Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2014
Publication Date: 7/8/2014
Citation: Bryla, D.R., Scagel, C.F. 2014. Salinity limits to shoot and root growth and nutrient uptake in ‘Honeoye’ strawberry. Journal of Horticultural Science and Biotechnology. 89:458-470. Interpretive Summary: The objectives of the present study were to determine salinity thresholds for strawberry and identify levels that limit shoot and root growth and lead to leaf tissue necrosis. The thresholds are needed not only for soil site selection but also to develop better irrigation and nutrient management practices for commercial strawberry production. The work was focused primarily on vegetative growth and propagation in the plants and not on flowering and fruit production. Plant tolerance to salinity often varies according to the growth stages at which salinization is initiated and to the final level of salinity reached. Leaf number, crown size, and initial plant weight all influence yield and fruit quality in strawberry. Successful fruit production is thus highly dependent on vegetative growth. Strawberry also propagates readily by formation of stolons (runners) that root and form new daughter plants. Daughter plants are commonly propagated for commercial production, initially in a greenhouse or screenhouse as plug plants and later in a field nursery. Runners are also the primary yield component when the plants are grown in matted row production systems. Therefore, the impact of salinity on production of stolons and daughter plants is likewise important in strawberry. The results of the study indicated that for optimum growth and runner production, water and nutrient management practices should be managed to maintain electrical conductivity (a measure of salinity) of soil or nutrient solution to < 1.3 dS/m during the first 3 months after planting and no higher than 3.4 dS/m once the plants mature. Higher levels of salinity reduced shoot growth and uptake of many nutrients, particularly by runners and daughter plants, but a mild level of salinity stimulated root growth, particularly of the feeder roots. Salinity also caused marginal leaf necrosis on the mother plants within 35 days and on the new daughter plants within 80 days. Effects of salinity on flowering and fruit development will be examined in a following study.
Technical Abstract: A study was done to identify salinity thresholds that limit shoot and root development and lead to leaf tissue necrosis in strawberry. Plants were exposed to five levels of salinity from CaCl2 mixed with nutrient solution. Electrical conductivity (EC) of the solutions ranged from 0.3-3.7 dS/m initially but was increased to 0.4-8.8 dS/m after 90 d to adjust for plant growth. Salinity had no effect on dry weight (DW) of leaves, the crown, or mature primary roots, but levels > 2.2 dS/m reduced DW of stolons and new daughter plants within 87 d. The same level of salinity reduced DW of new primary roots within 114 d but a mild level of 1.3 dS/m initially, and 3.4 dS/m after 90 d, increased DW of the feeder roots. Salinity also reduced stomatal conductance and leaf chlorophyll and resulted in marginal leaf necrosis by 35 d in the higher treatments. The percentage of leaves with necrotic tips increased linearly with salinity level and within 114 d was 40-60% at 3.4-5.7 dS/m and 85-90% at 7.5-8.8 dS/m. Leaf necrosis was likewise observed on the daughter plants by 80 d of treatment and, in this case at 114 d, occurred on 40-80% of the new plants at the lower salinity levels and on 100% at the higher levels. Not surprisingly, CaCl2 in the salinity treatments increased accumulation of Ca in each plant part, but also increased other nutrients, including Fe in leaves, stolons, and daughter plants, B in daughter plants, and Zn in the crown, daughter plants, and feeder roots. Most of the other nutrients measured were reduced by salinity, however, including N in stolons, daughter plants, new primary roots, and feeder roots, P and Mn in all but the feeder roots, K in all but the leaves, Mg in all parts but the crown, S in daughter plants and each root part, and B and Zn in new primary roots. These results indicate that for optimum growth and runner production in strawberry, water and nutrient management practices should be managed to maintain EC < 1.3 dS/m during the first 3 months after planting and no > 3.4 dS/m once the plants mature.