Requirements for a Seedling Quality Test

1987

S. 41-47

Unselbständiges Werk

200054429

Throughout the reforestation chain, from the seed lot to established stand, there is a need to characterize the growth, development, and overall quality of the planting stock. It is important to monitor those seedling characteristics that define its present status and predict its future development. The main argument has been that a seedling quality attribute helps in matching a specific seedling lot to a specific site. Selection of good seedling stock ensures acclimatization of seedlings to the planting site, thus enabling a fuller expression of site and plant growth potential. Therein, seedling quality is a decisive criterion. The need for an unequivocal test of seedling quality in practice is manifold. The basis and implications of current test methods, especially those of the physiological ones, are only partially known and evaluated. The aim of this paper is to evaluate the concepts applied in characterization of seedling quality and develop requirements for a quality test. Acclimatization of seedlings to the planting site is the final test of seedling fitness. Proper morphological and physiological characters of seedlings are undoubtely required for it. The performance potential of a seedling stock is related to its stock type and physiological status but the expression of the potential is largely regulated by site conditions. Therefore, seedling quality should be determined on the basis of characteristics and process vital to the acclimatization. A seedling quality attribute estimates seedling potential for acclimatization at the planting site. The following ten criteria for a quality test are discussed: prediction span, accountability for changes, properties of the approach and control, scale of measurement, applicability to different culling methods, design to site specific conditions, enable repeated sampling, sampling size of destructive, possible control over nursery growing process. Any seedling quality test method would probably compromise one or more of the requirements described. The test would be the more compromised the less theoretical basis it has on plant physiology and sampling design. The requirements above can be considered as a set of criteria for judging existing techniques and developing new ones. First, we have to list the methods available, then select the most promising ones, and finally evaluate their applicability. Use of ecophysiological modelling ins encouraged to find quality tests with adequate prediction ability.