Investigating water use efficiency in sunflower under furrow and wick irrigation methods

Introduction: Drought is the most limiting factor for production in arid and semi-arid areas. Iran agricultural sector uses more than 90% of water (Masomi et al., 2015). So drought is an unavoidable problem in Iran. Wick irrigation system is a sub-surface system including an instrument for water conduction by capillary movement from a source to plant roots. Sub-surface systems are more efficient than common irrigation system in terms of time and cost (Son et al, 2006). Research on bean showed that sub-irrigation method reduced water consumption by 55% compared to furrow irrigation (Sepaskhah et al., 1976). Because of rainfall reduction, global warming and remarkable surface water loss by evaporation, this study aim was to determine water consumption amount in wick irrigation compared to common irrigation (surface irrigation) and design and practice wick irrigation system in farm. Materials and methods: In order to investigate effect of wick irrigation on water use efficiency in sunflower, an experiment was research was carried out as a randomized complete block design with three replications at research farm, college of agricultural science and engineering, Razi Uinversity, Kermanshah, Iran in 2015. Treatments included common irrigation (surface irrigation) as a control and wick irrigation. Plant and stem height, leaf dry weight, stem dry weight and total dry weight were recorded. Leaf area was calculated by Digimizer (P30download, 2016). Turner and Kramer (1980) method was used for computing leaf relative water content. Specific leaf weight (SLW) was calculated using leaf dry weight (LDW) and leaf area (LA) as SLW=LDW/LA. Water use efficiency (WUE) was computed using water consumption (WC) and dry matter (DM) production as WUE= DM/WC (Farre et al., 2006). Data was analyzed using SAS (ver. 9.2) software and means were compared using LSD at probably level of 0.05. Results and discussion: Wick irrigation had more leaf relative water content than surface irrigation. It was probably due to more and stable access to water in wick irrigation. Wick irrigation had higher plant and stem height than surface irrigation. Our result is in accordance with Bhattarai et al., (2003) findings. Wick irrigation had leaf area as much as surface irrigation; however its water consumption was lower than surface irrigation. Rafeie et al., (2004) reported that drought reduced leaf area. There was no difference between irrigation systems in terms of specific leaf weight. Wick irrigation was more water-efficient than surface irrigation. It was due to that soil capping and soil surface wetting is lower in wick irrigation. Continuous availability to water and no waterlogging condition can also improve plant growth and increase water use efficiency. Wick irrigation produced higher dry matter than surface irrigation. Probably, wick irrigation increased dry matter production through improving soil ventilation, reducing soil capping and weeds. Conclusions: Wick irrigation had higher performance than surface irrigation in terms of many traits. For example water use efficiency and dry matter were increased by 46 and 43%, respectively. So, it seems that wick irrigation is one of the best irrigation systems in arid and semi-arid areas and more research should be conducted to economize and practice this method in farm.