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Tolerance of young (Ceratonia siliqua L.) carob rootstock to NaCl
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Orientador(es)
Resumo(s)
One-year-old carob (Ceratonia siliqua L.) rootstock was grown in fertilised substrate to evaluate the
effects of NaCl salinity stress. The experiment consisted of seven treatments with different
concentrations of NaCl in the irrigation water: 0 (control), 15, 30, 40, 80, 120 and 240 (mmol L 1),
equivalent to electrical conductivities of 0.0, 1.5, 2.9, 3.9, 7.5, 10.9 and 20.6 dS m 1, respectively. Several
growth parameters were measured throughout the experimental period. At the end of the experiment,
pH, extractable P and K, and the electrical conductivity of the substrate were assessed in each salinity
level. On the same date, the mineral composition of the leaves was compared. The carob rootstock
tolerated 13.4 dS m 1 for a period of 30 days but after 60 days the limit of tolerance was only 6.8 dS m 1.
Salt tolerance indexes were 12.8 and 4.5 for 30 and 60 days, respectively. This tolerance to salinity
resulted from the ability to function with concentrations of Cl and Na+ in leaves up to 24.0 and
8.5 g kg 1, respectively. Biomass allocation to shoots and roots was similar in all treatments, but after 40
days the number of leaves was reduced, particularly at the larger concentrations (120 and
240 mmol NaCl L 1). Leaves of plants irrigated with 240 mmol NaCl L 1 became chlorotic after 30 days
exposure. However, concentrations of N, P, Mg and Zn in leaves were not affected significantly (P > 0.05)
by salinity. Apparently, K+ and Ca2+ were the key nutrients affected in the response of carob rootstocks to
salinity. Plants grown with 80 and 120 mmol L 1 of NaCl contained the greatest K+ concentration. Na+/K+
increased with salinity, due to an elevated Na+ content but K+ uptake was also enhanced, which
alleviated some Na+ stress. Ca2+ concentration in leaves was not reduced under salinity. Salinization of
irrigation water and subsequent impacts on agricultural soils are now common problems in the
Mediterranean region. Under such conditions, carob seems to be a salt as well as a drought tolerant
species.
Descrição
Palavras-chave
Biomass Ceratonia siliqua Leaf nutrients Models Salinity Salt tolerance index
Contexto Educativo
Citação
Agricultural Water Management 97 (2010) 910–916
Editora
Elsevier