A contribution to the diversification of vegetable crops: ecophysiological research on the salt optimum of Salicornia spp.
1994
Bogaert, G. | Jaeger, I. de | Cock, L. de | Boever, A. de | Lemeur, R. (Gent Univ. (Belgium). Faculty of Agricultural and Applied Biological Sciences. Lab. of Plant Ecology)
The impossibility of carrying out large-scale experiments on halophytic species (e.g. Salicornia) forces studies on growth and productivity to use the so-called mechanistic model approach. The ecophysical study on leaf and plant carbon balance determining characteristics allows a system-ecological upscaling from low organizing levels (i.e. at subcellular and cellular level) to a middle organizing level (i.e. at leaf level) and finally, to a top organizing level (i.e. at plant and at crop level). In this study, the salt optimum for Salicornia cultivation was detected by consecutively interpreting a number of processes at different levels. Both, genotypic differences (between Salicornia dolichostachya and Salicornia brachystachya) and phenotypic changes (modifications) due to the different regimes applied (0; 25; 50; 75 and 100 (Vol.) per cent compared to seawater) were analysed. Most of the indirectly growth determining plant characteristics, such as the chlorophyll a fluorescence quenching patterns (process at cellular level), the stomatal density and diffusive resistance for water vapour, as well as the photosynthesis related parameters (processes at leaf level) show a functional optimum at the 25 per cent and/or the 50 per cent salinity levels. The same is true for the directly growth determining plant characteristics: the shoot growth rate, the fresh weight, the relative water content, the number of secundary axes, and the number of articulations showed maximal values at 25 and 50 per cent salinity levels. Genotypic differences between the root to shoot ratio of both species, though existing in their natural habitats, were not found under these greenhouse conditions. Fluorescence quenching, photosynthetic quantum efficiency and stomatal conductivity of the low-marsh species (S. dolichostachya), on the other hand, were less affected by high salinity when compared to the high-marsh species (S. brachystachya).
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