Plant Water Requirements Research Articles

Physiological responses of pepper plant (Capsicum annuum L.) to drought stress

ABSTRACTWater shortage is the most important factor constraining agricultural production all over the world. New irrigation strategies must be established to use the limited water resources more efficiently. This study was carried out in a completely randomized design with three replications under the greenhouse condition at Shahrekord University, Shahrekord, Iran. In this study, the physiological responses of pepper plant affected by irrigation water were investigated. Irrigation treatments included control [full irrigation (FI) level] and three deficit irrigation (DI) levels—80, 60, and 40% of the plant's water requirement called DI80, DI60, and DI40, respectively. A no plant cover treatment with three replications was also used to measure evaporation from the soil surface. Daily measurements of volumetric soil moisture (VSM) were made at each 10-cm intervals of the soil column, considered as a layer. The differences between the measured VSM and the VSM in the next day and evaporation rate at the soil surface at the same layer of the bare soil with no plant cover treatment were calculated. Eventually, by considering the applied and collected water in each treatment, evapotranspiration (ETC) and root water uptake in each layer per day were estimated. Furthermore, fruit number per plant, fresh fruit weight/day, root fresh/dry weights, shoot fresh/dry weights, root zone volume, root length and density, crop yield, and water use efficiency (WUE) were measured under different water treatments. The results showed that the maximum and minimum of all the studied parameters were found in the FI and DI40 treatments, respectively. ETC in the DI80, DI60, and DI40 treatments were reduced by 14.2, 37.4, and 52.2%, respectively. Furthermore, applying 80, 60, and 40% of the plant's water requirement led to the reduction in crop yield by 29.4, 52.7, and 69.5%, respectively. The averages of root water uptakes in the DI80, DI60, and DI40 treatments reduced by 17.08, 48.72, and 68.25%, respectively. WUE and crop yield also showed no significant difference in the FI and DI80 treatments. Moreover, in the DI80 treatment, the reduced rate of water uptake was less than the reduced rate of plant's applied water. According to these results, it can be concluded that 20% DI had no significant reduction on the yield of pepper, but above this threshold, there was an adverse effect on the growth and yield. Therefore, for water management in the regions with limited water resources, rate of plant's applied water can be decreased by around 20%.

山东油用牡丹高产优质栽培技术

对位于济南市长清区双泉镇基地的油用牡丹——凤丹进行了多年观察和栽培试验，总结了凤丹牡丹的生长发育、需水、需肥和病虫草害发生规律，提出了以育苗、移栽、抚育管理及采收等为主要内容的栽培管理技术，为凤丹牡丹的大面积种植和产业化开发提供了技术支持。 Through years of observation and cultivation experiments on oilseed peony—Paeonia ostii in Shuangquan Town station of Changqing District, Jinan, Shandong Province, we summarized the pattern of plant growth, water and fertilizer requirement and pest occurrence in P. ostii. The cul-tivation and management techniques including seedling raising, transplanting, field management, harvesting, etc. were established, which provide a technical support for the development of large acreage and industrialization of the P. ostii.

Modified TOMGRO outputs as guide factors to estimate evapotranspiration and water use efficiency of three tomato fresh cultivars, grown in a low-tech Italian glasshouse

In Low-Tech Italian greenhouses, the adoption of more rational criteria in resources management would lead to significant economic and environmental advantages for producers. Reliable crop growth and evapotranspiration models, may allow real time assessment of water and nutrient plant requirements and the evaluation of the productive system efficiency, supporting decision-making processes for short, long and medium-term strategies. This paper presents the results of an experimental trial carried out in 2011, in the research facilities of the DISAAA-a at Pisa University, to set a cross-control method for the evaluation of the Water Use Efficiency (WUE) and of the real plant water requirements. A modified version of TOMGRO model was used to simulate Leaf Area Index (LAI) and total dry biomass (shoot and fruits) of three different cultivars of tomato (Solanum lycopersicum L.), grown in the same environmental conditions. For each cultivar, the hourly values of LAI provided by the TOMGRO model were used as input in the Baille equation for the estimation of the evapotranspiration (ET) rate, finding a significant agreement between simulated and measured ET values (R2=0.8 on average). A good prediction of the WUE of each thesis was also obtained (R2>0.8),, offering interesting elements for plant performance evaluation. Considering these evidences, a synthetic index (estimated biomass/estimated ET) may be used for a direct comparison between different scenarios.

Modelling water requirements of greenhouse spinach for irrigation management purposes

Estimating water requirements of plants cultivated in greenhouse environments is crucial, both for the design of greenhouse irrigation systems and the improvement of irrigation scheduling. Spinach is one of the main vegetables sold as ‘ready-to-eat’ bagged produce; it is very sensitive to water stress and thus requires accurate irrigation. In this work, a water balance model simulating the daily irrigation need for greenhouse crops based on the FAO-56 ‘single crop coefficient’ method was designed and applied (FAO-56-GH). Two experiments were conducted on two spinach varieties grown in pots in different periods. For each experiment, four nitrogen treatments were considered. Irrigation was managed weighing the pots every day, and restoring soil water to field capacity. Crop coefficient (Kc) values were calibrated using data of the first experiment, the model was successively validated using the second dataset. Results showed a good model performance both in the validation and calibration periods (R2 = 0.80 and 0.84, root mean square error (RMSE) = 0.41 and 0.21 mm day−1, Nash–Sutcliffe efficiency (NSE) = 0.78 and 0.83). Analysis of variance (ANOVA) test revealed a scarce dependence of irrigation needs to nitrogen treatments. This study suggests the possibility of adopting the FAO-56-GH model with site-specific Kc to improve irrigation management and planning in greenhouse environments.

Effects of partial root-zone drying irrigation and water quality on soil physical and chemical properties

Using recycled wastewater (RW) is considered to be a strategic choice for overcoming water scarcity worldwide, so there is a pressing need to improve irrigation and nutrient uptake to sustain crop yields and at the same time to reduce the negative impacts of RW. In the present study, tomato plants (Lycopersicon esculentum Mill. var. “Azmier”) were exposed to three different water qualities: recycled wastewater (RW); fresh municipal tap water (FW); and a blend of RW and stormwater (BW), in combination with five irrigation scenarios: full irrigation (FI) full plant water requirement; deficit irrigation (DI), with 75% and 50% of FI as DI75 and DI50, respectively; and partial root-zone drying (PRD), with 75% and 50% as PRD75 and PRD50, respectively. The effects of these treatments on soil hydraulic conductivity (Ks), soil pH, root growth, leaf area (LA) as well as the residual phosphorus (P), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) in the soil were investigated. The results showed that there was no significant difference in the soil Ks. However, different types of irrigation waters significantly affected the soil pH, while irrigation scenarios had no effect on soil pH. Also, irrigation scenarios influenced root growth and LA, while PRD scenarios lowered soil P, K+, and Mg2+ concentration compared to DI. The results also showed that water quality influenced canopy coverage 107days after planting (DAP). It is clear that PRD is a promising scenario for sustaining agriculture in areas with high water scarcity.

Phytostabilization of Zn-Pb ore flotation tailings with Dianthus carthusianorum and Biscutella laevigata after amending with mineral fertilizers or sewage sludge

Zinc-lead mining wastes remain largely unvegetated and prone to erosion for many years because of phytotoxic levels of residual heavy metals, low nutrient status and poor physical structure. The optimal solution for these areas is to restore plant cover using species which spontaneously appear on the spoils. These species are adapted to the conditions of tailings, and their establishment will promote further vegetation by increasing soil organic matter and development of a soil system capable of supporting the nutrient and water requirements of plants and microoorganisms. The potential of Dianthus carthusianorum and Biscutella laevigata to stabilize mine spoils was analysed in a three-year pot experiment. Post-flotation wastes accumulated after Zn and Pb recovery from ores, were collected from tailings and used as a substrate for plant growth. Seeds for seedling production were collected from plants growing spontaneously on mine tailings. Prior to the establishment of the three-year pot experiment, the substrate was amended with fertilizer NPK or municipal sewage sludge, supplemented with K2O (SS). Substrate samples were collected for chemical analyses, dehydrogenase and urease activities measurements each year at the end of the growing season. The plants were harvested three years after the amendments. Both tested plant species were equally suitable for revegetation of the tailings. The amendment including both SS and NPK resulted in an increase of Corg, Nt, available P, K, Mg contents, an increase of dehydrogenase (DHA) and urease activities and a decrease in the concentrations of the soluble forms of Zn, Pb and Cd. However, nutrient content, DHA activity and plant biomass were higher with SS than NPK addition. NPK application enhanced the substrate properties after the first growing season, while positive effects of SS use were still observed after three years. A longer-lasting positive effect of SS than NPK application was probably due to the high organic matter content in SS, which was gradually decomposing and releasing nutrients.

Consumptive Water Use from Electricity Generation in the Southwest under Alternative Climate, Technology, and Policy Futures.

This research assesses climate, technological, and policy impacts on consumptive water use from electricity generation in the Southwest over a planning horizon of nearly a century. We employed an integrated modeling framework taking into account feedbacks between climate change, air temperature and humidity, and consequent power plant water requirements. These direct impacts of climate change on water consumption by 2095 differ with technology improvements, cooling systems, and policy constraints, ranging from a 3-7% increase over scenarios that do not incorporate ambient air impacts. Upon additional factors being changed that alter electricity generation, water consumption increases by up to 8% over the reference scenario by 2095. With high penetration of wet recirculating cooling, consumptive water required for low-carbon electricity generation via fossil fuels will likely exacerbate regional water pressure as droughts become more common and population increases. Adaptation strategies to lower water use include the use of advanced cooling technologies and greater dependence on solar and wind. Water consumption may be reduced by 50% in 2095 from the reference, requiring an increase in dry cooling shares to 35-40%. Alternatively, the same reduction could be achieved through photovoltaic and wind power generation constituting 60% of the grid, consistent with an increase of over 250% in technology learning rates.

Evaluation of yield, quality and crop water stress index of sugar beet under different irrigation regimes

This study was carried out to evaluate the use of the crop water stress index (CWSI) for irrigation scheduling of sugar beet for two years under the semi arid climate of Iran. Statistical relationships between CWSI and yield, quality parameters and irrigation water use efficiency (IWUE) were investigated. Irrigations were scheduled based on 100 (I100), 85 (I85), 70 (I50) and 0% (I0) of plant water requirement. CWSI values were calculated from the measurements of canopy temperatures by infrared thermometer, air temperatures and vapor pressure deficit values for all the irrigated treatments. The highest IWUE was found in I70 with 9.16 and 1.66 kg m−3 for the root and sugar yield, respectively, in 2013. A non-water stressed baseline (lower line) equation for sugar beet was measured from full irrigated plots as (Tc − Ta)ll = −0.832VPD + 2.1811; R2 = 0.6508. There was a high determination coefficient between CWSI with the root and sugar yield and IWUE. The CWSI could be used to determine the irrigation time of sugar beet, and 0.3 could be offered as a threshold value. Results indicated that the CWSI can be used to evaluate crop water stress and improve irrigation scheduling for sugar beet under semiarid conditions.

Hemispherical photography to estimate biophysical variables of cotton

ABSTRACT The Leaf Area Index (LAI) is a key parameter to evaluate the vegetation spectral response, estimating plant nutrition and water requirements. However, in large fields is difficult to obtain accurate data to LAI determination. Therefore, the objective of this study was the estimation of LAI, biomass and yield of irrigated cotton through digital hemispherical photography. The treatments consisted of four nitrogen doses (0, 90, 180 and 270 kg ha-1) and four phosphorus doses (0, 120, 240 and 360 kg ha-1). Digital hemispherical photographs were collected under similar sky brightness conditions at 60 and 75 days after emergence (DAE), performed by the Digital Plant Canopy Imager - CI-110® of CID Inc. Biomass and LAI measurements were made on the same dates. LAI was also determined by destructive and non-destructive methods through a leaf area integrator (LI-COR® -LI-3100C model), and by measurements based on the midrib length of all leaves, respectively. The results indicate that the hemispherical images were appropriate to estimate the LAI and biomass production of irrigated cotton, while for the estimation of yield, more research is needed to improve the method.

Comparing Three Approaches of Evapotranspiration Estimation in Mixed Urban Vegetation: Field-Based, Remote Sensing-Based and Observational-Based Methods

Despite being the driest inhabited continent, Australia has one of the highest per capita water consumptions in the world. In addition, instead of having fit-for-purpose water supplies (using different qualities of water for different applications), highly treated drinking water is used for nearly all of Australia’s urban water supply needs, including landscape irrigation. The water requirement of urban landscapes, particularly urban parklands, is of growing concern. The estimation of evapotranspiration (ET) and subsequently plant water requirements in urban vegetation needs to consider the heterogeneity of plants, soils, water, and climate characteristics. This research contributes to a broader effort to establish sustainable irrigation practices within the Adelaide Parklands in Adelaide, South Australia. In this paper, two practical ET estimation approaches are compared to a detailed Soil Water Balance (SWB) analysis over a one year period. One approach is the Water Use Classification of Landscape Plants (WUCOLS) method, which is based on expert opinion on the water needs of different classes of landscape plants. The other is a remote sensing approach based on the Enhanced Vegetation Index (EVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra satellite. Both methods require knowledge of reference ET calculated from meteorological data. The SWB determined that plants consumed 1084 mm·yr−1 of water in ET with an additional 16% lost to drainage past the root zone, an amount sufficient to keep salts from accumulating in the root zone. ET by MODIS EVI was 1088 mm·yr−1, very close to the SWB estimate, while WUCOLS estimated the total water requirement at only 802 mm·yr−1, 26% lower than the SWB estimate and 37% lower than the amount actually added including the drainage fraction. Individual monthly ET by MODIS was not accurate, but these errors were cancelled out to give good agreement on an annual time step. We conclude that the MODIS EVI method can provide accurate estimates of urban water requirements in mixed landscapes large enough to be sampled by MODIS imagery with 250-m resolution such as parklands and golf courses.

VitiCanopy: A Free Computer App to Estimate Canopy Vigor and Porosity for Grapevine.

Leaf area index (LAI) and plant area index (PAI) are common and important biophysical parameters used to estimate agronomical variables such as canopy growth, light interception and water requirements of plants and trees. LAI can be either measured directly using destructive methods or indirectly using dedicated and expensive instrumentation, both of which require a high level of know-how to operate equipment, handle data and interpret results. Recently, a novel smartphone and tablet PC application, VitiCanopy, has been developed by a group of researchers from the University of Adelaide and the University of Melbourne, to estimate grapevine canopy size (LAI and PAI), canopy porosity, canopy cover and clumping index. VitiCanopy uses the front in-built camera and GPS capabilities of smartphones and tablet PCs to automatically implement image analysis algorithms on upward-looking digital images of canopies and calculates relevant canopy architecture parameters. Results from the use of VitiCanopy on grapevines correlated well with traditional methods to measure/estimate LAI and PAI. Like other indirect methods, VitiCanopy does not distinguish between leaf and non-leaf material but it was demonstrated that the non-leaf material could be extracted from the results, if needed, to increase accuracy. VitiCanopy is an accurate, user-friendly and free alternative to current techniques used by scientists and viticultural practitioners to assess the dynamics of LAI, PAI and canopy architecture in vineyards, and has the potential to be adapted for use on other plants.

Effect of soil texture and wheat plants on N2O fluxes: A lysimeter study

Agricultural soils are a major source of nitrous oxide (N2O) emissions and an understanding of factors regulating such emissions across contrasting soil types is critical for improved estimation through modelling and mitigation of N2O. In this study we investigated the role of soil texture and its interaction with plants in regulating the N2O fluxes in agricultural systems. A measurement system that combined weighing lysimeters with automated chambers was used to directly compare continuously measured surface N2O fluxes, leaching losses of water and nitrogen and evapotranspiration in three contrasting soils types of the Riverine Plain, NSW, Australia. The soils comprised a deep sand, a loam and a clay loam with and without the presence of wheat plants. All soils were under the same fertilizer management and irrigation was applied according to plant water requirements. In fallow soils, texture significantly affected N2O emissions in the order clay loam>loam>sand. However, when planted, the difference in N2O emissions among the three soils types became less pronounced. Nitrous oxide emissions were 6.2 and 2.4 times higher from fallow clay loam and loam cores, respectively, compared with cores planted with wheat. This is considered to be due to plant uptake of water and nitrogen which resulted in reduced amounts of soil water and available nitrogen, and therefore less favourable soil conditions for denitrification. The effect of plants on N2O emissions was not apparent in the coarse textured sandy soil probably because of aerobic soil conditions, likely caused by low water holding capacity and rapid drainage irrespective of plant presence resulting in reduced denitrification activity. More than 90% of N2O emissions were derived from denitrification in the fine-textured clay loam—determined for a two week period using K15NO3 fertilizer. The proportion of N2O that was not derived from K15NO3 was higher in the coarse-textured sand and loam, which may have been derived from soil N through nitrification or denitrification of mineralized N. Water filled pore space was a poorer predictor of N2O emissions compared with volumetric water content because of variable bulk density among soil types. The data may better inform the calibration of greenhouse gas prediction models as soil texture is one of the primary factors that explain spatial variation in N2O emissions by regulating soil oxygen. Defining the significance of N2O emissions between planted and fallow soils may enable improved yield scaled N2O emission assessment, water and nitrogen scheduling in the pre-watering phase during early crop establishment and within rotations of irrigated arable cropping systems.

Response of Drip Irrigation and Plastic Mulch on Quality of Sapota(Achras Zapota)Fruits

The field experiment was conducted to study the response of sapota (Achras zapota) crop under drip irrigation and plastic mulch. Different amounts of irrigation water application through drip and ring basin irrigation methods along with plastic mulch treatments were experimented with five replications. The Sapota crop water requirement was estimated using reference evapotranspiration data and crop co-efficient for different crop growth stages. Reference evapotranspiration was estimated using FAO-56 Penman Monteith approach. The irrigation water was applied at 60%, 80%, and 100% of the crop water requirement using drip and ring basin irrigation system. The quality analysis of sapota fruit was performed to investigate the effect of different treatments. Economic analysis was carried out to study the economic feasibility of using drip irrigation and plastic mulch for sapota cultivation. The water requirement of sapota crop varies between 10.71 L per day per plant in winter and 34.43 L in summer for the treatment of 100% water requirement of the sapota plant. The physical properties like fruit weight, volume, dimension, peel-pulp ratio was found to be increased due to increase in amount of irrigation water application from 60% to 100% using drip irrigation. A small decrease in true density of fruit was observed with the increase of size of fruit. The pH of fruit increased with decrease in irrigation water application through drip system. The TSS, total sugar and reducing sugar were estimated to increase with reduced irrigation water application. Sweetness of the fruit increased with reduced irrigation water application. Increase in Sapota fruit yield varied from 7.62% to 41% in mulched treatments. Increase in fruit yield by 21.05% for the drip treated plants was over ring basin. Based on the water use efficiency, benefit-cost analysis and fruit quality analysis 80% irrigation requirement supplied through drip system along with plastic mulch treatment can be recommended for Sapota irrigation.

Soil water monitoring in a vineyard and assessment of unsaturated hydraulic parameters as thresholds for irrigation management

Monitoring soil water status is a well-known method to efficiently control irrigation in order to optimally meet plant water requirements and at the same time avoid unproductive water losses through deep percolation. A common approach is to keep soil water status within a certain range that is defined via soil-specific unsaturated hydraulic parameters. In this study, water content and matric potential were monitored in a soil profile in a vineyard. The soil hydraulic properties required for irrigation control were determined by water retention analyses using a pressure plate apparatus, and estimated by means of pedotransfer functions. While the soil matric potential sensors delivered calibrated absolute values, their range was limited and soil water dynamics were not always reflected properly. The soil water content probe, on the other hand, properly illustrated soil water dynamics, but the readings were possibly inaccurate as no onsite calibration was executed. Furthermore, the determined unsaturated hydraulic parameters differed considerably depending on the applied method. Alternatively, a modified approach was applied. It was based on measurements of a sensor pair in a representative depth and should combine the advantages of both sensors types. The respective thresholds for irrigation management were determined based on sensor data using in-situ soil water retention functions. The main advantages were that neither field calibration of soil water content sensors nor laborious soil analyses were required. Furthermore, data interpretation was more plausible compared to the standard approach. Due to the reduced sensor setup and the omitted soil sampling and analyses, the modified approach represented a practical and economical alternative as basis for irrigation control.

Daily whole-seedling transpiration determined by minilysimeters, allows the estimation of the water requirements of seedlings used for dryland afforestation

In dryland areas, knowledge of plant water requirements and water use strategies of species are essential for use in afforestation, to ensure the establishment of seedlings in the first summer after planting. In this context, we used minilysimeters to estimate the daily whole-plant transpiration requirements in seedlings of Pinus halepensis, Pistacia lentiscus and Quercus coccifera, which are frequently used in afforestation. This estimate was calculated according to the following two conditions: high-soil moisture and a drought period. The results in both conditions indicated the highest daily rate (0.90–1.33 L m−2 day−1) for Q. coccifera, P. lentiscus was moderate (0.50–0.75 L m−2 day−1) and P. halepensis showed the lowest rate (0.37–0.44 L m−2 day−1). Species response under drought conditions was in accordance with their drought-avoidance strategy. P. halepensis and P. lentiscus displayed a water-saver mechanism, while Q. coccifera exhibited a water-spender mechanism. Our results show that the use of minilysimeters is a suitable method to determine whole-seedling transpiration rate and to accurately estimate the water requirements of species used for afforestation in dryland areas.

Surfactant and Limited Irrigation Effects on Forage and Seed Production and Water Use Efficiency in Alfalfa (Medicago Sativa L.)

Alfalfa is one the most important forage resources in arid and semiarid regions of the world. To evaluate the response of alfalfa to limited irrigation and surfactant application, an experiment was conducted at Research Farm of College of Agriculture, University of Tehran, Iran, during 2013 and 2014 growing seasons. The experimental treatments were arranged as split plots based on a complete randomized block design with three replications. The limited irrigation treatments comprised of replenishment of 100%, 75% and 50% of weekly evaporation and plant water requirements assigned to the main plots. Water treatments of control (water alone) and water + surfactant, assigned to the subplots. The quantitative and physiological characteristics of alfalfa forage were recorded at 10% flowering stage. The seed yield of alfalfa was measured after the plants reached full physiological maturity stage. The result of the experiment showed that as the severity of limited irrigation increased, plant height, tiller number per plant, RWC, total forge yield and seed yield followed a decreasing trend. Across all the limited irrigation systems, surfactant application increased plant height, RWC, seed yield and total forge yield. As the severity of limited irrigation increased, water use efficiency (WUE) in forage yield followed a significant increasing trend. The highest forage (7500 kg/ha) and seed yield (820 kg/ha) under limited irrigation treatments were achieved at 75% weekly evaporation and plant water requirements + surfactant, while the highest irrigation water use efficiency for forage (1.5 kg/m3) and seed (0.16 kg/m3) production was observed in limited irrigation treatment of 50% weekly evaporation and plant water requirements + surfactant.

Surfactant effect on forage yield and water use efficiency for berseem clover and basil in intercropping and limited irrigation treatments

Quantifying crop response to irrigation is important for establishing effective irrigation management strategies. The present study was conducted to evaluate the response of berseem clover and basil to limited irrigation in an additive intercropping system using a surfactant. The experimental treatments were carried out in split–split plots based on a completely randomized block design with three replications. The limited irrigation treatments comprised of replenishment of I100 full irrigation, I75=25% limited and I50=50% limited weekly evaporation and plant water requirements which were assigned to the main plots. The planting systems of sole berseem clover and sole basil culture along with additive inter cropping of berseem clover+50% basil were assigned to the subplots. Water treatments of control (water alone) and water+surfactant were assigned to the sub-subplots. Results show that severely limited irrigation (I50) dramatically reduced the forage yield of berseem clover and basil by 19.5% compared with the control (I100). The severity of the adverse effects of limited irrigation stress decreased by the surfactant application in irrigation by water+surfactant (9.5% decrement compared to full irrigation). The highest irrigation water use efficiency (2.7kgm−3) was achieved in I50 treatment with an added surfactant. The highest total dry matter yield (berseem clover+basil dry matter) (9257.9kgha−1) was obtained from additive intercropping of berseem clover 100%+basil 50% while irrigated by water+surfactant.

Comparison of lysimeter based and calculated ASCE reference evapotranspiration in a subhumid climate

The standardized form of the well-known FAO Penman-Monteith equation, published by the Environmental and Water Resources Institute of the American Society of Civil Engineers (ASCE-EWRI), is recommended as a standard procedure for calculating reference evapotranspiration (ETref) and subsequently plant water requirements. Applied and validated under different climatic conditions it generally achieved good results compared to other methods. However, several studies documented deviations between measured and calculated reference evapotranspiration depending on environmental and weather conditions. Therefore, it seems generally advisable to evaluate the model under local environmental conditions. In this study, reference evapotranspiration was determined at a subhumid site in northeastern Austria from 2005 to 2010 using a large weighing lysimeter (ETlys). The measured data were compared with ETref calculations. Daily values differed slightly during a year, at which ETref was generally overestimated at small values, whereas it was rather underestimated when ET was large, which is supported also by other studies. In our case, advection of sensible heat proved to have an impact, but it could not explain the differences exclusively. Obviously, there were also other influences, such as seasonal varying surface resistance or albedo. Generally, the ASCE-EWRI equation for daily time steps performed best at average weather conditions. The outcomes should help to correctly interpret ETref data in the region and in similar environments and improve knowledge on the dynamics of influencing factors causing deviations.

EFEITO DO SUBSTRATO BOVINO NA GERMINAÇÃO DE PIMENTA BIQUINHO (CAPSICUM CHINENSE) IRRIGADO COM ÁGUA RESIDUÁRIA

The Brazilian semiarid region characterized by prolonged drought and poor rainfall distributed, reducing the quality and quantity of water available. In this context, the present study performed in a protected environment at the Federal University of Campina Grande aiming to analyze the germination of pepper pout with bovine substrate irrigated with different levels of wastewater treated.The treatments consisted on 5 water levels (N) using the water supply and wastewater derived from an upflow anaerobic (UASB) based on plant water requirement (NH), as follows: 100% of NH (N5) 80% of NH (N4), 60% of NH (N3), 40% of NH (N2) and 20% of NH (N1). Germination percentage (PG) the germination speed index (GSI ), mean velocity (MV) and the average time (Tm) of germination were evaluated, on biquinho pepper (BRS Moema). The germination percentage for water supply averaged 42.3% and 46.5% for wastewater. For water levels applied the average germination rate of biquinho pepper ranged from 0.086 to 0.089. The germination of pepper had better results with the use of water residuaria. O reuse of water in semi-arid regions is a viable alternative reducing costs and providing nutrients culture.

BIO-CLOD를 이용한 고도처리공정에서의 영양염류 제거

Objectives: The purpose of this study was to investigate the effect of BIO-CLOD on advanced wastewater treatment for enhanced removal efficiency and meeting the stringent discharge water requirements of wastewater treatment plants. Methods: Two experimental apparatuses consisting of anaerobic, anoxic and aeration tanks were operated. One included a BIO-CLOD cultivation tank. Organic and nutrient parameters and removal efficiency were analyzed by pH, BOD, CODcr, SS, T-N and T-P. Results: The average removal efficiencies of BOD, COD and SS from the apparatus with BIO-CLOD tank installation were 95.5%, 88.6% and 92.9%, respectively, and these were higher than the results from the apparatus without BIO-CLOD. The average TP removal efficiency with BIO-CLOD tank marked 56.0%, higher than the 47.3% from the apparatus without one. BIO-CLOD showed a higher performance for TN removal at 49.6%, compared to the result without BIO-CLOD of 34.3% Conclusion: By reaction with BIO-CLOD, ammonia removal was effective in the aeration tank, as was phosphorus release in the anaerobic tank. Phosphorus luxury uptake and nitrification in aeration tank proceeded smoothly. The application of BIO-CLOD can improve the decrease of odor and settleability of activated sludge in a wastewater treatment plant, as well as increase the removal efficiency of organic and nutrient materials in water.