ISHS Acta Horticulturae 191: Symposium on Protected Cultivation of Solanacea in Mild Winter Climates
CONCLUDING REMARKS. |
| Author: | D. BLANC |
| Abstract:
After four days of working sessions, time has now come for conclusions. During the five sessions of the symposium, not less than fifty papers were presented. With a few exceptions, all of them concerned specific problems of protected cultivation under mild winter climate. From their analysis we can see what are actually the main preoccupations of researchers in these countries. It appears that the related works refer to three main themes: The first one is the problem of too low temperatures in non heated greenhouses. It has been shown that an increase of 2 or 4 degrees can be obtained by using economic techniques (double wall, radiant mulch, geothermal water, sunstock systems). In this respect, the effect on fruit production of low temperatures at different stages of the development is analyzed, as well as the effect of growth regulators. But the expectation is also in the selection of varieties improved in fruit setting at low temperature. The second theme concerns the problem of irrigation with water in limited quantity and of poor quality. This point justifies such studies as:
The last theme concerns pathologic problems. An inventory of the diseases has been achieved, the control of nematods by plastic sheet has been considered, and the drip irrigation as a mean to control phytophtora. But in this field also, the research for resistant varieties to pathogens must be developped. It appears that these problems are not precisely those which were raised with a greater emphasis in the symposia on protected cultivation, but rather for example:
These items concern more specially the protected cultivation under cold climatic conditions. These differences can have a double explanation. The first one is that in cold countries, the control of temperature implies closed structures with their effect on the ambiant environment of the plant. Whereas in southern countries, protected cultivation can be only a simple shelter, without heating and with a large natural ventilation. In this last case, the problem will rather be the control of too high temperature and insolation during the summer time. This aspect has been evocated during the symposium. Another season for such differences in the research programs lies in the fact that in southern countries, protected cultivation is a relative recent | |
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