Articles
CONTROL OF SALINITY IN THE RHIZOSPHERE OF PLANTS GROWN IN SOILLESS MEDIA
Article number
408_7
Pages
73 – 80
Language
Abstract
Control of plant quality and control of the amount of nutrient solution leached seem to be related in plants irrigated with a dripping system.
High salinity levels tend to cause a decrease in stomatal conductivity and photosynthesis.
This, in time, will obviously affect yield and it will also affect cell elongation and some metabolic reactions involved with plant quality.
More precisely, the partial closing of the stomata is not, in general, caused by the average salinity of the medium but by sudden and steep increases in salinity in the roots surroundings.
These increases will develop when the amount of nutrient supplied exceeds the instantaneous demand of the plants.
To limit these rises, producers leach the medium by supplying more nutrient solution than necessary.
But, of course, this leads to water and nutrient waste as well as to pollution of surface and underground water.
Nowadays, this type of pollution is unacceptable.
Therefore, it is now urgent to find ways to reduce it without affecting yield and production quality.
Two technical solutions seem worth accounting for 1) supplying the exact amount of water and nutrient to meet the instantaneous plant demand.
In fact, this will make leaching unnecessary and will reduce waste; 2) increasing the medium mixing rate with temporary or permanent recycling of the nutrient solution leached.
This will eliminate concentration gradients and stress due to sudden increases in salinity.
High salinity levels tend to cause a decrease in stomatal conductivity and photosynthesis.
This, in time, will obviously affect yield and it will also affect cell elongation and some metabolic reactions involved with plant quality.
More precisely, the partial closing of the stomata is not, in general, caused by the average salinity of the medium but by sudden and steep increases in salinity in the roots surroundings.
These increases will develop when the amount of nutrient supplied exceeds the instantaneous demand of the plants.
To limit these rises, producers leach the medium by supplying more nutrient solution than necessary.
But, of course, this leads to water and nutrient waste as well as to pollution of surface and underground water.
Nowadays, this type of pollution is unacceptable.
Therefore, it is now urgent to find ways to reduce it without affecting yield and production quality.
Two technical solutions seem worth accounting for 1) supplying the exact amount of water and nutrient to meet the instantaneous plant demand.
In fact, this will make leaching unnecessary and will reduce waste; 2) increasing the medium mixing rate with temporary or permanent recycling of the nutrient solution leached.
This will eliminate concentration gradients and stress due to sudden increases in salinity.
Publication
Authors
L. Urban, A. Jaffrin, R. Brun
Keywords
Photosysnthesis, quality, salinity, soilless cultivation
Online Articles (15)