EQUIPMENT PERFORMANCE FOR DETERMINING WATER NEEDS OF TOMATO PLANTS GROWN IN SAWDUST BASED SUBSTRATES AND ROCKWOOL
There might be a benefit in using sawdust for replacing rockwool in terms of reducing substrate costs while maintaining an adequate productivity and root growth.
However, recent research showed that water availability and transfers in sawdust were limited, thereby increasing water stress during active plant growth.
To lessen this risk, the objective of this study was to characterize the relationship of substrate matric potential with volumetric water content and dielectric (TDR) sensor in a range of soilless substrates moisture that could be observed in greenhouses.
In addition, we investigated whether TDR, load cell, tensiometer and canopy temperature could accurately sense plant water stress and monitor and control irrigation scheduling for tomato plants grown in sawdust based substrates.
Thus, equipments were installed in three substrates (1- rockwool, 2- pure sawdust, and 3- 70% sawdust + 30% wood fibers) for the production of greenhouse tomato grown on raised-gutters with supplemental lighting.
Under different solar radiation in winter and spring, and different water contents of the growing media, we measured gas exchanges, Chl a fluorescence and leaf water potential.
We also measured plant growth and productivity during the whole growing seasons.
For sawdust + wood fiber substrate, results showed significant correlations between TDR, load cell, and tensiometer.
Matric potentials were generally correlated to TDR and load cell of sawdust and rockwool substrates.
The canopy temperature was a poor indicator of the matric potential but a good indicator of the substrate water content during spring.
Regardless of the growing season, TDR and load cell measurements were correlated to CO2 assimilation rate and Fv/Fm ratio of plant grown in sawdust based substrates and rockwool.
However, relationships between water content measurements, matric potential, and physiological parameters varied with the growing media and season.
No significant differences were observed for the plant development, leaf area, plant dry weight, carbohydrate partitioning and yield of tomato plants grown under different growing media.
Dorais, M., Caron, J., Bégin, G., Gosselin, A., Gaudreau, L. and Ménard, C. (2005). EQUIPMENT PERFORMANCE FOR DETERMINING WATER NEEDS OF TOMATO PLANTS GROWN IN SAWDUST BASED SUBSTRATES AND ROCKWOOL. Acta Hortic. 691, 293-304
DOI: 10.17660/ActaHortic.2005.691.34
https://doi.org/10.17660/ActaHortic.2005.691.34
DOI: 10.17660/ActaHortic.2005.691.34
https://doi.org/10.17660/ActaHortic.2005.691.34
Chl a fluorescence, load cell, photosynthesis, reflectometer, TDR, tensiometer
English