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Pretreated cheese whey wastewater (CWW) has been used at different salinity levels: 1.75, 2.22, 3.22, 5.02 and 10.02 dS m-1 and compared with fresh water (1.44 dS m-1). Two cultivars (cv.) of the tomato plant Lycopersicon Esculentum Mill. (Roma and Rio Grande) were exposed to saline conditions for 72 days. Salinity level (treatment) had no significant effects on the fresh weight and dry matter of the leaves, stems and roots. Similar results were found when specific leaf area, leaflet area, ramifications number of 1st order/plant, stem diameter and length, nodes number/stem and primary root length were considered. Conversely, the salinity level significantly influenced the Soil Plant Analysis Development (SPAD) index and the distance between nodes in the plant stem. In the first case, an increase of 21% was obtained in the salinity levels of 5.02 and 10.02 dS m-1 for cv. Rio Grande, compared with the control run. The results showed that the pretreated CWW can be a source of nutrients for tomato plants, with reduced effects on growth and development. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report an original option for cheese wastewater management and tomato production. [•] Tomato crops were irrigated with pretreated and saline cheese whey wastewater. [•] Epidermis firmness and soluble solids increments were obtained. [•] Fruit calipers were unaffected by pretreated cheese whey wastewater fertirrigation. [•] Soil salinity level increased linearly with the irrigation water salinity level. [ABSTRACT FROM AUTHOR]

Abstract: The agricultural reuse of pretreated industrial wastewater resulting from cheese manufacture is shown as a suitable option for its disposal and management. This alternative presents attractive advantages from the economic and pollution control viewpoints. Pretreated cheese whey wastewater (CWW) has high contents of biodegradable organic matter, salinity and nutrients, which are essential development factors for plants with moderate to elevated salinity tolerance. Five different pretreated CWW treatments (1.75 to 10.02dSm−1) have been applied in the tomato plant growth. Fresh water was used as a control run (average salinity level=1.44dSm−1). Chemical characterization and indicator ratios of the leaves, stems and roots were monitored. The sodium and potassium leaf concentrations increased linearly with the salinity level in both cultivars, Roma and Rio Grande. Similar results were found in the stem sodium content. However, the toxic sodium accumulations in the cv. Roma exceeded the values obtained in the cv. Rio Grande. In this last situation, K and Ca uptake, absorption, transport and accumulation capacities were presented as tolerance mechanisms for the osmotic potential regulation of the tissues and for the ion neutralization. Consequently, Na/Ca and Na/K ratios presented lower values in the cv. Rio Grande. Na/Ca ratio increased linearly with the salinity level in leaves and stems, regardless of the cultivar. Regarding the Na/K ratio, the values demonstrated competition phenomena between the ions for the cv. Rio Grande. Despite the high chloride content of the CWW, no significant differences were observed for this nutrient in the leaves and stems. Thus, no nitrogen deficiency was demonstrated by the interaction NO3 −/Cl−. Nitrogen also contributes to maintain the water potential difference between the tissues and the soil. Na, P, Cl and N radicular concentrations were maximized for high salinity levels (≥2.22dSm−1) of the pretreated CWW. [Copyright &y& Elsevier]