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• Physiological characteristics of a promising black locust (Robinia pseudoacacia L.) clone under marginal site conditions

  27-34

  Tamás Ábri

  Views:

  427

  This paper studies the physiological characteristics of a promising black locust (Robinia pseudoacacia L.) clone, Farkasszigeti, compared to common black locust (control), under marginal site conditions in Eastern Hungary. A clone trial was established in 2022 near Debrecen to test new black locust clones, with measurements of photosynthesis (net assimilation, efficiency of photosystem II, intercellular CO₂ level) and water-use characteristics (transpiration, stomatal conductance, water use efficiency etc.), using LI-6800 (LI-COR) portable photosynthesis system. However, the measured values were very low, indicating drought and heat stress. The results revealed that Farkasszigeti exhibited better net assimilation (2.13±0.75 µmol CO₂ m^-2 s^-1), transpiration (1.41±0.20 mmol H₂O m^-2 s^-1) and stomatal conductance (0.017±0.002 mol m^-2 s^-1) than the control, with significant differences (p=0.05). Furthermore, its photosystem II was more efficient, thus it has better heat tolerance. Although the clone Farkasszigeti was proved to be better in terms of water use efficiency values, no significant difference was observed in comparison with the control common black locust. Today, under changing climatic conditions, the study of physiological adaptation of tree species and clones has a crucial role.

• Improvement of black locust (Robinia pseudoacacia L.) growing under marginal site conditions in Hungary: case studies

  129-133

  Károly Rédei

  Zsolt Keserű

  Imre Csiha

  János Rásó

  Beatrix Bakti

  Marianna Takács

  Views:

  512

  In Hungary, black locust (Robinia pseudoacacia L.) is considered as an important exotic stand-forming tree species growing mostly under unfavourable ecological conditions for forest management. Due to climate change effects, its importance is increasing in many other countries, too. As a result of a selection programme, new black locust clones were tested in clone trials. Juvenile growth of 12 micropropagated black locust clones in two plots series established at different dates were evaluated in central Hungary under marginal site conditions. At age of 7 the clone R. p. ‘Bácska’ (‘KH 56A2/5’), at age of 10 the clones R.p. ‘Homoki’ (‘MB17D3/4’) and ‘PV201E2/4’ appeared to be especially promising for mass production. Based on the data obtained from the performed trials, it can also be concluded that tissue culture can be considered as a suitable tool for propagating superior individuals and offers new prospects for the rapid cloning of selected genotypes used for plantation forestry.

• Comparative study of newly-bred black locust clones with regard to photosynthetic rate and water use efficiency: early evaluation

  5-10

  Tamás Ábri

  József Csajbók

  Views:

  517

  Black locust (Robinia pseudoacacia L.) is one of the most important tree species in Hungary, due to its positive economic impacts. Research to increase its yield, improve its stem quality and enhance its drought tolerance has been ongoing since the 1960s. Of the current research works in this field, the clone trial of the Forest Research Institute, University of Sopron, established in 2020 in the Nyírség region, is worth highlighting. In this experiment 4 newly-bred clones and a state-approved black locust cultivar ('Üllői') are being tested. In the summer of 2022, ‘on site’ measurements of assimilation parameters – net assimilation (A_n), transpiration (Tr) – were carried out using the LI-6800 portable photosynthesis system. From the data obtained, the water use efficiency (WUE) was calculated. The results of the statistical analysis (Kruskal-Wallis H test) have shown significant differences (p < 0.05) between the clones for all three parameters (A_n, Tr, WUE) tested. The NK2 clone has performed the highest value for all the parameters studied. However, no significant differences were found between clones NK2 and PL040 for Tr or between NK2 and control ('Üllői') for WUE. Studies of this kind contribute to the improvement of black locust growing through the production and selection of cultivars, which are relatively resistant to the negative effects (drought) of climate change.

• Productivity of thinned black locust (Robinia pseudoacacia L.) stands in Hungary: case studies

  181-186

  Károly Rédei

  Tamás Ábri

  Views:

  279

  Black locust (Robinia pseudoacacia L.) is one of the most important introduced tree species in Hungary, covering more than 24% of the stocked area and providing approximately 20% of the country’s annual timber cut. Consequently, the research and development activities related to the improvement of the growing technology of black locust are also important, especially in mitigating the negative effects of climate change. The aim of this study was to quantify growth and yield, responses of even-aged 12–31–year–old black locust stand to thinning in Hungary. The study has proved that irrespective of the yield class, age and thinning intensity, thinning could not increase effectively the cumulative volume production. As percentage of the control it has changed between +0.6 and -8.4%. On the other hand, it could increase the stand value based on stem quality index by 10–21%.