Showing papers in "Current Science in 2010"

The subcellular basis of seed priming.

Abstract: Seed priming is a commercially used technique for improving seed germination and vigour. It involves imbibition of seeds in water under controlled conditions to initiate early events of germi- nation, followed by drying the seed back to its initial moisture content. This review article summa- rizes the recent information available on the various subcelluar processes associated with priming which lead to seed enhancement. The paper discusses the role of synthesis of specific proteins in re- sponse to priming. The effect of priming on DNA repair, gene expression and synthesis of new mes- sage and protein synthesizing machinery are included. The enhancement in the energy metabolism of the cell by priming and the effect of priming in advancing and synchronizing the stage of the cell cycle are discussed. The article also includes information on the role of priming in specific cases, such as alleviation of dormancy in thermosensitive crops which require ethylene. The relationship between seed longevity and priming and methods to prolong longevity, wherever required after priming and the role of desiccation-related proteins, which accumulate during these treatments are also discussed. An illustration summarizing the information on all the metabolic processes which could possibly contribute towards the enhancement in seed performance achieved by priming is included. The paper identifies areas where information is lacking and potential for more in-depth research exists.

The decline of the West

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The impact of global elevated CO2 concentration on photosynthesis and plant productivity

Abstract: The alarming and unprecedented rise in the atmospheric concentration of greenhouse gases under global climate change warrants an urgent need to understand the synergistic and holistic mechanisms associated with plant growth and productivity. Photosynthesis is a major process of sequestration and turnover of the total carbon on the planet. The extensive literature on the impacts of climate change demonstrates both positive and negative effects of rising CO 2 on photosynthesis in different groups of higher plants. Significant variation exists in the physiological, biochemical and molecular responsiveness to elevated CO 2 atmosphere, among terrestrial plant species including those with C 3 , C 4 and crassulacean acid metabolic (CAM) pathways. However, the regulatory events associated with the inter- and intraspecific metabolic plasticity governed by genetic organization in different plants are little understood. The adaptive acclimation responses of plants to changing climate remain contradictory. This review focuses primarily on the impacts of global climate change on plant growth and productivity with special reference to adaptive photosynthetic acclimative responses to elevated CO 2 concentration. The effects of elevated CO 2 concentration on plant growth and development, source-sink balance as well as its interactive mechanisms with other environmental factors including water availability, temperature and mineral nutrition are discussed.

Biochar in agriculture - prospects and related implications

Abstract: Sequestration of atmospheric carbon to the soil is a challenging task for the scientific community to mitigate the rising concentration of atmospheric carbon dioxide (CO2). Biochar, due to its aromatic structure and long mean residence time in the soil (more than 100 years) has the potential for long-term carbon sequestration in the soil. The trend obtained from the meagre published literature raised our hopes of achieving the goal of enhancing the productivity of different crops along with environmental sustainability. According to an estimate, global production of black carbon has been reported between 50 and 270 Tg yr –1 , with as much as 80% of this remaining as residues in the soil. Biochar decomposition rate is slow in the soil, which indicates that it could be the possible answer to mitigation of elevated atmospheric CO2. It is reported that black carbon can produce significant benefits when applied to agricultural soils in combination with some fertilizers. Increase in crop yield to the tune of 45–250% has been reported by application of biochar along with chemical fertilizers. Soil water retention properties, saturated hydraulic conductivity and nutrients availability increased with the application of biochar. Biochar application reduced CO2 respiration, nitrous oxide and methane production, and decreased dissipation rate of herbicide in the soil.

The Copenhagen accord.

Abstract: Climate change has received unprecedented attention of the world leaders and media as well as activists, industrialists and ordinary citizens. The scientific community and the Intergovernmental Panel on Climate Change (IPCC) in particular have been pleading for action to halt global warming and the resulting climate change. The Copenhagen Climate Convention is a great success to the extent it brought a global environmental issue to the centrestage as evidenced by the assembly of the largest number of heads of state and governments, nearly 130 of them and government delegations from 191 countries, and over 40,000 delegates (scientists, activists, industrialists, etc.) registering for the convention. It was also a success in that no leader, for the first time, doubted the science of climate change; in fact leader after leader quoted IPCC scientific findings and spoke passionately and emotionally about the threats of climate change and how it will affect their people, food production, water supply and environment, and a last chance to save the world.

Status of organic farming in India.

Abstract: A survey was made on certified organic farms in the country to ascertain the real benefits and feasibility of organic farming in terms of the production potential, economics and soil health in comparison to the conventional farms. The study revealed that organic farming, in spite of the reduction in crop productivity by 9.2%, provided higher net profit to farmers by 22.0% compared to conventional farming. This was mainly due to the availability of premium price (20-40%) for the certified organic produce and reduction in the cost of cultivation by 11.7%. In cases, where such premium prices were not available and the cost of cultivation was higher primarily due to purchased off-farm inputs, organic farming was not found economically feasible. However, there was an overall improvement in soil quality in terms of various parameters, viz. physical, chemical, biological properties, availability of macro- and micronutrients, indicating an enhanced soil health and sustainability of crop production in organic farming systems.

Conservation agriculture towards achieving food security in North East India.

Abstract: Productivity of rainfed monocropping farming system in North Eastern Region of India is low and it is a high economic risk activity. Intensive natural resources mining, continuous degradation of natural resources (soil, water, vegetation) and practice of monocropping under conventional agricultural practices will not ensure farm productivity and food security in the coming years. In order to keep the production system in different land situations sustainable, conservation agriculture based on no-till system is an alternative to reconcile agriculture with its environment and overcome the imposed constraints of climate change and continuous inputs cost. Studies on conservation tillage and residue management in different land situations were conducted during 2006–2009 and they are highlighted in this article. In terrace upland, growing mustard completely on residual moisture following upland rice/maize was possible when it is practised under conservation tillage (crop residue of all crops, including weed biomass incorporated). Similarly, in valley upland, growing second crop of pea in rice fallow is possible if two-thirds or half of rice residues are retained on the soil surface under zero tillage. A longterm study (2006–2009) revealed that double no-till practice in rice-based system is cost-effective, restored soil organic carbon (70.75%), favoured biological activity (46.7%), conserved water and produced yield (49%) higher than conventional tillage. Therefore, conservation tillage practised in terrace upland, valley upland and low-land situations ensured doublecropping, improved farm income and livelihood in rainfed NE India

DNA barcoding in plants: taxonomy in a new perspective

Abstract: DNA barcoding is the process of identification of species based on nucleotide diversity of short DNA segments. It is well established in animals with the introduction of cytochrome c oxidase subunit 1 (COI) as a standard barcode. In plants, however, due to the difficulty in finding a universally acceptable barcode, it is yet to be well established. Based on the relative efficacy testing, the Consortium for the Barcode of Life–Plant Working Group has recently identified a few loci as potential barcode candidates and from them a two-locus standard barcode (rbcL + matK) has been recommended for initiating the barcoding process of plant species. With 70% species discriminatory power, this two-locus barcode is capable of serving many projects, but for better resolution additional loci need to be used. This article provides an overview of the technical details, and merits and demerits of these loci as plant barcodes.

Piper betle Linn. a maligned Pan-asiatic plant with an array of pharmacological activities and prospects for drug discovery

Abstract: Piper betle L is one of the important plants in the Asiatic region which ranks second to coffee and tea in terms of daily consumption Though the plant is known for abuse, in recent years several reports have been published on the effects of the plant extract and chemical constituents on different biological activities in vitro and in vivo The leaf extract, fractions and purified compounds are found to play a role in oral hygiene, anti-diabetic, cardiovascular, anti-inflammatory/immunomodulatory, anti-ulcer, hepato-protective and anti-infective, etc Patents were also awarded for some of the biological activities like anti-inflammatory, anti-cancer and immunomodulatory associated with leaf extracts and purified compounds The active compounds isolated from leaf and other parts are hydroxychavicol, hydroxylchavicol acetate, allypyrocatechol, chavibetol, piperbetol, methylpiperbetol, piperol A and piperol B Phenol-rich leaves of P betle show high antioxidant activities A number of biologically active compounds from P betle have potential for use as medicines, neutraceuticals and industrial compounds Since the traditional use of P betle involves chewing, it offers possibilities of use in drug delivery through buccal mucosa bypassing the gastric route

Adapting to climate change in the Volta Basin, West Africa.

Abstract: Impacts of climate change vary from region to region The 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) mentions that drier areas will be affected by more droughts while the rainfall regime, in general, will become 'rougher' In West Africa, specifically the area below the Sahel, the climate change signal may be more subtle Anecdotal evidence from farmers suggests that the onset of rainy season has been shifting forward in time over the past two generations Recently, detailed atmospheric modelling over the region shows that in the near future too, the onset of rainy season will shift to later periods in the year, roughly from April towards May The end of rainy season as well as the total amount of rainfall will remain more or less fixed This implies that adaptation strategies should be twofold The first part of a comprehensive adaptation strategy would be a continuation of the efforts to produce faster growing rain-fed crop cultivars, mainly corn and sorghum The second part would consist of increased water storage during the wet season for use during dry season

Prospects of botanical pesticides in sustainable agriculture

Abstract: Sustainable agriculture aims at reducing the incidence of pests and diseases to such a degree that they do not seriously damage crops without upsetting nature’s balance. One of the aims of sustainable agriculture is to rediscover and develop strategies whose cost and ecological side-effects are minimal. The use of synthetic pesticides has undoubtedly resulted in achievement of green revolution in different countries through increased crop production. However, in recent years there has been considerable pressure on consumers and farmers to reduce or eliminate synthetic pesticides in agriculture. This concern has encouraged researchers to look for better alternatives to synthetic pesticides.

National food security vis-à-vis sustainability of agriculture in high crop productivity regions.

Abstract: CURRENT SCIENCE, VOL. 98, NO. 1, 10 JANUARY 2010 33 B. S. Dhillon is in the Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70593 Stuttgart, Germany; Poonam Kataria is and P. K. Dhillon was in the Department of Economics and Sociology, Punjab Agricultural University, Ludhiana 141 004, India. *For correspondence. (e-mail: dhillonbaldevsingh@gmail.com) National food security vis-à-vis sustainability of agriculture in high crop productivity regions

Changes in honeybee behaviour and biology under the influence of cellphone radiations.

Abstract: Increase in the usage of electronic gadgets has led to electropollution of the environment. Honeybee behaviour and biology has been affected by electrosmog since these insects have magnetite in their bodies which helps them in navigation. There are reports of sudden disappearance of bee populations from honeybee colonies. The reason is still not clear. We have compared the performance of honeybees in cellphone radiation exposed and unexposed colonies. A significant (p < 0.05) decline in colony strength and in the egg laying rate of the queen was observed. The behaviour of exposed foragers was negatively influenced by the exposure, there was neither honey nor pollen in the colony at the end of the experiment.

Forest cover change detection of Western Ghats of Maharashtra using satellite remote sensing based visual interpretation technique.

Abstract: In this article, we attempt to quantify change in forest area of the Western Ghats of Maharashtra over a 20year time period (1985–87 to 2005) using visual interpretation technique at 1 : 250 K scale. The study was conducted using the Forest Survey of India vegetation maps for 1985–87, prepared using Landsat TM data and IRS LISS III imagery for 2005. The results reveal loss of dense forest at an annual rate of 0.72% and that of open forest at 0.49%. It also reports an increase in mangrove vegetation and water bodies in the study area. In addition, it also reports districtwise pattern of change in forest cover.

Regeneration status of tree species in forest of Phakot and Pathri Rao watersheds in Garhwal Himalaya.

Abstract: This paper reports regeneration status of trees in two watersheds namely Phakot and Pathri Rao in Uttarakhand. Seedling, sapling and tree density were greater in Phakot watershed forest than those in Pathri Rao watershed forest. In general, both forests were regenerating, although seedling and sapling population was higher in Phakot watershed forest. As far as the regeneration status is concerned, maximum tree species was found with fair regeneration in the forests of both the watersheds. In Phakot watershed, three species (Accacia nilotica, Engelhardtia spicata and Olea glandulifera) and in Pathri Rao watershed seven species (Acacia nilotica, Anogeissus latifolius, Casearia elliptica, Cassia fistula, Holarrhena pubescens, Mallotus phillippensis and Ougeinia oojeinensis) were found not regenerating. In Phakot watershed, general densities– diameters class distribution showed decline in density from small diameter class to higher diameter class whereas in Pathri Rao watershed no trend was evident.

A ground-dwelling rhacophorid frog from the highest mountain peak of the Western Ghats of India

Abstract: C dating of the samples; the DST for financial support under Kangra pro-ject. We acknowledge the support provided by Prof. Vinod Nautiyal, Prof. R. C. Bhatt, Dr P. M. Saklani, Dr Y. S. Farswan and the support staff of the Department of History, Ancient Indian History and Culture and Archaeology of the H.N.B. Garhwal University, Srinagar for ar-chaeological excavation and study. Dr N. R. Phadatare provided useful inputs. Received 19 March 2009; revised accepted 22 March 2010

Zinc biofortification of food grains in relation to food security and alleviation of zinc malnutrition

Abstract: Exemplary agricultural research supported by good government policies has ensured food security in India. It is the right time to focus on micronutrient malnutrition in the country. Recently, Zn deficiency in diet especially of young children below 5 years of age has received global attention. Zn deficiency diseases in infants and children include diarrhoea, pneumonia, stunted growth, weak immune system and retarded mental growth. Zn deficiency in pregnant women can lead to these problems and even mortality in infants. Over 450 thousand infant deaths in the world during 2004 were ascribed to Zn deficiency. Although Zn deficiency to some extent can be cured by Zn supplementation and improvement in dietary composition, it is better to increase the Zn content in cereals, the staple food in India and as a matter of fact in the entire south and southeast Asia. This can be achieved by biofortification of foodgrains either by developing crop cultivars with high concentration of Zn in grains or by adequate Zn fertilization of crops grown on Zn-deficient soils. Animals also suffer from Zn malnutrition.

Attenuation of camptothecin production and negative relation between hyphal biomass and camptothecin content in endophytic fungal strains isolated from Nothapodytes nimmoniana Grahm (Icacinaceae)

Abstract: Endophytic fungi, a group of fungi living inside the host plant tissues without causing visible symptoms of disease, are known to occur ubiquitously in plants. Existing in a mutualistic association with their host plants, they have been shown to enhance the plant’s ability to tolerate abiotic and biotic stresses3. In culture, many endophytic species have been shown to produce a number of important secondary metabolites including anticancer,antidiabetic, antifungal and immunosuppressant compounds. Many of these compounds closely mimic those produced by the respective host plants, suggesting that the fungi could in fact potentially serve as an alternative source of plant secondary metabolites. Notwithstanding these findings, to date, there has been no major breakthrough in commercially exploiting the endophytic fungi as a source of important secondary metabolites. Among the reasons attributed is the severe attenuation of production of the secondary metabolite by the fungi in culture. Li et al. showed that successive cultures of an endophytic fungi Pericornia sp. isolated from Torreya grandifolia, resulted in the attenuation of taxol production, though the fungal growth itself was unaffected. Although the reasons for such attenuation are not extensively studied, it is conjectured that it could be due to lack of host stimulus in the culture media.

Is the biological productivity in the Bay of Bengal light limited

Abstract: Recent measurements of chlorophyll, primary productivity (PP) and nutrients along the central Bay of Bengal (BOB) during summer, fall and spring inter-monsoons showed that the northern bay becomes less productive compared to the south in summer and fall intermonsoon, in spite of the nutrient input to the upper ocean by way of river influx as well as eddy-pumping. Along the western boundary also, highest PP in the northern bay did not occur during summer or in the fall intermonsoon, but occurred in the spring intermonsoon. The reason for this was explored using diffuse attenuation (K d (490)) and photosynthetically active radiation (PAR) which indicates the influence of the river flux in curtailing the downward penetration of solar radiation and cloud cover respectively. During summer and fall intermonsoon, biological productivity in the northern BOB is severely limited by the reduced downward penetration of solar radiation due to the large quantities of sediment brought by the adjoining rivers. Though the cloud cover reduces PAR in the northern BOB, this has only a secondary effect in comparison to the light limitation due to turbidity, which showed an order of magnitude increase in the northern Bay.

Isotopic characterization of dual monsoon precipitation - evidence from Kerala, India

Abstract: The stable isotopes oxygen-18, deuterium and the radioactive isotope tritium of the precipitation samples collected from Kozhikode, Kerala were analysed from 2005 to 2007 for the isotopic characterization of the rainfall derived from two monsoons in the region. The isotopic composition varied from δ 18 O =-1.33‰ and δD =-3.9‰ in August 2005 to δ 18 O =-5.6‰ and δD =-33.42‰ in June 2007 for the southwest monsoon (June to September) and from δ 18 O - 5.92‰ and δD =-31.43‰ in October 2007 to δ 518 O =-8.64‰ and δD =-53.2‰ in November 2007 for the northeast monsoon (October to January) samples. In addition to the two monsoon derived rainfalls, the region also receives pre-monsoon showers (March to May), whose isotopic composition varies from δ 18 O = -1.54‰ and δD =-15.85‰ in April 2007 to δ 18 O =-10.26‰ and δD =-70.92‰ in April 2005. The tritium content of rainwater was higher in the northeast monsoon period compared to the southwest monsoon period. The tritium level in precipitation was below 5 TU for most of the samples. The rainfall during southwest and the northeast monsoons shows two distinct isotopic signatures which cannot be totally ascribed to the difference in vapour sources but also to the difference in rainout histories of the air masses before reaching Kozhikode. Pre-monsoon rains in Kozhikode lacked any distinct isotope signatures. The tritium level in precipitation supports our observations. Excess tritium in northeast monsoon rains may be due to their origin from higher latitude.

Microsatellite markers linked to drought resistance in rice (Oryza sativa L.)

Abstract: Among the abiotic stresses, drought is a serious limiting factor that reduces rice production and yield stability in rainfed ecosystems. Conventional breeding for drought resistance is slow in attaining progress due to poor understanding of genetic control of drought resistance. Molecular markers help in identification of quantitative trait loci (QTLs) associated with drought resistance traits and their indirect selection using marker assisted selection. But QTL mapping requires genotyping of large mapping progenies demanding time and labour. Bulked segregant analysis (BSA) serves as an alternative approach for rapid identification of markers associated with drought resistance traits. BSA was carried out to identify markers linked to drought resistance using 23 recombinant inbred (RI) lines of IR20/Nootripathu, two indica ecotypes with extreme drought response. The parents were screened for polymorphism using 1206 rice microsatellite primer pairs. Out of 134 SSR polymorphic primers between parents, three primers showed polymorphism between bulks. These three primers co-segregated among the individual RI lines constituting the respective bulks. The genomic regions flanked by these markers have been reported to be associated with several drought resistance component traits and will be useful in marker assisted breeding for drought resistance in rice.

State-level inventory of invasive alien plants, their source regions and use potential.

Abstract: A comprehensive inventory of the invasive alien flora of India's fifth largest and most populous state, Uttar Pradesh, revealed 152 species from 109 genera and 44 families. Dicots represented 137 species and monocots 15 species. About 73% of these alien species were introduced from tropical America including South America, followed by tropical Africa (10.5%). Maximum number of species (30) were from the family Asteraceae, followed by Fabaceae (12 species), and then Amaranthaceae, Solanaceae and Convolvulaceae with eight species each. Herbs accounted for 128 species, shrubs 12 species, climbers 8 species, whereas trees and lianas 3 and 1 species respectively. People have found a large number of these alien species useful.

Plant diversity in two forest types along the disturbance gradient in Dewalgarh Watershed, Garhwal Himalaya.

Abstract: This study deals with the plant diversity and effects of disturbance on two types of forest namely, Anogeissus latifolius mixed forest (700-1200 m asl) and Quercus leucotrichophora forest (1500-2200 m asl) in Dewalgarh Watershed in Pauri District of Uttarakhand. Undisturbed, moderately disturbed and highly disturbed stands were identified within both types of forest of the watershed on the basis of canopy cover percentage, tree density ha -1 and cut stumps analysis. For Q. leucotrichophora forest, the undisturbed forest stand had canopy cover >60%, cut stump index 7 and 804 trees ha -1 . For A. latifolius mixed forest, the undisturbed forest stand had canopy cover >45%, cut stump index 7 and 845 trees ha -1 . The moderately disturbed stand occupied the intermediate position with respect to these parameters for both types of the forest. The study showed that the moderately disturbed stand favoured density and species richness in both the forest types. The Margalef index, Shannon diversity index and evenness index exhibited a similar trend, the highest value in moderately disturbed stand and lowest in highly disturbed stand. A sharp decline was recorded in tree density and basal area with increasing disturbance magnitude in both types of forests.

Estimation of sediment yield and areas vulnerable to soil erosion and deposition in a Himalayan watershed using GIS.

Abstract: Erosion is a natural geomorphic process occurring continually over the earth’s surface and it largely depends on topography, vegetation, soil and climatic variables and, therefore, exhibits pronounced spatial variability due to catchment heterogeneity and climatic variation. This problem can be circumvented by discretizing the catchment into approximately homogeneous sub-areas using Geographic Information System (GIS). In this study, the remote sensing and GIS techniques (through ERDAS Imagine 8.6 and ArcGIS 9.1 software) were used for derivation of spatial information, catchment discretization, data processing, etc. for the Himalayan Chaukhutia Watershed (India). Various thematic layers for different factors of Universal Soil Loss Equation (USLE) were generated and overlaid to compute spatially distributed gross soil erosion maps for the watershed using 18-year rainfall data. The concept of transport limited accumulation was formulated and used in ArcGIS for generating the transport capacity maps. Using these maps, the gross soil erosion was routed to the catchment outlet using hydrological drainage paths for the derivation of transport capacity limited sediment outflow maps. These maps depict the amount of sediment rate from a particular grid in spatial domain and the pixel value of the outlet grid indicates the sediment yield at the outlet of the watershed. Upon testing, the proposed method simulated the annual sediment yield with less than ±40% error.