Irrigation Doses Research Articles

Effect of balance dose of fertilizers and irrigation on yield and yield component of wheat cultivar

Effect of balance dose of fertilizers and irrigation on yield and yield component of wheat cultivar

Comparison of the effect of intravenous saline hydration on serum creatinine concentration between patients with or without iodine contrast administration

Objective: The aim of the project is to determine influence of intravenous prophylactic hydration on serum creatinine (SCR) levels changes in healthy subjects who have been hospitalized (without iodine contrast administration). The project also aims to compare the effects of intravenous hydration on the SCR levels in subjects with and without iodine contrast administration. Existing data in this regard are very scarce. Materials and Methods: We used retrospective clinical as well as laboratory data from 391 patients. 50 healthy subjects were included in the EXPERIMENTAL group. They were intravenously hydrated before surgical treatment of hernia iunginalis. SCR were measured at admission and 24 h later. The remaining 341 subjects (CONTROL group) underwent elective coronary angiography/ angioplasty, received a prophylactic hydration and had serum creatinine concentration measured prior to and 12-18 h after the invasive procedure with iodine contrast administration. Results: In EXPERIMENTAL group the results for SCR at admission and after hydration (but before surgical procedure) were as follows (mg/dl) (0.72 ± 0.18 vs. 0.75 ± 0.18 p=0.006). In CONTROL group the SCR measured prior to and 12-18 h after the invasive procedure with iodine contrast administration were as follows (mg/dl) (0.94 ± 0.45 vs. 0.87 ± 0.45, p<0.001). The results were significantly different between these groups (341/91 vs. 50/37, p<0.001). Conclusion: After 24 h intravenous hydration in healthy individuals, can lead to serum creatinine increase, probably due to over diuresis (we may only speculate that). This effect is significantly less frequent in patients exposed to intra-arterial iodine contrast administration with the same dose and manner of prophylactic irrigation.

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

In this paper, we present the results of our study on the operational application of the reflectance-based crop coefficient for assessing table grape irrigation requirements. The methodology was applied to provide irrigation advice and to assess the irrigation performance. The net irrigation water requirements (NIWR) simulated using the reflectance-based basal crop coefficient were provided to the farmer during the growing season and compared with the actual irrigation volumes applied. Two treatments were implemented in the field, increasing and reducing the irrigation doses by 25%, respectively, compared to the regular management. The experiment was carried out in a commercial orchard during three consecutive growing seasons in Northern Chile. The NIWR based on the model was approximately 900 mm per season for the orchard at tree maturity. The experimental results demonstrate that the regular irrigation applied covered only 76% of the NIWR for the whole season, and the analysis of monthly and weekly accumulated values indicates several periods of water shortage. The regular management system tended to underestimate the water requirements from October to January and overestimate the water requirements after harvest from February to April. The level of the deficit of water was quantified using such plant physiological parameters as stem water potential, vegetative development (coverage), and fruit productivity. The estimated NIWR was roughly covered in the treatment where the irrigation dose was increased, and the analyses of the crop production and fruit quality point to the relative advantage of this treatment. Finally, we conclude that the proposed approach allows the analysis of irrigation performance on the scale of commercial fields. These analytic capabilities are based on the well-demonstrated relationship of the crop evapotranspiration with the information provided by satellite images, and provide valuable information for irrigation management by identifying periods of water shortage and over-irrigation.

Multiyear Life Cycle Assessment of switchgrass (Panicum virgatum L.) production in the Mediterranean region of Spain: A comparative case study

An LCA of the cultivation of switchgrass in the Mediterranean region of Spain is carried out, based on 2010–2013 inventory data from experimental plots of two sites, Moncofar and Orihuela. Thus, a 4-year cycle is evaluated, considering different sources of variability. The functional unit is 1 t of switchgrass (dry basis) for electricity generation. Besides typical impact categories, blue and green water consumption impacts are also addressed by using watershed-specific characterization factors. In 2010, the production in Orihuela is more input-intensive than it is in Moncofar, while the biomass yield is lower. This causes greater climate change as CO2-eq. (709.1 vs. 65.0 kg t−1) and greater metal depletion as Fe-eq. (8.1 vs. 1.5 kg t−1). In the subsequent years, the yields are higher in Orihuela, and Moncofar performs worse for some specific impact categories, mainly the toxicity-related ones, and also metal depletion as Fe-eq., but only in 2011 (2.0 vs. 1.2 kg t−1). Due to larger irrigation doses, the blue water impact as ecosystem-eq. water is always higher in Orihuela (e.g. in 2010, 2020 vs. 390 m3 t−1). On the contrary, the green water impact, also as ecosystem-eq. water, is greater in Moncofar, except for the first year (86.8 vs. 15.2 m3 t−1). Switchgrass from the two locations could be eligible for bioelectricity production in the European Union in accordance with the sustainability requirements for greenhouse gas savings. Ad hoc decisions on crop management are, however, critical to the environmental impacts, evidencing the importance of taking a multi-year approach.

Simulation of soil water movement under subsurface irrigation with porous ceramic emitter

Subsurface irrigation has been achieved by using ceramic emitters, pitchers, pots and ceramic tubes, which have gained a certain degree of interest in arid regions due to their efficient use of water. Research on the formation of wetting patterns around the ceramic emitter is essential for the design of irrigation system. In this study, numerical simulations were carried out to investigate the effects of emitter installation method, emitter buried depth, emitter structural parameters, irrigation doses and initial soil water content on the wetting patterns in clay loam with Hydrus-2D. Finally, two field application experiments were conducted to test the practicality and reliability of simulation results. The simulation results were in good agreement with the experimental data. Results showed, emitter installation method had the least effect on the wetting pattern. A 25cm buried depth would be suit for irrigating vegetables, a 45cm deep buried depth would suit for irrigating fruit trees. The structure parameters had a significant effect on cumulative fluxes and horizontal wetting front, the structural parameters (emitter length is 7.00cm, emitter external diameter is 1.25cm, and emitter inner diameter is 0.60cm) would be a better fabricate parameters for ceramic emitter. Wetting front increased with increasing irrigation doses and initial water content. To prevent percolation, when the initial water content was high, it should be better to cut down the irrigation duration of ceramic emitter. The field results indicated that Hydrus-2D could be used to investigate the suitable parameters for ceramic emitter in subsurface irrigation systems and determine the suitable arrangement and operation mode of ceramic emitter.

A Review of Warm‐Season Turfgrass Evapotranspiration, Responses to Deficit Irrigation, and Drought Resistance

Knowledge of turfgrass evapotranspiration (ETc) and drought resistance can enable water conservation by guiding turfgrass selection for various climates and irrigation scheduling. Turfgrass ETc, crop coefficients (K c = ETc/ET0, where ET0 is reference evapotranspiration), responses to deficit irrigation, and drought resistance, are reviewed for warm‐season species (perennial, sod‐forming, C4 grasses). In well‐watered conditions, ETc was 2.44 to 10.53 mm d−1 (nine species in six climates during late spring to early autumn) and K c was 0.34 to 1.27 (seven species in seven climates). Under deficit irrigation, ETc was 2.14 to 5.71 mm d−1 and K c was 0.52 to 0.94 (seven species in four climates). Crop evapotranspiration was greater with increasing aridity. The K c data provide benchmarks for irrigation. Field irrigation dose–response experiments show that some warm‐season turfgrasses differ in water requirements. Inter‐ and intraspecies variations in drought resistance have also been documented. Additional research is required to elucidate the mechanisms underlying the observed variations in turfgrass ETc and drought resistance and to test the influence of management practices (e.g., cutting height, nitrogen fertilizer, and growth regulators) in field situations. Looking forward, process‐based modeling could increase understanding of turfgrass traits and other factors influencing ETc and drought resistance and further assist efficient use of water in warm‐season turfgrass systems.

Impact of the Irrigation Dose Amount on the Wheat Yield

Abstract The paper presents analysis of the impact of irrigation dose on the winter wheat Bystra yield, which is recommended for cultivation in Poland. It is a low-growing high-yield wheat cultivar. A reel sprinkler equipped with a computer for control of parameters of its operation, which was supplied with pond water was used for irrigation. Test were carried out on five fields, where four irrigation doses were used: 15, 20, 25, 30 mm. A change of weather during research in May and June caused the need to irrigate a field four times. During research, the size of the irrigation dose was measured with rain gauges on each of the investigated fields in five measurement points. One of the fields was a control field, which was not irrigated. The investigated wheat was characterized during harvesting. Research proved that the size of the irrigation dose influences the wheat yield. The grain yield between a control field and a field with the highest irrigation dose increased by twofold. Moreover, analysis of costs incurred during sprinkling were analysed.

Severe trimming and enhanced competition of laterals as a tool to delay ripening in Tempranillo vineyards under semiarid conditions

Aim: An advance in grapevine phenological stages (including ripening) is occurring worldwide due to global warming and, in the hottest seasons, already results in a lack of synchrony between sugar and phenolic ripeness, leading to unbalanced wines. In order to cope with this fact, a general effort is being made by researchers and growers aiming at delaying ripening through cultural practices, particularly under warm growing conditions, where these effects are more deleterious. The aim of this work is to evaluate to which extent severe trimming and enhanced competition of laterals can delay ripening in Tempranillo vineyards under semiarid conditions.Methods and results: The experiment took place during two consecutive seasons in Traibuenas (Navarra, Spain) in a cv. ‘Tempranillo’ vineyard trained to a vertical shoot positioned (VSP) spur-pruned bilateral cordon. Severe mechanical pruning was performed ca. 3 weeks after fruit-set in order to reduce leaf-to-fruit ratio, and in the trimmed plants, three irrigation doses were applied until harvest aiming at enhancing lateral growth, hypothesized to compete with ripening. All measurements were performed in six 10-vine replicates per treatment. Trimming significantly reduced leaf area and yield, resulting in higher water availability in trimmed plants. The whole ripening process was delayed by trimming: mid-veraison was delayed by about 5 days, and the delay in sugar accumulation and acid degradation was longer, differences being more marked in malic than in tartaric acid concentration. The use of increased irrigation levels compensated the losses in yield caused by trimming, enhanced laterals’ growth and implied an additional delay in ripening.Conclusion: trimming and increased irrigation had an additive effect in terms of delaying ripening, and they can be used jointly when that delay is needed.Significance and impact of the study: this study proves the potentiality of the joint use of trimming and increased irrigation to delay ripening, although it is necessary to analyze the implications the obtained delay has on other quality aspects. The lower anthocyanin and phenolic values observed in trimmed vines were not solely due to delayed ripening, as lower values were observed even when data were compared for a given total soluble solid content.

Severe trimming and enhanced competition of laterals as a tool to delay ripening in Tempranillo vineyards under semiarid conditions

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aim:&lt;/strong&gt; An advance in grapevine phenological stages (including ripening) is occurring worldwide due to global warming and, in the hottest seasons, already results in a lack of synchrony between sugar and phenolic ripeness, leading to unbalanced wines. In order to cope with this fact, a general effort is being made by researchers and growers aiming at delaying ripening through cultural practices, particularly under warm growing conditions, where these effects are more deleterious. The aim of this work is to evaluate to which extent severe trimming and enhanced competition of laterals can delay ripening in Tempranillo vineyards under semiarid conditions.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results:&lt;/strong&gt; The experiment took place during two consecutive seasons in Traibuenas (Navarra, Spain) in a cv. ‘Tempranillo’ vineyard trained to a vertical shoot positioned (VSP) spur-pruned bilateral cordon. Severe mechanical pruning was performed ca. 3 weeks after fruit-set in order to reduce leaf-to-fruit ratio, and in the trimmed plants, three irrigation doses were applied until harvest aiming at enhancing lateral growth, hypothesized to compete with ripening. All measurements were performed in six 10-vine replicates per treatment. Trimming significantly reduced leaf area and yield, resulting in higher water availability in trimmed plants. The whole ripening process was delayed by trimming: mid-veraison was delayed by about 5 days, and the delay in sugar accumulation and acid degradation was longer, differences being more marked in malic than in tartaric acid concentration. The use of increased irrigation levels compensated the losses in yield caused by trimming, enhanced laterals’ growth and implied an additional delay in ripening.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;trimming and increased irrigation had an additive effect in terms of delaying ripening, and they can be used jointly when that delay is needed.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study:&lt;/strong&gt; this study proves the potentiality of the joint use of trimming and increased irrigation to delay ripening, although it is necessary to analyze the implications the obtained delay has on other quality aspects. The lower anthocyanin and phenolic values observed in trimmed vines were not solely due to delayed ripening, as lower values were observed even when data were compared for a given total soluble solid content.&lt;/p&gt;

Increasing water productivity in arid regions using low-discharge drip irrigation: a case study on potato growth

Potato is sensitive to excess or deficit irrigation and therefore requires the efficient use of water, especially in arid regions. Low-discharge drip irrigation has been suggested as an efficient irrigation method, providing an optimal amount of water and fertilizer directly to the root zone. However, field studies using a continuous irrigation system with low discharge have rarely been reported, in particular for arid regions. The main objective of the current study was to optimize the irrigation regime of low-discharge drip irrigation under potato growth. Specifically, we examined combinations of dripper discharge, dripper spacing, and irrigation doses. We report the results from two subsequent years of potato growth in the Arava Desert, Israel. The results obtained suggest that the lower the irrigation dose, the higher the water productivity (i.e., yield/dose), regardless of the dripper discharge (first year 0.6 vs. 1.6 L h−1 and second year 0.6 L h−1) or spacing (first year 20 vs. 40 cm and second year 25 vs. 50 cm). In terms of economic viability and/or food production, the results of this study imply that one may consider using low irrigation doses relative to the optimal. Specifically, for a given field, the total tuber yield will be smaller. However, if available agricultural lands are not a limiting factor (such as in the Arava Desert), higher yields can be obtained with a small irrigation dose in a larger area, with no significant reduction in tuber quality.

Evaluation of Different Drought Stress Regimens on Growth, Leaf Gas Exchange Properties, and Carboxylation Activity in Purple Passionflower Plants

A greenhouse experiment was conducted to evaluate the effects of water stress on leaf water potential, plant growth, and photosynthesis in purple passionflower (Passiflora incarnata). Twenty 4-L pots with two plants in each pot were arranged in a completely randomized design. Ten pots received a daily irrigation dose of 100% evapotranspiration (ET) throughout the 43-day experiment (control). The other 10 pots were subjected to a reduced irrigation (RI) treatment, which was implemented stepwise to achieve a gradual increase in stress, by irrigating them with 50% ET first, then with 25% ET and, finally, with 10% ET. The last stress phase was followed by a recovery phase in which all treatments received the same amount of water (100% ET). A lower water potential was obtained at 10% ET compared with control plants (−2.51 and −0.98 MPa, respectively). Plants in both 25% and 10% ET irrigation treatments had reduced net CO2 assimilation rates (4.25 and 3.50 μmol·m−2·s−1, respectively) than plants watered with 100% ET (8.53 and 6.77 μmol·m−2·s−1, respectively). Values of maximum carboxylation rate allowed by rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), calculated 31 days after treatment (DAT) application (when RI plants were irrigated with 10% ET) decreased by ≈60%, whereas rate of photosynthetic electron transport and triose phosphate use (TPU) were reduced by ≈30% and ≈45% in the stress treatment compared with the control during the 10% ET irrigation period, respectively. Values of water potential and net CO2 assimilation rates in previously stressed plants were not different from the control treatment in the recovery phase, suggesting that P. incarnata plants could adapt well to landscaping situations where periods of extreme drought can be expected.

Nutrition of Tithonia diversifolia and attributes of the soil fertilized with biofertilizer in irrigated system

ABSTRACT The fertilization with biofertilizer associated with the use of irrigation favors nutrient uptake by plants and soil chemical properties; however, these effects are little studied in Tithonia diversifolia in semiarid regions. This study evaluated the effect of doses of bovine biofertilizer and irrigation on accumulation of nutrients in the leaves of Tithonia diversifolia plants and on soil chemical attributes. The study was carried out from December 3, 2014 to November 28, 2015, and arranged in a 2 x 5 factorial scheme, consisting of five doses of bovine biofertilizer (0, 40, 80, 120 and 160 m3 ha-1), combined with and without irrigation. The experiment was set in a randomized block design, using three replicates. Irrigation promoted increased accumulation of N, P, K, Ca, Mg, S, Zn, Fe, Mn, Cu and B in leaves of Tithonia diversifolia in the first cutting. However, the high bicarbonate concentration in the irrigation water and the occurrence of rainfall during the second crop increased the accumulation of Cu in the leaves of Tithonia diversifolia under rainfed condition, compared with irrigated plants. The increase in biofertilizer doses contributed to the increment of base saturation and the contents of organic matter, P and K in soil.

Optimizing Tomato Water and Fertilizer Uses in Smallholder Farms in South Africa Using the Piloten Model

AbstractThe objectives of this paper are twofold: (i) to calibrate and validate the PILOTEN crop model for tomato (Solanum lycopersicum L.), and (ii) to use the model to examine the response of tomato yield to different irrigation and fertilization scheduling scenarios under varying climatic conditions in order to draw up management recommendations for smallholder farms. The calibration and validation were performed by using data collected from field experiments carried out in the north‐east of South Africa, on shallow Ferrosol and Luvisol soils. The scenarios dealt with: (i) the initial soil‐water availability (fulfilling or not the soil‐water reserve at planting); (ii) the irrigation dose frequency (high versus low irrigation doses ranging from 10 to 40 mm per application); (iii) the fertilization dose frequency (full versus split fertilization application). The results indicated that only the fertilization scheduling may significantly affect tomato yields, while irrigation scheduling has a minor role. However, compared to the local official irrigation guidelines, it is recommended to slightly increase the irrigation doses during the first 4 weeks of growth for tomato grown between early September and mid‐December, and to slightly decrease the doses in the second part of the growing cycles starting in February and May. It is also suggested to avoid applying the entire fertilizer dose after seedling planting for tomato grown between mid‐February and late June. Copyright © 2020 John Wiley &amp; Sons, Ltd.

Effect of irrigation frequency and water distribution pattern on leaf gas exchange of cv. ‘Syrah’ grown on a clay soil at two levels of water availability

The implications of water availability in grapevine physiology have been widely studied before. However, for a given irrigation water amount, the effect of other aspects such as application frequency, or emitter spacing and flow rate (i.e.: distribution pattern) has been scarcely studied, with nearly no previous research on their implications on leaf gas exchange. The aim of this work was to evaluate the physiological response of grapevine to two irrigation frequencies (IrrF, every 2 and 4days) and two water distribution patterns (DisP, 2L h−1 emitters every 0.6m vs. 4L h−1 emitters every 1.2m). The experiment was carried out in a cv. Syrah vineyard with a clay soil in central Spain, and the two factors were evaluated under two water availability conditions (low and medium). IrrF and DisP promoted changes in leaf gas exchange. Under low WA conditions, plants irrigated every 4days had higher average net assimilation than plants irrigated every 2days. Under medium WA conditions leaf gas exchange depended on the day of measurement with respect to irrigation. Water distribution pattern effect was less evident, but plants with closer emitters performed better under medium WA. The results obtained suggest that variations in irrigation frequency and water availability promote plant acclimation to water deficit conditions, more intense as irrigation dose was lower and as irrigation frequency was higher.

Irrigation dose and plant density affect the volatile composition and sensory quality of dill (Anethum graveolens L.).

Two independent field experiments were carried out to investigate the influence of (i) three irrigation treatments (ID0 = 1585 m3 ha-1 , considered as a control; ID1 = 1015 m3 ha-1 ; and ID2 = 2180 m3 ha-1 ) and (ii) three plant density treatments (PD0 = 5.56 plants m-2 , considered as a control; PD1 = 4.44 plants m-2 ; and PD2 = 7.41 plants m-2 ) on the production, volatile composition of essential oil, and sensory quality of dill. The highest plant yield was obtained with intermediate conditions of both irrigation dose (ID0) and plant density (PD0). The main compounds of the essential oil were α-phellandrene, dill ether and β-phellandrene. The highest irrigation dose (ID2) produced the highest concentrations of most of the main compounds: α-phellandrene (49.5 mg per 100 g), β-phellandrene (6.89 mg per 100 g) and limonene (2.49 mg per 100 g). A similar pattern was found for the highest plant density (PD2): α-phellandrene (71.0 mg per 100 g), dill ether (16.7 mg per 100 g) and β-phellandrene (9.70 mg per 100 g). The use of descriptive sensory analysis helped in reaching a final decision, and the dill plants with the highest sensory quality were those of the ID2 and PD0 treatments. The final recommendation is to use the irrigation dose ID2 and the plant density PD2 if the objective is to produce dill samples with the highest aromatic and sensory quality; however, if the only objective is to produce high amounts of dill, the best options are ID0 and PD0. © 2016 Society of Chemical Industry.

Microeconomics of Deficit Irrigation and Subjective Water Response Function for Intensive Olive Groves

This research paper analyzes the economics of deficit irrigation based on the use of subjective estimates of the crop yield–water relationship to determine water supply in irrigated olive groves. Interviewed farmers were asked to give three estimates for the yield-water relationship as a function of water supply (full irrigation, usual deficit irrigation and extreme deficit irrigation). Those responses are contrasted with the actual irrigation dose and the results appear to support the hypothesis that a majority of farmers use deficit irrigation as a strategy that maximizes the value of limited water input rather than the conventional microeconomic behavior of maximizing the return to land.

Potato Response to Different Irrigation Regimes Using Saline Water

Field experiments were performed to study potato response to irrigation regimes using saline water on a sandy soil in southern Tunisia during the years 2011–2014. Irrigation regimes consisted in the replenishment of cumulated ETc when 35% of the root zone holding capacity is depleted at levels of 100% (I100), 70% (I70) and 40% (I40). The farmer used a fixed irrigation dose and interval, applying 16 mm every 4 days from planting till harvest. Higher soil salinity is observed at harvest under I40 and farmer treatments compared to I100. Highest potato yield was obtained with I100 treatment (24.4–27.5 t ha-1) across 3 years. Significant reductions in yields were observed under I70 and I40 as compared to I100. The farmer's method also caused significant reductions in yield and resulted in using 15–22% more irrigation water than I100. Water productivity (WP) values varied between 4.3 kg m−3 (farmer) and 18.5 kg m−3 (I40) across different years and treatments. The scheduling technique using the soil water balance (SWB) with variable amounts is more efficient than the farmer's method. Full and deficit treatments (I100 and I70) generated the highest net income. I100 appears to be a promising irrigation strategy for the potato crop in the arid climate of Tunisia. Nonetheless, under water scarcity, irrigation of potato could be scheduled using I70 deficit strategy, with some yield reductions (12.5–23.0%). Copyright © 2016 John Wiley & Sons, Ltd.

Irrigation dose and plant density affect the essential oil content and sensory quality of parsley (Petroselinum sativum)

In the current study the influence of 3 irrigation treatments (ID0 as a control, ID1, and ID2), and 3 plant density treatments (PD0 as a control, PD1, and PD2) were investigated on the production (total yield), volatile composition of essential oil, and sensory quality of parsley (Petroselinum sativum). The results showed that the highest plant yield was obtained when using the highest values of both irrigation dose (ID2=1788m3ha−1) and plant density (PD2=7.41 plants m−2). Hydrodistillation technique was used to extract the essential oil of parsley shoots and GC–MS and GC-FID were used to identify and quantify the components of the essential oil, respectively. The results showed that the main compounds of the essential oil were β-phellandrene, 1,3,8-p-menthatriene, myristicin, myrcene, terpinolene, limonene, α-pinene, and α-phellandrene. The treatment ID1 (861m3ha−1) led to the highest concentrations of most of the main compounds: 1,3,8-p-menthatriene (150mgkg−1), myristicin (46.8mgkg−1), and myrcene (33.7mgkg−1); a similar pattern was found for the plant density PD0 (5.56 plants m−2), with contents being 1,3,8-p-menthatriene (143mgkg−1), β-phellandrene (130mgkg−1), and myristicin (38.1mgkg−1). Aroma attributes, such as parsley-like, citrus, and green grass significantly had the highest intensities in ID1 and PD0 plants. The final recommendation based on all data generated is to use the irrigation dose of 861m3ha−1 (ID1) and the plant density of 5.56 plants m−2 (PD0) for better yield and quality of the final product under the assayed conditions.

Effects of long-term summer deficit irrigation on ‘Navelina’ citrus trees

The effects of long-term summer deficit irrigation (RDI) strategies on ‘Navelina’ orange trees (Citrus sinensis L. Osbeck) were assessed in a drip-irrigated commercial orchard located in Senyera (Valencia, Spain). Three irrigation treatments were applied during five consecutive years (2007–2011): a control treatment, without restriction, and two RDI treatments, in which the water reduction was applied during the summer (initial fruit enlargement phase). During the first three seasons, the trees under the control treatment received 110% of the theoretically required irrigation dose (ID), and the RDI treatments received 40% and 60% of the full ID during the deficit period. During the last two years of the study, the control treatment was irrigated at 100% of the ID and the amount of water applied in the RDI treatments was additionally decreased 20% from the reduced ID of the preceding years. The crop’s response to summer deficit irrigation was analysed in relation to tree water status, which was assessed by relying on midday stem water potential (Ψst). The lowest Ψst values were reached, as expected, at the end of the water deficit period and with the most stressed treatment. These minimum Ψst values ranged between −1.6MPa in 2008 and −2.5MPa in 2010. In most occasions, the trees under RDI treatments showed a fast hydric recovery and had completely re-hydrated one week after restarting irrigation. Summer RDI treatments did not cause negative effects on either the amount or on the quality of the yield if the threshold value of Ψst=−2.0MPa was not surpassed. According to the results, it can be concluded that long-term RDI strategies may be applied successfully on Navelina orange trees during summer without negatively affecting the studied parameters while allowing water savings between 12% and 27%.

The water needs of urban green areas

Abstract The aim of the research was to evaluate the irrigation needs of urban green spaces in terms of automatic irrigation system. For this purpose, four research stations: two on the surface of shrubs and two on the lawn were founded. The analysis included two vegetation seasons in 2009 and 2010. To estimate the water requirements of the analyzed surfaces a method based on water balance was used. After comparison of simulation result with instrumental results, difference between soil water reserves was calculated. Normalized mean square error (NRMSE) for the post of ornamental shrubs during the vegetation season in 2009 was 0.80, and 2.76% for the lawn. However, in the same period in 2010, it was 0.21% for ornamental shrubs and 1.54% for the lawn. The assessment of the irrigation system for the whole operating period was based on indicators of effectiveness and efficiency of irrigation. The performance indicator of irrigation ranged from 83 to 100%, while the rate of irrigation efficiency from 87 to 100%. To assess the relationship between the components of the water balance multiple linear regression model was used. The analysis takes into account the impact of the many independent features on selected dependent feature. For this purpose the impact of temperature, humidity, initial retention in a balance layer, irrigation doses and natural precipitation on the water supply in the soil profiles was analyzed. As a result of the analyzes the size of a single dose of irrigation, in order to maintain a certain level of humidity for different surfaces of urban green areas, can be determined.