Applied Botany

The effects of dry-heat and seed soaking in distilled water on germination performance of W. somnifera and Sida cordifolia L. were studied. Dry-heat pretreatments for several times (1-60 min) significantly increase germination percentage. The highest germination was obtained at 1000 C (80% and 83%, respectively). A significant increase in germination rate was achieved under different pretreatments. The physiological dormancy caused by an impermeable seed coat can be overcome by dry-heat pretreatments. Further micrography and anatomical studies of both the plants were also made.

Pectinase producing microorganisms were isolated from fruit waste disposable area soil samples of Pazhamuthir Nilayam, Coimbatore, TamilNadu and screened in modified Czapek- Dox media with citrus pectin as sole carbon source. Among the isolates, only four fungal strains showed hydrolyzing zone. The fungal strain showing maximum clearance zone of 36 mm (out of colony diameter of 57 mm) was selected and it was identified as Paecilomyces variotii. The effects of the various carbon sources like dextrose, maltose and cellulose and nitrogen sources like ammonium sulphate, potassium nitrate and urea on the pectinase activity by Paecilomyces variotii were carried out in surface culture fermentation. The results of the investigation revealed that the maximum pectinase production of 9.71 Umg-1protein and of 9.66 Umg-1protein were obtained at both intracellular and extracellular level in 3% dextrose and 3% maltose as carbon sources. Among the nitrogen sources, the maximum pectinase activity of 9.73 Umg-1proteinand 8.65 Umg-1protein was observed in 3% and 2% ammonium sulphate at both intracellular and extracellular level.

The germination study was made to understand the genetic variability in Zea mays (L.) variety JKMH-1001which was subjected to chemical mutagenic treatments for two generations. The chemical mutagens namely, EMS, DES and Sodium azide were used. The mutagen treated seeds were tested for lethal dose of 50 per cent for all mutagens, separately and the dose at which 50 per cent of the seed germination was considered as LD50 values were grown in the field. The spectrum of chlorophyll mutation consisted of albino, chlorina, viridis and xandha. The morphological mutations observed at tall, dwarf, early maturity, late maturity, triangular leaf, bold size seed, long ear, short ear and male sterility in all the concentration recorded. In EMS was found to be more effective and efficient than the other mutagens. The effectiveness was producing germination and chlorophyll mutants. Effectiveness means frequency of mutations induced by unit dose/concentration of a mutagen. The efficiency means undesirable biological effect like lethality and sterility caused by the mutagen. The effectiveness and efficiency generally decreased with increased in the higher doses of the mutagens in certain level.

The aim of study was to screen out rice (Oryzae sativa L.) genotypes with better drought tolerance, to explore observable responses of rice plants towards drought stress and multivariate statistics were used to compare the relationships among the responses as well as their effects on yield and yield reduction under drought stress. Genotypes responded differently under same level of stress. Results revealed that as a response to drought, all the genotypes showed 42 % average increase in seedling root length; 39 % average decrease in seedling shoot length; 21 % average reduction in 1000 grain weight; delay in heading time of 13 days in average; average yield per plant reduction of 47 %; reduction in grains per panicle of 52% in average, when subjected to simulated drought stress. It was concluded that in addition to correlation and path analysis of yield components, cluster analysis, factor analysis and principal component analysis are also very important methods for screening drought tolerant cultivars of rice in large populations and give better understandings of associations and helps better to choose important variables and genotypes. Factor analysis and Principal component analysis revealed the importance of drought response index, as a best measurement for yield under stress condition. Seedling root length to shoot length ratio, followed by seedling root length ratio contrubute majorly in yield per plant under drought stress. Reduction in plant height and delay in heading time were main causes of yield reduction under stress. It was further concluded that selecting the genotypes showing higher drought response index, higher increase in s ling root length, seedling root to shoot length ratio and less reduction in plant height and delay in heading time, are important criteria in screening for drought tolerance. Also these characters showed high heritability and genetic advance, signifying their values in selection breeding, and higher phenotypic correlation values indicating their polygenic behavior and high influence of environment.

Plants have been an important source of medicine for thousands of years. Recently, the world health organization estimated that upto 80% of people still rely mainly on traditional remedies such as herbs for their medicines. In the present study various plant parts of Tridax procumbens were evaluated separately for the presence of primary metabolites. Tridax procumbens Linn belongs to family Asteraceae, and commonly known as Dhaman grass, is a common herb. It is employed as an indigenous medicine for variety of ailments including Jaundice. The plant also has hepatoprotective activity and it is used in Ayurveda in various liver disorders. Phytochemical screening and quantification of primary metabolites in different plant parts i.e leaf and stem (in vivo) as well as its callus (in vitro) quantification revealed the presence of total soluble sugars, proteins, lipids chlorophyll and proline. It showed higher concentration of total soluble sugar, lipid and protein in leaves whereas chlorophyll content and proline was found higher in callus as compared to other parts of plant.

Nano-biotechnology is recognized as offering revolutionary changes in various fields of medicine. Biologically synthesized silver nanoparticles have a wide range of applications. The biosynthesis of silver nanoparticles is an eco-friendly method in the field of nanotechnology. Seaweed extracts of Caulerpa racemosa (Forsskål) J. Agardh and Ulva lactuca Linnaeus was used as a reducing agent in the eco-friendly extracellular synthesis of silver nanoparticles from an aqueous solution of silver nitrate (AgNO3). High conversion of silver ions to silver nanoparticles was achieved with Ulva lactuca at reaction temperature of 100° and a seaweed extract concentration of 10% with a residential time of 1 h using reflux extractor when compared with the other methods. Formation of silver nanoparticles was characterized by spectrophotometry and the electron microscopic technique. The average particles size was ranging from 35 to 75 nm. Antimicrobial activities indicate the minimum inhibitory concentration of biologically synthesized nanoparticles tested against the pathogen Staphylococcus aureus (1 mg/ml). High inhibitions over the growth of Pseudomonas aeruginosa, Vibrio cholerae and Escherichia coli were witnessed against the concentrations of 1 mg/ml. Enzyme assay of the collected seaweeds performed using standard protocol to assess the potency level. Further photocatalytic degradation and seed germination test proved that synthesized nanoparticles were environmentally safe, for which the same can be used for effluent treatment process.

Water pollution is a major global problem that requires ongoing evaluation and revision of water resource policy at all levels (from international down to individual aquifers and wells). It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily. In addition to the acute problems of water pollution in developing countries, industrialized countries continue to struggle with pollution problems as well. Water quality issues are a major challenge that humanity is facing in the twenty-first century. Here, we review the main groups of aquatic contaminants, their effects on human health, and approaches to mitigate pollution of freshwater resources. Emphasis is placed on chemical pollution, particularly on inorganic and organic micro-pollutants including toxic metals and metalloids as well as a large variety of synthetic organic chemicals. Some aspects of waterborne diseases and the urgent need for improved sanitation in developing countries are also discussed. The review addresses current scientific advances to cope with the great diversity of pollutants. It is organized along the different temporal and spatial scales of global water pollution. Persistent organic pollutants (POPs) have affected water systems on a global scale for more than five decades; during that time geo-genic pollutants, mining operations, and hazardous waste sites have been the most relevant sources of long-term regional and local water pollution. Agricultural chemicals and waste-water sources exert shorter-term effects on regional to local scales.