Abstract
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.
Highlights
While food demand follows a significant increasing trend in response to the rapid population growth, freshwater scarcity is becoming a momentous restriction to food production all over the world
Among various insights introduced for increasing water use efficiency (WUE) (Sezen et al, 2011a; Yazar et al, 2015; Rahil and Qanadillo, 2015; Consoli et al, 2017), partial root-zone drying (PRD), introduced by Dry and Loveys (1998), is known as one of the most effective pathways regarding its positive effect on crop and water productivity
We could conclude that the significant reduction in leaf area index (LAI) either under the PRD2 or SI treatments with the highest contribution of diluted seawater in total irrigation water, is an indication of root water uptake restriction under improper soil water status induced by water/salinity stress, which results in reduced leaves’ sizes through decreased cell elongation and cell division (Sezen et al, 2011b)
Summary
While food demand follows a significant increasing trend in response to the rapid population growth, freshwater scarcity is becoming a momentous restriction to food production all over the world. Kang and Zhang, 2004; Liu et al, 2006b, 2007; Shahnazari et al, 2007, 2008; Sepaskhah and Ahmadi, 2010; Jovanovic et al, 2010; Mousavi et al, 2010; Sezen et al, 2011a; Pedrero et al, 2014; Beis and Patakas, 2015; Lima et al, 2015; Ghadami-Firouzabadi et al, 2015; Karandish and Simunek, 2016a, 2016b, Karandish and Simunek, 2017, 2018) In this method, only half of the rooting zone is irrigated at each irrigation event, while the other half is dried out (Dry and Loveys, 2000). There is a general belief among these scientists that PRD’s efficiency may vary by crop types and the experimental conditions such as climatic condition, the duration of the stress period, the level of water deficit over the stress period, the time of shifting the wetted and dried parts over the stress period, and irrigation water quality are among those parameters (Shahnazari et al, 2007; Sezen et al, 2011a; Ghrab et al, 2013 and 2014; Pedrero et al, 2014)
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