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  • Weight-length relationships for selected fish species of the small-scale demersal fisheries of the south and south-west coast of Portugal
    Publication . Gonçalves, J. M. S.; Bentes, L.; Lino, P. G.; Ribeiro, J.; Canario, Adelino V. M.; Erzini, Karim
    Weight-length relationships were estimated for 31 fish species from the south and south-west coasts of Portugal. These species, which are mainly sea breams (Sparidae), dominate the catches of the main fixed gears used in this region and account for more than 50% and 40% of the total fish landings by weight and by value. (C) 1997 Elsevier Science B.V.
    1997-06Journal article Restricted access Show more
  • The role of abscisic acid and water relations in drought responses of subterranean clover
    Publication . Socias, X; Correia, MJ; Chaves, M; Medrano, H
    The role of water relations and abscisic acid (ABA) in the responses to drought were studied in a mediterranean forage crop, Trifolium subterraneum L. under field conditions. soil and plant water status, leaf gas exchange parameters, and xylem sap ABA content were determined at different times during a long-term soil drying episode in irrigated and droughted plants. The diurnal time-courses of these parameters were also measured at the end of a drought period. In response to soil drying stomatal conductance (g) was reduced early to 50% that of irrigated plants before any substantial change in water potential was detected. A close logarithmic regression between photosynthesis rate (A) and g was present. For the first weeks of drought the decline in A was less pronounced than in g, thus increasing water use efficiency. Stomatal conductance during diurnal time-courses showed no consistent relationships with respect to either ABA or leaf water potential. throughout the experimental period dependence of g on leaf water status was evident from the tight correlation (r(2) = 0.88, P < 0.01) achieved between stomatal conductance and midday water potential, but the correlation was also high when comparing g with respect to ABA content in xylem sap (r(2) = 0.83, P < 0.001). However, the stomata from drought acclimated plants were apparently more sensitive to xylem ABA content. For similar xylem ABA concentrations stomatal conductance was significantly higher in irrigated than in water-stressed plants.
    1997-06Journal article Open access Show more