Irrigated Sunflower Research Articles

The Water Footprint of Biodiesel Produced from Sunflower in South Africa

The use of feedstock crops for the production of biodiesel suggests that biodiesel production may have a major impact on the scarce freshwater resource in South Africa. This paper aimed to assess the green plus blue water footprints (WFgreen+blue) of biodiesel produced from sunflower in South Africa using the Global Water Footprint Standard approach. The green (WFgreen) and blue water footprint (WFblue) at the farm level were assessed for sunflower grown under the rain-fed and irrigation production system respectively. The results show that 2617 m3 and 2477 m3 are required to produce 1 ton of rain-fed and irrigated sunflower respectively. At the processing level, about 7.12 L of blue water is required to produce 1 L of biodiesel from sunflower. The WFblue at the processing stage of biodiesel produced from irrigated sunflower was 1.01 m3/GJ, compared to 1.15 m3 m3/GJ from rain-fed sunflower. The WFgreen+blue of biodiesel produced from irrigated and rainfed sunflower was 2477 and 2617 m3/ton, respectively. WFgreen was the largest, accounting for about 59% and 99% for biodiesel produced from irrigated and rain-fed sunflower, respectively. It was further found that water consumption at the farm level accounted for about 99% of the WFgreen+blue of biodiesel in both production systems. Management practices that improve water use efficiency at the farm level may help to lower the WFgreen+blue of biodiesel. Interestingly, the WFgreen+blue is lower for biodiesel produced from irrigated sunflower than for rainfed sunflower. The blue water scarcity assessment showed that blue water scarcity is low during the period when sunflower requires water. As such, purely from a water use perspective, irrigated sunflower production in the Orange Riet Irrigation Scheme may be considered sustainable.

Integrating partial root-zone drying and saline water irrigation to sustain sunflower production in freshwater-scarce regions

Applying saline water resources for irrigating croplands requires serious attentions when sustainable agriculture is considered. A two-year field investigation was carried out in a drip-irrigated sunflower field under six irrigation treatments, including (i) full freshwater irrigation (FI), full irrigation with diluted seawater (DS) (SI), alternate DS-freshwater irrigation (FSI), freshwater-PRD (partial root-zone drying) irrigation with 25 % less water than full (PRD1), DS-PRD irrigation with 25 % less water than full (PRD2), alternate DS-freshwater irrigation under PRD with 25 % less water than full (PRD3), in three replicates. Compared to the FI treatment, crop yield was reduced by 3.1–32 %, with the lowest one under PRD1. Among the DS treatments, PRD3, resulted in the highest grain yield (4306 kg ha−1), grain nitrogen content (2.83 %), oil yield (1907 kg ha−1) and irrigation water productivity (1.10). PRD3 also saved freshwater by 20 %, and kept soil salinity of the rooting-zone below the maximum crop tolerance threshold. Based on the results, PRD3 might be a cost-effective pathway which guarantees the sustainable application of diluted seawater in the irrigated sunflower lands.

Software tools for management of conjunctive use of surface- and ground-water in the rural environment: integration of the Farm Process and the Crop Growth Module in the FREEWAT platform

The coordinated use of surface- and ground-water over time and space as two components of a single irrigation system is of outmost importance in many rural areas of the world, in order to assure crop production sustainability, to restore ongoing and to prevent future issues related to freshwater quality and quantity mismanagement/deterioration. New technological solutions, such as GIS-integrated simulation models, may provide reliable tools in order to evaluate impacts in space and time and to properly manage conjunctive use of surface water and groundwater and water-constrained agricultural production. After presenting the common open source simulation programs for dealing with conjunctive use, we discuss and present the integration of the Farm Process (FMP; embedded in the USGS’s MODFLOW One-Water Hydrologic Model) coupled to a Crop Growth Module (CGM) within the open source and public domain QGIS-integrated FREEWAT platform. Using FMP in FREEWAT gains the benefit of the spatial environment and data management tools of a GIS solution, and to perform proper analysis of dynamically integrated terms of the hydrological cycle, to effectively balance crop water demand and supply from different sources of water. A simple hypothetic, yet realistic, application of the proposed approach with FMP and CGM is presented, simulating the yield of irrigated sunflower at harvest in a Mediterranean area. Results provide an insight on the potential exploitation of the developed solution, including, but not limited, to: quantitative temporal analysis of irrigation water sources, detailed analysis of evaporation and transpiration terms (from irrigation, groundwater or rainfall). The coupling of FMP with CGM to estimate crop yield at harvest provides further management tools when dealing with crop productivity. In the simulated case study, the analysis of the water balance terms allowed identifying the relevance of the groundwater contribution to ETc-act, highlighting the role of natural root uptake. The proposed solution is thought to be deployed by water authorities, large farms and public/private companies managing irrigation areas. The use of these tools calls for dedicated capacity building to boost digitalization in the agricultural water sector in order to achieve data-based agricultural water management.

Effect of Irrigation Strategies on Yield of Drip Irrigated Sunflower Oil and Fatty Acid Composition and its Economic Returns

A field trial was conducted to observe the effects of different irrigation strategies on the yield and the water use, oil content and marginal return of sunflower which was irrigated by means of a drip system during 2010 and 2011 under Cukurova condition of Turkey. The irrigation strategies include three irrigation intervals (A1: 25 mm; A2: 50 mm; A3: 75 mm of cumulative pan evaporation) and six water levels (WL) based upon the percentages of cumulative pan evaporation (WL1= 0.50, WL2= 0.75, WL3= 1.00 and WL4= 1.25). In addition, WL5= PRD50 and WL6= PRD75 treatments were evaluated. They obtained water from alternative laterals 50% and 75% of the WL3 treatment. Additionally, a nonirrigated treatment (NI) was included as control plot in the experiment. In each of the experimental years, the largest and the smallest average yields were acquired from the A2WL4 and NI treatments, respectively. The oil content and fatty acid composition were significantly affected by irrigation strategies. The oil content increased with the increasing amount of irrigation. Among all irrigation intervals, PRD-50 (WL5) treatment provided the largest water use efficiency (WUE) and irrigation water use efficiency (IWUE) values in both growing seasons. In order to attain higher yields and a generated the marginal return, A2WL4 irrigation regime is suggested for sunflower production in the Mediterranean region. A2WL3 water strategy is proposed for an acceptable marginal return in case of water shortage.

Improvement in estimation of soil water deficit by integrating airborne imagery data into a soil water balance model

Abstract: In this study, an approach that integrates airborne imagery data as inputs was used to improve the estimation of soil water deficit (SWD) for maize and sunflower grown under full and deficit irrigation treatments. The proposed model was applied to optimize the maximum total available soil water (TAWr) by minimizing the difference between a water stress coefficient ks and crop water stress index (1-CWSI). The optimal value of maximum TAWr was then used to calibrate a soil water balance model which in turn updated the estimation of soil water deficit. The estimates of SWD in the soil profile of both irrigated maize and sunflower fields were evaluated with the crop root zone SWD derived from neutron probe measurements and the FAO-56 SWD procedure. The results indicated a good agreement between the estimated SWD from the proposed approach and measured SWD for both maize and sunflower. The statistical analyses indicated that the maximum TAWr estimated from CWSI significantly improved the estimates of SWD, which reduced the mean absolute error (MAE) and root mean square error (RMSE) by 40% and 44% for maize and 22% for sunflower, compared with the FAO-56 model. The proposed procedure works better for crops under deficit irrigation condition. With the availability of higher spatial and temporal resolution airborne imagery during the growing season, the optimization procedure can be further improved. Keywords: soil water deficit, soil water balance model, airborne imagery, total available water, CWSI, deficit irrigation DOI: 10.3965/j.ijabe.20171003.3081 Citation: Zhang H H, Han M, Chavez J L, Lan Y B. Improvement in estimation of soil water deficit by integrating airborne imagery data into a soil water balance model. Int J Agric & Biol Eng, 2017; 10(3): 37–46.

Field Assessment of Basin Irrigation Performance in Hetao, Inner Mongolia

Hetao irrigation district (Hetao) is located in the upper reaches of Yellow River basin. Surface irrigation is used because there is a high charge of sediments in the irrigation water and is appropriate to leach salts. Basin irrigation is the most used irrigation method. Traditional practices are inadequate for saving water and surface irrigation modernization is needed. A better knowledge of the performance of irrigation systems is required to base that modernization. An experimental research work was developed at Dengkou Experimental Station to assess the irrigation performance in laser land leveled fields. It is located on an irrigation sector supplied in agreement with a rotational delivery scheme managed by the Water Users Association (WUA), which usually practices a total of 7 events and the autumn irrigation. The typical field length is 50 m, with a width between 10 and 50 m, with a silt loamy soil. The irrigation performance was assess from field measurements carried out in several fields, cropped with the main irrigated crops, wheat, maize and sunflower. The irrigation field evaluation was based on observations of advance and recession times, soil moisture, inflow discharges, application time, topographic survey and crop development data. In addition, infiltration curves for typical and seasonal irrigation events were developed, and the Kostiakov infiltration parameters were estimated from field observations using the inverse method with the SIRMOD model. The irrigation operative parameters and the performance indicators were obtained, concluding that the distribution uniformity is very high, between 90 and 96%, and that the cutoff time has a very sensitive effect on beneficial water use fraction. Finally, the results of this study allowed the appropriate knowledge, including the crop irrigation scheduling data, for the irrigation design models aimed at developing irrigation alternatives.

Sunflower Water Requirements Using Single and Dual Crop Coefficients

A field experiment of drip-irrigated Sunflower (Helianthus annuus) was conducted at the Experimental Farm, Faculty of Agriculture (Saba-Basha), Alexandria University, Egypt during 2013 growing season to develop seasonal Kc values for drip irrigated sunflower. In this context the objectives were: 1. to analyze the ability of the FAO-56 single and dual crop coefficient models for assessment the regional evapotranspiration and water requirements, 2. to estimate an adequate water quantity needed for the sunflower. The sunflower variety Sakha 53 was cultivated at 28th April and harvesting was done at 8 August, 2013. Seeds were sown at 4-5 seeds in each hill with a spacing of 0.3 m within each row and 0.6 spacing, then thinned to one plant after 2 weeks from sowing. After emergence, the plots were irrigated by the drip irrigation method. All field practices were done as usually recommended for sunflower cultivation. The irrigation treatments based on replenishment of soil water depletion according to reference evapotranspiration (ET0). The irrigation treatments were; irrigation at 20, 40, 60, 80 and 100% of ET0. The results indicated that seasonal sunflower evapotranspiration (mm) has higher value with field irrigation approach and the lower value was for standard FAO single approach. The seasonal evapotranspiration (single crop coefficient approach) was less than the seasonal evapotranspiration of dual crop coefficient approach. It appears that ETc estimation of sunflower crop is more accurate by dual crop coefficient approach than those produced by single crop coefficient approach because of using more parameters and taking the soil practices and crop characteristics in consideration. The basal crop coefficient values cannot be proposed for all climates and regions because of different climatic conditions and crop management practice under different regions. The present study recommended that for the present conditions and the same other conditions, the irrigation of sunflower crop must be done according to the dual crop coefficient approach because it is more accurate than single crop coefficient and close up to the field conditions.

Life-cycle assessment of irrigated and rainfed sunflower addressing uncertainty and land use change scenarios

Sunflower is an important feedstock for food and energy purposes in southern European countries. The main goal of this article is to present an environmental life-cycle assessment of sunflower cultivated in Portugal comparing irrigated and rainfed systems, incorporating parameter uncertainty and assessing alternative land use change scenarios. The functional unit adopted was 1 kg of sunflower seeds (hectare of land was also addressed in a sensitivity analysis). The average productivity (kg ha−1 year−1) of irrigated sunflower was 3.5 times higher than of rainfed. Irrigated sunflower presented higher acidification impact than rainfed. Similar greenhouse gas intensity and eutrophication impact were found for irrigated and rainfed systems taking into account the high variability and uncertainty levels calculated. Higher uncertainty levels were observed for the impacts of irrigated sunflower compared with rainfed, due to field emissions. Greenhouse gas intensity of sunflower greatly depends on land use change scenarios (the lowest emissions occur for the conversion of severely degraded grassland into irrigated sunflower and the highest emissions for the conversion of improved management grassland into rainfed sunflower). The sensitivity analysis performed for the functional unit showed very different impacts per hectare of land compared with those calculated per kg of sunflower seeds: the irrigated system had the highest impacts for all categories.

Evapotranspiration, water productivity and crop coefficients for irrigated sunflower in the U.S. Southern High Plains

Sunflower is a diverse crop grown for oil or confectionary uses in the U.S. Southern High Plains, often under irrigation, but its water use, water productivity (water use efficiency) and crop coefficients for irrigation scheduling are not well known for the Texas High Plains. Crop water use (evapotranspiration or ET) was measured in 2009 and 2011 in two 4.4-ha fields using two precision 9m2 weighing lysimeters containing 2.3-m deep monoliths of Pullman clay loam soil. The fields were irrigated with a lateral move sprinkler system with nozzles about 1.7–1.8m above the ground and 1.5-m apart. The sunflower ET averaged 638mm; seed yields averaged 308gm−2; and the lysimeter crop water productivity averaged 0.49kg (dry seed+hull) m−3. Even in the 2011 record drought season with limited soil water reserves, seed yield and oil content appeared similar to those for the 2009 season with greater precipitation and less irrigation requirement. Also, a month later sowing date in 2011, which might occur following an early cotton crop failure, did not appear to greatly affect ET, crop coefficients, or sunflower seed yields. The basal crop coefficients were 0.15 for the initial period after planting (Kcbini) and 1.22 for the peak water use rate at full cover (Kcbmid) based on the daily ASCE short “grass” reference ET (ETos) and FAO 56 climate adjustment. The Kcbmid based on the ASCE taller, rougher “alfalfa” Reference ET (ETrs) was 0.80. Using a thermal-time base (growing degree day) for the crop coefficient did not greatly improve the representation of the crop coefficient. Comparisons of ASCE reference ET computed using hourly versus daily summary data, and for short and tall reference crops, to each other and to FAO 56 reference ET showed that the relationships between reference ET methods varied significantly from one year to the next. This climate effect means that conversions of crop coefficients from one standard ET formulation to another will not be straightforward.

Modelling approach to optimize sulphur fertilization in irrigated sunflower under semi-arid conditions in north-west India

Sulphur fertilization assumes substantial influence in improving the yield and quality of oilseed crops. The relationship between sunflower seed yield and sulphur dose applied was determined using quadratic model and the economically optimum sulphur dose was calculated via marginal analysis for yield maximization and profit over fertilizer cost. Economically optimum dose of sulphur for sunflower was found to be 32.99 and 38.95 kg/ha under semi-arid irrigated conditions during 2008 and 2009, respectively. Over-fertilized condition of S for maximum output did not bring out any significant advantage viewing almost identical seed yield both at physical and economic optimum of S indicating a saving of S from 2.8 to 4.0 kg/ha.

Biometria do girassol em função da salinidade da água de irrigação e adubação nitrogenada

The cultivation of irrigated sunflower in semiarid areas highlights the need for information about its response to the quality of irrigation water simultaneously with fertilizer management that allows increments of productivity indices. In this context, the present experiment was conducted during November 2011 to February 2012 under field conditions in the municipality of Remígio, Paraíba, with the objective to evaluate the growth of sunflower (Helianthus annuus L.) cv. EMBRAPA 122 V-2000, subjected to salinity levels of irrigation water and nitrogen. Treatments were arranged in a randomized block design with three replications and 30 plants per plot, using a 5 x 4 factorial arrangement with irrigation water salinity levels of 0.15, 1.5, 2.5, 3.5 and 4.5 dS m-1 and nitrogen rates of 40,60, 80 and 100 kg ha-1. The increase in water salinity above 0.15 dS m-1 affectednegatively the growth in height, stem diameter, number of leaves and leaf area of sunflower, but increasing doses of nitrogen stimulated them, while the interactive effect was significant only for the leaf area at 15 days after emergence. Among the variables evaluated the leaf area of sunflower is more sensitive to increasing salt content of the water.

Consumptive water use and crop coefficients of irrigated sunflower

In semi-arid environments, the use of irrigation is necessary for sunflower production to reach its maximum potential. The aim of this study was to quantify the consumptive water use and crop coefficients of irrigated sunflower (Helianthus annuus L.) without soil water limitations during two growing seasons. The experimental work was conducted in the lysimeter facilities located in Albacete (Central Spain). A weighing lysimeter with an overall resolution of 250 g was used to measure the daily sunflower evapotranspiration throughout the growing season under sprinkler irrigation. The lysimeter container was 2.3 m × 2.7 m × 1.7 m deep, with an approximate total weight of 14.5 Mg. Daily ET c values were calculated as the difference between lysimeter mass losses and lysimeter mass gains divided by the lysimeter area. In the lysimeter, sprinkler irrigation was applied to replace cumulative ET c, thus maintaining non-limiting soil water conditions. Seasonal lysimeter ET c was 619 mm in 2009 and 576 mm in 2011. The higher ET c value in 2009 was due to earlier planting and a longer growing season with the maximum cover coinciding with the maximum ET o period. For the two study years, maximum average K c values reached values of approximately 1.10 and 1.20, respectively, during mid-season stage and coincided with maximum ground cover values of 75 and 88 %, respectively. The dual crop coefficient approach was used to separate crop transpiration (K cb) from soil evaporation (K e). As the crop canopy expanded, K cb values increased while the K e values decreased. The seasonal evaporation component was estimated to be about 25 % of ET c. Linear relationships were found between the lysimeter K cb and the canopy ground cover (f c) for the each season, and a single relationship that related K cb to growing degree-days was established allowing extrapolation of our results to other environments.

A thermal time model for predicting parasitism of Orobanche cumana in irrigated sunflower—Field validation

A major part of its life cycle, the root parasitic weed broomrapes (Orobanche and Phelipanche species) grow underground. Predicting their developmental stages underground is a challenge that can be met by using a modeling approach, as reported for Phelipanche aegyptiaca and Orobanche cumana, in sunflower grown under temperature-controlled conditions. In those studies the relation between parasitism dynamics and thermal time was described by Sigmoid functions. To confirm these relations and calibrate the parameters under field conditions, a 5-year field study was conducted in nine fields in Israel, in various locations under different climatic conditions. As a result, a robust thermal time model that allows precisely estimating the parasitism dynamics was developed. Development of O. cumana in the subsurface was detected, monitored and recorded non-destructively in situ by the use of a minirhizotron. The data from field experiments, conducted in 2006, 2007, 2008 and 2009, were used for model calibration. For model validation, five field experiments were independently performed in 2009 and 2010. To relate the number of attachments and shoot emergence to thermal time, the following equations were tested: Sigmoid, Gompertz (both three-parameter) and Weibull (four parameters with lag phase). In the calibration studies, the number of attachments was best fitted to thermal time using the Weibull equation, which further resulted in very good fit in the validation studies for number of attachments (RMSE=0.066; R2=0.99) and O. cumana shoot emergence (RMSE=0.0096; R2=0.97). The Weibull equation thus adds a biological dimension (lag phase) to the model that the other equations lack, as the lag phase allows estimating the precise timing of parasite attachment to host roots and shoot emergence. This information is crucial in any attempt to develop control strategies for these parasitic weeds.

Temporal dynamics of light and nitrogen vertical distributions in canopies of sunflower, kenaf and cynara

To enhance eco-physiological and modelling studies, we quantified vertical distributions of light and nitrogen in canopies of three Mediterranean bio-energy crops: sunflower ( Helianthus annuus), kenaf ( Hibiscus cannabinus) and cynara ( Cynara cardunculus). Field crops were grown with and without water stress in 2008 and 2009. Canopy vertical distributions of leaf area index (LAI), photosynthetically active radiation (PAR), specific leaf area (SLA), nitrogen concentration ( N conc) and specific leaf nitrogen (SLN) were assessed over time for each crop × year × water input combination. Light and nitrogen distributions were quantified by the Beer's law (exponential model) and extinction coefficients for light ( K L) and nitrogen ( K N) were calculated. Within a year, K L did not change significantly over the studied period in all irrigated crops, but differences in K L were significant between years (sunflower: 0.74 vs. 0.89; kenaf: 0.62 vs. 0.71; cynara: 0.77). K L estimates were always lower (−48 to −65%) in water-stressed sunflower and kenaf crops because of the reduction in leaf angle. These results should be taken into account, when simulating water-limited biomass production. Vertical SLN distributions were found in canopies when LAI was >1.5 (40 from 51 cases). These distributions were significantly correlated with the cumulative LAI from the top ( r 2 = 0.75–0.81; P < 0.05), providing parameters to upscale photosynthesis from leaf to canopy levels. Vertical SLN distributions followed species-specific patterns over the crop cycle and varied less compared to PAR distributions between years. Lastly, we observed strong associations between SLN and PAR distributions in irrigated sunflower and kenaf canopies ( r 2 > 0.66; P < 0.001). However, observed SLN distributions were less steep than the distributions that would maximize canopy photosynthesis.

Comparison of drip and sprinkler irrigation strategies on sunflower seed and oil yield and quality under Mediterranean climatic conditions

Abstract This study compares the effects of different irrigation regimes on seed yield and oil yield quality and water productivity of sprinkler and drip irrigated sunflower (Helianthus annus L.) on silty-clay-loam soils in 2006 and 2007 in the Mediterranean region of Turkey. In sprinkler irrigation a line-source system was used in order to create gradually varying irrigation levels. Irrigation regimes consisted of full irrigation (I1) and three deficit irrigation treatments (I2, I3 and I4), and rain-fed treatment (I5). In the drip system, irrigation regimes included full irrigation (FI-100), three deficit irrigation treatments (DI-25, DI-50, DI-75), partial root zone drying (PRD-50) and rain-fed treatment (RF). Irrigations were scheduled at weekly intervals both in sprinkler and drip irrigation, based on soil water depletion within a 0.90 m root zone in FI-100 and I1 plots. Irrigation treatments influenced significantly (P

Relating energy performance and water productivity of sprinkler irrigated maize, wheat and sunflower under limited water availability

The energy potential of a crop may be evaluated through life cycle assessment methodologies. These refer to the computation of the crop’s energy balance and related indicators, such as the energy efficiency. This study concerns sprinkler irrigated sunflower, wheat and maize crops using data relative to the campaign of 2008. It is applied to selected farms in the Vigia Irrigation District, Alentejo, using pressurised water distribution systems. A model was developed and various scenarios were considered in order to assess the impacts on the crops’ energy balance of (1) full and deficit irrigation, (2) climatic demand scenarios, and (3) upgrading irrigation systems performance. The model allows the energy efficiency and the energy balance of the three referred crops using centre-pivot and solid set sprinkler systems to be computed. The different irrigation scenarios and crop yield thresholds were defined in a previous study ( Rodrigues & Pereira, 2009 ). The modelling results lead to the conclusion that the maize crop is the most efficient in producing energy and wheat is the least for all the alternative scenarios considered. The results of full irrigation scenarios present higher energy performance than deficit irrigation because it depends greatly on the yields achieved. Weak relationships were found when relating energy efficiency and water productivity (WP) because while the first mainly depends upon yields, the second is highly influenced by water use. Results also show that improving irrigation systems performance has little impact on energy performance, which contrasts with WP.

Yield and yield structures of irrigated sunflower cultivars as influenced by tillage and wheat residue management systems

Limited information is available on heavy surface residue tillage systems on yield of irrigated sunflower (Helianthus annuus L.) grown following irrigated wheat (Triticum aestivum L.) as double cropping. A two-year field study was conducted as a split plot arranged in randomized complete block design with four replications to compare the yield and yield structures of three sunflower cultivars (Alzan, Euroflor, and Armavirsky) under conventional tillage (CT) (residue removal or burning followed by moldboard plowing and two times disk harrowing) and reduced tillage (RT) (chisel plow, disk harrow and a row crop planter equipped with row cleaner) system at various residue levels (0, 25, 50, 75 and 100%). Tillage systems and residue levels had a significant influence on yield and yield structures and the highest seed and oil yields were achieved when 25–50% of wheat residues were incorporated into the soil and the seeds were sown with row cleaner in both years and in all cultivars. The lower early crop growth under RT systems did not affect yields in both years, but partial residue incorporation into soil favored yield formation. It is recommended that farmers bale part of the previous residues and till the field with chisel plow, followed by disk harrow and plant with a modified row crop planter and this is the most reliable tillage system for sunflower production as double cropping.

Evapotranspiration, seed yield and water use efficiency of drip irrigated sunflower under full and deficit irrigation conditions

Deficit irrigation occurrence while maintaining acceptable yield represents a useful trait for sunflower production wherever irrigation water is limited. A 2-year experiment (2003–2004) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to investigate sunflower response to deficit irrigation. In the plots, irrigation was held at early flowering (stage F1), at mid flowering (stage F3.2) and at early seed formation (stage M0) until physiological maturity. Deficit-irrigated treatments were referred to as WS1, WS2 and WS3, respectively, and were compared to a well-irrigated control (C). Reference evapotranspiration (ET rye-grass) and crop evapotranspiration (ET crop) were measured each in a set of two drainage lysimeters of 2 m × 2 m × 1 m size cultivated with rye grass ( Lolium perenne) and sunflower ( Helianthus annuus L., cv. Arena). Crop coefficients ( K c) in the different crop growth stages were derived as the ratio (ET crop/ET rye-grass). Lysimeter measured crop evapotranspiration (ET crop) totaled 765 mm in 2003 and 882 mm in 2004 for total irrigation periods of 139 and 131 days, respectively. Daily ET crop achieved a peak value of 13.0 mm day −1 at flowering time (stage F3.2; 80–90 days after sowing) when LAI was >6.0 m 2 m −2. Then ET crop declined to 6.0 mm day −1 during seed maturity phase. Average K c values varied from 0.3 at crop establishment (sowing to four-leaf stage), to 0.9 at late crop development (four-leaf stage to terminal bud), to >1.0 at flowering stage (terminal bud to inflorescence visible), then to values <1.0 at seed maturity phase (head pale to physiological maturity). Measured K c values were close to those reported by the FAO. Average across years, seed yield at dry basis on the well-irrigated treatment was 5.36 t ha −1. Deficit irrigation at early (WS1) and mid (WS2) flowering stages reduced seed yield by 25% and 14% ( P < 0.05), respectively, in comparison with the control. However, deficit irrigation at early seed formation was found to increase slightly seed yield in WS3 treatment (5.50 t ha −1). We concluded that deficit irrigation at early seed formation (stage M0) increased the fraction of assimilate allocation to the head, compensating thus the lower number of seeds per m 2 through increased seed weight. In this experiment, while deficit irrigation did not result in any remarkable increase in harvest index (HI), water use efficiency (WUE) was found to vary significantly ( P < 0.05) among treatments, where the highest (0.83 kg m −3) and the lowest (0.71 kg m −3) values were obtained from WS3 and WS1 treatments, respectively. Finally, results indicate that irrigation limitation at early flowering (stage F1) and mid flowering (stage F3.2) should be avoided while it can be acceptable at seed formation (stage M0).

Effects of climate change on growth criteria and yield of sunflower and chickpea crops in Iran

Yield and growth criteria of irrigated and rainfed sunflower Helianthus annus and chickpea Cicer arientinum were studied under simulated climate change for Tabriz in Iran. Monthly average temperature and rainfall under doubling CO2 were predicted using Goddard Institute for Space Studies (GISS) and Geophysical Fluid Dynamics Laboratory (GFDL) models. The effects of cli- matic change on crop growth period, yield components and water requirements of those crops were evaluated by a crop simulation model (OSBOL). Based on GISS and GFDL predictions, with doubling CO2 concentration, mean annual temperature for Tabriz increased by 4.6 and 4.3°C, respectively. The results obtained by GISS showed that doubling CO2 will lead to an increase in mean tempera- ture of 3.7°C, and a 40% increase in mean rainfall, during the first 5 mo of the year. However, GFDL predicted an increase of 4.7°C in mean temperature and a reduction of 12% in mean rainfall during the first 5 mo of the year. According to OSBOL under GDFL predictions, the period from sowing to maturity and harvest index were reduced by climate change, whereas yield, biomass and water requirement for irrigated sunflower were increased. The biomass for rainfed sunflower increased, while days to maturity and harvest index were reduced. Yield predictions of OSBOL based on GISS contrasted with those based on GFDL. Doubling CO2 caused a reduction in days to maturity, biomass, yield and water requirements for irrigated chick pea. The number of days to maturity for rainfed chickpea was reduced and harvest index, biomass and yield were increased due to climate change.

Response of irrigated sunflower (Helianthus annuus L.) hybrids to nitrogen fertilization: growth, yield and yield components

N fertilization has a substantial influence on sunflower (Helianthus annuus L.) seed yield and quality. It was also well established that high-yielding sunflower hybrids had more N requirement than old cultivars such as open-pollinated ones. However, in Turkey, no sufficient information regarding the response of new developed oilseed sunflower hybrids to nitrogen fertilization under irrigated conditions. Therefore, a 2-year study was conducted to determine the effects of nitrogen application rates on the growth, yield, and yield components of two oilseed sunflower hybrids (AS-508 and Super 25) under irrigated conditions. In this study, all plant parameters were significantly influenced by applied nitrogen fertilizer rates. Yield response to nitrogen rates was positive and linear. Our research data indicated that under irrigated conditions N rate of 120 kg/ha was adequate for sunflower production in this region.