Growth, yield and ion relations of strawberry in response to irrigation with chloride-dominated waters

Authors: Suarez, Donald; Grieve, Catherine

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2013
Publication Date: 1/30/2013
Citation: Suarez, D.L., Grieve, C.M. 2013. Growth, yield and ion relations of strawberry in response to irrigation with chloride-dominated waters. Journal of Plant Nutrition. 36(13):1963-1981. doi:10.1080/01904167.2013.766210.

Interpretive Summary: Uncertainties concerning the allocation and dependability of good quality water have led to increased interest in the use of alternative, non-potable waters for irrigated agriculture. These waters are salty and contain ions such as sodium and chloride. Strawberry appears to be extremely salt-sensitive, showing loss of vigor, leaf injury, and reduction of berry yield when irrigated with saline waters. Just which ion (sodium or chloride or both) is causing these negative effects is controversial. This study was initiated to provide an understanding of the response of strawberry to irrigation with saline waters containing chloride salts of sodium, magnesium and calcium. Two strawberry varieties, Camarosa and Ventana, were grown in outdoor sand tanks. Saline irrigation waters were prepared by adding chloride salts of sodium, magnesium and calcium to complete nutrient solutions to give six salinity treatments with electrical conductivities (EC) = 0.835, 1.05, 1.28, 1.48, 1.71, 2.24 dS/m. Each treatment was replicated four times. Although Camarosa plants were larger than those of Ventana, the marketable fruit yield of Ventana was significantly higher than that of Camarosa. Camarosa was also more sensitive to salinity; fruit yield declined consistently as salinity increased. Fruit yield of Ventana, however, was not reduced until the EC of the irrigation waters exceeded 1.7 dS/m. Weight of individual berries decreased as salinity increased and at each salt level, Ventana berries were heavier than Camarosa berries. Sodium was retained in the roots of both varieties, thus preventing sodium transport to the leaves and avoiding leaf injury due to the toxic nature of this ion. Chloride, however, was partitioned to the shoot tissues of both cultivars in concentrations high enough to cause leaf scorch in plants irrigated with the most saline waters. This study demonstrates that strawberry production using recycled waters will require precise crop and water management practices. Growers, extension specialists, and research scientists will find this information valuable for balancing the drive for maximizing yields of this high-value crop against sound environmental stewardship.

Technical Abstract: Strawberry is listed as the most salt sensitive fruit crop in comprehensive salt tolerance data bases. Recently, concerns have arisen regarding declining quality of irrigation waters available to coastal strawberry growers in southern and central California. Over time, the waters have become more saline, with increasing proportions of sodium (Na+) and chloride (Cl-). Due to the apparent extreme Cl-sensitivity of strawberry, the rising Cl- levels in the irrigation waters are of particular importance. In order to establish the specific ion (Cl-) causing yield reduction in strawberry, cultivars ‘Ventana’ and ‘Camarosa’ were grown in twenty-four outdoor sand tanks at the ARS-USDA U. S. Salinity Laboratory in Riverside, CA and irrigated with waters containing a complete nutrient solution plus Cl- salts of Ca2+, Mg2+, Na+ and K+. The experiment was a randomized block design with two cultivars, six salinity treatments with electric conductivities (EC) = 0.835, 1.05, 1.28, 1.48, 1.71, and 2.24 dS m-1, and four replications. Fresh and dry weights of Camarosa shoots and roots were significantly higher than those of Ventana at all salinity levels. Marketable yield of Camarosa fruit decreased from 770 to 360 g/plant as salinity increased and was lower at all salinity levels than the yield from the less vigorous Ventana plants. Ventana berry yield decreased from 925 to 705 g/plant as salinity increased from 0.835 to 2.24 dS m-1. Relative yield of Camarosa decreased 43% for each unit increase in salinity once irrigation water salinity exceeded 0.80 dS m-1. Relative Ventana yield was unaffected by irrigation water salinity up to 1.71 dS m-1, and thereafter, for each additional unit increase in salinity, yield was reduced 61%. The cultivars exhibited two fruiting flushes whose timing and intensity were cultivar-dependent and also differed with treatment. Both cultivars appeared to possess an exclusion mechanism whereby Na+ was sequestered in the roots, and Na+ transport to blade, petiole and fruit tissues was limited. Chloride content of the plant organs increased as salinity increased to 2.24 dS m-1 and substrate Cl increased from 0.1 to13 mmolcL-1. Chloride was highest in the roots, followed by the leaves, petioles and fruit. Based on plant ion relations and relative fruit yield, we determined that, over the range of salinity levels studied, specific ion toxicity exists with respect to Cl-, rather than to Na+ ions, and, further, that the salt tolerance threshold is lower for Camarosa than for Ventana.