Application Of Different Levels Research Articles

Effect of canopy and nutrient management on senile orchards of Indian gooseberry (Emblica officinalis) cv Francis

A study was conducted on 15 years old senile orchard of Indian gooseberry (Emblica officinalis G.) cv Francis to convert into productive through canopy and nutrient management. The results revealed that 50% pruning of previous season growth (P2) was statistically superior which resulted in maximum duration of flowering, fruit set and retention, yield, physical and chemical qualities of fruit and leaf as well as soil nutrient status. Further, nutrient management revealed that application of 40 kg FYM (M1) resulted maximum fruit set, retention, yield and phosphorus content in leaves and NPK in soil and minimum fruit drop, days taken to maturity and fibre content. Similarly 100 per cent RDF (N2) resulted in maximum fruit set (64.90 %), retention (20.51 %), yield (118 kg/tree), nitrogen and phosphorus content in leaves (2.46 and 0.44 %) as well as in soil (238.6 and 17.75 kg/ha). A critical observation of the results showed that interactions had been most effective to improve yield and quality parameters of fruits and nutrient status in leaves of aonla as well as soil than the individual application of different levels of pruning, organic manure and nutrient. Among flowering, fruiting and yield parameters, maximum duration of flowering (29 days), fruit set (74.61 %), retention (28.33 %) and yield (145 kg/tree) and minimum fruit drop (71.67 %) and days taken to fruit maturity (216 days) was found under P2M2N2 followed by P2M2N1. Interaction P2M2N2 has been noticed statistically superior to enhance physical and chemical characteristics of fruit followed by P2M2N1. This treatment has not only enhanced bearing and quality parameters in aonla but also increased the leaf nutrient status as well as soil fertility status. A significant increased yield of Indian gooseberry with application of pruning intensity, organic and inorganic nutrients was found due to vigorous vegetative growth and increased chlorophyll content, which together accelerated the photosynthesis that increased the supply of carbohydrates to plants. There is a positive correlation among nutrient doses with leaf nutrient content yield and quality of fruits. The supplemented organic manures have improved the physical, chemical and biological activities of soil which helped in better nutrient absorption by plants, resulting higher yield.

Effect of Carbon, Nitrogen Sources and Water Activity on Growth and Ochratoxin Production of Aspergillus carbonarius (Bainier) Thom.

Background:Ochratoxin A (OTA) is a toxic secondary metabolite produced by fungi belonging to Aspergillus and Penicillium genera. The production of OTA is influenced by environmental conditions and nutritional requirements. The postharvest application of bunches of table grape fruit (TGF), with water activity of 0.8 aw, was highly effective for controlling OTA contamination in vitro and in vivo (table grape).Objectives:The aim of this study was to determine the influence of environmental conditions and nutritional requirements on growth and OTA production by Aspergillus carbonarius, as well as, the impact of water activity on OTA production and growth characters of A. carbonarius. Furthermore, we also examined the influence of the application of different levels of water activity (aw 0.8) on the preservation of the general appearance of TGF and control of their contamination with OTA.Materials and Methods:The growth and OTA production by A. carbonarius were studied using glucose-ammonium nitrate salt broth medium. Effect of water activity was studied using glycerol (0.80, 0.85, 0.90, and 0.98 aw). The bunches of table grape fruits were immersed in glycerol solution (equivalent to 0.80 aw) and placed as a double layer in cardboard boxes (25 × 35 × 10 cm). The boxes were stored at 20°C for 15 days to simulate local market conditions.Results:The maximum OTA production by A. carbonarius was observed on broth medium after eight days of incubation at 20°C, with pH 4, and fructose and ammonium nitrate supplementation as carbon and nitrogen sources, respectively. The water activity (0.9, 0.85 aw) caused significant decrease in OTA production by A. carbonarius. The postharvest application of water activity (0.8 aw) was highly effective for maintenance of the table grape quality, which was expressed as weight loss, firmness and decay, while it also controlled OTA contamination of fruits under concept of local market conditions.Conclusions:Our results reported that deterioration of TGF by A. carbonarius could be minimized by application of aw. Our experiments were performed under conditions of local markets, which support the economy of many thousands of families in Egypt, especially in the poor rural areas. In future adequate research is required to use these technologies commercially.

Effects of elemental sulfur and soil compaction on microbial biomass carbon and soil enzyme activities

The soil enzymes and microbial biomass play a key role in nutrient cycling and sensitivity to management and environmental change compared to most physical and chemical properties. Thus these parameters have been monitored as essential indicators of soil quality. The aim of this study was to investigate the effects of sulfur and soil compaction on microbial biomass and enzyme activities. Therefore a greenhouse experiment was designed at four levels of sulfur (0, 500, 1000 and 2000kgha-1) and three levels of compaction (C0, C1, C2). Microbial biomass carbon, urease and arylsulphatase activities were determined. The results showed that application of different levels of sulfure dicreased microbial biomass carbon but urease and arylsulphatase activities dicreased at the highest levels of sulfur. Microbial biomass carbon and arylsulphatase activitiy were not influenced by soil compaction but the highest of soil compaction dicreased urease activity.

Effect of Salinity and Potassium Levels on Different Morpho-Physiological Characters of two Soybean (Glycine max L.) Genotypese

A field experiment was conducted in the field of Department of Agronomy of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh to assess the effect of potassium on different mineral ions accumulation pattern in leaves of salt affected soybean and to draw the relationship between the dry matter production and mineral ions accumulation in leaves for better understanding the effect of potassium in mitigating salinity stress. The plant height decreased with the increase in salinity levels. In general, Galarsum (V1 ) was taller than Bangladesh Soybean-4 (V2 ) at all levels of salinity. Potassium in general increased relative plant height under salinity. Galarsum with K2 (119.52 kg/ha) potassium showed relatively higher plant height at mild salinity, though at the high level of salinity the plant height increased with the higher level of potassium. The minimum relative plant height of Galarsum was obtained at the highest salinity with no potassium fertilizer. Application of different levels of K increased the production of relative stem dry weight at both 5 dS/cm (S1 ) and 7.5 dS/cm (S2 ) levels of the salinity compared to the control (S0 ). At 5 dS salinity the relative stem DW in Galarsum ranged from 46 to 66% and that at 7.5 dS salinity from 35 to 40%. Whereas, in Bangladesh Soybean-4 the stem DW ranged from 58 to 75% at S1 and that from 34 to 52% at S2 level of salinity. Therefore, the percent reduction in stem DW due to salinity was more in V2 than V1 when salinity increased from S1 to S2 under K0 and K1 potassium treatments. Moreover, the positive effect of K on the production of relative stems DW under different level of salinity. Irrespective of K levels salinity decreased the leaf dry weight in both the genotypes and the reduction in leaf DW increased with the increasing of salinity levels. The leaf DW of Galarsum (V1 ) was much higher than that of Bangladesh Soybean-4 at all level of salinity and potassium. At the control (S0 ) the increasing levels of K application decreased the leaf DW production in V1 , though in V2 the weight increased substantially. The relative leaf DW of two soybean genotypes increased with increasing K application in each salinity level except S1 K2 , S2 K3 treatments of V1 . Bangladesh Soybean-4 showed higher negative relationship (y=-40.89x+17.92, R2 =0.80) than Galarsum (y=-46.96x+24.22, R2 =0.74) between Na:Ca ratio and total dry weight. The R2 value indicates that about 73% of the contribution to the TDW of V1 and 80% of V2 can be explained by the Na:Ca ratio. TDW decreased with increasing Na:Ca ratio concentration in leaves of two soybean genotypes.

A poroelastic model for the perfusion of the lamina cribrosa in the optic nerve head

In this work we present a mathematical model for the coupling between biomechanics and hemodynamics in the lamina cribrosa, a thin porous tissue at the base of the optic nerve head which is thought to be the site of injury in ocular neurodegenerative diseases such as glaucoma. In this exploratory two-dimensional investigation, the lamina cribrosa is modeled as a poroelastic material where blood vessels are viewed as pores in a solid elastic matrix. The model is used to investigate the influence on the distributions of stress, blood volume fraction (or vascular porosity) and blood velocity within the lamina cribrosa due to the application of different levels of the intraocular pressure (IOP) and the enforcement of different mechanical constraints at the lamina’s boundary. The model simulations suggest that the degree of fixity of the boundary constraint strongly influences the lamina’s response to IOP elevation. Specifically, when the boundary is mechanically clamped, IOP elevation leads to an increase in stress close to the lamina’s boundary, making it more susceptible to tissue damage. On the other hand, when rotations are allowed at the boundary, the most vulnerable region appears to be located at the lamina’s central axis, in proximity of the eye globe, where increased stress and reduced vascular porosity and blood velocity are predicted for increased levels of IOP.

Phytochemical and Morphological Attributes of Borage (<i>Borago officinalis</i>) Affected by Salicylic Acid as an Enhancer

The objective of this study was to determine the response of borage (Borago officinalis) phytochemical and morphological attributes in relation to application of different levels of salicylic acid. Borage planted in pots and salicylic acid was sprayed on the shoots at concentrations of 0, 0.5, 1.0 and 1.5 mM with 6 replications in a completely randomized block design. Morphological attributes such as shoot height, shoot dry matter, flower dry matter, flower weight and shoot wet weight were measured. In the other hand, phytochemical attributes such as ion leakage, chlorophyll a, b, carotenoid, and antioxidant activity were also investigated under induced stress by different concentrations of salicylic acid. Results showed that some morphological traits such as shoot dry matter (31.23%), flower dry matter (20.43%), flower weight (38.54 g), shoot wet weight (109.43 g), possessed the highest values under treatment of 1.5 mM salicylic acid. Also, some phytochemical traits in plants treated with 1.5 mM salicylic acid reached the highest values during the growth stage with the exception of ion leakage (0.54%). These measured traits with higher values consisted of chlorophyll a (4.16 mg.l-1), chlorophyll b (1.65 mg.l-1), total chlorophyll (5.81 mg.l-1), carotenoid (1.18 mg.l-1), antioxidant activity (53.73%).

Características físicas de solos salino-sódicos do semiárido pernambucano em função de diferentes níveis de gesso

Objetivou-se, com este trabalho, avaliar a eficiência da aplicação de diferentes níveis de necessidade de gesso sobre as características físicas de solos salino-sódicos da região semiárida de Pernambuco. O experimento foi realizado no Laboratório de Mecânica do Solo e Aproveitamento de Resíduos da Universidade Federal Rural de Pernambuco. Os tratamentos foram dispostos em delineamento em blocos casualizados com arranjo fatorial de dois solos (S1 e S2) e cinco níveis da necessidade de gesso (50, 100, 150, 200 e 250%) determinada pelo método de Schoonover M-1, incorporados aos primeiros 12,5 cm da coluna de solo, com cinco repetições. A utilização de níveis crescentes de gesso para a correção de solos salino-sódicos proporcionou maior taxa de infiltração de água nos solos. O nível de 100% da necessidade de gesso promoveu menor grau de dispersão e maior estabilidade de agregados dos solos. No decorrer do experimento pôde-se observar, a partir do nível de 150% da necessidade de gesso, ocorreu perda de coloides (mineral e/ou orgânico).

Nuclear magnetic resonance relaxation characterisation of water status of developing grains of maize (Zea mays L.) grown at different nitrogen levels

Changes in water status of developing grains of maize (Zea mays L.) grown under different nitrogen levels were characterized by nuclear magnetic resonance (NMR) spectroscopy. There were distinct changes in water status of grains due to the application of different levels of nitrogen (0, 120 and 180 kg N ha(-1)). A comparison of the grain developmental characteristics, composition and physical properties indicated that, not only the developmental characteristics like grain weight, grain number/ear, and rate of grain filling increased, but also bound water characterized by the T2 component of NMR relaxation increased with nitrogen application (50-70%) and developmental stages leading to maturation (10-60%). The consistency in the patterns of responses to free water and intermediate water to increasing levels of nitrogen application and grain maturity suggested that nitrogen application resulted in more proportion of water to both bound- and intermediate states and less in free state. These changes are further corroborated by the concomitant increases in protein and starch contents in grains from higher nitrogen treatments as macromolecules like protein and starch retain more amount of water in the bound state. The results of the changes in T2 showed that water status during grain development was not only affected by developmental processes but also by nitrogen supply to plants. This study strongly indicated a clear nutrient and developmental stage dependence of grain tissue water status in maize.

Influence of Arbuscular Mycorrhiza and Phosphorus Levels on Dry Matter Production and Nutrients Uptake by Tomato Seedlings

To investigate the effects of arbuscular mycorrhiza (AM) and phosphorus (P) rates on the uptake of primary and secondary nutrients by tomato (Lycopersicon esculentum Milli) cv. BARI Tomato-2 seedlings, under P levels ranging from low to excessive, plants were grown in five levels of P (0, 7.5, 15.0, 22.5 and 30.0 mg P kg-1 soil) as TSP, either inoculated with AM or without AM. The total dry matter yield and uptake of N, P, K, S, Ca and Mg nutrients was significantly influenced by AM inoculation. Nutrient use efficiency in the AM-inoculated seedlings was also significantly higher than that in uninoculated seedlings. The application of different levels of P lonely increased different nutrients and its uptake positively up to certain level, but at higher level influenced negatively. The N, P, K, S, Ca and Mg content and uptake all were the highest when P applied @ 30 kg ha-1 and the lowest @ 0 kg P ha-1 but uptake found the lowest @ 60 kg P ha-1. There was a significant interaction effect of AM and P levels on nutrients content and their uptakes positively up to certain level, but at higher level of P combination influenced negatively. Among the treatment combinations, P30 x I showed the highest nutrient contents under study and their uptakes but dry matter yield gave the highest value when AM was applied with P @ 15 kg ha-1.DOI: http://dx.doi.org/10.3329/pa.v19i2.16932 Progress. Agric. 19(2): 75 - 84, 2008

Enhancing effect of nitrogen on grain production of hybrid maize in Chitwan valley

Nitrogen is one of the key factors for increased grain production of hybrid maize. A newly developed hybrid maize variety Rampur Hybrid-2 was evaluated for grain production by the application of different levels of nitrogen (60, 120 and 180 kg N/ha) at varying plant densities (55555, 66666 and 83383 plants/ha) along with 60 kg P2O5 and 40 kg K2O /ha in the acidic soil (pH 5.3) of National Maize Research Program, Rampur, Chitwan during the years of 2008/09 and 2009/10. Factorial randomized complete block design (RCBD) with three replications was the design of experiment. The crop was planted at the plot size of 18 m2 (3.6 m × 5 m). maize was planted in the month of September and harvested in February. The result indicated a sharp response of nitrogen application to this crop whereas the effect of density was observed to be non-significant. Two years mean yield results showed that highest grain yield (11.10 t /ha) was recorded when the crop was supplied with 180 kg nitrogen and with 83383 plants /ha followed by the crop supplied with 120 kg N /ha and 66,666 plant population (10.69 t /ha). The experimental results revealed that application of high dose of N (180 kg N /ha) could help increase hybrid maize grain production in the acidic soils of Chitwan valley. Agronomy Journal of Nepal (Agron JN) Vol. 3. 2013, Page 33-41 DOI: http://dx.doi.org/10.3126/ajn.v3i0.8984

Rapid changes in microbial biomass and aggregate size distribution in response to changes in organic matter management in grass pasture

Adding high quantities of organic matter can increase carbon (C) inputs to soil and help maintain soil structure. This study investigated short-term effects of application of different levels of composted dairy manure (CDM) versus interseeding a legume into grass pasture on aggregate stability and soil C and nitrogen (N) contents. CDM was added to a mixture of perennial grasses at 22.4, 33.6 or 44.8Mgha−1. A grass–legume treatment was established by interseeding alfalfa (Medicago sativa) into the grass mixture. A no-input control was sampled as a reference. Soils (0–5 and 5–15cm) were sampled approximately 1.5years after study implementation and wet sieved to obtain four aggregate size classes: large macroaggregates (>2000μm), small macroaggregates (250–2000μm), microaggregates (53–250μm) and silt and clay fraction (<53μm). Significant CDM influences were found in the 5–15cm depth. The addition of 44.8Mg CDM ha−1 and alfalfa resulted in higher proportions of macroaggregates (>250μm) and mean weight diameter (MWD) than CDM added at 22.4 or 33.6Mgha−1. Addition of CDM at low dose rate and alfalfa did not affect total soil or aggregate-associated organic C or N. However, addition of CDM at 44.8Mgha−1 and alfalfa resulted in higher total soil microbial biomass C and N compared to CDM added at 22.4 and 33.6Mgha−1. Large macroaggregates were found to be positively correlated with total soil microbial biomass C (R=0.81, p=0.002). In conclusion, compared to a low application rate of CDM, addition of a high application rate of CDM or alfalfa interseeding resulted in higher total soil microbial biomass C and N and macroaggregates, and these changes in microbial biomass and aggregation occurred very rapidly.

The influence of phosphate fertilizer application levels and cultivars on cadmium uptake by Komatsuna (Brassica rapa L. var. perviridis)

Cadmium (Cd) is a common impurity in phosphate fertilizers and application of phosphate fertilizer may contribute to soil Cd accumulation. Changes in Cd burdens to agricultural soils and the potential for plant Cd accumulation resulting from fertilizer input were investigated in this study. A field experiment was conducted on Haplaquept to investigate the influence of calcium superphosphate on extractable and total soil Cd and on growth and Cd uptake of different Komatsuna (Brassica rapa L. var. perviridis) cultivars. Four cultivars of Komatsuna were grown on the soil and harvested after 60 days. The superphosphate application increased total soil Cd from 2.51 to 2.75 mg kg−1, 0.1 mol L−1 hydrochloric acid (HCl) extractable Cd from 1.48 to 1.55 mg kg−1, 0.01 mol L−1 HCl extractable Cd from 0.043 to 0.046 mg kg−1 and water extractable Cd from 0.0057 to 0.0077 mg kg−1. Cd input reached 5.68 g ha–1 at a rate of 240 kg ha–1 superphosphate fertilizer application. Superphosphate affected dry-matter yield of leaves to different degrees in each cultivar. ‘Nakamachi’ produced the highest yield in 2008 and ‘Hamami No. 2’ in 2009. Compared with the control (no phosphate fertilizer), application of superphosphate at a rate of 240 kg ha–1 increased the Cd concentration in dry leaves by 0.14 mg kg−1 in ‘Maruha’, 1.03 mg kg−1 in ‘Nakamachi’, 0.63 mg kg−1 in ‘SC8-007’ in 2008, and by 0.19 mg kg−1 in Maruha’, 0.17 mg kg−1 in ‘Hamami No. 2’, while it decreased by 0.27 mg kg−1 in ‘Nakamachi’ in 2009. Field experiments in two years demonstrated that applications of different levels of calcium superphosphate did not influence Cd concentration in soil and Komatsuna significantly. However, there was a significant difference in Cd concentration of fresh and dry Komatsuna leaves among four cultivars in 2008 and 2009. The highest Cd concentration was found in the ‘Nakamachi’ cultivar (2.14 mg kg−1 in 2008 and 1.91 mg kg−1 in 2009). The lowest Cd concentration was observed in the ‘Maruha’ cultivar (1.51 mg kg−1 dry weight (DW)) in 2008 and in the ‘Hamami No. 2’ cultivar (1.56 mg kg−1 DW) in 2009. A decreasing trend in Cd concentration was found in ‘Nakamachi’, followed by ‘SC8-007’, ‘Hamami No. 2’ and ‘Maruha’ successively. It is necessary to consider a low-uptake cultivar for growing in a Cd polluted soil. In these two years’ results, ‘Maruha’ cultivar was the lowest Cd uptake cultivar compared to the others.

Modeling the Effect of Midrotation Fertilization on Specific Gravity of Loblolly Pine (Pinus taeda L.)

Abstract Ring specific gravity, earlywood and latewood specific gravity, and percent latewood were measured on cores collected at breast height from a thinned and fertilized midrotation loblolly pine (Pinus taeda L.) plantation in the lower Coastal Plain of North Carolina. The study was laid out in a randomized complete block design receiving four levels of nitrogen (N) fertilizer in 1984: 000 (control), 112, 224, and 336 kg/ha plus 28 kg/ha of phosphorus with each treatment. A consistent pattern of response was observed in latewood specific gravity (LWSG) after the application of different levels of fertilizer and used as a variable for modeling. The LWSG profiles of unfertilized trees followed a nonlinear relation with ring number from pith. A three-parameter asymptotic function was used to explain the LWSG profile of unfertilized trees with ring number as a covariate. Application of N reduced LWSG and was modeled using a two-parameter response function with year since fertilization as a covariate and separate parameter estimates for each fertilization level. On the basis of the model, the magnitude of maximum cumulative response was −0.025, −0.049, and −0.074 attained at 3.7, 1.9, and 0.8 years after fertilization for the 112, 224, and 336 kg/ha treatments, respectively.

Distribution of phosphorus in size fractions of sandy soils with different fertilization histories

AbstractA major challenge in sustainable crop management is to ensure adequate P supply for crops, while minimizing losses of P that could negatively impact water quality. The objective of the present study was to investigate the effects of long‐term applications of different levels of mineral fertilizers and farmyard manure on (1) the availability of P, (2) the relationship between soil C, N, and P, and (3) the distribution of inorganic and organic P in size fractions obtained by wet sieving. Soil samples were taken from the top 20 cm of a long‐term (29 y) fertilization trial on a sandy Cambisol near Darmstadt, SW Germany. Plant‐available P, determined with the CAL method, was little affected by fertilization treatment (p &lt; 0.05) and was low to optimal. The concentration of inorganic and organic P extracted with a NaOH‐EDTA solution (PNaOH‐EDTA) averaged about 350 mg (kg dry soil)–1, with 42% being in the organic form (Po). Manure application tended to increase soil C, N, and Po concentrations by 8%, 9%, and 5.6%, respectively. Across all treatments, the C : N : Po ratio was 100 : 9.5 : 2 and was not significantly affected by the fertilization treatments. Aggregate formation was weak due to the low clay and organic‐matter content of the soil, and the fractions &gt; 53 μm consisted predominantly of sand grains. The different fertilization treatments had little effect on the distribution of size fractions and their C, N, and P contents. In the fractions &gt; 53 μm, PNaOH‐EDTA ranged between 200 and 300 mg kg–1, while it reached 1260 mg kg–1 in the fraction &lt; 53 μm. Less than one third of PNaOH‐EDTA was present as Po in the fractions &gt; 53 μm, while Po accounted for 70% of PNaOH‐EDTA in the smallest fraction (&lt; 53 μm). Therefore, 16% and 28% of PNaOH‐EDTA and Po, respectively, were associated with the smallest fraction, even though this fraction accounted for &lt; 5% of the soil mass. Therefore, runoff may cause higher P losses than the soil P content suggests in this sandy soil with a weak aggregate formation. Overall, the results indicate that manure and mineral fertilizer had similar effects on soil P fractions.

The utilization of long‐chain fatty acids as markers for diet composition estimates in ruminants: effects of animal species, diet composition and marker combination

AbstractUtilization of long‐chain fatty acids (LCFA) as diet composition markers, combined or not with alkanes, was evaluated in a study performed with sheep, goats and cattle fed on two different diets composed of herbaceous species and heather. Proportions of plant species were estimated from LCFA concentrations in plant species and faeces, using least‐square procedures, and were compared with those obtained using alkanes or LCFA + alkane. The impact of grouping plant species with similar LCFA + alkane profiles and the application of different levels of feeding selectivity within the dietary group on the accuracy of estimates were also assessed. Results showed that LCFA faecal recoveries were incomplete and tended to increase with carbon‐chain length in a curvilinear fashion in both diets and all animal species. Furthermore, differences between ruminant species and diets in the LCFA faecal recovery were observed. Combination of alkanes and LCFA provided the most accurate estimates of diet composition, while estimates based on LCFA alone were better than those using alkanes alone. Accuracy of these estimates differed among animal species but was not influenced by diet composition. Grouping plant species with similar LCFA + alkane profiles reduced the accuracy of estimates with a clear underestimation of the dietary group.

Phosphorus and humic acid application alleviate salinity stress of pepper seedling

Humic acid is a commercial product that contains many elements which improve the soil fertility and increase the availability of nutrient elements. It consequently affects plant growth and yield and ameliorates the deleterious effects of salt stress. The objective of the study was to determine the effect of humic acids and phosphorus on growth and nutrient content of pepper seedlings (cv. Demre) grown under moderate salt stress in growth chamber conditions. Applications of different levels of phosphorus [0 (P0), 50 (P1), 100 (P2) and 150 (P3) mg kg-1] and humic acid [0 (HA0), 750 (HA1) and 1500 (HA2) mg kg-1] to growing media containing moderate salt dose (8 mM NaCl treatment) were studied. The study was replicated four times with 20 plants in each replicate. Humic acid (HA) and phosphorus applications increased the growth and growth parameter of plants. In company, effects of HA and P application was more effective on growth and growth parameter than each separate effect. The optimum total yield was obtained from 69 mg kg-1 P application with HA2 doses according to regression analysis. Humic acid application significantly increased N, P, K, Ca, Mg, S, Mn and Cu contents of shoot of pepper seedling. Also, N, P, K, Ca, S, Fe, Mn, Zn and Cu contents of root were increased with humic acid application. Na contents of both shoot and root of pepper decreased with increased humic acid doses. It can be concluded that high humic acid doses has positive effects on salt tolerance based on the plant growth parameters and nutrient contents. The present study suggests that HA treatments can ameliorate the deleterious effects of salt stress on pepper plants and HA could offer an economical and simple application to reduce problems of pepper production in moderately saline soil. Key words: Nutrient uptake, plant growth parameter, salt stress, pepper.

Effect of elevated PEEP on dynamic variables of fluid responsiveness in a pediatric animal model

Previous studies have demonstrated that stroke volume variation (SVV), pulse pressure variation (PPV) and global end-diastolic volume (GEDV) can be used to predict the response to fluid administration. Currently, little information is available whether application of different levels of positive end-expiratory pressure (PEEP), especially in infants and neonates, affects their ability to predict fluid responsiveness. The aim of our study was to assess the effect of increasing PEEP levels on the predictive value of SVV, PPV and GEDV with respect to fluid responsiveness. Stroke volume variation and PPV were monitored continously in 22 anesthetized piglets during changing PEEP levels (5 and 10 cmH(2)O) both before and after fluid loading (FL). GEDV was measured by transpulmonary thermodilution; cardiac output and stroke volume (SV) were measured by pulmonary artery thermodilution. A positive response to FL was defined as > or =15% increase in SV. Fluid loading induced significant changes in all hemodynamic variables except of heart rate and systemic vascular resistance. At PEEP 5 cmH(2)O, SVV, PPV and GEDV significantly correlated with volume induced percentage change in SV, whereas at PEEP 10 cmH(2)O, this correlation was abolished for PPV. As assessed by receiver operating characteristic curve analysis, SVV and GEDV, independent of PEEP level applied, were the best predictors of a positive response to FL [area under the curve: SVV = 0.88; GEDV = 0.80]. In this pediatric animal model, SVV and GEDV were sensitive and specific predictors of fluid responsiveness during increasing PEEP levels.

Assessment of upper airway mechanics during sleep

Obstructive sleep apnea, which is the most prevalent sleep breathing disorder, is characterized by recurrent episodes of upper airway collapse and reopening. However, the mechanical properties of the upper airway are not directly measured in routine polysomnography because only qualitative sensors (thermistors for flow and thoraco-abdominal bands for pressure) are used. This review focuses on two techniques that quantify upper airway obstruction during sleep. A Starling model of collapsible conduit allows us to interpret the mechanics of the upper airway by means of two parameters: the critical pressure (Pcrit) and the upstream resistance (Rup). A simple technique to measure Pcrit and Rup involves the application of different levels of continuous positive airway pressure (CPAP) during sleep. The forced oscillation technique is another non-invasive procedure for quantifying upper airway impedance during the breathing cycle in sleep studies. The latest developments in these two methods allow them to be easily applied on a routine basis in order to more fully characterize upper airway mechanics in patients with sleep breathing disorders.

Effects of plant nutrient availability and host plant species on the performance of two Pieris butterflies (Lepidoptera: Pieridae)

We assayed the interaction on the availability of plant nutrient and species of host plant on the performance of two species of Pieris butterfly. The results indicated that constant application of different levels of fertilizers to the four different host plants resulted to an increase in their content of plant nutrients. The chemical analysis showed that the added nutrients increased foliar nitrogen and water contents, but there was no effect on the level of glucosinolates. Larvae that fed on highly-nutritious foliage increased their growth rates and showed a shorter development period. The results of feeding trials revealed that the 4th-instar larvae, which had fed on host plants with higher levels of fertilization had a shorter duration of development, less consumption rate, higher growth rate and food processing efficiency. To summarize, this research revealed that both the availability of plant nutrient and species of host plant can strongly influence the physiology and foliar chemistry of host plants. Moreover, the changes of phytochemical in the host plants may play an important role in affecting the performance (growth and food utilization efficiency) of both species of Pieris butterflies.

Microbial biomass carbon and some soil properties as influenced by long-term sodic-water irrigation, gypsum, and organic amendments

Long-term sodic-water irrigation may adversely affect the quality of soil organic carbon along with some soil properties. The extent to which the adverse effects can be ameliorated through the use of gypsum and amendments needs to be known. Soil properties and microbial biomass carbon (MBC) were studied after 14 years of sodic water (SW) irrigation and application of different levels of gypsum, farmyard manure (FYM), green manure (GM), and wheat straw (WS) to a sandy loam soil. Irrigation with SW increased pH, electrical conductivity, sodium adsorption ratio, exchangeable sodium percentage (ESP), and bulk density, and decreased final infiltration rate of soil. Application of gypsum and organic amendments reversed these trends. Decrease in MBC due to SW irrigation was from 132.5 to 44.6 mg/kg soil in the 0–75 mm soil layer and from 49.0 to 17.3 mg/kg soil in the 75–150 mm soil layer. Application of gypsum and organic amendments significantly increased MBC; GM and FYM were more effective than WS. Changes in soil ESP explained 85 and 75% variation in MBC in the unamended and organically amended SW treatments, respectively. Soil pH as additional variable improved the predictability of MBC to 96% and 77%. Irrigation with SW reduced yield of rice plus wheat by 5 t/ha. Application of gypsum and organic amendments significantly increased the rice and wheat yield; it was significantly correlated with MBC (r = 0.56**, n = 60). It confirms that MBC rather than organic C is a more sensitive indicator of environmental stresses in soils caused by long-term sodic water irrigation.