THE PRESENT STATUS OF THE SUBSTRATE AS AN ECOSYSTEM COMPONENT AND ITS FUNCTION AND IMPORTANCE IN CROP PRODUCTIVITY
Although choice of a good substrate is obviously important, climatic factors and specific characteristics of the plant, also need to be taken into account, as an integrated ecosystem, of which the substrate is only one component. Lack of control of these other parameters will mean less than optimum results.
Of all the above mentioned variables, the amount of available water in the substrate seems to be the one that directly or indirectly has the greatest incidence on the physiology and the production of the plant. Different forms and degrees of water stress affect several plants physiological processes. A special mention on its incidence on gaseous exchange is made in this review. The role of hormones in stomatal conductance and photosynthetic activity is analyzed, incorporating the most recent findings on the transmision of information of root water stress to the stomata and mesophyll.
From an ecological point of view it seems that these processes are very complex.
Because of the small number of species worked, with most authors consider that it is premature to make excessive generalisations. It is probable that other kind of responses, which will allow for a better understanding of the behavior of plants will be found.
We need to pay special attention to the advances in plant physiology in this field in order to be able to apply their discoveries in the improvement of container cultivation.