Prediction of grain yield and nitrogen uptake by basmati rice through in-season proximal sensing with a canopy reflectance sensor

Precision Agriculture - The present study was conducted to establish prediction models for grain yield and nitrogen (N) uptake using normalized difference vegetation index (NDVI) measurements with...     

Scientific analysis of indigenous techniques for guggal （Commiphora wightii） tapping in India

Guggal, a threatened species that is endemic to western India, is tapped to extract medicinally important oleo–gum–resin(guggul). However, the plant dies after gum exudation. The indigenous tapping techniques used by local people were examined in Gujarat, India to discover the scientific basis behind these techniques: selection of gum inducer, season of tapping, and plant parts to be tapped. First, the presence of Xanthomonas axonopodis pv. commiphorae(Xac) in the gum suspension used for tapping was established. This bacterium induces gum oozing from the tapped plants and later, causes them to die off. The population of Xac in gum was found to decrease with the age of the gum. With that, fresh gum increased the tapping success. Second, local people preferred tapping during the warm season, which we validated by determining that Xac growth was best at 30 °C. Tapping during September(mean temperature 25.7–30.0 °C) clearly favoured growth of the pathogen and yielded maximum guggul. Multiple tapping on a mature tree ensured maximum gum extraction before its death. Finally, application of indigenous technology under natural plant stands by the local people ensured availability of this important raw drug for consumption. Our study established that the age–old traditional methods have a strong scientific basis. However, it is imperative to formulate strategies based on contemporary scientific understanding to protect this natural resource before it becomes extinct.     

Redox state of Mars' upper mantle and crust from Eu anomalies in shergottite pyroxenes

The oxidation state of basaltic martian meteorites is determined from the partitioning of europium (Eu) in their pyroxenes. The estimated redox conditions for these samples correlate with their initial neodymium and strontium isotopic compositions. This is interpreted to imply varying degrees of interaction between the basaltic parent melts, derived from a source in the martian mantle, and a crustal component. Thus, the mantle source of these martian basalts may have a redox state close to that of the iron-wüstite buffer, whereas the martian crust may be more oxidized (with a redox state higher than or equal to that of the quartz-fayalite-magnetite buffer). A difference in redox state of more than 3 log units between mantle and crustal reservoirs on Mars could result from oxidation of the crust by a process such as aqueous alteration, together with a subsequent lack of recycling of this oxidized crust through the reduced upper mantle.     

Morphological, anatomical and molecular investigation into witches’ broom disease of mamejvo (Enicostemma axillare)

Mamejvo (Enicostemma axillare Raynal) is a perennial herb with diversified health benefits. It was found to be affected by a witches?? broom disease under the field conditions at Anand, Gujarat, India. Affected plants were 53.33% reduced in height due to shortened internodes, leading to typical witches?? broom symptoms. Flower size was reduced significantly in the affected plants compared with the healthy ones and their petal color gradually turned green (virescence). Affected plants produced 2.5 times more dry herbage than the normal plants but with less active ingredient (swertiamarin). Symptomatic plants died early while root suckers from such plants failed to establish after transplanting. DAPI stained transverse sections of affected shoot tips showed the presence of discrete greenish fluorescence in the phloem cells under UV light. Amplification of 1.2?kb phytoplasma specific rDNA fragment from diseased tissue confirmed the presence of the pathogen. Further characterization of the pathogen through virtual rDNA?CRFLP pattern and rDNA sequence based phylogeny suggested that the pathogen, Enicostemma witches?? broom phytoplasma, belonged to 16SrII?CC group of ??Ca Phytoplasma aurantifolia??.     

The absorption of phosphate ions from the ovine reticulorumen

The reticulorumen is now recognised to be an important site of net absorption of phosphate ions from ruminal fluid containing phosphate concentrations appropriate to those found in normal farming practice. These rates of absorption were measured in vivo from solutions placed in the washed reticulorumen, isolated in situ, in conscious, trained sheep. Reducing the ruminal sodium concentration led to reduced absorption of phosphate, suggestive that phosphate and sodium fluxes across the apical wall of the ruminal epithelial cell are linked, as they are in the kidney. Increased absorption of short chain fatty acids led to enhanced absorption of phosphate ions. Conversely, inhibition of carbonic anhydrase activity, by the addition of 1 mM acetazolamide to the ruminal fluid, led to a reduction in phosphate absorption. An increase in the acidity of the ruminal fluid also increased the absorption of phosphate, as did an increase in the ruminal Ca(2+) concentration over the range 1-4 mmol per litre. It is suggested that these effects can be accounted for by a Na(+)/H(+) antiporter coupled with a phosphate/proton symporter in the apical membrane of the ruminal epithelial cell.     

Antibody dependent haemolysin, complement and opsonin in sera of a major carp, Cirrhina mrigala and catfish, Clarias batrachus and Heteropneustes fossilis

The present communication is a continuation of our earlier study on the natural serum haemagglutinin/lectins of Cirrhina mrigala, Clarias batrachus and Heteropneustes fossilis. Sera of Cirrhina mrigala, belonging to the major carp family, could not only agglutinate heterologous rabbit erythrocytes, but also lyse them spontaneously. This lysis of rabbit RBC by Cirrhina mrigala sera was calcium ion dependent and heat sensitive, indicating thereby that the haemolysis was mediated by the fish serum complement system via the classical pathway. Quantification of CH50 and APCH50 levels in the sera of Clarias batrachus and Heteropneustes fossilis as well as in the sera of amphibia, aves and mammals showed that lower vertebrates predominantly possessed an alternative pathway of the complement system, while on the other hand, in the higher vertebrates the major pathway of complement activation was classical. Furthermore sera of Clarias batrachus and Heteropneustes fossilis had opsonins, which could stimulate heterologous rat peritoneal macrophages to engulf Staphylococcus aureus with the production of superoxide anion. From this study we concluded that fishes have been armed with various powerful natural humoral defense systems for their protection against environmental pathogens.     

Proanthocyanidin-rich extracts from cranberry fruit (Vaccinium macrocarpon Ait.) selectively inhibit the growth of human pathogenic fungi Candida spp. and Cryptococcus neoformans

Cranberry ( Vaccinium macrocarpon ) has been shown in clinical studies to reduce infections caused by Escherichia coli and other bacteria, and proanthocyanidins are believed to play a role. The ability of cranberry to inhibit the growth of opportunistic human fungal pathogens that cause oral, skin, respiratory, and systemic infections has not been well-studied. Fractions from whole cranberry fruit were screened for inhibition of five Candida species and Cryptococcus neoformans , a causative agent of fungal meningitis. Candida glabrata , Candida lusitaniae , Candida krusei , and Cryptococcus neoformans showed significant susceptibility to treatment with cranberry proanthocyanidin fractions in a broth microdilution assay, with minimum inhibitory concentrations as low as 1 μg/mL. MALDI-TOF MS analysis of subfractions detected epicatechin oligomers of up to 12 degrees of polymerization. Those containing larger oligomers caused the strongest inhibition. This study suggests that cranberry has potential as an antifungal agent.     

Compatibility of Mesorhizobium sp. Cicer with seed treatment of fungicide and insecticide in chickpea

This investigation was undertaken to study the compatibility of Mesorhizobium sp. Cicer with captan (fungicide) and chlorpyrifos (insecticide) for growth, symbiotic parameters and yield in chickpea. In an in vitro experiment, a significant reduction in the number of viable mesorhizobia was observed in Mesorhizobium sp. Cicer treated chickpea seeds at the recommended doses of captan (3 g kg^?1 seed) and chlorpyrifos (10 ml kg^?1 seed) after 4 h storage at 4°C, and further reduction was seen after 8–16 h contact with Mesorhizobium. The results showed that captan was more toxic than chlorpyrifos. In field experiments, improved growth and symbiotic parameters (plant height, dry weight of shoot, nodulation, leghaemoglobin content, chlorophyll content and nitrogen content) and a reduction in per cent damaged by termites and diseases were observed in the Mesorhizobium alone treatment compared with the uninoculated control. Grain yield was increased significantly in treatments with Mesorhizobium alone or in a mixture with fungicide and insecticide (captan and chlorpyrifos) compared with the control treatment. It is evident that chemically treated seeds should always be sown as soon as possible after inoculation. Recommended rates of captan and chlorpyrifos application with Mesorhizobium inoculant as a seed treatment was innocuous to chickpea–Mesorhizobium symbiosis.     

Potential of Azotobacter spp. as biocontrol agents against Rhizoctonia solani and Fusarium oxysporum in cotton (Gossypium hirsutum), guar (Cyamopsis tetragonoloba) and tomato (Lycopersicum esculentum)

During the current investigation, 51 bacterial isolates/mutants of Azotobacter chroococcum, Azospirillum spp. and Gluconacetobacter diazotrophicus were tested for antifungal activity against three fungal pathogens, namely Rhizoctonia solani cotton, Rhizoctonia solani rice and Fusarium oxysporum tomato using a dual-culture technique under laboratory conditions. Ten isolates/mutants were found to be inhibitory against R. solani cotton, six against R. solani rice and twelve against F. oxysporum tomato. Nearly 50% of the isolates/mutants were siderophore positive. The antimicrobial substance was found to be extracellular and proteinaceous in nature, but in some strains it was found to be associated with other complex material also. Almost all the positive isolates/mutants showed production of antibiotic and antifungal compounds. On the basis of this study, in vitro results under laboratory conditions were reproduced in pot experiments in the greenhouse and chosen isolates/mutants of A. chroococcum were found to be effective biocontrol agents against R. solani cotton (disease index 16.7%) and R. solani rice (2.5%) in cotton crop, whereas in guar, the crop disease index was 2.5% against R. solani cotton, 13.3% against R. solani rice and 0% against F. oxysporum tomato in tomato crop compared with their respective checks.     

In planta detection of Macrophomina phaseolina from jute (Corchorus olitorius) by a sodium acetate-based direct PCR method

Macrophomina phaseolina (Tassi) Goid. is the most important pathogen of jute and primarily causes seedling blight, leaf spot and stem rot. The pathogen was detected from field samples by a simple method of direct PCR (dPCR) which obviates the steps of DNA extraction. The leaf bits were treated with a lysis buffer at 65°C for 25 min, whereas the stem pieces were initially incubated at 65°C for 5 min followed by incubation at 60°C for 25 min and the lysate was used as PCR template. Based on the type of tissue, the composition and concentration of lysis buffer systems were optimized. For leaf samples the optimized buffer system composed of 20 mmol l ^-1 tris (hydroxymethyl aminomethane (Tris)-Cl (pH 8.0), 1.5 mmol l ^-1 ethylene diamine tetra acetate (EDTA) (pH 8.0), 1.4 mol l ^-1 sodium acetate and 200 μg/ml proteinase K. Further, 3% PVP (w/v) and β-mercaptoethanol (1% w/v) were added into the buffer. In case of stem samples, PVP was not applied and higher concentrations were used for other components. M. phaseolina could be detected from both leaf and stem samples generating amplicon of 350 bp. This is the first report of detecting M. phaseolina by a direct PCR method without DNA extraction.