Three-year field response of young olive trees (Olea europaea L., cv. Arbequina) to soil salinity: Trunk growth and leaf ion accumulation

Abstract

Irrigated olive is rapidly increasing in arid and semiarid areas, many of which may be negatively affected by soil salinity. We evaluated changes in trunk growth and leaf Cl ) , Na + and K + concentrations in young Arbequina olives (Olea europaea L.) grown in a saline-sodic field over a three-year period. The trunk diameter was measured at the beginning and the end of the 1999 (70 trees), 2000 (59 trees) and 2001 (42 trees) growing periods. Leaves, sampled in August of each year, were analyzed for Cl ) , Na + and K + concentrations. Soil salinity (apparent electrical conductivity, ECa) of each monitored tree was measured 14 times during the 1999-2001 experimental period with an electromagnetic sensor and converted to root zone electrical conductivity of the soil saturation extract (ECe) based on ECa-ECe calibration curves. Salinity tolerance was determined using the Maas and Hoffman 'threshold-slope' response model. Based on salinity thresholds (ECe thr ), the tolerance of olive in terms of trunk growth was high in 1999 (ECe thr = 6.7 dS m )1 ), but declined with age and time of exposure to salts by 30% in 2000 (ECe thr = 4.7 dS m )1 ) and by 55% in 2001 (ECe thr = 3.0 dS m )1 ). Based on the high absolute slopes obtained in all years (values between 16% and 23% dS )1 m), olive was classified as very sensitive to ECe values above the threshold. Trunk growth thresholds based on leaf ion concentrations varied, depending on years, between 2.6 and 4.0 mg g )1 (Cl thr ) and between 1.0 and 1.2 mg g )1 (Na thr ), indicating that Arbequina olive was less sensitive to leaf Cl ) and much more sensitive to leaf Na + than values reported as toxic in greenhouse studies. Leaf K + slightly decreased with increasing salinity, whereas the K + /Na + ratio sharply decreased with increasing salinity. We concluded that the initial salinity tolerance of olive was high, but declined sharply with time of exposure to salts and became quite sensitive due primarily to increasing toxic concentrations of Na + in the leaves.

Salinity Differentially Affects Growth and Ecophysiology of Two Mastic Tree (Pistacia lentiscus L.) Accessions

“…This mechanism was previously observed in Salvadora oleoides [33]. The uptake of potassium and magnesium did not change based on the different levels of salinity, in agreement with the findings of other authors on different species [12,31,34]. Moreover, the ability of the mastic tree to maintain an adequate selectivity in the uptake of potassium under a saline environment is often associated with salinity tolerance [35].…”

Three-year field response of drip-irrigated grapevine (Vitis vinifera L., cv. Tempranillo) to soil salinity

“…This upper boundary will represent the limiting response to soil salinity, and variates that fall below the boundary will represent those sites where stress factors other than salinity limit growth (Milne et al 2006). We fitted the maximum ΔRD and Δ i RD observations to soil salinity using the eye-fitting upper-envelope approach that we have previously validated with other quantitative statistical analysis (Aragüés et al 2004) and applied in the study of the field response of olive to soil salinity (Aragüés et al 2005).…”

“…Hence, Cl is the principal toxic ion for grapevines growing under saline conditions. Bernstein et al (1969) concluded that leaf Cl levels in excess of 300 mmol kg −1 were injurious in the five studied cultivars. Injury by Cl toxicity in grapevine varies depending on the ability for rootstocks to accumulate Cl and restrict its transport to the shoots (Downton 1977).…”

Vegetative growth and fruit set of olive (Olea europaea L. cv. �Zard�) in response to some soil and plant factors

“…They found a negative and significant correlation (r=-0.797 ** ) between the percentages of silt and clay in the soil and olive shoot growth. Melgar et al (2009) indicated that soil salinity did not cause changes in any of the growth variables measured, including shoot length, whereas Aragues et al (2005) found significant decreases in trunk diameter growth with increases in soil salinity.…”