Articles
BEHAVIOR OF PEAT SUBSTRATES DURING CYCLAMEN AND POINSETTIA CULTIVATION
The aim of the present work is to evaluate the influence of age, granulometry and species on the shrinkage and air content in peat based substrates as well as the effects of these physical parameters on the growth and final quality of the plants.
Finnish, German, Irish, Lithuanian and Swedish sphagnum peats with two granulometry ranges were used.
All these materials were characterized by physical and physico-chemical analysis.
During the cultivation, the most important morphological characteristics of plants were determined.
The final field shrinkage was influenced by the type of peat, the species and their interaction, but not by the granulometry.
The Irish and the German 1 peats tested were more stable than German 2. The effect of shrinkage on cyclamen was more serious than on poinsettia.
Lithuanian and Swedish peats changed radically their mechanical stability depending on the cultivated species.
The field final volume of air and the total loss of it were higher in the youngest peats.
Species and an interaction between species and granulometry affected the air content.
On cyclamen the highest granulometry fraction gave the best air stability.
The growth parameters and the plant final quality were influenced in large part by the age.
The data suggest that air content stability, growth and plant quality are positively related with the degree of decomposition.
The substrates with moderate shrinkage, and least loss of air gave the best plant quality.
The relation between field and laboratory determination of shrinkage and volume of air were discussed.