Behavior of peat substrates during cyclamen and poinsettia cultivation.

摘要

The influence of age, grade (particle size range) and species of plant on the shrinkage and air content of peat-based substrates as well as the effects of these physical parameters on growth and final plant quality was examined in experiments on media made from 7 different peats in Italy. Finnish, German, Irish, Lithuanian and Swedish sphagnum peats with two particle size ranges (0-12 and 0-18 mm) were used to grow pot plants of Cyclamen persicum cv. Europa and poinsettia cv. Peterstar. The final shrinkage was influenced by the type of peat, the species grown and their interaction, but not by the particle size range. The Irish and the first German peats tested were more stable than the second German peat. The effect of shrinkage on C. persicum wasmore serious than on poinsettia. Lithuanian and Swedish peats radically changed their mechanical stability depending on the species grown. The final air-filled porosity and the amount by which it decreased were higher in the youngest peats. Species andan interaction between species and peat particle size affected the air-filled porosity. Crop growth parameters and final quality were influenced in large part by the age of the peat. The data suggest that air content stability, growth and plant quality are positively related to the degree of decomposition. The substrates with moderate shrinkage, and least loss of air produced the best plants. The relation between field and laboratory determination of shrinkage and air-filled porosity are discussed.