DEPENDENCE OF SPRING PHENOLOGY AND PHOTOSYNTHESIS OF DIFFERENT POPLAR HYBRIDS AND THEIR CLONES ON ENVIRONMENTAL CONDITIONS DURING REPRODUCTION

Abstract

This study examines the dependence of the phenology and photosynthesis of various poplar hybrids and clones on environmental conditions during propagation. The assessment was carried out in the poplar plantation established by the Dubrava Regional Division of the State Forest, in order to evaluate the vegetatively propagated plants that were rooted and grown under different environmental conditions. The object of the research is poplar (Aigeros and Tacamahaca) hybrids. Clones of one infraspecific poplar hybrid (P. trichocarpa), different four interspecific poplar hybrids (P. deltoides × P. nigra, P. deltoides × P. trichocarpa, P. maximoviczii × P. trichocarpa, P. balsamifera × P.trichocarpa) were used. During the research, it was aimed to carry out phenological observations, guided by the rating scale: 1 – very late (buds have not yet started to spread); 2 – late (buds have started to spread); 3 - mid-early (leaves half open); 4 - early (leaves fully open and shoots extending), the purpose of which was to find out how many days different poplar hybrids and their clones  produce leaves, as well as to determine the intensity of photosynthesis under different environmental factors. Phenology observations were made in spring, and photosynthesis intensity measurements were made in summer. The results show differences between hybrids and their clones in phenology, photosynthesis and transpiration and environmental conditions, which can be used in tree selection.