Higher Sap Research Articles

Water-nutrient management enhances root morpho-physiological functioning, phosphorus absorption, transportation and utilization of cotton in arid region

Phosphorus (P) plays a key role in regulating plants physio-biochemical processes of plants and is indispensable for cotton production. However, the mechanism how does root morpho-physiological characteristics can affect P uptake, assimilation and use efficiency in different soil layers at various fertigation depths have not been studied. To fill this knowledge gap, a two-year pot experiment under field conditions was conducted to evaluate the effects of two irrigation levels, i.e., presowing irrigation (W80, 0.28 m3 water equivalent to 80 ± 5 % field capacity) and no presowing irrigation (W0, no water applied to the entire depth of the tube), and two basal fertilization methods [surface application (F10) and deep application (F30)] on root physiology, biomass accumulation, P uptake, transportation, and distribution in the cotton crop. The W80 treatment had 2.4–11.1% lower soil available P content (SAP) in the 0−50 cm soil layer but 6.1–14.4% higher SAP in the 60−120 cm soil layer than those in the W0 treatment. In the fertilization treatments, F10 had 0.35–17.0% greater SAP content in the 0−20 cm soil layer than F30. The W80F10 combination resulted in higher root length (RL) in the 0−20 cm soil layer, higher root acid phosphatase activity (ACP) in the 0−40 cm and 60−80 cm soil layers, and increased root phosphorus content (RP) in the 0−60 cm soil profile. W80F10 increased sap flow (SF), dry matter, and P accumulation in the reproductive organs compared with those in the other treatments. P utilization was positively associated with RL and root ACP in the 0−40 cm soil layer. Root ACP RL in the 0−40 cm soil layer and root ACP in the 60−80 cm soil layer were also positively related with SF, but SF had a negative relationship with RP in the 0−60 cm soil layer. In conclusion, presowing irrigation in conjunction with basal surface fertilization can increase P absorption and translocation by improving RL and ACP in the 0−40 cm and 60−80 cm soil layers before the full flowering stage. This also improves the competitive ability of the reproductive organs to access RP in the 0−60 cm soil layer, leading to higher P utilization in cotton.

Water Transfer Between Bamboo Culms in the Period of Sprouting.

Bamboo culms are connected to neighboring culms via rhizomes, which enable resource exchange between culms. We assessed water transfer between established and neighboring, freshly sprouted culms by thermal dissipation probes (TDP) inserted into culms and the connecting rhizome. During the early phase of sprouting, highest sap flux densities in freshly sprouted culms were observed at night, whereas neighboring established culms had high sap flux densities during daytime. After leaf flushing on freshly sprouted culms, the nighttime peaks disappeared and culms switched to the diurnal sap flux patterns with daytime maxima as observed in established culms. TDP in rhizomes indicated water flowing from the established to the freshly sprouted culms. When the established culms of a clump were cut, freshly sprouted culms without leaves reduced sap flux densities rates by 79%. Our findings thus suggest that bamboos exchange water via rhizomes and that nighttime fluxes are highly important for the support of freshly sprouted culms. The (water) resource support may facilitate the very fast growth of the bamboo shoots, and enable the colonizing of new places.

Interactive Effects of Grafting Techniques and Scion-Rootstocks Combinations on Vegetative Growth, Yield and Quality of Cucumber (Cucumis sativus L.)

The density of herbaceous crops creates a suitable environment to produce pathogens in the soil that intensify the attack of pathogens traditionally controlled by disinfectant, which are mostly prohibited and unlisted because of their toxicity. Grafting is an alternative technique to enhance abiotic stress tolerance and reduce root diseases due to soil-borne pathogens, thus enhancing crop production. This research study was conducted during the crop season of 2017 and 2018 in order to investigate the interactive effect of different grafting techniques of hybrid scion onto local rootstocks on plants survival, plant phenological growth, fruit yield and fruit quality under a controlled environment. The hybrid cucumber was also planted self-rooted. The cucumber (Cucumis sativus L.) cv. Kalaam F1, Syngenta was grafted onto four local cucurbitaceous rootstocks; ridge gourd (Luffa operculate Cogn.), bitter gourd (Momordica charantia L.), pumpkin (Cucurbita pepo L.), bottle gourd (Lagenaria siceraria (Molina) Standl.) using splice grafting, tongue approach, single cotyledon and hole insertion grafting techniques and self-rooted hybrid cucumber under greenhouse conditions. The experimental results indicated that all local cucurbitaceous rootstocks showed a high compatibility with hybrid cucumber scion in the splice grafting method compared to other grafting and non-grafted methods. Lagenaria siceraria rootstocks were found highly compatible with cucumber cv Kalaam scion which gave significantly maximum plant survival rates (95%) due to high sap contents, high SPAD value, better vegetative growth and maximum fruit yield when compared with other rootstocks by employing the splice grafting method followed by tongue approach, single cotyledon and hole insertion grafting while the fruit quality of all rootstocks was observed to be similar. The non-grafted cucumber cv. Kalaam F1 showed significant results of plant vegetative growth, fruit development and fruit quality and encountered grafting methods while the lowest result were associated with the hole insertion grafting method in all scion/rootstock combinations. The grafted plants have no significant effect on cucumber fruit dry matter and fruit quality while the fruit mineral compositions (N, P, K, Ca and Mg) were higher among grafted and non-grafted plant fruits. The results indicate that grafting hybrid cucumber onto four local cucurbitaceous rootstocks influenced growth, yield and fruit quality. Grafting can be alternative and control measure for soil-borne disease and to enhance cucumber production.

Mitral Valve Prosthesis Design Affects Hemodynamic Stasis and Shear In The Dilated Left Ventricle.

Dilated cardiomyopathy produces abnormal left ventricular (LV) blood flow patterns that are linked with thromboembolism (TE). We hypothesized that implantation of mechanical heart valves non-trivially influences TE risk in these patients, exacerbating abnormal LV flow dynamics. The goal of this study was to assess how mitral valve design impacts flow and hemodynamic factors associated with TE. The mid-plane velocity field of a silicone dilated LV model was measured in a mock cardiovascular loop for three different mitral prostheses, two with multiple orientations, and used to characterize LV vortex properties through the cardiac cycle. Blood residence time and a platelet shear activation potential index (SAP) based on the cumulative exposure to shear were also computed. The porcine bioprosthesis (BP) and the bileaflet valve in the anti-anatomical (BL-AA) position produced the most natural flow patterns. The bileaflet valves experienced large shear in the valve hinges and recirculating shear-activated flow, especially in the anatomical (BL-A) and 45-degree (BL-45) positions, thus exhibited high SAP. The tilting disk valve in the septal orientation (TD-S) produced a complete reversal of flow and vortex properties, impairing LV washout and retaining shear-activated fluid, leading to the highest residence time and SAP. In contrast, the tilting disk valve in the free-wall position (TD-F) exhibited mid-range values for residence time and SAP. Hence, the thrombogenic potential of different MHV models and configurations can be collectively ranked from lowest to highest as: BP, BL-AA, TD-F, BL-A, BL-45, and TD-S. These findings provide new insight about the effect of fluid dynamics on LV TE risk, and suggest that the bioprosthesis valve in the mitral position minimizes this risk by producing more physiological flow patterns in patients with dilated cardiomyopathy.

Comparison of intraocular pressure and pupil diameter after sedation with either acepromazine or dexmedetomidine in healthy dogs

ObjectiveTo compare intraocular pressure (IOP) and pupillary diameter (PD) following intravenous (IV) administration of dexmedetomidine and acepromazine in dogs. Study designProspective, randomized experimental trial. AnimalsA group of 16 healthy adult dogs aged (mean ± standard deviation) 4.9 ± 3.3 years and weighing 15.7 ± 9.6 kg, without pre-existing ophthalmic disease. MethodsIV dexmedetomidine hydrochloride (0.002 mg kg–1; DEX) or acepromazine maleate (0.015 mg kg–1; ACE) was administered randomly to 16 dogs (eight per group). The IOP and PD, measured using applanation tonometry and Schirmer's strips mm scale, respectively, and the heart rate (HR), systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures and respiratory rate (fR) were recorded at baseline, at time of injection, and then 5, 10, 15, 20 and 25 minutes after injection. A single ophthalmologist, unaware of treatment, performed all measurements under consistent light conditions. Values were compared with baseline and among treatments using a multivariate mixed-effects model (p ≤ 0.05). ResultsThe IOP was significantly lower in the DEX group compared with the ACE group at 10 (p < 0.01) and 15 minutes (p < 0.01) after drug injection. PD was significantly smaller compared to baseline for the entire duration of the study (p < 0.01) in both groups. Dogs in the DEX group had significant lower HR (p < 0.01) and fR (p < 0.01), higher SAP (p < 0.01) and DAP (p < 0.01) at all time points, and higher MAP (p < 0.01) during the first 15 minutes following drug injection in comparison with the ACE group. Conclusions and clinical relevanceOur results suggest that premedication with IV dexmedetomidine temporarily decreases IOP when compared with IV acepromazine. Both drugs cause miosis.

Sap Flow Measurements in a Socotra Dragon’s Blood Tree (Dracaena cinnabari) in its Area of Origin

For the first time, in situ field measurements of sap flow were conducted in adult Dracaena cinnabari plant native to the arid tropical climate of Socotra Island. The heat field deformation (HFD) method was applied using both single and multi-point sensors to study azimuthal and radial sap flow variability in stem, roots and first-order branches over two weeks during a winter monsoon. The main aim of this work was to monitor sap flow in adult D. cinnabari in-situ to better understand its physiological adaptation to extreme arid environments. The second aim was to compare our results with earlier sap flow measurements in adult D. draco uing the same HFD method. The last question we wanted to answer was comparison of sap flow measurements in both, young and adult Dracaena species. We found that sap flow magnitude is low and of a similar range in all observed D. species. High sap flow variability was recorded in different parts of adult D. cinnabari plant which changed throughout the day responding to interplay between intrinsic and extrinsic water potential gradients induced by sunlight. Maximum sap flow levels had variable pattern around stem in response to sun exposure, similarly as it was observed in adult D. draco plant. Sensors installed tangentially in stem xylem showed that water transport in adult D. cinnabari may move in lateral direction. This work also presents several methodological aspects detected from earlier observations of dicots which proved to be more pronounced in adult D. species. These methodologies relate to interpreting negative sap flow rates in conjunction with established axial flow reversal during hydraulic redistribution usually occurring under low evaporative demands and dry soil. Conversely, flow reversal during the day under high evaporative demands and wet soil may designate lateral water movement induced by internal water redistribution.

Characterization of reproductive morphological characteristics of sugar palm (Arenga pinnata) and its relationship with sap yield and Brix value

Arenga pinnata (sugar palm) is a multipurpose palm species with interesting economic potential, well known for the high sugar content of its sap. We characterized various morphological characteristics of male and female inflorescences and correlations between these parameters and sap yield were determined. We found strong correlations between peduncle girth and various morphological parameters in both types of inflorescence. Our results revealed a highly significant correlation between the average sap volume/day and various morphological parameters of male inflorescences such as the peduncle girth and average rachillae length. These morphological parameters are proposed as potential indicators for the identification of superior germplasm with high sap yield.

Sap Flow Study on Two Different Diameter Sizes of Tectona grandis

Sap flow pattern of Tectona grandis planted at lowland forest assessed. This study aimed to determine the sap movement of two different diameter sizes T. grandis. Two sizes selected were 16 and 38 cm in diameter at breast height (dbh). Sap flow meter (SFM) used to assess the sap velocity rates at the interval of 30 min within 24 h for 15 days. Diurnal sap flow of T. grandis shows that mean velocity is high during day time compared night time. Small diameter has high sap flow compared to that of bigger diameter. A flow rates was high at the inner layer and less at outer layer for smaller tree. The variation was vice versa when the tree was getting bigger. Variations in sap flow of T. grandis characterized by several environmental factors. It was found that size contribute in the differed sap flow of T. grandis.

Indapamide SR/Amlodipine Fixed Dose Combination: Novel Approach to Effective Control of Systolic Arterial Pressure

Effective control of arterial pressure (AP) is achieved only in ⅓ of patients with arterial hypertension. It is especially difficult to achieve control of systolic (S) AP in elderly patients in whom SAP is the strongest prognostic factor of cardiovascular complications. Thiazide and thiazide-like diuretics and calcium antagonists are effective for lowering of elevated SAP and pulse (P) AP including aortic PAP elevation of which is associated with high stiffness of arterial wall and is typical for elderly people. Combination of a thiazide diuretic and a calcium antagonist has been recommended by modern guidelines on arterial hypertension (AH) management but until recently it has not found wide application because of absence of a fixed preparation. Evidence base of indapamide-retard and amlodipine use in AH, their profiles of efficacy and safety are such that their combination can become an alternative variant for treatment of patients with AH. Appearance of a fixed indapamide-retard/amlodipine combination opens new perspectives of effective therapy of AH with high SAP and PAP in elderly and other patients with high stiffness of arterial wall.

Sap volatile components in relation to susceptibility of anthracnose and Aspergillus rot of mangoes (Mangifera indica L.)

ABSTRACTSap burn injury and postharvest diseases are major causes of mango fruit quality deterioration, resulting in considerable postharvest losses in many countries. Susceptibility of selected cultivars of mango in Sri Lanka to sap burn injury and the incidence of anthracnose and Aspergillus rot of mango were examined in this study. Volatile components of non-aqueous (oil) phase were investigated using GC-MS, and artificial inoculation studies were carried out to assess disease resistance with Colletotrichum queesnlandicum (KC 820802) and Aspergillus niger (KC 820801). It was observed that the popular ‘Karuthakolumban’ and ‘Willard’ mangoes with high sap flow at harvest and high sap burn incidence were more susceptible to sap burn injury compared with ‘Chembaddan’ and ‘Ambalavi’ mangoes. Cultivar variations in susceptibility to Aspergillus rot of mangoes are reported for the first time in this study, where ‘Willard’ mangoes were more resistant to Aspergillus rot than other cultivars. The sap exudates of ‘Ambalavi’ and ‘Karuthakolumban’ mangoes were observed to contain the preformed antifungal compounds 5-pentadecyl resorcinol and 5-(Heptadeca-8,11- dienyl) benzene1,3-diol, with variety ‘Ambalavi’ showing a high resorcinol level. These cultivars were found to be resistant to anthracnose disease. These results suggest that presence of sap volatiles is cultivar dependent and could be used to identify cultivars resistant to postharvest diseases and sap burn.

The annual pattern of sap flow in two Eucalyptus species established in the vicinity of gold-mine tailings dams in central South Africa

Several hundred mine tailings dams occur in the Witwatersrand Basin Goldfields in central South Africa. Seepage of acid mine drainage (AMD) from these unlined structures is widespread, and a variety of contaminants is released into soil and groundwater. The ‘Mine Woodlands Project’ is aimed at evaluating the use of high-density tree stands over surrounding contaminant plumes to limit the spread of contaminants through hydraulic control of groundwater and enhanced uptake or immobilisation of contaminants. The annual pattern of hourly sap flow in four contiguous Eucalyptus dunnii trees (aged three years) was followed over a full year in a species trial situated near Carltonville. The annual pattern of hourly sap flow was also recorded in four contiguous sample trees (aged four years) of the clonal hybrid E. grandis × E. camaldulensis (E. G×C) at another trial near Orkney. Both species showed high sap flow rates close to reference evaporation rates in response to summer rains. Both showed greatly reduced sap flow rates during the latter half of the dry winter season. Sap flow rates only recovered after the arrival of the first spring rains. Annual sap flow (E. dunnii, 673 mm; E. G×C, 767 mm) was similar to the recorded annual rainfall at each site (E. dunnii, 629 mm; E. G×C, 795 mm), and was substantially lower than total annual reference evaporation (E. dunnii, 1 273 mm; E. G×C, 1 330 mm). We conclude that the roots of both species are not yet deep enough to access the AMD-influenced groundwater, which lies at depths of 14 and 10 m below the ground at the Carltonville and Orkney sites, respectively. Despite prolonged water deficits, both species survived well and maintained sufficient vigour to permit the quick recovery of high transpiration rates in the following summer. This resilience is essential to hasten root growth and improve the chance of contact with groundwater plumes.

Environmental and physiological effects on grouping of drought-tolerant and susceptible rice varieties related to rice (Oryza sativa) root hydraulics under drought.

Background and Aims Root hydraulic limitations (i.e. intra-plant restrictions to water movement) may be related to crop performance under drought, and groupings in the hydraulic function of drought-tolerant and drought-susceptible rice (Oryza sativa) varieties have been previously reported. This study aimed to better understand the environmental and physiological relationships with rice root hydraulics under drought. Methods Xylem sap bleeding rates in the field (gsap g-1shoot) were measured on seasonal and diurnal time frames, during which time environmental conditions were monitored and physiological measurements were conducted. Complementary experiments on the effects of vapour pressure deficit (VPD) on root hydraulic conductivity and on transpiration rates of de-rooted tillers were conducted in growth chambers. Key Results The diurnal effects on bleeding rate were more closely related to irradiance than VPD, and VPD effects on root hydraulic conductivity measured on 21-day-old plants were due to effects on plant growth including root surface area, maximum root depth and root:shoot ratio. Leaf osmotic potential was related to the grouping of drought-tolerant and drought-susceptible varieties in rice root hydraulics, and these groupings were independent of differences in phenology. Low single-tiller bleeding rates were observed under high evapo-transpirational demand, higher bleeding rates were observed at more negative leaf osmotic potentials in drought-susceptible varieties, and drought-tolerant and susceptible varieties differed in the VPD-induced increase in transpiration rates of de-rooted tillers. Low root suberin amounts in some of the drought-susceptible varieties may have resulted in higher ion transport, as evidenced by higher sap K+ concentration and higher bleeding rates in those varieties. Conclusions These results provide evidence of the environmental effects on shoots that can influence root hydraulics. The consistent groupings of drought-tolerant and susceptible varieties suggest that traits affecting plant osmotic status may regulate root hydraulic response to drought in rice.

Examining diel patterns of soil and xylem moisture using electrical resistivity imaging

Summary The feedbacks among forest transpiration, soil moisture, and subsurface flowpaths are poorly understood. We investigate how soil moisture is affected by daily transpiration using time-lapse electrical resistivity imaging (ERI) on a highly instrumented ponderosa pine and the surrounding soil throughout the growing season. By comparing sap flow measurements to the ERI data, we find that periods of high sap flow within the diel cycle are aligned with decreases in ground electrical conductivity and soil moisture due to drying of the soil during moisture uptake. As sap flow decreases during the night, the ground conductivity increases as the soil moisture is replenished. The mean and variance of the ground conductivity decreases into the summer dry season, indicating drier soil and smaller diel fluctuations in soil moisture as the summer progresses. Sap flow did not significantly decrease through the summer suggesting use of a water source deeper than 60 cm to maintain transpiration during times of shallow soil moisture depletion. ERI captured spatiotemporal variability of soil moisture on daily and seasonal timescales. ERI data on the tree showed a diel cycle of conductivity, interpreted as changes in water content due to transpiration, but changes in sap flow throughout the season could not be interpreted from ERI inversions alone due to daily temperature changes.

Water Use Patterns of Four Tropical Bamboo Species Assessed with Sap Flux Measurements.

Bamboos are grasses (Poaceae) that are widespread in tropical and subtropical regions. We aimed at exploring water use patterns of four tropical bamboo species (Bambusa vulgaris, Dendrocalamus asper, Gigantochloa atroviolacea, and G. apus) with sap flux measurement techniques. Our approach included three experimental steps: (1) a pot experiment with a comparison of thermal dissipation probes (TDPs), the stem heat balance (SHB) method and gravimetric readings using potted B. vulgaris culms, (2) an in situ calibration of TDPs with the SHB method for the four bamboo species, and (3) field monitoring of sap flux of the four bamboo species along with three tropical tree species (Gmelina arborea, Shorea leprosula, and Hevea brasiliensis) during a dry and a wet period. In the pot experiment, it was confirmed that the SHB method is well suited for bamboos but that TDPs need to be calibrated. In situ, species-specific parameters for such calibration formulas were derived. During field monitoring we found that some bamboo species reached high maximum sap flux densities. Across bamboo species, maximal sap flux density increased with decreasing culm diameter. In the diurnal course, sap flux densities in bamboos peaked much earlier than radiation and vapor pressure deficit (VPD), and also much earlier than sap flux densities in trees. There was a pronounced hysteresis between sap flux density and VPD in bamboos, which was less pronounced in trees. Three of the four bamboo species showed reduced sap flux densities at high VPD values during the dry period, which was associated with a decrease in soil moisture content. Possible roles of internal water storage, root pressure and stomatal sensitivity are discussed.

Effect of phosphorus, potassium, and chloride nutrition on cold tolerance of winter canola (Brassica napus L.)

ABSTRACTWinter varieties of canola (Brassica napus L.) are susceptible to winterkill. Measurements of photosynthetic efficiency and survival of field-grown canola were used to evaluate the effect of chloride (Cl), potassium (K), and phosphorus (P) nutrition on winter field survival in northwestern USA. In a growth chamber experiment, effects of calcium chloride (CaCl2), potassium chloride (KCl), ammonium chloride (NH4Cl), or sodium chloride (NaCl) on the ability to tolerate subfreezing temperatures were evaluated. In the field, overwinter survival was higher, and greater photosynthetic activity continued later into the autumn in plants with increased sap Cl concentrations. In the greenhouse experiment, significantly greater survival occurred in plants with higher sap Cl concentrations, but only in plants that had not been cold acclimated. These results suggested that a greater concentration of chloride ion in the sap of canola plants is related to an increased ability to tolerate subfreezing temperatures, but other processes resulting from cold acclimation may largely obscure this effect.

Xylem Sap Flux Affects Conventional Stem CO2 Efflux Measurements in Tropical Trees

AbstractThe relationship between sap flux and stem CO2 efflux was assessed for three mango trees. We observed higher than expected CO2 effluxes at the place of measurement under intermediate sap flux velocities and lower fluxes under high sap flux velocity. This variation disappeared after removing the tree crown.

Effect of irrigation on sap flux density variability and water use estimate in cherry (Prunus avium) for timber production: Azimuthal profile, radial profile and sapwood estimation

Information on tree water use in plantations for high quality wood is scarce, thus studies are needed to properly estimate the irrigation demand of these plantations. Plant water use estimation with sap flow sensors has been used extensively. However, biases in tree sap flow estimate can arise from variations on radial and azimuthal profiles of sap flux density and also from the sapwood area considered for the up-scaling from sap flux density to sap flux. This work aimed to (1) study the spatial variations of sap flux density in cherry trees in a timber orientated plantation, (2) compare several methods to estimate sapwood depth in cherry trees and (3) to evaluate the effect of drip irrigation on these factors. The results showed that most of the studied trees had decreasing radial sap flux density profiles with depth as expected. However, the three irrigated trees of bigger sizes still showed high sap flux densities in their inner tissues, at contrast with the rest of the trees and especially with the non irrigated ones of similar size with values close to 20% of the sap flux density measured at 1cm depth from cambium. On the other hand, the different methods tested to estimate sapwood depth gave significantly different results and only the two methods of visual identification in wood cores based on color change and measurements of sap flux densities along the xylem radius may be considered suitable for scaling purposes. Moreover, azimuthal variation pattern was found to be random in all the studied trees, and the ranking between the aspects (north, south, east and west) was not affected by either drip irrigation or sun exposition, and thus measuring sap flux density in any particular aspect has been shown to be suitable to estimate the overall tree sap flux. We conclude that more studies are necessary to properly assess the radial profile of sap flux density, especially when considering the high sap flux density in the inner tissues of the three bigger irrigated trees as compared to the other trees, and also how this pattern seemed to indicate sapwood depths values very contrasted to the ones estimated from color change in wood cores.

Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees

Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species’ hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

Spatial Variation of Soil Available Phosphorous in the Dal Lake Catchment of Lesser Himalayas

The study attempts to evaluate the spatial pattern of soil available phosphorus, and its availability with respect to various factors including elevation, slope and landuse using statistical methods and GIS spatial analysis techniques. The results showed that the Ordinary Kriging Spherical method performed the best in the prediction of soil available phosphorus in the Dal Lake catchment. The spatial variation of soil available phosphorus was high in Dal Lake catchment and the upstream regions around Dal Lake, including the north of Dal Lake, had the highest soil available phosphorus content. The mean and standard deviation of soil available phosphorus content gradually decreased as the slope increased. The cultivated land comprised 24.36% of the catchment and out of that land 50.81% belonged to the medium to very high SAP level classes, and it played a major role in SAP availability within the catchment and a potential source of phosphorus to Dal Lake resulting in eutrophication. Among land use types, paddy fields have some of the highest maximum values and variation of coefficients. Sub watershed scale soil available phosphorus was significantly affected by elevation, slope and landuse and was decided by not only these environmental factors but also some other factors such as artificial phosphorus fertilizer application.

Mechanochemical synthesis and investigations of calcium titanate powders and their acrylic dispersions

Abstract In this paper we studied calcium titanate (CaTiO 3 ) nanopowders obtained via a mechanochemical method assisted by microwave irradiation from calcium oxide and titanium dioxide, as well as its suspensions with addition of acrylic-poly(ethylene glycol) suspensions (SAP) obtained using microwave irradiation as a stabilizing agent. Experiments carried out using X-ray diffraction technique confirmed success of mechanochemical synthesis assisted by microwave irradiation and scanning electron microscopy images allowed to determine the structure as well as dimensions of CaTiO 3 nanopowders. Suspensions of CaTiO 3 and SAP were examined and the results showed relationships between the SAP concentration and both viscosity and stability. Both viscosity and stability are significantly increased upon addition of SAP and the dependency is nearly linear for higher SAP concentrations. Based on the results, we conclude that addition of SAP allows to successfully stabilize CaTiO 3 nanopowders and the stabilizing effect can be explained by both electrostatic and steric forces.