Abstract:
On wednesday afternoon the 4th of March a general discussion was held during which emphasis was given towards important topics to be investigated on water relations.
This matter was discussed along the following subjects:
- General problems
- Problems concerned with protected cultivation in temperate zones
- Ibid in a warm climate
- Problems concerned in outdoor cultivation in temparate zones
- Ibid in a warm climate.
- It was felt important e.g. to investigate in general plant resistances, xylem and phloem transport, sink-source relationships, shoot-fruit relationships, fruitgrowth, physiological background of rootgrowth, water use efficiency and pollution problems.
- Research in protected cultivation should be devoted towards growth control by watering, salinity, CO2 supply and water use efficiency, energy saving by double layer (greenhouseroof), in relation to air humidity, calcium deficiency and diseases, the use of various methods in water application including nutrient film techniques, rockwool, desalinization.
- In a warm climate the same topics as mentioned sub b are important but also heat stress studies.
- Emphasis on research for outdoor cultivation in temperate zones should be given towards microclimate studies, frost damage, irrigation and water use efficiency, waterbalance studies during different stages of development, effect of waterstress on plant development, cost-benefit calculation of supplementary sprinkling irrigation.
- In a warm climate, the topics sub d are important including air humidity and heat stress, especially water use efficiency studies are important and also leaching when salizisation occurs.
Due to the high capital investment in protected cultivation (b and c) often fairly expensive methods for water application can be applied in order to achieve earliness and/or a high yield.
For outdoor cultivation (d and e) a comparison between yield without irrigation and with supplementary irrigation is important in order to analyse whether the cost of irrigation gives sufficient returns by the increasing yield.
Cost-benefit studies in the open as well as under protected cultivation, however, are important in order to achieve an optimal production efficiency.
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