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The purpose of this research is to determine the duration of fertilization effect on the different properties, needle quantitative parameters, needle nutrient element contents and, first and foremost, cone- and seed-bearing capacity of spruce grafts. As well, it is important to establish the effect of the clone and the year's weather conditions on spruce seed-bearing capacity at a seed orchard. In assessing the effect of fertilizers, it is necessary to also take into account the duration of the generative cycle of Norway spruce. The research should provide information about nutrient availability to Norway spruce grafts and about changes in graft growth characteristics and enable regulation of seed yield in grafts of clones of different cone-bearing capacities in seed orchards. The expected results will be important for both research on forest tree breeding and improvement of practical seed management, since at present it is very important to satisfy the forest regeneration needs of the Republic of Estonia with high-quality spruce seed. The results should establish the usefulness and economic efficiency of spruce seed orchard fertilization. The regularities discovered can be used in developing Norway spruce forest seed production. |