Effect of Irrigation Water Salinity and Deficit Irrigation on Soil Ions Variation and Uptake by Saffron (Crocus sativus L.) Under Two Planting Methods

Abstract

A 2-years field experiment in a split-split plot arrangement was considered to investigate the effects of different irrigation water salinity [0.45 (well water, S 1 ), 1.0 (S 2 ), 2.0 (S 3 ), 3.0 (S 4 ) dS m −1 ], irrigation water levels [100% (I 1 ), 75% (I 2 ) and 50% (I 3 ) of saffron water requirement (WR)] and planting methods [basin (P 1 ) and in-furrow (P 2 )] on the dynamics of salt ions and their uptake by saffron plant ( Crocus sativus L.). The electrical conductivity of soil saturation extract (EC e ) was increased by 104% in S 4 compared to control (S 1 ), on average, in two growing seasons. S 4 treatment increased concentration of sodium (Na + ), calcium (Ca 2+ ), potassium (K + ) and chloride (Cl − ) in soil by 102%, 92%, 124% and 128% in comparison with S 1 , on average, in two growing seasons. The concentration of Na + , Ca 2+ , K + and Cl − in soil in S 4 were 30%, 15%, 28% and 29% higher and NO 3 was 30.3% lower in I 1 in comparison with I 3 , respectively. The ions concentration in soil were 3.5–14.7% higher in P 1 in comparison with those in P 2 . Leaf Na + , Ca 2+ and Cl − concentration was increased by increase in irrigation water salinity while K + , nitrogen (N) and phosphorus (P) concentrations were decreased by 28.4%, 25.7% and 29.8% in S 4 in comparison with that obtained in S 1 , on average, which is presumably due to reduced NO 3 and P concentrations in soil and increased Na + uptake by saffron. Also, deficit irrigation reduced soil and leaf ions (Na + and Cl − ) threshold and increased the slope of relative yield-ions concentration reduction function, which indicated that water stress aggravates saffron sensitivity to salinity and ions concentration in soil and leaf. Results indicated that saffron was more sensitive to Na + concentration in soil extract compared with Cl − . Na + and Cl − threshold was 19.3% and 27.1% higher in P 2 , on average, in different irrigation levels, respectively. Therefore, the in-furrow planting method is suggested to cope with unfavorable saffron field conditions.