New technologies and improvement of nursery stock quality

This four years experimentation work was aimed at research on using various waste organic materials and especially timber bark in cultivation substrates as a substitute of peat. Sixty-four special isolated cultivation beds were established for this purpose, each of 4.8 m³ volume, in which 11 variants of substrates consisting of different proportions of different components in several replications were tested. Standard substrates Horticultural substrate B and RKS I. were used as controls. Another variant was used as a control for growing tests of plants in containers. All tested substrates were enriched with hydroabsorbent TerraCottem. In some variants reserve fertilisers with slow release of nutrients (Silvamix Forte) were applied. For cultivation testing of studied substrates four ornamental tree species (Alnus glutinosa, Fraxinus excelsior, Salix alba, Salix matsudana) were chosen. The best evaluated variants were the ones containing 50 and 75% of bark in combination with sand. The worst was the variant composed of chips and sawdust. Thanks to the use of hydroabsorbents, even the variant containing 100% of sand appeared to be very good. The tested trees had different reactions to the different types of substrates depending on their species requirements. The limiting growth factor for Alnus was the content of water in the substrate. Similarly, the content of available nutrients in the substrate was essential for Fraxinus. The hardwood cuttings of Salix not only rooted into the substrate in a few weeks, but also formed aboveground parts of the required sizes. Obtained data on growth parameters differed according to the diversity of requirements of the different studied species.

The Practicality of Top-root Ratio in Nursery Stock Characterization

Top-root ratios (T/R) form a non-normal frequency distribution which is positively skewed or skewed to the right, creating a bias in the estimate of a sample mean. T/R's determined by volume displacement give larger estimates than those determined by oven-dry weight. This difference increases with the size and T/R of the tree. Top length, stem diameter, top volume and root volume are all better indicators of nursery stock quality and potential growth performance than T/R. As top-root ratio is difficult to interpret or use in an objective manner it is of little value in nursery stock evaluation.