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Effects of application timing of saline irrigation water on broccoli production and quality

Di Gioia, Francesco, Rosskopf, Erin N., Leonardi, Cherubino, Giuffrida, Francesco
Agricultural water management 2018 v.203 pp. 97-104
Brassica oleracea var. italica, application timing, basins, biomass, broccoli, carbon dioxide, chlorides, crop yield, developmental stages, flavor, florets, glucobrassicin, harvesting, irrigation management, irrigation water, leaves, nutritive value, osmotic pressure, plant growth, saline water, salt stress, semiarid zones, sodium, total soluble solids, toxicity
Irrigation with moderately saline water is a necessity in many semi-arid areas of the Mediterranean Basin, and requires adequate irrigation management strategies. Broccoli (Brassica oleracea var. italica), a crop moderately sensitive to salinity stress, was used to evaluate the effects of the application of saline (S) and non-saline (NS) irrigation water during two growth phases in terms of plant growth, water status, floret yield, glucosinolate profile, and quality. Use of S-water (4 dS m−1) from transplanting to appearance of the inflorescence, alternated with NS-water (2 dS m−1) from inflorescence appearance to harvest and vice versa were compared with continuous use of S- or NS-water. Irrigation with S-water during the first growth-phase decreased leaf water and osmotic potential, net CO2 assimilation rate, and favoured Na+ and Cl− accumulation at toxic levels causing ion imbalances and reducing broccoli plant growth. Application of S-water exclusively after inflorescence appearance caused a 22.2% decrease of the head dry biomass compared to NS-NS plants. Regardless of application timing, irrigation with S-water decreased broccoli yield and head mean fresh weight compared to NS-NS plants by 20% and 24%, respectively. Use of S-water in one or both growth stages improved broccoli dry matter and soluble solid content, while had no impact on total glucosinolate concentration. However, application of S-water during the first growth-phase resulted in an increase of indolic glucosinolates (glucobrassicin and neoglucobrassicin) and potential effects on broccoli nutritional properties and flavour.