Impact of Climate Variability on Groundnut Rust (Puccinia arachidis Speg.) at Hot Semi-Arid Region of Gujarat

Severity of groundnut rust disease caused by pathogen Puccinia arachidis Speg was studied over eight kharif seasons between 2010 and 2020 at Junagadh located in hot semi-arid eco region under agro climatic zone of Gujarat plains and hills. Rust severity was measured on five cultivars (GG 20, GJG 22, TG 37A, TLG 45 and Western 66) grown during three sowing periods (May II fortnight, first and second fortnights of June). Climatic variability for the kharif period of groundnut cultivation was quantified for three climatic variables viz., temperature (maximum and minimum) and rainfall so as to relate to rust severity. The rust progressions in respect of seasons aggregated over cultivars and sowing time on calendar and crop age basis indicated varying duration and severity of the disease. Mean rust severity differed significantly across seasons, cultivars and sowing periods. The rust severity was significantly higher in 2011, GJG 22 and June (both first and second fortnight) sowings, respectively. Although the progression of rust severity varied on calendar as well as crop age basis amongst cultivars, the disease commencement in respect of sowing times was during 34th standard meteorological week (third week of August) coinciding with crop age of eight weeks. Magnitude of climatic variability worked out for kharif of 2011-2020 over long term normals (40 years’ average) indicated a significant change in respect of maximum temperature ( + 0.7 °C) and rainfall ( + 16.9 mm/week). The significant impact of climatic variability on rust severity over seasons indicated positive and negative association of the unchanging minimum temperature and increasing rainfall, respectively. Climate variability impacts on rust severity brought out CJG 22 and TLG 45 as climate resilient cultivars, and sowing groundnut during second fortnight of May as an adaptive practice for recommendation to farmers under the current climate change scenario

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Not AvailableBio-efficacy of Acorus calamus for in managing Caryedon serratus in peanutNot Availabl

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Not AvailableCluster analysis using Mahalnobis D2 was performed using 97 groundnut diverse genotypes for 14 yield contributing and water use efficiency related traits. The genotypes were grouped into twelve clusters based on D2 statistic. Cluster II was the largest with 54 genotypes followed by cluster I with 33 genotypes and remaining ten clusters had one genotype each. The inter cluster D2 values revealed maximum divergence between cluster VI and cluster III (1736), followed by cluster XII and cluster III (1622); cluster VI and cluster X11 (1389); cluster IX and cluster XI (1171) and cluster XI and cluster II (1041). It was observed that plant height was the largest contributor (65%) towards genetic divergence followed by days to maturity (10%) and secondary branches per plant (10%), SPAD Chlorophyll Meter Reading (SCMR; 4.3%) kernel length and hundred pod weight (1.2%) and Specific Leaf Area (SLA; 0.06%) contributed the least for divergence. Estimates of GCV and PCV were high for plant height, primary and secondary branches and pod yield per plant indicating higher genetic variation present in the genotypes studied. High heritability coupled with high genetic advance as per cent of mean was observed for days to fifty per cent flowering, secondary branches per plant, hundred pod and kernel weight, kernel length and, SCMR. SLA exhibited moderate estimates of heritability and genetic advance as per cent of meanNot Availabl

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Developing Disease-Suppressive Soil Through Agronomic ManagementSoilborne plant pathogens are major limitation in most of the agroecosystems for production of sustainable yield. These pathogens produce resting bodies in the soil which are long lasting and difficult to eliminate. Various approaches have been used to prevent, mitigate, or control the plant diseases. Considering limitations in the practices for managing plant disease through genetic resistance in the host plants and use of synthetic chemicals, focus was given to the management of the plant and its environment through agronomic managements. Soil properties, soil microbiome and its diversity, and nature of the crops and its root system are altered for the development of suppressive soil to manage the soilborne pathogens through one or more mechanisms like antibiosis, allele-chemicals, competition for niche and nutrients, root camouflage, parasitism and induce resistance, etc. Agronomic management practices, viz., tillage, soil solarization, use of organic amendments, organic manures including green manures, crop rotation, bio-fertilizers and biocontrol agents, etc., manipulate the soil–plant–microbial system favorably to the development of suppressive soil and to crop for sustainable high yield.Not Availabl

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Arbuscular Mycorrhizal Fungi (AMF) for Sustainable Soil and Plant Health in Salt-Affected SoilsContinuous utilization of quality land in civilization and industrialization has gained interest in the utilization of salt-affected soils for crop production. However, crop growth and productivity is severely affected in saline soil. Many strategies were proposed to overcome the salt detrimental effects like development of salt-tolerant cultivars through breeding and/or genetic engineering, removal of excessive salt accumulation in soil, desalinization of irrigation water etc. Though these strategies are efficient but costly. Hence, a cost-effective new alternative attempt has taken up to mitigate soil salinity which involves inoculation of salt-tolerant arbuscular mycorrhizal fungi (AMF) in agricultural crop. Mechanisms of amelioration of salt stress in AMF-plant symbiosis involve enhancing the uptake of less mobile phosphorus, increasing nutrient acquisition, maintaining osmotic balance, enhancing antioxidants and polyamines, altering hormonal status, reducing ion toxicity and enhancing photosynthetic efficiency. AMF colonization induces an increase in root hydraulic conductivity of the host plants under osmotic stress conditions. Furthermore, AMF symbiosis also alters expression of cation channels and transporters, late embryogenesis abundant protein and aquaporins. AMF symbiosis not only changes plant physiology but also changes nutritional and physical properties of the rhizosphere. In the mycorrhizosphere, AMF interact with natural and introduced microorganisms and affect soil properties and quality. The quality of soil largely depends on its physical and chemical properties as well as diversity and activity of soil biota. Thus, AMF have been considered as bio-ameliorators of saline soils.Not Availabl

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Not AvailableA total of 60 compounds of known structure, comprising sugars, sugar alcohols, fatty acids, amino acids, organic acids, phenols and sterols were identified in stem extracts of groundnut using GC-MS. Sugars and fatty acids were predominant in stem extracts as compared to other metabolites. Distinguished metabolite patterns were observed in control and 96 h after infection (h.a.i.). Succinic acid, pentitol, scopolin, D-glucose and D-turanose, myo-inositol, fructose and mannitol were observed to be higher in control plants, whereas, D-ribopyranoside, thymol, pentadecanoic acid and octadecanoic acid increased at 24 hai than that of control. Interestingly, phenol related compounds such as phenol, hydroquinone, guaicol-.beta.-d-glucopyranoside, scopolin were also found lower in non-infected stems of TG37A. Moreover, tolerant genotypes (CS 319 and CS 19) had higher content of Thymol-.beta.-d-glucopyranoside, pentitol, D-glucose, D-turanose, scopolin and hydroquinone than that of moderately tolerant and susceptible genotypes. Sugar profiles using Ion chromatography revealed that glucose content decreased in moderately susceptible and susceptible genotype after S. rolfsii infection. Both constitutive and induced levels of cinnamic acid was observed higher in resistant genotypes than that of susceptible ones which was further supported by phenylalanine ammonia lyase activity. Thus, our study demonstrates the biological role of metabolites specifically sugars, phenolics and fatty acids in plant defense responses.Not Availabl

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Not AvailableAlternaria leaf blight is major fungal disease of summer groundnut, causes significant loss of haulm and pod yield. Aims of this study were to understand the role of metabolites and phenylpropanoid related enzymes in Alternaria leaf blight resistance and to find out metabolic marker for disease resistance. Alternaria leaf blight resistant (GPBD4 and CS186) and susceptible genotypes (GG2 and TPG41) of groundnut were grown in pots during rabisummer 2015. Groundnut plants were infected with Alternaria alternata (Fr.) Keissler at 40 days after sowing. 5 days after infection, upper second leaves were collected from both control and infected plants for analysis. A total of 67 metabolites comprising sugars, sugar alcohols, amino acids, organic acids, fatty acids, sterols and phenolic were identified using gas chromatography–mass spectrometry (non-targeted metabolomics). Constitutive levels of alpha- D-galactoside, D-mannitol, D-erythropentitol, glycine, and hexadecanoic acid were observed higher in resistant genotypes compared to susceptible genotypes. Moreover, arabinofuranose, cinnamic acid, 2-butendioic acid, and linoleic acid were observed only in resistant genotypes at both control and infected stage. In susceptible genotypes myo-inositol, glucose and fructose content was increased after infection with pathogen while decreased in resistant genotypes. Resistant genotypes had higher constitutive level of cinnamic and salicylic acid compared to susceptible genotypes. Non-infected leaves of resistant genotypes also had higher activities of phenylalanine ammonia lyase and tyrosine ammonia lyase activities. Our results suggest that metabolites specifically present in resistant genotypes impart defense mechanism against Alternaria pathogen and can be used as bio-marker for screening of germplasm.Not Availabl

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