Open Pan Evaporation Research Articles

Energy requirement in non‐centrifugal sugars production units and its mitigation via steam controlled concentration techniques

AbstractNon‐centrifugal sugars (NCS) are traditionally consumed sweeteners which are gaining momentum in the global market due to the presence of nutritional and mineral content. Traditionally NCS is produced by concentrating sugarcane juices in an open pan evaporation process using dried bagasse as a fuel. Field trials at the traditional production site of NCS showed the energy efficiency as low as 8%–10%. Moreover, the effective bagasse consumption as a fuel stands at 7–8 kg/kg NCS production, whereas, as per stoichiometry and theoretical calculations, the actual bagasse consumption required for the production of NCS is a mere 0.65 kg/kg NCS production. Hence, as an alternative to the existing process, the concentration of cane juices by steam‐controlled evaporation has been studied and it has been found that the steam‐controlled evaporation can enhance the energy efficiency to 78%–83% with an effective bagasse consumption of 1.05 ± 0.04 kg/kg NCS production.

A case study of the RothC soil carbon model with potential evapotranspiration and remote sensing model inputs

Soil carbon modeling is an important tool to inform scientists, land managers, and policy makers about the impacts of land management decisions on soil health and climate change mitigation. Models can require a wide range of data inputs to make predictions, not all of which are readily available but can often be substituted with estimates. Understanding the impact that inputs have on the model output is critical to understand the uncertainties of their predictions. This study evaluated the output of the RothC soil carbon model using three potential evapotranspiration (PET) models (Tegos et al., 2017; Droogers and Allan, 2002; and Thornthwaite and Mather, 1955; Te, DA, and TM, respectively) to estimate open pan evaporation, and three vegetation indices (NDVI, SAVI, and MSAVI) from satellite imagery to estimate corn (Zea mays L.), soybean (Glycine max (L.) Merr.), and wheat (Triticum aestivum L.) yield to convert to C input for the RothC model to predict soil organic carbon over 11 years at a research farm in Michigan. The objectives of this study were to evaluate the correlation with observed data for each estimated input as well as the variability in RothC output they produced. The TM, Te, and DA PET models resulted in 13%, 38%, and 40% wet bias, respectively, resulting in increases of 1.6, 5.5 and 7.4 Mg C ha−1, respectively, over the baseline model output. All three vegetation indices estimated corn yields poorly (R2 = 0.25, 0.26, and 0.26 for NDVI, SAVI, and MSAVI, respectively), but soybean yields exceptionally well (all R2 = 0.91). However, despite NDVI producing significantly higher values (p < 0.001), there were no significant differences between each index's estimated yield used to calculate C input for RothC, and the resulting model runs are almost indistinguishable.

Simulation of climate change impact on water productivity of maize in central Punjab

Field experiments were conducted at the Research Farm, Department of Climate Change and Agricultural Meteorology, Punjab Agricultural University, Ludhiana during kharif 2016 and 2017. Maize variety PMH-1 was sown with a row spacing of 60 cm and plant spacing of 20 cm on three dates viz. D1-Third week of May, D2-Second week of June and D3- First week of July under two irrigation levels i.e. irrigation at IW: CPE of 1.00 (I1) and 0.75 (I2) and mulch viz. application of straw mulch @ 5 t ha–1 (M1) and without mulch (M2) in split plot design (SPD) with dates of sowing and mulch in main plots and irrigation levels in the sub-plots. Actual moisture depletion by the crop under different treatments was recorded by soil moisture depletion method. Among the dates of sowing, moisture extraction was observed to be highest under D1 (540.5 and 477.5 mm), whereas among the irrigation and mulch levels, it was lower under IW/CPE = 0.75 (461.2 and 376.9 mm) and mulch application @ 5t/ha (473.0 and 387.1 mm) during both the seasons. The ETo was calculated by open-pan evaporation, Priestley-Taylor, FAO-56, Papadakis and CROPWAT models. Among all the four methods, the Priestley-Taylor method gave higher ETo in all three dates of sowing and it was close to open-pan evaporation values except in first date of sowing during 2016, in which ETo was higher in FAO-56 (602.4 mm). The crop coefficients calculated by Papadakis method were comparatively higher (1.3 and 1.1 mm) as compared to that calculated by CROPWAT method (1.2 and 1.0 mm) and FAO-56 (1.0 and 1.1 mm) methods gave higher values of crop coefficients as compared to Priestley-Taylor method of DSSAT model (1.0 and 0.9 mm). The water use efficiency of maize was higher in D2 (11.02 kg/ha-mm, 13.43 kg/ha-mm) w.r.t grain yield as compared to D3 (10.72 kg/ha-mm, 12.97 kg/ha-mm) and D1 (9.69 kg/ha-mm, 10.65 kg/ha-mm) w.r.t grain yield, during 2016 and 2017 respectively. Among mulch and irrigation treatment was higher in M1 and I2 levels in both the years. Simulation results showed that rise in temperature would result in decreased water productivity of maize, but this decrease could be compensated by increase in CO2 concentration.

Effect of Drip Irrigation and Inter Cropping Systems on Growth Characters of Maize

Aims: The main aim of the study is to reduce the irrigation quantity for maize and intercrop adds extra value to the sole crop by generating additional income to the farmers.&#x0D; Study Design: Factorial Randomised Block Design (FRBD).&#x0D; Place and Duration of Study: Eastern block farm, Tamil Nadu Agricultural University, Coimbatore during summer and Kharif 2021.&#x0D; Methodology: Maize as a sole crop and inter crop was grown under drip and flooded conditions. To quantify the irrigation with different set of irrigation as treatments (75% PE, 100% PE and 125% PE) was followed. Irrigation under flooded conditions was quantified using parshall flume. Different inter crops like Lab Lab, Green gram, Black Gram and Cow pea was raised within the rows of maize. The duration of inter crops was less than 60 days than that of maize.&#x0D; Results: During its peak cob formation stage (61-90 days), the quantity of water applied to the plant was higher with 125 % PE (205858.8 l/day) followed by 100% PE (123515.3 l/day) and 75 % PE (164687.1 l/day). The higher plant height was observed with 280.5 cm in Maize + Lab Lab followed by black gram, green gram and cowpea. Irrigation level varied significantly with 100% open pan evaporation on plant growth (254.8 cm) followed by 75% open pan evaporation. Interaction effect was significant in Maize + Lab Lab cropping system alone, irrespective of the irrigation treatments (75, 100, 125 % PE and flooding).&#x0D; Conclusion: Water requirement with the month and stage wise during the crop growth clearly indicates that the minimum amount of water is required for the crop growth and development.

Sweet pomegranate pekmez production: Effect of different production methods and activated carbon treatment on some quality parameters and 5‐hydroxymethyl furfural formation

In the present study, “sweet pomegranate pekmez” (PP), was produced by three different methods as open pan evaporation (OPE), application of activated carbon prior to open pan evaporation (AC), and vacuum evaporation (VE). The effects of activated carbon treatment and production methods on pH, density, soluble solids, water activity, total phenolic content, HMF formation, mineral content, and texture characteristics were investigated. Textural properties of PP increased with increasing soluble solids content. HMF was not detected in AC and VE products. HMF content of OPE product was measured as 2.77 ± 0.28 mg.100 g. Activated carbon treatment resulted in significant reductions in mineral, HMF, and TPC contents of pekmez samples. HMF formation kinetics of PP was investigated at various accelerated storage temperatures. HMF formation was well described by the zero-order reaction model among five kinetic models applied. The rate of reaction was determined as highly temperature-dependent by an Arrhenius equation. Practical applications In recent years, consumer interest and demand for potentially health-promoting products has motivated the production of such food products. In this context, in this study, sweet pomegranate pekmez is introduced as a potentially healthy product produced by different methods, and the production stages and conditions that may enlighten the industrial production of this traditional product are provided. In addition, the application of activated carbon used in the production of pekmez has been presented as an alternative method to reduce the potential formation of HMF during heat treatment.

Standardization of stage wise water requirement in drip irrigated Kinnow mandarin orchards under sub-tropical conditions

&#x0D; An experiment on drip irrigation scheduling based on pan evaporation replenishment was conducted in Kinnow orchard at Punjab Agricultural University, Ludhiana during 2010-2018. Year was divided into six stages (stage 1 to stage VI) including two months in each stage. First treatment included irrigation scheduling with 30 and 40% ER, treatment two with 40 and 60% ER, treatment three with 60 and 80% ER, alternatively during stages I to VI. However, fourth and fifth treatments had irrigation with 80% ER and 30% ER, respectively, in all the stages. Maximum daily open pan evaporation (9.15 mm) was recorded in May and minimum (1.19 mm) was recorded in January. The water requirement varied from 2.8 liters day-1 tree-1 in stage-I to 58.3 liters day-1 tree-1 in stage-III. Linear increase in vegetative and reproductive growth was observed with increase in irrigation water. Polynomial relationship studies indicated the increase in water quantity applied to Kinnow with increase in temperature subject to the prevailing relative humidity. Similarly, volumes of water applied increased with increased mean evaporation. The study concluded that drip irrigation scheduling with 60 to 80% ER alternatively, starting from January to December save significant amount of water, without affecting yield and quality of Kinnow under subtropical conditions.&#x0D;

Quantification of water stress impacts on canopy traits, yield, quality and water productivity of onion (Allium cepa L.) cultivars in a shallow basaltic soil of water scarce zone

Understanding and mitigating the adverse impacts of water stress on agriculture production have become global concern in water scarce environments. Particularly, Deccan plateau, the largest semi-arid zone of peninsular India, is confronted with severe water resources conflicts and extensive pressure for food production under climate change scenario. For sustainable agriculture, it is critical to quantify the impact of water stress on major crops like winter onion (Allium cepa L.) which is grown under diverse water management practices on shallow basaltic soils of this region. We conducted a field experiment during two growing seasons (2017–18 and 2018–19) for evaluating responses of different cultivars of red (B. Raj, B. Kiran, B. Super, B. Red and Local-Fursangi) and white (B. Shubra, B. Sweta and B. Safed) onion to variable water stress created using a line source sprinkler (LSS) system. There was a 1.1, 1.6, 3.9, 9.2 fold decline in total bulb yields (TBY) with increasing water deficit i.e. when depth of irrigation water (IW) applied equalled 0.60, 0.40, 0.20 and 0.00 times the cumulative open pan evaporation (CPE) as compared with the recommended practice (IW:CPE 0.80). The TBY increased between 86.2 and 106.6 Mg ha−1 in red cultivars when irrigation was scheduled at excess to optimum water regimes (IW: CPE 0.80–1.00), while it was improved by 5.0–20.4% for white cultivars under medium (0.40–0.59) to severe (0.0–0.39) water deficit stress. Further, highest (4.3–16.2%) improvement in TBY of Local cultivar was reported irrespective to different water stress levels. Local and white cultivars could have better tolerance to water stress by keeping cooler canopy temperatures, higher leaf relative water content and modulating the stomatal opening. Lower yield losses due to rotting (0.30–1.81%) and splitting (4.4–6.5%) of bulbs were observed in red and white cultivars. This study further endorses the appropriate selection of onion cultivars reduces water requirements by 37.5–61% to attain similar water productivity (16.0 kg m−3) as with recommended irrigation level. Increased in water stress levels though reduced quality of physical traits of harvested bulbs viz., mean weight, average dia., shape index (SI), harvest index (HI) and firmness, these improved the storage quality. Water deficit also increased accumulation of soluble solids, total phenolics, protein, dry matter and elevated the pH and rehydration quality besides potentially affecting the enzymatic activity (SOD and POD) of onion cultivars. It was concluded that white onion cultivars like B. Shubra with higher WP under medium and severe water deficit stress and ‘Local’ red cultivar should be preferred for efficient utilisation of water resources both in terms of the productivity and post-harvest quality of onion under drought prone and shallow basaltic regions of Deccan plateau.

Spectral Signature-Based Water Stress Characterization and Prediction of Wheat Yield under Varied Irrigation and Plant Bio-regulator Management Practices

Canopy reflectance based spectral indices help in effective irrigation scheduling of wheat for optimization of yield in water-scarce regions. A field experiment for two consecutive years (2013 to 2015) was conducted to evaluate the responses of wheat crop to exogenous application of plant bio-regulators (PBRs) in the water-scarce Deccan region of India (Baramati, Pune, Maharashtra). We predicted grain and biomass yields of wheat using water stress-sensitive spectral indices under varied water regimes. The water regimes were seven levels of irrigation water (equaling to 1.00, 0.85, 0.70, 0.55, 0.40, 0.25 and 0.10 times of cumulative open pan evaporation, CPE) and applied using a line-source sprinkler system). There were five PBRs, viz. thiourea, salicylic acid, potassium nitrate, gibberellin and ortho−silicic, with concentration 10 mM, 10 μM, 15 g L−1, 25 ppm and 8 ppm, respectively, applied at various growth stages, namely crown root initiation, flag leaf and seed milking stages. Water stress indices were computed from spectral reflectance pattern recorded at different crop growth stages using ASD FieldSpec-4 Spectroradiometer (350–2500 nm). The PBRs significantly influenced the canopy reflectance pattern and maintained superior values of water stress indices over the control (without PBRs) by stabilizing leaf pigments and water contents, controlling the stomatal opening and better water use. Among the five PBRs, thiourea and salicylic acid mitigated water stress better and improved overall grain yield (4.6–17.5%) and total biomass (3.6–15.3%). There was no significant (p < 0.05) variation in both yields (grains and biomass) up to IW: CPE 0.70, indicating that irrigation scheduling at 0.70 IW: CPE could be a better option rather than full irrigation in water-scarce areas. At flowering and milking stages, all spectral indices were correlated significantly with the wheat yields. Thus, these stages could be considered as more water-sensitive stages during entire wheat growth period. Regression models based on WI and NWI-2 accounted for 92% and 78% variation in the observed yields for grain and biomass, respectively, with minimum root-mean square error. Hence, to predict the grain and biomass yields of wheat, regression models based on WI and NWI-2 at milking stage can be used successfully.

Effect of IW:CPE-Based Irrigation Scheduling and N-Fertilization Rate on Yield, Water and N-Use Efficiency of Wheat (Triticum aestivum)

Under emerging water scarcities in the face of global warming, optimization of irrigation and nutrient inputs is essential to maximize input-use efficiency. Thus, a field experiment was conducted with wheat for 2-years to evaluate the effects of N and deficit irrigations on yield formation, water productivity (WP) and nitrogen-uptake efficiency (NUE). Treatment consisted of combinations of four N application levels, i.e., 60, 90, 120 and 150 kg ha−1 as main-plot factors and seven levels of irrigation water (IW; equaling 1.00, 0.85, 0.70, 0.55, 0.40, 0.25 and 0.10 times of the cumulative open pan evaporation, CPE) as sub-plot factors. After pre-plant and first post-planting irrigation through flood method, line-source sprinklers were used. Grain yield increased with applied N and was the maximum (3.39–4.66 Mg ha−1) at IW:CPE 0.85 and declined @ 0.67–0.81 Mg ha−1 for every 0.1 IW:CPE. Application of 150 kg N ha−1 improved the grain yield by 6.0–8.9% over 120 kg N ha−1 under medium stress (IW:CPE 0.41–0.70) and no stress (> 0.70) conditions, but showed little impact under severe stress (0.10–0.40) conditions. Rather it declined by 45.3–66.1 and 13.0–26.1% at 60 and 90 kg N ha−1 over 120 kg N ha−1, respectively under the latter. The WP and NUE ranged between 1.28–1.36 kg m−3 and 37.4–38.4%, respectively, with 120–150 kg N ha−1, while the counter figures were 0.99 kg m−3 and 30.2% with 60 kg N ha−1. On the whole, results indicate basing N applications on the water availability for irrigation for optimal grain yields where, WP and NUE vis-a-vis benefits can be maximized under deficit irrigation conditions.

Effect of plant growth regulators and deficit irrigation on canopy traits, yield, water productivity and fruit quality of eggplant (Solanum melongena L.) grown in the water scarce environment

Deficit irrigation (DI) and plant growth regulators (PGRs) have strategic role for sustaining crop productivity and mitigating water stress in drought prone areas. However, their impacts are yet to be quantified for eggplant (Solanum melongena L.), a popular drought tolerant vegetable crop grown in water scarce Deccan Plateau of India. We conducted field experiments during 2016–17 and 2017–18 in a drought prone region of Deccan Plateau, India to evaluate the interactive effect of PGRs viz., 1.38 mg L−1 salicylic acid (SA), 1.5% potassium nitrate (PN), 500 ppm thio-urea (TU) and 100 ml L−1 bio-stimulant (BS) and varied levels of DI generated using line source sprinkler system. The marketable fruit yields were reduced to 86, 74, 50, 30, 12 and 8% with increased level of DI i.e. when the applied irrigation water (IW) equalled 0.00, 0.15, 0.30, 0.45, 0.60 and 0.75 times the cumulative open pan evaporation (CPE) against the recommended irrigation practice (IW:CPE 0.90). Application of PGRs improved fruit yields by 7.3–22.7% and their role to alleviate water stress was indicated by lower canopy temperatures, maintaining higher leaf relative water content, modulation of stomatal opening and higher consumptive use of water. Particularly SA and TU were superior under low to medium water stress (IW:CPE 0.45–0.75) whereas PN was effective in severe water stress (IW:CPE 0.0–0.44) while the effect of BS was almost similar with PGRs like TU under medium stress conditions. The maximum water productivity (WP) varied between 5.50 and 6.77 kg m−3 for different PGRs and it was 5.16 kg m−3 without PGRs indicating water savings to the order of 28.8–57.4% with the former. The fruit quality attributes such as mean diameter, sphericity, fruit weight and firmness traits declined with water stress while these were considerably rectified with PGRs. Higher accumulation of dry matter, sugar, protein, total phenolics, flavonoids and improved rehydration quality as well as potentially affecting enzymatic activity were monitored with PGRs. It is concluded that exogenous application of PGRs like SA and PN along with medium levels of DI can help in rational utilization of water resources and could effectively improve yield and post-harvest quality of eggplant fruits especially under water scarce environment of Deccan Plateau.

Climatic Variability and its Implications on Agricultural Productivity in Central Punjab

Enhanced greenhouse effect due to anthropogenic activities has resulted in climatic changes and their adverse impacts on agricultural productivity. Different regions of earth are experiencing climatic changes of varying magnitudes. To deal with the situation; there is a dire need of temporal analysis of climatic records to quantify the climatic changes and their likely impacts on agricultural productivity. In the present investigation, long term climatic records of central Punjab (Ludhiana) w.r.t. maximum temperature (Tmax), minimum temperature (Tmin), relative humidity (RH), wind speed (WS), sunshine hours (SSH) and open pan evaporation (PE) for a period of 47 years (1970 to 2016) were analysed on monthly, seasonal and annual basis. Analysis indicated significant annual increase in mean minimum temperature (@0.06°C), relative humidity (@1.3per cent) and decrease in wind speed (@0.67 km day−1), sunshine hours (@0.03 hr day−1) and open pan evaporation (@ 6.0 mm), whereas no significant trend has been observed in maximum temperature. Monthly variability in minimum temperature indicated the highest rate of increase (0.7°C per decade) during reproductive growth and maturity period of rabi (February and March) and Kharif (September and October) crops, which can have adverse effects on their productivity. Similarly increase in relative humidity and decrease in wind speed and sunshine hours can have serious implications on occurrence of insect-pests, rate of crop photosynthesis and yields indicating a dire need of exploring genetic and agronomic manipulations to counterbalance the adverse effects of climate change, minimize climatic risks and sustain agricultural productivity in the region.

Effect of plant bioregulators on growth, yield and water production functions of sorghum [Sorghum bicolor (L.) Moench

Use of plant bioregulators has been shown to mitigate the impacts of water stress and benefit crops under water scarce conditions. Therefore, a field experiment was conducted to evaluate the interactive effects of plant bioregulators (PBR’s) and supplemental irrigation on growth and grain yield of sorghum [Sorghum bicolor (L.) Moench]. Exogenous application of PBR’s included: 10μM salicylic acid (SA), 100mgL−1 sodium benzoate (SB), 500ppm thiourea (TU), 1.5% potassium nitrate (KNO3) at seedling elongation (20 DAS), reproductive (50 DAS) and panicle emergence (75 DAS) stages and control (no spray of PBR). Line source sprinkler system (LSS) was used to apply variable quantities of irrigation water (IW) i.e. equalling 0.95, 0.80, 0.65, 0.50, 0.35, 0.20 and 0.05 times the CPE (cumulative open pan evaporation). The maximum grain yield (3.60–3.88Mgha−1) was obtained at IW: CPE 0.80 and declined @ 0.43–0.49Mgha−1 for every 0.1 IW: CPE for PBR’s and the corresponding values were 3.49 and 0.53Mgha−1 without PBR. The application of PBR’s mitigated water stress and improved gain yield by 6.8–18.5%. SA was more effective under moderate (IW: CPE 0.79–0.50) while SB and TU were better under severe water deficits (IW: CPE 0.49–0.05). PBR’s maintained higher leaf water content, lower canopy temperature, modulated the stomatal opening and ultimately the source–sink relations thereby improving the yield and water productivity under deficit irrigation. The maxima of water productivity varied between 1.16–1.41kgm−3 with PBR’s while it was 1.12kgm−3 without PBR and the latter could be achieved with 25.2–49.7% lesser irrigation water (IW) with PBR’s. It is concluded that PBR’s like SB and TU present viable option for improving sorghum yield and water productivity under the conditions of deficit irrigation.

The effects of production methods and storage on the chemical constituents of apple pekmez

The purposes of this study were to investigate the effects of two different pekmez production methods namely open pan evaporation (OPE) and vacuum evaporation (VE) on the final products, and to observe the changes in constituents as well as aromatic components after 4months of storage. The initial and poststorage (4months) 5-hydroxymethyl furfural (HMF) content in OPE apple pekmez were respectively 5.48, and 7.04mg/kg. No HMF was detected in VE apple pekmez. Both initial and poststorage content of phenolic compounds was higher in VE pekmez compared to OPE pekmez. The effects of production methods and storage time were statistically significant on phenolic compounds in apple pekmez. The content of all analyzed minerals except calcium has significantly decreased in pekmez compared to raw material on dry weight basis. OPE resulted in a 55.97% loss in the amount of ascorbic acid, whereas the loss in VE has been 23.45%. Poststorage loss in ascorbic acid has respectively been 69.54, and 89.28%, for VE and OPE samples. None of the aromatic components of fresh apple was detected in pekmez.

Influence of three different concentration techniques on evaporation rate, color and phenolics content of blueberry juice.

The present study was undertaken to assess the effects of three different concentration processes open-pan, rotary vacuum evaporator and microwave heating on evaporation rate, the color and phenolics content of blueberry juice. Kinetics model study for changes in soluble solids content (°Brix), color parameters and phenolics content during evaporation was also performed. The final juice concentration of 65° Brix was achieved in 12, 15, 45 and 77min, for microwave at 250 and 200W, rotary vacuum and open-pan evaporation processes, respectively. Color changes associated with heat treatment were monitored using Hunter colorimeter (L*, a* and b*). All Hunter color parameters decreased with time and dependently studied concentration techniques caused color degradation. It was observed that the severity of color loss was higher in open-pan technique than the others. Evaporation also affected total phenolics content in blueberry juice. Total phenolics loss during concentration was highest in open-pan technique (36.54%) and lowest in microwave heating at 200W (34.20%). So, the use of microwave technique could be advantageous in food industry because of production of blueberry juice concentrate with a better quality and short time of operation. A first-order kinetics model was applied to modeling changes in soluble solids content. A zero-order kinetics model was used to modeling changes in color parameters and phenolics content.

Optimising supplemental irrigation for wheat (Triticum aestivum L.) and the impact of plant bio-regulators in a semi-arid region of Deccan Plateau in India

Understanding the effects of water stress on yield formation is essential for planning irrigation and other mitigation strategies in arid and semiarid regions. Therefore, a field experiment was conducted for 3 years to evaluate the impact of irrigation regimes and plant bio-regulators (PBR’s) on grain yield and water productivity of spring wheat (Triticum aeastivum L). PBR’s applied through exogenous sprays included: 10mM thiourea (TU), 10μM salicylic acid (SA), 15gL−1 potassium nitrate (KNO3), 25ppm gibberellic acid (GA3), 8ppm ortho-silicic acid (OSA) at crown root initiation (CRI), flag leaf and seed milking stages and control (no PBR). Seven irrigation levels were generated through a line source sprinkler system (LSS) viz., application of irrigation water (IW) equalling 1.0, 0.85, 0.70, 0.55, 0.40, 0.25 and 0.10 times the CPE (cumulative open pan evaporation). The maximum yield obtained with PBR’s varied between 4.11–4.46Mgha−1 at IW:CPE 0.85 against 4.09Mgha−1 without PBR. While the yield decline equalled 0.35–0.42Mgha−1 for every 0.1 IW:CPE for PBR’s against 0.43Mgha−1 without PBR. The overall improvement in grain yield and total biomass with PBR’s ranged between 5.9–20.6% and 4.8–15.3%, respectively. Specifically TU and SA showed a major role under medium (IW:CPE 0.40–0.69) and severe (0.10–0.39) stress conditions in terms of maintenance of leaf water content, modulating the stomatal opening and better water usage and thereby improved yield by 0.41–0.88Mgha−1. The maximum water productivity ranged between 1.20–1.35kgm−3 with different PBR’s while it was 1.18kgm−3 without PBR and the latter could be achieved with 19–56% lesser irrigation water with PBR’s. Overall conclusions are that the effects of deficit irrigation could be substantially enhanced in terms of grain yield and water productivity when used conjunctively with PBR’s like TU and SA. Thus for integrating PBR’s with supplemental irrigation, large scale testing is required for defining their economic spray schedules under water scarcity conditions.

Study of trends in weather parameters at Akola using moving average technique

Climatic parameters (maximum temperature, minimum temperature, wind speed, bright sunshine hours, morning relative humidity, evening relative humidity and open pan evaporation) for 37 years (1971-2007) were collected from Agricultural Meteorological Observatory Dr. PDKV, Akola. Mean monthly climatic data for the period were used to determine reference evapotranspiration (ET 0 ) by FAO-56 Penman-Monteith method. The trends of change of these parameters were analyzed by working out seven years moving average and forming regression equations. The mean monthly maximum air temperature showed slightly decreasing trend for most of the months during the year except February, August and December. Whereas, there was unsteady variation in minimum air temperature and showed linear increasing trend during monsoon period. There was strong variation in wind speed and bright sunshine hours and showed continuous linear decreasing trend. However, mean monthly morning and evening relative humidity showed the linear increasing trend for most of the period of the year. The mean monthly pan evaporation also showed the decreasing trend throughout year. There was major variation in monthly reference evapotranspiration and showed linear decreasing trend for all the months of the year.

Comparison of the values of potential evapotranspiration estimated through different methods and their relationship

In the present study, six empirical methods, namely, Modified Penman, Blaney Criddle, Christiansen, Thornthwaite, Open pan, Turc and FAO penman method are computed using the daily weather data for the period 1981-2012 (32 years) was collected for three stations in Chhattisgarh state representing 3 agroclimatic zones. It is found that FAO Penman method is the best method for estimating potential evapotranspiration. The comparison of ETo estimates was done based on the weekly averages of PET using correlation co-efficients and regression methods through different methods. At Ambikapur the highest correlation co-efficient between FAO Penman and Modified Penman method 0.998 and lowest in between Christiansen and Blaney criddle method 0.918. At Jagdalpur and Raipur also having the highest correlation co-efficient between FAO penman and Modified penman method 0.999 and lowest correlation co-efficient in between Christiansen and Turc method 0.85 or 0.84. Regarding regression with Open pan evaporation, highest R 2 values are with Modified Penman and Christiansen methods at Ambikapur while at Jagdalpur and Raipur highest R 2 was with Christiansen method. Thus, the open pan evaporation can be estimated by Christiansen method.

Effect of long-term irrigation with wastewater on growth, biomass production and water use by Eucalyptus (Eucalyptus tereticornis Sm.) planted at variable stocking density

Irrigation of high transpiring forest species has been put forward for recycling and reuse of wastewater and conservation of nutrient energy into biomass and thereby bringing multiple benefits such as fuel wood production, environmental sanitation and eco-restoration. But loading rates, the tree plantations can carry, continue to be contradictory. Therefore, the growth patterns, biomass production, water use and changes in soil properties were evaluated for a 10-year rotation of Eucalyptus (Eucalyptus tereticornis Sm.) plantations of variable stocking density and irrigated with either sewage (SW) or a good quality groundwater (GW). The irrigated trees grew rapidly and the stock volumes attained after 10 years were 164.0 and 127.1m3ha−1 with SW and GW, respectively. The tree growth improved with stocking density and the maximum shoot biomass (262Mgha−1) was produced under high (HD, 1993stemsha−1), followed by the recommended (RD, 517stemsha−1; 178Mgha−1), very high (VHD, 6530stemsha−1; 127Mgha−1) and low stocking density (LD, 163stemsha−1; 55Mgha−1). Sap flow values almost coincided with growth rates and increased until sixth year of planting and stabilised thereafter. The annual sap flow values ranged between 418–473, 1373–1417 and 1567–1628mm during 7–10 year of planting under LD, RD and HD, respectively. The daily sap flow values were 0.56*PAN-E (USWB Class A Open Pan Evaporation) during summer months of April–June, 1.24*PAN-E during August–October, i.e. active growth period and 1.12*PAN-E during winter months of December–February. Reference evapotranspiration (ETref) computed using Penman–Monteith method could better describe water use; the sap flow being 0.87–1.23*ETref with an average 1.03*ETref. The water productivity for timber was 1.54, 1.71 and 1.99kgm−3 for LD, RD and HD, respectively. Similarly, the water use efficiency increased by about 40% with HD and also with SW (11%) under RD. The soil quality improved considerably with sewage irrigation and the plant absorbed carbon was also greater. The annual carbon absorption was 3.5, 12.0, 13.9 and 7.0Mgha−1 under LD, RD, HD and VHD, respectively. It is concluded that Eucalyptus plantations can act as potential sites for year round and about 1.5 fold recycling of sewage than the annual crops. However, cautions, rather regulatory mechanism should be devised to control loading rates since these are not as profligate consumers of water as has been claimed.

Wood properties of Eucalyptus globulus at three sites in Western Australia: effects of fertiliser and plantation stocking

SummaryWood properties of 10-year-old trees in Eucalyptus globulus plantations at three sites in Western Australia were examined. Silvicultural treatments applied at age two years were stocking (unthinned, 1250 stems ha–1; thinned to 600 stems ha–1 or 300 stems ha–1) and nitrogen fertiliser application (0 or 250 kg ha–1 elemental nitrogen) in factorial combination. The three sites differed markedly in their annual rainfall (620–1100 mm), open-pan evaporation and soil water-holding capacity. Wood cores were collected at breast height from a total of 263 trees (~15 trees for each site-by-treatment combination), and radial samples prepared for analysis by SilviScan to produce radial profiles of air-dry density and microfibril angle (MFA) and modulus of elasticity (MOE), and by radial near infrared (NIR) surface scanning to produce radial profiles of NIR-predicted Kraft pulp yield (KPY) and cellulose content (CC). Sampling interval was 0.025 mm for density and 5 mm for the other properties. For wood property mean values (i.e. wood property averages of each pith-to-cambium sample), sites differed significantly only in air-dry density. The Boyup Brook site, which had low annual rainfall, the lowest climate wetness index and soil water-storage capacity and the slowest diameter growth, had the highest mean wood density (648 kg m–3), while Scott River, with the highest rainfall, had mean density that was 10% lower. The Wellstead site (low rainfall but highest soil water-storage capacity) was intermediate for density. The only other significant differences for mean wood properties were caused by fertiliser addition, which reduced NIR-predicted KPY from 54.6% (without fertiliser) to 54.1% and predicted CC from 43.7% to 43.1%. Clear radial trends were evident for all wood properties. Density, MOE, KPY and CC all increased from pith to the cambium, while MFA declined. From the innermost (pith) 10% to the outermost (cambial) 10% of the radius, density increased on average by 21%, MOE by 103%, KPY by 9% and cellulose by 11%, while MFA declined by 47%. NIR calibrations developed using the SilviScan and NIR spectral data explained 71% of variance in MOE for an independent set of radial wood samples of E. globulus from Victoria, but less than 50% of variance for density and MFA. Implications for paper pulp and veneer manufacture are briefly considered.

Reference crop evapotranspiration over India: A comparison of estimates from open pan with Penman-Monteith method

In the present study the daily reference crop evapotranspiration (ET0) estimated from open pan evaporation data for 52 widely distributed locations across India are compared with P-M estimated ET0. The annual and intra-seasonal variability of ET0 and the inter comparison of these two methodologies has been carried out. Results showed that estimates of ET0 from open pan were always lower than those of P-M and error range was d” 29% across locations. Calibration coefficients evolved from the present study were found to reduce the errors considerably in ETo estimates.