Salt tolerance of spinach as related to seasonal climate

Authors: ORS, SELDA - University Of California; Suarez, Donald

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2015
Publication Date: 5/2/2016
Citation: Ors, S., Suarez, D.L. 2016. Salt tolerance of spinach as related to seasonal climate. HortScience. 43(1):33-41. doi: 10.17221/114/2015-HORTSCI.

Interpretive Summary: Arid and semi-arid regions of the world face increasing salinization of water resources, increasing demands on fresh water supplies, and increasing demand to grow more food to meet human nutritional needs. The extent of irrigated agriculture in these regions must be increased in order to increase food production yet supplies of fresh water are decreasing. One part of the solution is to use more saline water for irrigation of high value vegetable crops that are relatively salt tolerant. In this paper we evaluate the salt tolerance of spinach, a cool season vegetable and relate the response to climatic conditions. We determined that spinach salt tolerance was very dependent on climatic conditions, being more salt tolerant when grown under cool season conditions. The data indicate that spinach can be grown with soil water salinity up to 9 dS/m without yield loss under cool climatic conditions, indicating that this cultivar (cv Racoon) is considerably more salt tolerant than spinach varieties reported in the literature. Future expected increases in spring temperatures will result in increased sensitivity of spinach and likely other vegetable crops to salinity. This research is of interest to crop advisors, producers, extension specialists and those assessing the impact of climate change on crop production.

Technical Abstract: There is decreasing availability of fresh water for irrigated agriculture in semiarid regions throughout the world. Unfortunately most high value irrigated crops are relatively sensitive to salinity, mostly limiting use of saline waters for irrigation to use with low value crops. Spinach is an exception, as one of the high-value moderately salt tolerant crops suitable for irrigation with brackish and treated wastewaters. We conducted three sets of experiments with spinach (Spinacia oleracea L., cv. Racoon) under saline water irrigation in the sand tank facility at U.S. Salinity Laboratory, Riverside during different time periods (December 2012- March 2013 and April- May 2013 and late April- mid June 2013). The first experiment consisted of 4 different salinity levels (either sulfate dominated or chloride dominated irrigation waters) at EC: 4, 7, 9, dS/m and the two subsequent experiments each had 6 different levels of saline water (sulfate dominated, mixed cation composition) at EC: 0, 4, 7, 9, 12, 15 dS/m. We evaluated the effect of saline water irrigation on spinach yield, growth parameters, ion composition, photosynthesis, stomatal conductance, transpiration, and chlorophyll content under seasonal climate differences. The results obtained from the three different experiments show that higher ET0 values caused higher yield loss and when ET0 was lower during the early growth period the salt tolerance was higher. Moderate salinity levels improved plant growth and gas exchange parameters (except transpiration rate) relative to the non-saline control. Severe irrigation water salinity caused yield loss and decreased all gas exchange and vegetative parameters. Soil water salinity up to 9 dS/m did not cause any yield loss during the first set of experiments, indicating that this cultivar is considerably more salt tolerant than spinach varieties reported in the literature. Increases in spring temperatures will result in increased sensitivity of spinach and likely other vegetable crops to salinity.