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, S1), 1.0 (S2), 2.0 (S3), 3.0 (S4) dS m−1], irrigation water levels [100% (I1), 75% (I2) and 50% (I3) of saffron water requirement (WR)] and planting methods [basin (P1) and in-furrow (P2)] on the dynamics of salt ions and their uptake by saffron plant (Crocus sativus L.). The electrical conductivity of soil saturation extract (ECe) was increased by 104% in S4 compared to control (S1), on average, in two growing seasons. S4 treatment increased concentration of sodium (Na+), calcium (Ca2+), potassium (K+) and chloride (Cl−) in soil by 102%, 92%, 124% and 128% in comparison with S1, on average, in two growing seasons. The concentration of Na+, Ca2+, K+ and Cl− in soil in S4 were 30%, 15%, 28% and 29% higher and NO3 was 30.3% lower in I1 in comparison with I3, respectively. The ions concentration in soil were 3.5–14.7% higher in P1 in comparison with those in P2. Leaf Na+, Ca2+ 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 S4 in comparison with that obtained in S1, on average, which is presumably due to reduced NO3 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 P2, on average, in different irrigation levels, respectively. Therefore, the in-furrow planting method is suggested to cope with unfavorable saffron field conditions.