cultivation cost, and building up soil organic matter. Conventional tillage can lead to soil microbial communities dominated by aerobic microorganisms, while conservation tillage practices increase microbial population and activity as well as microbial biomass. Long-term no tillage application increases organic carbon content, positively affecting not only soil structure, but also microbiota activity. The effect of tillage on soil microbial population has generally been studied by comparing microbial numbers, soil microbial community enzyme activities (dehydrogenase, phophatase, cellulase and urease) and microbial biomass. Enzymes are responsible for carrying out mineralization of different soil nutrients such as phosphatase for P, urease for N and dehydrogenase represents total microbial activity of soil. In the present study, soil samples (0-15 and 15-30 cm depths) were collected after harvesting of wheat from different fields under different crop rotations and analyzed for various physico-chemical and microbiological properties. The long- term zero tillage in different cropping systems affected the soil physical properties such as bulk density at 0-15 and 15-30 cm depths in the different textured soils and it was comparatively higher at 0-15 cm depth as compared to 15-30 cm depth under zero-tillage and vice-versa under conventional tillage. Chemical properties of soil such as EC, pH were not significantly affected at different depths under zero and conventional tillage but CaCO3 content of different soil samples was affected by different tillage practices at different locations to different extent. Total N, P and K and available N, P, K and S and ammonical-N, nitrate- N contents were higher at surface layer under zero-tillage. Various microbiological properties like microbial biomass carbon and nitrogen, enzymatic activities i.e. dehydrogenase, alkaline phosphatase, cellulase and urease and viable counts of bacteria, fungi, actinomycetes, Azotobacter and P solubilising bacteria were affected by tillage system under different cropping patterns. The C and N mineralization rate was found more pronounced at 0-15 cm depth but variable at different locations. Functional microbial diversity at different locations was changing with passage of time, indicating that microbial diversity changed with adoption of no-tillage practices.
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    ThesisItemOpen Access
    Growth stimulation of pigeon pea (Cajanus cajan L.) by using antagonistic rhizospheric bacteria
    (CCSHAU, 2019) Sharma, Ruchi; Sindhu, S.S.
    Pigeon pea (Cajanus cajan L.) is one of the important grain legume crop in the developing countries of the tropical and subtropical regions of the world. It is an excellent source of protein (20-22%), supplementing energy rich cereal diets in a mainly vegetarian population. One of the major factors adversely affecting pigeon pea productivity is poor nodulation in fields due to prevalence of poor nodulating native rhizobia. Moreover, the crop productivity of pigeon pea is also adversely affected by biotic stresses such as Fusarium wilt (FW), Alternaria blight and Rhizoctonia root rot disease. In the present study, 83 rhizobacterial isolates and 24 rhizobial isolates were isolated from different soil samples. Screening of the isolates for antagonistic activity against three Alternaria tenuissima, Fusarium udum and Rhizoctonia bataticola showed that only 21% of the rhizobacterial isolates inhibited the growth of all the three pathogenic fungi. Four isolates i.e., HPR6, HPR22, HPR71 and HPR78 showed more than 4.0 halo zone to growth ratio against Alternaria tenuissima wheareas three isolates i.e., HPR37, HPR41 and HPR42 showed more than 4.0 halo zone to growth ratio against Fusarium udum and 3 isolates i.e., HPR5, HPR71 and HPR78 showed more than 4.0 halo zone to growth ratio against Rhizoctonia bataticola. Out of the 24 rhizobial isolates tested only 2 isolates i.e., RPR17 and RPR24 showed inhibition activity against all the three pathogenic fungi. Bradyrhizobial isolate RPR16 showed maximum halo-zone to growth ratio i.e., 4.78 against Fusarium udum. Five rizobacterial isolates i.e., HPR49, HPR77, HPR80, HPR83 and HPR17 showed significant ACC utilization activity. Eight isolates i.e. HPR54, HPR58, HPR59, HPR65, HPR67, HPR71 and HPR83 produced IAA ranging from 12.3-26.31 μg/ml. Rhizobacterial isolates showed ALA production in the range of 0.1-23.45 μg/ml. Potassium solubilization studies showed that 28 isolates showed significant activity in the range of 4.1-6.0 and 42 rhizobacterial isolates showed KSI in the range of 2.1-4.0. The ability of siderophore production was found in only 41% of the rhizobacterial isolates. Significant cyanide production was observed in isolate HPR40 i.e., 76.54 μl/ml. Among the 83 rhizobaterial isolates, only six isolates i.e., HPR1, HPR36, HPR39, HPR15, HPR48 and HPR69 showed growth up to 8% NaCl salt concentration, whereas 26 isolates showed growth up to 4% salt with different colony size. Maximum increase in SDW (101.85%) was observed by co-inoculation of isolates RPR17+HPR78 followed by 97.68% increase in SDW by inoculation of isolate RPR17+HPR78 at 45 days of pigeon pea growth under chillum jar conditions. Coinoculation of isolates RPR17 + HPR78 and RPR17 + HPR17 resulted in 86.95 and 83.18% increase in RDW, respectively. Likewise, 108.59% increase in SDW was observed on inoculation of RPR17 + HPR78 isolates followed by 118.3 and 94.05% increase in SDW on inoculation of RPR17+HPR17 isolates, respectively at 60th day of observation. The inoculation effect of four antagonistic i.e., HPR17, HPR40, HPR49 and HPR78, and two bradyrhizobial isolates i.e., RPR19 and MRH46 was studied under pot house conditions on pigeon pea growth. At 45 DAS, the coinoculation treatment of RPR19 + HPR40 alongwith F. udum showed maximum nodulation i.e., 26 nodules/plant and 79.59 and 98% increase in SDW and RDW, respectively. At 60 DAS, the coinoculation treatment of RPR19 + HPR17 showed maximum nodulation i.e., 31 nodules/plant and 37.10 and 21.70% increase in SDW and RDW, respectively. At 75 DAS, coinoculation of RPR19 + HPR40 showed maximum nodulation i.e., 52 nodules /plant and showed significant increase in root and shoot dry weight of pigeon pea under pot house conditions. Rhizobacterial isolates HPR78 showed 100% disease control of F. udum at different stages of pigeon pea growth under pot house conditions. Coinoculation treatments i.e., RPR19 + HPR49 showed 100% disease control of Fusarium wilt at different stages of pigeon pea growth under pot house conditions. Rhizobacterial isolates HPR40 and HPR78 were identified as Pseudomonas aeruginosa strain SSR207 and Paenibacillus polymyxa strain SSR2_207. These plant growth promoting rhizobacterial isolates can be used for the enhancement of crop productivity under salinity stress in field conditions.
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    ThesisItemOpen Access
    Evaluation of thermotolerant bacteria for growth and yield of summer mungbean (Vigna radiata L.)
    (CCSHAU, 2019) Parashar, Atul; Leela Wati
    Mungbean (Vigna radiata (L.) Wilczek), also known as green gram, is one of the important pulse crops of India. Mungbean is grown during spring, summer and kharif season in Northern India, while grown during Rabi season in Southern India. Summer mungbean being a crop of very short duration is grown after the harvesting of wheat and before sowing autmn crops.Various environmental stresses hamper the productivity of mungbean among which temperature plays key role.Plant growth promoting bacteria can play important role in increasing crop productivity and relieving environmental stress.In the present study, mungbean rhizobial and non-rhizobial bacterial isolates available in Plant Microbial Interaction Laboratary Deptt. of Microbiology, CCSHAU, Hisar were assessed for temperature tolerance and various plant growth promoting traits viz.IAA production,Ammonia excretion, P-solubilization, Siderophore production, ACC utilization and HCN production at different temperatures. Out of nine rhizobial isolates, only five isolates and out of five non rhizobial bacterial isolates four isolates were able to grow up to 450C.Under in vitro conditions rhizobial isolates MRH59 and MRH46 and non rhizobial isolates E13 and E17 were adjudged as promising plant growth promoting thermotolerant bacteria. All thermotolerant rhizobial isolates were tested for nodulation efficiency under sterilized conditions. Maximum nodule no.(16.67/plant) was, observed in isolate MRH 59.On the basis of various plant growth promoting traits and nodulation test isolates MRH59,MRH46 ,E13 and E17 were selected for plant growth promotion of mungbean (MH-421) under pot culture as well as field conditions during summer season. Nodulation efficiency and seed yield was better when thermotolerant rhizobial isolate MRH 59 was coinoculated with thermotolerant nonrhizobial bacterial isolate E13 in comparison to coinoculation of Rhizobium (MB703 reference culture) and phosphate solubiliser P-36 (reference culture).Under field conditions seed yield was 27.84% higher on coinoculation of rhizobial isolate MRH59 and non rhizobial isolate E13 suggesting that thermotolerant bacteria exerted beneficial effect on mungbean due to multiple plant growth promoting traits.
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    ThesisItemOpen Access
    Molecular diversity of indigenous rhizobial population infecting chickpea (Cicer arietinum L.)
    (CCSHAU, 2019) Swati; Gera, Rajesh
    Chickpea is one of the most important legume crop in India and the world‟s second most cultivated legume grown as a winter crop in Indian subcontinent. It is highly rich in good quality proteins and mainly used in vegetarian diet. A total of 52 rhizobial isolates were included in the present study, out of which 48 rhizobial isolates were retrieved from nodule samples collected from four different districts of Rajasthan and 4 chickpea rhizobial isolates were obtained from departmental culture collection. Screening of these rhizobial isolates for abiotic stress tolerance showed that almost all the rhizobial isolates tested were able to grow up to 30°C. However, 36 and 5 rhizobial isolates showed good growth at 35 and 40°C, respectively. Similarly all the rhizobial isolates showed growth at 100 mM NaCl concentration. However, increase in NaCl concentration from 300 mM to 500 mM significantly reduced the growth of most of the rhizobial isolates. In addition only 25 isolates showed growth upto 40% PEG concentration. On the basis of abiotic stress tolerance, 24 rhizobial isolates were selected, which further characterized for different PGP traits. Ten isolates showed phosphate solubilization on Pikovskaya,s agar medium plates. The P-solubilization index of these isolates varied from 2.15-3.33. Fifty percent of rhizobial isolates were also found to be bacteriocin producer. However, only 7 rhizobial isolates showed siderophore production. The ammonia excretion and IAA production was observed in all the rhizobial isolates which varied from 1.79 to 4.89 μg/ml and 2.32 to 57.06 μg/ml, respectively. ACC utilization was observed in 96% rhizobial isolates. Genomic DNA of all the stress tolerant rhizobial isolates showed the presence of nodC gene however, only 18 rhizobial isolates showed the presence of nifH gene using two different sets of gene primers i.e. 19F, 407R and nifH1, nifH2. Genomic DNA of all the selected chickpea rhizobial isolates were also amplified for 16S rRNA gene using 27F and 1378R primers. The 16S rRNA amplified product was subjected to RFLP analysis with MspI and HaeIII restriction enzymes. Dendrogram based on restriction analysis showed enormous diversity among themselves with both of the restriction enzymes. Three chickpea rhizobial isolates i.e., CPR40E, CPR59A and CPR24B were found as most efficient rhizobial isolates on the basis of nodulation efficiency and plant growth promotion parameters in pots under screen house conditions. These rhizobial isolates can be used as potential biofertilizer for rain-fed areas after testing their efficacy under field conditions.