Browsing by Author "Correia, P.J."
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- Floral Analysis and Seasonal Dynamics of Mineral Levels in Carob Tree LeavesPublication . Custódio, L.; Correia, P.J.; Martins-Loução, M. A.; Romano, A.The mineral concentration of flowers and the seasonal fluctuation of macro- [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] and micronutrients [iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu)] in leaves of male, female, and hermaphroditic carob trees (Ceratonia siliqua L.) were studied. The nutrient dynamics were linked not only to phenological events, but also to the gender of the trees. The females were able to allocate more nutrients to leaves than male trees, even though male flowers were richer in particular elements such as N and Zn. The hermaphrodites supported the development of both inflorescences and fruits with a lower seasonal variation and a lower leaf nutrient concentration, as compared to the other genders, which may indicate a more efficient use of resources. Flowers had, in general, a higher concentration of N, P, and K, and a lower Mn concentration than in leaves. Flowers of the females had a lower nutrient concentration compared to males or hermaphrodites.
- Práticas alternativas de correcção da clorose férrica em citrinosPublication . Varennes, A.; Pestana, M.; Correia, P.J.; Faria, E.A.The correction of iron chlorosis in trees grown on calcareous soils is normally achieved by the application of Fe (III)chelates such as iron ethylenediaminedi-ohydroxyphenylacetate (Fe-EDDHA) to the soil. This practice is very expensive and has to be repeated every year because iron is rapidly immobilized in the soil or leached out of the root zone. The responses of orange trees (Citrus sinensis (L.) Osb. cv. ‘Valencia Late’) grown on a calcareous soil to different foliar sprays were studied. In all the experiments, the recovery from iron chlorosis was evaluated with the SPAD-502 apparatus and the values converted to total chlorophyll concentration. The effects of treatments on themineral composition of flowers were studied. The residual effect of some treatments was also evaluated one year later. These results suggest that foliar sprays with Fe could help to avoid yield and quality losses caused by Fe chlorosis in citrus orchards. Furthermore, these treatments could be done with relatively cheap materials such as solutions containing Fe (II) sulphate
- Tolerance of young (Ceratonia siliqua L.) carob rootstock to NaClPublication . Correia, P.J.; Gama, F.; Pestana, M.; Martins-Loução, M. A.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.