Search

Quercus pubescens Willd. is a deciduous species that can retain leaves in the winter either as dead, standing leaves (marcescence), or as living, winter-green leaves. The retention of green leaves through winter is rare in continental areas. Winter-green leaves were observed on one-year-old seedlings of Q. pubescens in the winter of 2020 in the nursery of the Faculty of Forestry that lasted until the end of April 2021. The photosynthetic activity of photosystem II was measured using the rapid light curve method based on modulated pulse chlorophyll fluorescence. We assessed the potential photosynthetic activity of the leaves across the range of physiological stages: winter-green leaves retained from the previous growing season and on the leaves from the first, second, and third growth flush during the growing season. Photosystem II of winter-green leaves attained ~50-60% of the maximal photosynthetic activity obtained in spring and summer leaves, respectively. Climate data indicated that winter-green leaves exhibited frost resistance in the winter of 2020/2021, as their photosynthetic activity was preserved despite 33 days with sub-zero temperatures. The rapid light curve method also revealed the gradual acclimation of seedlings on a flush level, with leaves from the third flush best able to use available light under high temperatures and insolation efficiently. The results of rapid light use as an indicator of seedling acclimation are discussed. Some remarks on the possible practical significance of the winter-green leaves phenomenon (as in genetic selection) are highlighted. [ABSTRACT FROM AUTHOR]

Black poplar (Populus nigra L.) belongs to endangered species of Serbia that grow in wetlands. This research was conducted on the Great War Island, which is located at the confluence of the Sava and Danube rivers, in Belgrade. This research aimed to determine the survival rate and growth dynamics of seedlings of different black poplar clones in the first year after planting in the flood conditions of the Great War Island. Recording of surviving seedlings and measurements of heights and diameters were performed in 2019, firstly in the spring (April 18, 2019), the second time during the summer (July 18, 2019), after the flooding period, and the third time in the autumn (October 4, 2019), at the end of the vegetation period. The results of descriptive statistics, one-way analysis of variance (One-Way ANOVA), and cluster analysis are presented in this paper. Based on the obtained results, the highest survival rate after the flooding period was recorded in clone number 9 (85.70%), in which 78.60% of seedlings survived at the end of the vegetation period. It can be stated that the seedlings of black poplar clone number 9, based on a high survival rate, have the potential to be used for afforestation of wetlands, such as the Great War Island. However, the seedlings of this clone showed significantly lower values of measured heights and diameters, compared to the seedlings of most clones and mostly the seedlings were damaged. On the other hand, seedlings of clone 3 were superior based on the mean values of heights and diameters, obtained after the measurements in all three periods, including the period after flooding. Seedlings of this clone had a satisfactory survival rate, but it was constantly declining. Clone number 1 showed the lowest results, both in terms of survival at the end of the vegetation period and in terms of mean heights and diameters of seedlings. When using this species, special attention should be paid to preserving the gene pool and avoiding the establishment of commercial monoclonal plantations, especially in protected areas such as the Landscape of Outstanding Features "Great War Island". [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Faculty of Forestry / Glasnik Šumarskog Fakulteta is the property of University of Belgrade, Faculty of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)