Photosynthesis and Biomass Studies in \u3cem\u3eLasiurus sindicus\u3c/em\u3e of Chandan Grassland in Thar Desert

Grasslands comprise about one third of the world’s area of natural vegetation (Adams et al., 1990). Uncertainties prevail in the arid ecosystem with reference to carbon balance and fluxes which are primarily attributed to the sensitivity of grasslands to variation in annual precipitation, temperature and other regulating mechanisms of eco-physiological processes (Flanagan et al., 2002). It is therefore necessary to study radiation and water use efficiency of Lasiurus sindicus which is a predominant grass species in Chandan grassland of Thar desert to understand and evaluate its growth in relation to variation in climate. Also, it is pertinent to resolve whether grassland ecosystem function as a source or sink to atmospheric CO2. We therefore, measured diurnal variability of net photosynthesis, diurnal trend in light and water use efficiency and root and shoot biomass studies (10 days interval) of L. sindicus (Sewan) grass species in relation to ambient micrometeorological conditions during growth period along three points viz., initial, peak and declining phenophase to have basic understanding of eco-physiological responses to prevailing micrometeorology to evaluate its carbon use efficiency

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Not AvailableLand surface processes in data scarce arid northwestern India and their influence on the regional climate including monsoon are now gaining enhanced scientific attention. In this work the seasonal variation of land surface parameters and surface-energy flux components over Lasiurus sindicus grassland system in Thar Desert, western India were simulated using the mesoscale WRF model. The data on surface fluxes from a micrometeorological station, and basic surface level weather data from the Central Arid Zone Research Institute’s experimental field station (260 59’ 41”N;71o29’”10E), Jaisalmer, were used for comparison. Simulations were made for typical fair weather days in three seasons [12–14 January (peak winter); 29–31 May (peak summer), 19–21 August (monsoon)] during 2012. Sensitivity experiments conducted using a 5-layer soil thermal diffusion (5TD) scheme and a comprehensive land surface physics scheme (Noah) revealed the 5TD scheme gives large biases in surface fluxes and other land surface parameters. Simulations show large variations in surface fluxes and meteorological parameters in different seasons with high friction velocities, sensible heat fluxes, deep boundary layers in summer and monsoon season as compared to winter. The shortwave radiation is underestimated during the monsoon season, and is overestimated in winter and summer. In general, the model simulated a cold bias in soil temperature in summer and monsoon season and a warm bias in winter; the simulated surface fluxes and air temperature followed these trends. These biases could be due to a negative bias in net radiation resulting from a high bias in downward shortwave radiation in various seasons. The Noah LSM simulated various parameters more realistically in all seasons than the 5TD soil scheme due to inclusion of explicit vegetation processes in the former. The differences in the simulated fluxes with the two LSMs are small in winter and large in summer. The deep mixed layers are distributed in the northeastern parts in summer, northern areas in southwest monsoon and in southwestern parts during winter seasons and associated with the land-cover and vegetation dynamics. Our results present a baseline simulation study in this data scarce arid region.Not Availabl

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International Symposium on “New Dimensions in Agrometeorology for Sustainable Agriculture” held at G.B. Pant University of Agriculture & Technology, Pantnagar, INDIA from 16 to 18 October 2014, Abst.vol.pp.102-Best paper presentation award.Not AvailableNot Availabl

Polyoxypregnane glycosides from the flowers of Dregea volubilis

Three novel polyoxypregnane glycosides, volubiloside A, B and C (1–3), were isolated from the flowers of Dregea volubilis Linn., and their structures were elucidated as drevogenin d-3-O-b-d-glucopyranosyl (1!4)-6-deoxy-3-O-methyl-b-d-allopyranosyl (1!4)- b-d-cymaropyranosyl (1!4)-b-d-cymaropyranoside, drevogenin d-3-O-b-d-glucopyranosyl (1!4)-6-deoxy-3-O-methyl-b-d-allopyranosyl (1!4)-b-d-cymaropyranosyl (1!4)-b-d-digitoxopyranoside and drevogenin P-3-O-b-d-glucopyranosyl (1!4)-6-deoxy- 3-O-methyl-b-d-allopyranosyl (1!4)-b-d-cymaropyranosyl (1!4)-b-d-cymaropyranoside, respectively, on the basis of extensive NMR experiments, MALDI-TOF MS, and some chemical strategies

A Triterpenoid Saponin Possessing Antileishmanial Activity from the Leaves of Careya Arborea

Bioguided-fractionation of the methanol extract of the leaves of Careya arborea led to isolation of a triterpenoid saponin, designated arborenin, and characterized as 3-O-b-D-glucopyranosyl(1!2)-b-D-glucopyranosyl-2a,3b-dihydroxy-taraxast-20-en-28-oic acid (1), together with desacylescin III (2). The structures were determined on the basis of extensive 2D NMR spectroscopic analysis. The saponin showed in vitro antileishmanial activity against Leishmania donovani (strain AG 83)

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Woodfordia Fruticosa: Traditional Uses and Recent Findings

Woodfordia fruticosa Kurz of the family Lythraceae is a plant of tropical and subtropical region with a long history of medicinal use. A wide range of chemical compounds including tannins (especially those of macrocyclic hydrolysable class), flavonoids, anthraquinone glycosides, and polyphenols have been isolated from this species in recent times. Extracts and metabolites of this plant, particularly those from flowers and leaves, possess useful pharmacological activities. A comprehensive account of the chemical constituents and the biological activities is presented and a critical appraisal of the ethnopharmacological issues is included in view of the many recent findings of importance on this plant

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Not AvailableRegions of strong land–atmosphere coupling will be more susceptible to the hydrological impacts in the intensifying hydrological cycle. In this study, micrometeorological experiments were performed to examine the land– atmosphere coupling strength over a heat low region (Thar desert, NW India), known to influence the Indian summer monsoon (ISM). Within the vortex of Thar desert heat low, energy–water exchange and coupling behaviour were studied for 4 consecutive years (2011–2014) based on sub-hourly measurements of radiative–convective flux, state parameters and sub-surface thermal profiles using lead-lag analysis between various E–W balance components. Results indicated a strong (0.11–0.35) but variable monsoon season (July–September) land–atmosphere coupling events. Coupling strength declined with time, becomes negative beyond 10-day lag. Evapotranspiration (LE) influences rainfall at the monthly time-scale (20–40 days). Highly correlated monthly rainfall and LE anomalies (r = 0.55, P< 0.001) suggested a large precipitation memory linked to the local land surface state. Sensible heating (SH) during March and April are more strongly (r = 0.6–0.7) correlated to ISM rainfall than heating during May or June (r = 0.16–0.36). Analyses show strong and weak coupling among net radiation (Rn)–vapour pressure deficit (VPD), LE–VPD and Rn–LE switching between energy-limited To water-limited conditions. Consistently,+ve and-ve residual energy [(dE) = (Rn - G) - (SH + LE)] were associated with regional wet and dry spells respectively with a lead of 10–40 days. Dew deposition (18.8–37.9 mm) was found an important component in the annual surface water balance. Strong association of variation of LE and rainfall was found during monsoon at local-scale and with regional-scale LE (MERRA 2D) but with a lag which was more prominent at local-scale than at regional-scale. Higher pre-monsoon LE at local-scale as compared to low and monotonous variation in regional-scale LE led to hypothesize that excess energy and water vapour brought through advection caused by pre-monsoon rainfall might have been recycled through rainfall to compensate for early part of monsoon rainfall at local-scale. However, long-term measurements and isotope analysis would be able to strengthen this hypothesis. This study would fill the Key gaps in the global flux studies and improve understanding on local E–W exchange pathways, responses and feedbacks.Not Availabl

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Not AvailableA complete annual cycle of micrometeorological measurements were carried out to characterize the dynamics of radiation and energy balance over a grassland ecosystem at Central Arid Zone Research Institute experimental area at Chandan, Jaisalmer, India from INSAT-linked ISRO-AMS (Agro-Met Station). The daytime average dekadal latent flux for actual evapotranspiration (AET) showed substantially lower magnitude (15-115 Wm-2) (AET: 0.3 mmd-1 to 2.5 mmd-1) with prominent peak coincident to south-west monsoon and peak growth stage. Sensible heat fluxes showed a large variation from 54 to 340 Wm-2 with peak during summer and minimum during winter and monsoon seasons. More than 70% energy balance closure (EBC) was observed. The non-closure of energy balance periods were characterized by strong local advections in summer. The daytime average net radiation showed bimodal behavior (195 to 420 Wm-2) with primary peak in spring-summer and secondary peak coincident to the start of the withdrawal of south-west monsoon. Significant complementary exponential relation (Y=0.045 e12.13X, R2 = 0.65) was found between dekadal albedo and Bowen ratio which was generally high (1.5 to 5.3) with intermittent dips (0.3 to 1.3) coincident to wet spells. Similarly, the dekadal albedo showed a higher magnitude (0.15 to 0.39), recording the highest (0.39) in the month of April and the lowest (0.15) in the month of September post-monsoon period when green grass growth was maximum.Not Availabl

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Not AvailableRegions of strong land–atmosphere coupling will be more susceptible to the hydrological impacts in the intensifying hydrological cycle. In this study, micrometeorological experiments were performed to examine the land– atmosphere coupling strength over a heat low region (Thar desert, NW India), known to influence the Indian summer monsoon (ISM). Within the vortex of Thar desert heat low, energy–water exchange and coupling behavior were studied for 4 consecutive years (2011–2014) based on sub-hourly measurements of radiative–convective flux, state parameters and sub-surface thermal profiles using lead-lag analysis between various E–W balance components. Results indicated a strong (0.11–0.35) but variable monsoon season (July–September) land–atmosphere coupling events. Coupling strength declined with time, becomes negativebeyond 10-day lag. Evapotranspiration (LE) influences rainfall at the monthly time-scale (20–40 days). Highly correlated monthly rainfall and LE anomalies (r = 0.55, P < 0.001) suggested a large precipitation memory linked to the local land surface state. Sensible heating (SH) during March and April are more strongly (r = 0.6–0.7) correlated to ISM rainfall than heating during May or June (r = 0.16–0.36). Analyses show strong and weak couplings among net radiation (Rn)–vapour pressure deficit (VPD), LE–VPD and Rn–LE switching between energy-limited to water-limited conditions. Consistently, +ve and −ve residual energy [(dE) = (Rn − G) − (SH + LE)] were associated with regional wet and dry spells respectively with a lead of 10–40 days. Dew deposition (18.8–37.9 mm) was found an important component in the annual surface water balance. Strong association of variation of LE and rainfall was found during monsoon at local-scale and with regional-scale LE (MERRA 2D) but with a lag which was more prominent at local-scale than at regional-scale. Higher pre-monsoon LE at local-scale as compared to low and monotonous variation in regional-scale LE led to hypothesize that excess energy and water vapour brought through advection caused by pre-monsoon rainfall might have been recycled through rainfall to compensate for early part of monsoon rainfall at local-scale. However, long-term measurements and isotope analysis would be able to strengthen this hypothesis. This study would fill the key gaps in the global flux studies and improve understanding on local E–W exchange pathways, responses and feedbacks.Not Availabl