Effect Of Irrigation Scheduling Research Articles

Modelling soil moisture, water partitioning, and plant water stress under irrigated conditions in desert urban areas

ABSTRACTThis study conducts a comparative analysis of the effects of irrigation scheduling at two urban residential sites in the Phoenix, Arizona, metropolitan area: a xeriscaped site (gravel base with low water use plants) and a mesiscaped site (turf grass and shade trees). A model of soil moisture dynamics was calibrated to observed soil moisture data from irrigated and non‐irrigated sensors at the xeric site and an irrigated sensor at the mesic site. Model simulations were conducted at both irrigated sites to investigate effects of irrigation scheduling; plant stress parameters; and precipitation variability on soil moisture dynamics, water balance partitioning, and plant water stress. Results indicated a substantial difference in soil water storage capacity at the two sites. At the xeric site, seasonal variation of irrigation input was shown to be critical in avoiding losses from the rooting zone, while reducing plant water stress. At the mesic site, sensitivity to irrigation scenarios was lower, though small amounts of water savings were achieved with seasonal applications. The model was then used to determine the minimum annual irrigation required to achieve specified levels of plant stress using long‐term meteorological records. A bimodal schedule consisting of low winter and summer irrigation was identified as a means to conserve water while keeping moderate levels of dynamic water stress. Results from the quantitative model can potentially assist water and landscape managers in desert urban areas by identifying opportunities for water savings, while providing a deeper understanding of the ecohydrological differences between the two types of landscape designs. Copyright © 2014 John Wiley & Sons, Ltd.

Productivity, quality and soil fertility status as well as economics of multi-cut summer forage pearl millet as influenced by varying levels of irrigation and nitrogen

A field experiment was conducted during summer seasons of 2011 and 2012 on sandy loam soil at Sardarkrushinagar to study the effect of irrigation scheduling and nitrogen levels on multi-cut summer forage pearl millet. The results showed that of 2011 and 2012 as well as in pooled irrigation at 1.2 IW: CPE ratio producing significantly higher green fodder yield (1108.2 q/ha), dry matter yield (248.3 q/ha), crude protein content (9.7%) and yield (26.98 q/ha), available nitrogen (204.99 kg/ha) and phosphorus (38.64 kg/ha) over 0.6, 0.8 and 1.0 ratios. However, water use efficiency (86.07 kg/ha) was higher with 0.8 IW/CPE ratio. The green fodder yield (1045.1 q/ha), dry matter yield (249.7 q/ha), crude protein content (10.6%), crude protein yield (26.77 q/ha), water use efficiency (87.66 kg/ha), available nitrogen (214.53 kg/ha) and phosphorus (41.23 kg/ha) were maximum at 200 kg N/ha compared to other levels (100 and 150 kg N/ha). The treatment combination of I4N3 (1.2 IW: CPE ratio+200 kg N/ha) registered the highest net realization of (Rs. 99499/ha with B: C ratio (3.56). Consequently for higher productivity and profitability of multi-cut summer forage pearl millet, it should be grown with irrigation at 1.2 IW: CPE ratio and fertilized with 200 kg N/ha.

IRRIGATION, SPACING AND CULTIVAR EFFECTS ON NET PHOTOSYNTHETIC RATE, DRY MATTER PARTITIONING AND PRODUCTIVITY OF RICE UNDER SYSTEM OF RICE INTENSIFICATION IN MOLLISOLS OF NORTHERN INDIA

SUMMARYField experiments were conducted on a Typic Hapludoll (Mollisols) soil in the Indo-Gangetic Plains of India during the 2008 and 2009 rainy seasons to (1) find out the effect of irrigation schedules and plant spacing on physiological parameters, yield and water productivity of two rice cultivars under System of Rice Intensification (SRI), and (2) compare the performance of SRI with conventional transplanting (CT). Treatments under SRI included 12 combinations of three irrigation schedules, viz. irrigation at 1, 3 and 5 day(s) after disappearance of ponded water (DADPW), two spacing intervals (20 × 20 cm and 25 × 25 cm) and two cultivars (‘Pant Dhan 4’ and ‘Hybrid 6444’). The two control treatments were the CT of each cultivar. The experiment was set in a factorial randomized complete block design replicated thrice. The net photosynthetic rate (NPR) of the topmost fully expanded leaf at tillering and that of flag-leaf at flowering stage was affected significantly by irrigation schedules. Irrigating rice crop at 1 or 3 DADPW, being at par with each other, recorded significantly higher NPR than 5 DADPW. The increase in NPR at 1 and 3 DADPW was 17.1% and 8.4% at tillering and 13.6% and 6.1% at flowering stage, respectively, compared with that at 5 DADPW (tillering: 12.78 μmol CO2 m−2 S−1, flowering: 16.01 μmol CO2 m‑2 S−1). At closer spacing (20 × 20 cm) the cultivars did not differ significantly for NPR; however, at wider spacing (25 × 25 cm), ‘Hybrid 6444’ showed significantly higher NPR than ‘Pant Dhan 4’. Between two methods, SRI recoded higher NPR. Dry matter accumulation (DMA) in leaves and grains declined with delay in irrigation from 1 to 5 DADPW. Wider spacing significantly enhanced DMA in stems and grains. ‘Hybrid 6444’ showed higher DMA in all plant parts than ‘Pant Dhan 4’. Grain yield was not affected significantly by irrigation schedules in 2008, while in 2009, irrigation at 1 and 3 DADPW resulted in 12.8% and 8.0% higher grain yield, respectively, than 5 DADPW (5.84 t ha−1). Wider spacing was superior to closer spacing. SRI improved grain yield by 16.9% and water productivity by 18.5% over CT.

Differential Growth and Development Response of Sunflower Hybrid in Contrasting Irrigation Regimes

Water is the most important factor limiting crop productivity at different growth stages of crop growth and development. The study was conducted to investigate the effect of irrigation scheduling on sunflower hybrid (Hysun-38) at vegetative versus reproductive stages during spring season 2010. The trial was laid out in randomized complete block design (factorial arrangement), replicated thrice, having net plot size of 3.5 m × 9 m. The treatments comprised of irrigation application of 75 mm each, at different growth and development stages. viz., I1 = irrigation at plant establishment, I2 = irrigation at plant establishment and irrigation at vegetative phase, I3 = irrigation at plant establishment, irrigation at button stage and irrigation at flowering, and I4 = irrigation at plant establishment, irrigation at vegetative phase, irrigation at button stage and irrigation at achene’s formation. Days taken to 50% flowering was highest in I2, where irrigation was applied at plant establishment and vegetative phase, and in I4 treatment , where irrigation was given at seedling establishment, irrigation at vegetative phase, irrigation at button stage and irrigation at achene’s formation. Leaf area index at different growth intervals was significantly affected by irrigation levels. Crop growth rate was highest for treatment I4. Plant height (PH), stem girth (SG) head diameter (HD), 1000-achene’s weight (AW) and achene’s yield (AY) were significantly affected by different irrigation levels at various growth stages. Maximum AY (2415.68 kg·ha-1) was obtained in I4 treatment while, minimum AY (1275.35 kg·ha-1) was obtained in case of those plots which were irrigated only at plant establishment stage. Sunflower productivity was affected with irrigation regime at different growth stages with the strongest responses seen at early growth stages which ultimately affected the final achene yield adversely.

Effects of Irrigation Schedules on Photosynthetic Carbon Assimilation of Winter Wheat (Triticum aestivum L.) in North China Plain: from Leaf to Population

A field experiment was conducted to elucidate the regulation mechanism of different irrigation schedules on population photosynthetic of winter wheat. The experiment included five irrigation schedules, such as no irrigation (W0), irrigation once at jointing (W1j) or at booting (W1b), irrigation twice at jointing and booting (W2), and irrigation three times at jointing, booting and grain-filling (W3) and three planting densities, such as 180 (D1), 300 (D2) and 450 (D3) seedlings per square meter. The results indicated that irrigation significantly improved population photosynthesis. The relationship between population photosynthesis and irrigation time/volume was to some extent parabolic. Improvements in population photosynthesis (resulting from more irrigation time/volume) were mainly related to increase in leaf area index and population light interception. Population photosynthesis exhibited a significantly negative correlation with canopy light transmittance. Population photosynthesis at grain filling stage was significantly positively correlated with dry matter accumulation at post-anthesis and grain yield. Main effects and partial correlation analysis showed that population photosynthesis of W0, W1j, W1b and W3 were regulated by canopy light transmittance and leaf area. On the other hand, population photosynthesis of W2 was mainly influenced by flag leaf photosynthetic rate. On this basis, planting 300 seedlings per square meter was the optimum combination. The combination of W2D2 increased population photosynthesis during mid-late growth stages and extended high population photosynthesis duration, which ultimately increased grain yield.

Effect of phenophase based irrigation schedules on growth, yield and quality of baby corn (Zea mays L.)

The field experiment was conduced at the Agronomy Field Unit, Main Research Station, University of Agricultural Sciences, Hebbal, Bangalore, India during 2002 and 2003 to study the effect of irrigation schedules on growth, yield and quality of baby corn. The soil of the experimental site was red sandy loam in texture with neutral reaction. The experiment was laid out in a randomized complete block design with three replications. There were seven treatments of irrigation schedules based on IW/CPE ratio of 0.6 and 1.0 during different phenophases of baby corn. The results of the experiment revealed that the baby corn dry matter was significantly higher (75.57 g.plant–1) with higher green fodder yield of 43.47 t.ha–1 due to irrigation scheduled at IW/CPE ratio of 1.0 followed by moisture stress at early stage (I3). Irrigations scheduled at IW/CPE ratio of 1.0 registered significantly higher baby corn yield of 6.60 t.ha–1 followed by the delayed irrigation at early stage of 10 - 25 DAS. Significantly higher crude protein, phosphorus, potassium and lower reducing sugars and ascorbic acid content of baby corn was recorded under IW/CPE ratio of 1.0. Delayed irrigation at 0.6 IW/CPE ratio through-out produced baby corn with higher taste and juiciness. The total crop water use ranged from 294.10 to 469.10 mm, respectively under continuously delayed irrigation at 0.6 IW/CPE ratio and frequent irrigation at IW/CPE ratio of 1.0 which also recorded higher water use efficiency.

Plant based indicators for irrigation scheduling in young cherry trees

Abstract Using a correlation between trunk diameter fluctuation (TDF) and stem water potential (SWP) it appears possible to determine water deficit threshold values (WDTV) for young cherry trees. This correlation must be based on a significant effect between SWP and at least one variable associated with the vegetative or reproductive growth of the trees. The objectives of this study are: (1) to determine the effect of several irrigation treatments on vegetative and reproductive growth and the SWP of young cherry trees; (2) to determine the correlation between TDF and SWP, and; (3) to propose a first approximation of SWP and TDF water deficit threshold values for young cherry tree plants. The experiment was carried out between September and April of the 2005–2006 and 2006–2007 seasons, in Quillota, in the Valparaiso region, central Chile. The irrigation treatments consisted of applications of 50% ( T 50 ), 100% ( T 100 ) and 150% ( T 150 ) of potential evapotranspiration (ET 0 ) over the two growing seasons, using a randomized complete block design (RCB). The effect of irrigation scheduling was observed on: apical shoot growth rate (GR AS ), branch cross-sectional area (BCSA), canopy volume (CV), annual length of accumulated growth (AL AG ) and productivity. This effect showed that the T 50 treatment caused lower SWP (measured pre-dawn), vegetative growth and productivity. The fruit quality variables (cracking and size) were not affected by the different treatments. Combining the vegetative growth, productivity and SWP results shows that the water deficit threshold value, as a first approximation, is between 50% and 100% of ET 0 , and therefore the critical SWP for defining irrigation frequency should be close to −0.5 MPa. Upon applying a post-harvest drought period (14 days without irrigation), a linear correlation was determined both between SWP and maximum daily trunk shrinkage, MDS ( R 2 = 0.69) and between SWP and trunk growth rate, TGR ( R 2 = 0.57). Using these correlations and the SWP reference value, reference values were obtained for MDS (165 μm) and TGR (83 μm day −1 ), which would permit automated control of water status in young cherry trees.

The effect of irrigation scheduling and water stress on the maturity and chemical composition of Virginia tobacco leaf

The study was carried out in order to determine the effect of different irrigation scheduling programs and water stress, imposed at different growth stages, on the maturity and leaf chemistry of Virginia tobacco ( Nicotiana tabacum L.). Field experiments and lab investigations were carried out during 2000–2003, on a silty loam Entisol soil, poor in organic matter and rich in potassium, on the fields of Atatürk Soil and Water Resources Research Institute in Kirklareli, Turkey. A randomized complete block experimental design with three replications was applied, and K-326 Virginia tobacco cultivar was used in the experiment. Three known stages of the plant – vegetative (V), yield formation (F), and ripening (R) – were considered, and a total of 14 irrigation treatments (including rain-fed) were applied. All the experimental treatments were irrigated on the same day of VFR and were irrigated at each growth stage with the amount of water required to fill the 0–90 cm soil depth to field capacity; and three levels of water reductions (0%, 40% and 60%) were done at each development stage. Results of the investigations show that irrigation scheduling and the water stress imposed during different stages of growth influenced the ripening dynamics of Virginia tobacco leaves and that severe water stress causes delay in the ripening of the leaves. Favorable moisture conditions considerably decrease the nicotine and nitrogen content of the Virginia tobacco leaves, both of which are hazardous for humans, to the ranges of 0.85–1.21% versus 2.1–2.2% under stress (for nicotine), and 1.4–1.6% versus 1.8–2.0%, and 2.0–2.4% versus 2.9–3.1% (for nitrogen) for 2001 and 2003, respectively. However the percentage of chloride and sodium in the leaf increases if the amount of seasonal water is increased. It was determined also that close linear relationships exist between seasonal irrigation water amounts or seasonal evapotranspiration and any of the chemical traits. Mutual relationships between nicotine and each of the traits – i.e. nitrogen, chloride, potassium, and sodium – were also established.

YIELD AND SOME WATER RELATION OF MAIZE CROP AS INFLUENCED BY IRRIGATION SCHEDULING AND NITROGEN FERTILIZATION RATES AT MIDDLE NORTH NILE DELTA

Two field experiments were conducted at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, Egypt during the two successive seasons of 2007 and 2008. The objectives of this research were: (i) to study the effect of irrigation scheduling using three different pan evaporation coefficients on maize yield; (ii) to evaluate the growth, yield and N use efficiency of maize as affected by different rates of N fertilization. The treatments were arranged in a split plot design with four replicates. The main plots were assigned with three irrigation regimes I1, I2and I3 irrigated at 1.2 ,1.0 and 0.8 of accumulation of A.P.E. Five nitrogen rates i.e. zero,60, 90,120 and 150 kg N fed.-1 in the sub plots namely N1, N2, N3 , N4 and N5 . Results showed that 1.2 of A.P.E significantly increased grain yield by 5.4, 8.9% and straw yield by 5.7 , 11.3% compared to irrigation at 1.0, 0.8 of A.P.E. respectively. Also irrigation at 1.2 of A.P.E resulted in higher amount of irrigation water applied to be 3150 m3 /fed distributed on 7 irrigations , followed by irrigation at 1.0 to be 2830 m3 /fed distributed on 6 irrigations , and irrigation at 0.8 of A.P.E. was 2370 m3/fed distributed on 5 ones. The highest consumptive water used was obtained under irrigation with 1.2 pan evaporation coefficient i.e. 2386 m3 .while the lowest 1998 m3 obtained from irrigation at 0.8 of A.P.E.. Lower frequent irrigation due to irrigation at 0.8 of A.P.E. resulted in a significantly increased water productivity compared to the other two irrigation treatments it was 1.260, 1.903 and 1.957 kg/m3 for I1, I2 and I3 respectively Increasing nitrogen rates up to 150 kg N fed.-1 (N5 ) significantly increased grain and straw yield by 69 , 50 ; 11.9 ,22.5 ; 4.7 , 4.7 % as compared to N1 ; N2 ; N3 treatments respectively but not significant with N4 Nitrogen use efficiency (NUE) increased with decreasing water applied .It was 77.47 , 79.25 and 80.07 % for I1 , I2 , I3,respectively , and decreased with increasing N rate; 88.1 ,85.7 , 77.4 and 64.5 for N2 ; N3 ; N4 and N5 respectively. Therefore, to increase water productivity and to save irrigation water, it could be recommended to irrigate maize at 1.0 of A.P.E in middle north Nile Delta soils to save water of about 320 m3

Effect of Irrigation Scheduling on Growth Parameters and Water Use Efficiency of Barely and Faba Bean Crops in Al-Ahsa, Saudi Arabia

Effect of Irrigation Scheduling on Growth Parameters and Water Use Efficiency of Barely and Faba Bean Crops in Al-Ahsa, Saudi Arabia

Water relations of olive trees cultivated under deficit irrigation regimes

The experiment was carried out at the Experimental Field ‘Taoues’, southern Tunisia (34°N, 10°E) to examine the effect of irrigation schedules on water relations for young olive trees, cultivars Chétoui, Chemlali, Coratina, Picholine and Manzanille. Plants were cultivated at 7 m × 7 m spacing and drip irrigated from April to September. Irrigation amounts (IA) of 20%ET c, 50%ET c and 100%ET c were applied, where ET c is the FAO crop evapotranspiration. The effect of IA on midday leaf water potential ( Ψ leaf), stomatal resistance ( R s) and conductance ( g s), soil ( H v) and relative leaf (RWC) water contents was studied. Results showed that a further increase in IA was not systematically followed by an increase of water potential, production and WUE values. Some controversial responses were observed following to a variety with large seasonal variations. At the beginning of the growing season, differences between treatments were not very important because soil water content was still high enough to prevent important changes in Ψ leaf values. The most stressed trees showed potentials of −1.53 MPa for Picholine cv. and ranging between −2.30 MPa and −2.10 MPa for the other varieties depending on IA. The less stressed trees provided potentials of −0.97 MPa for Picholine cv. and varying between −1.63 MPa and −2.13 MPa for cultivars Coratina, Manzanille, Chétoui and Chemlali. Then, as the season progresses, and when IA was increased from 20%ET c to 50%ET c, Ψ leaf values decreased significantly for cultivars Chemlali (−3.05 MPa), Coratina (−3.75 MPa), Manzanille (−3.0 MPa) and Chétoui (−3.5 MPa). At 100%ET c, Manzanille and Picholine cultivars show better water status with respective potentials of −2.7 MPa and −2.6 MPa. Stomatal resistance monitoring showed maximums at midday for all cultivars with pick value of 4.45 s/cm recorded for Chétoui cultivar irrigated at 50% ET c. The most important variations were recorded for cultivar Chemlali which seem to be the ablest to regulate stomata aperture. Close coordination between Ψ leaf and g s and Ψ leaf and RWC measurements was found. But, the response varied following to treatment. At low irrigation levels (20%ET c and 50%ET c), g s was found to be linearly and positively correlated to Ψ leaf. It increased linearly and positively with increasing values of Ψ leaf ( r of 0.84 and 0.96, respectively). At 100%ET c, Ψ leaf is found to be correlated to g s following to a polynomial function with an optimum g s value of 450 mmol/m 2/s and Ψ leaf of about −2.5 MPa.

Use of Irrigation Technologies for Vegetable Crops in Florida

Major horticultural crops in Florida are vegetables, small fruit, melons, and tree fruit crops. Approximately half of the agricultural area and nearly all of the horticultural crop land is irrigated. Irrigation systems include low-volume microirrigation, sprinkler systems, and subsurface irrigation. The present review was divided into two papers, in which the first part focuses on vegetable crop irrigation and the second part focuses on fruit tree crop irrigation. This first part also provides an overview of irrigation methods used in Florida. Factors affecting irrigation efficiency and uniformity such as design and maintenance are discussed. A wide range of soil moisture sensors (e.g., tensiometers, granular matrix, and capacitance) are currently being used in the state for soil moisture monitoring. Current examples of scheduling tools and automated control systems being used on selected crops in Florida are provided. Research data on the effect of irrigation scheduling and fertigation on nutrient movement, particularly nitrate, are reviewed. Concluding this review is a discussion of potential for adoption of irrigation scheduling and control systems for vegetable crops by Florida growers and future research priorities.

Use of Irrigation Technologies for Citrus Trees in Florida

Florida is the most important center of processed citrus (Citrus spp.) production in the United States, and all of the crop is irrigated. Irrigation systems include low-volume microirrigation, sprinkler systems, and subsurface irrigation. This review details the relative irrigation efficiencies and factors affecting irrigation uniformity such as design and maintenance. A wide range of soil moisture sensors (e.g., tensiometers, granular matrix, and capacitance) are currently being used for citrus in the state. The use of these sensors and crop evapotranspiration estimation using weather information from the Florida Automated Weather Network in irrigation scheduling are discussed. Current examples of scheduling tools and automated control systems being used on selected fruit crops in Florida are provided. Research data on the effect of irrigation scheduling, soluble fertilizer injection, and soil nutrient movement, particularly nitrate and the use of reclaimed water in Florida, are also reviewed. Concluding this review is a discussion of the potential for adoption of irrigation scheduling and control systems for citrus by Florida growers and future research priorities.

Effect of Irrigation Scheduling on Gerbera Flower Yield and Quality

Better understanding of the effects of irrigation frequency and dose on flower production of gerbera plants (Gerbera jamesonii) can lead to optimal water management and crop yield. Measurements of greenhouse microclimate and production and quality characteristics of a gerbera crop were carried out under two irrigation frequency regimens in soilless cultivation in a greenhouse located in Arta, Greece. Irrigation scheduling was based on solar radiation and performed whenever accumulated solar radiation energy outside the greenhouse reached 1650 kJ·m−2 [high irrigation frequency (HIF)] or 3300 kJ·m−2 [low irrigation frequency (LIF)]. The amount of water applied was 0.125 mm and 0.250 mm for HIF and LIF, respectively. Stem fresh weight, length and thickness, and number of harvested gerbera flowers were measured along with crop evapotranspiration, crop leaf area, and greenhouse microclimate variables. Measurements started 8 months after transplanting and lasted 90 days (May to July). Leaf area, fresh weight, harvested cut flowers, and the main quality characteristics of gerbera flowers (stem length and flower diameter) were unaffected by the irrigation frequency. In the framework of the experiment, simple formulas for calculation of leaf area index were developed. Finally, a first approach study of an alternative remote sensing irrigation control method using a reflectance index was made and the results are presented.

Effect of irrigation scheduling on leaf yield of non-heading Chinese cabbage(Brassica rapa L. subsp. chinensis)

A field experiment conducted on the Dzindi canal irrigation scheme in the north of South Africa demonstrated that non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) needed to be irrigated at least twice per week to maintain the water content of the rooting zone close to field capacity and achieve maximum leaf yield. Irrigation scheduling practice affected both total consumptive water use and leaf yield of the crop and the latter two variables were strongly correlated (r = 0.91). Single applications of 20 mm per week, commonly practiced by smallholders on canal irrigation schemes in the region, limited yield to about two-thirds of the maximum achieved when the soil was irrigated to field capacity every other day. Pre-charging the upper 800 mm of the soil profile to field capacity followed by single applications of 20 mm per week increased yield, but only to 80% of the maximum, suggesting that the scope for improving water use efficiency in non-heading Chinese cabbage through the use of deficit irrigation was limited.

Effect of irrigation scheduling and method of irrigation on productivity and water economy in hybrid sunflower (Helianthus annuus L.)

SUMMARY An experiment was conducted during summer and kharif seasons of 2004 and 2005 at Agricultural Research Station, Bhavanisagar, to study different irrigation methods and regimes (IW/CPE ratio) on yield attributes, yield and water economy in hybrid sunflower (MSFH 17). Yield and yield attributes varied significantly during both summer and kharif seasons of 2004 and 2005. Irrigation at 0.80 and 0.60 IW/CPE ratios under alternate furrows and paired row system of irrigation (80/40 × 30 cm) proved better than other treatment combinations with regard to water use efficiency gross return, net return and B0 : C ratio. RESUMEN Se condujo un experimento durante las estaciones de verano y Kharif de 2004 y 2005 en la Agricultural Research Station de Bhavanigasagar para estudiar el efecto de diferentes regímenes de riego (relación IW/CPE) sobre atributos asociados al rendimiento, rendimiento y economía del agua en el híbrido de girasol MSFH 17. El rendimiento y sus atributos asociados variaron significativamente durante las estaciones de verano y Kharif de 2004 y 2005. Las relaciones IW/CPE de 0,80 y 0,60 bajo el sistema de dos hileras apareadas con surco de por medio (80/40 × 30 cm) probaron ser mejor que otras combinaciones de tratamientos con un incremento en la eficiencia en el uso del agua, ingreso bruto, ingreso neto y relación costo/beneficio. RÉSUMÉ Une experimentation a été menée durant les saisons d’été et du kharif de 2004 et 2005 à la Station de Recherches Agricoles de Bhavanisagar afin d’étudier différentes méthodes et régimes (rapport eau apportée par l’irrigation/ eau consommée par l’évapotranspiration; IW/CPE ratio) sur le rendement et ses composantes et sur l’économie d’eau chez l’hybride de tournesol MSFH 17. Le rendement et ses composantes ont varié considérablement au cours des deux saisons et des deux années. Des régimes d’ irrigation à 0.80 ou 0.60 IW/CPE avec un système de sillons d’irrigation alternés ou couplés (80/40 × 30 cm) se sont avérés être les meilleurs combinaisons avec une augmentation de l’efficience de l’eau consommée en marge brute ou nette, et du ratio B: C ratio.

Effect of Irrigation Scheduling on Growth Parameters and Water Use Efficiency of Barely and Faba Bean Crops in Al-Ahsa, Saudi Arabia

Effect of Irrigation Scheduling on Growth Parameters and Water Use Efficiency of Barely and Faba Bean Crops in Al-Ahsa, Saudi Arabia

Pengaruh Jadwal Irigasi Terhadap Pemakaian Air Konsumtif dan Produksi Nilam (Pogostemon cablin (Blanco) Benth)

The objective of this research was to study the effect of irrigation schedule on consumptive water use and yield of patchouli. The irrigation schedule treatment was combination between irrigation level and growth phase. Irrigation levels included irrigation until field capacity were applied every day (100% Available Water/AW 1 ), 3 days (100% AW 3 ), 6 days (100% AW 6 ), 9 days (100% AW 9 ), irrigation until 75% of available water every day (75% AW 1 ), 50% of available water every day (50% AW 1 ) and 25% of available water every day (25% AW 1 ). The growth phase was described into whole growth phase, 2 weeks before harvest and 4 weeks before harvest. Results showed that consumptive water-use ranged from 129.18 cm/4 months to 47.58 cm/4 months that was equivalent to 63379 l water in pot with 25 cm diameter (100% AW 3 applied at 4 weeks before harvest) to 23344 l water in pot with 25 cm diameter (25% AW 1 applied during whole growth phase), respectively. High water use efficiency was yielded by irrigation level of 50% AW 1 or 100% AW 6 . High productivity was reached by irrigation level of 50% AW 1 or 100% AW 3 . Key words: Irrigation schedule, water use efficiency, available water, Pogostemon cablin

In Situ Colloid Mobilization in Hanford Sediments under Unsaturated Transient Flow Conditions: Effect of Irrigation Pattern

Colloid transport may facilitate off-site transport of radioactive wastes at the Hanford site, Washington State. In this study, column experiments were conducted to examine the effect of irrigation schedule on releases of in situ colloids from two Hanford sediments during saturated and unsaturated transientflow and its dependence on solution ionic strength, irrigation rate, and sediment texture. Results show that transient flow mobilized more colloids than steady-state flow. The number of short-term hydrological pulses was more important than total irrigation volume for increasing the amount of mobilized colloids. This effect increased with decreasing ionic strength. At an irrigation rate equal to 5% of the saturated hydraulic conductivity, a transient multipulse flow in 100 mM NaNO3 was equivalent to a 50-fold reduction of ionic strength (from 100 mM to 2 mM) with a single-pulse flow in terms of their positive effects on colloid mobilization. Irrigation rate was more important for the initial release of colloids. In addition to water velocity, mechanical straining of colloids was partly responsible for the smaller colloid mobilization in the fine than in the coarse sands, although the fine sand contained much larger concentrations of colloids than the coarse sand.

The effect of irrigation schedules on the water relations and growth of a young olive ( Olea europaea L.) orchard

In recent years there has been a notable worldwide increase in the amount of land devoted to olive orchards. Most of these new orchards are irrigated and represent large financial investments. The irrigation of young olive trees should reduce the period during which their production is small or non-existent. Although the water requirements of young olive orchards are thought to be low, little is in fact known in this regard. In the present work, three irrigation treatments (100, 75 and 50% coverage of water needs) were designed using the Orgaz method, and their effects on young olive trees tested in different plots over a period of 3 years. The 50% deficit treatment was designed to provide the trees with an amount of water in the region of that stipulated by the FAO method, the most commonly used irrigation scheduling system for olive orchards. No significant differences in shoot water potential nor abaxial leaf conductance were seen between the trees receiving the different treatments. However, canopy volume and shoot growth were affected. These results indicate that the traditional FAO model, which would have supplied about 35% of the water supplied by the Control treatment, may well reduce the economic benefits to be derived from young olive orchards.