Physiological Performance of Pyrus pyraster L. (Burgsd.) and Sorbus torminalis (L.) Crantz Seedlings under Drought Treatment

In this study, seedlings of Pyrus pyraster and Sorbus torminalis were grown for 60 days in the regulated environment of a growth chamber under different water regimes. The measured indicators were the growth and distribution of mass to organs, total biomass, root to shoot mass ratio (R:S), and gas exchange parameters (gs, E, An, and water use efficiency (WUE)). The amount of total biomass was negatively affected by drought. Differences between species were confirmed only for the dry matter of the leaves. P. pyraster maintained the ratio of the mass distribution between belowground and aboveground organs in both variants of the water regime. S. torminalis created more root length for a given dry-mass under drought treatment, but its R:S was lower compared to P. pyraster. The water potential of the leaves (Ψwl) was affected by substrate saturation and interspecific differences. P. pyraster had a demonstrably higher water potential and maintained this difference even after prolonged exposure to drought. After 30 days of different water regimes, Pyrus maintained higher values of gs, An, and E in control and drought treatments, but over a longer period of drought (after 50 days), the differences between species were equalized. The changes of the leaf gas exchange for Pyrus were accompanied by a significant increase in WUE, which was most pronounced on the 40th day of the experiment. A significant and strong relationship between WUE and gs was demonstrated. The results confirmed the different physiological performances of seedlings of tree species and the different mechanisms of their response to water scarcity during drought treatment. P. pyraster presented more acclimation traits, which allowed this taxon to exhibit better performance over a longer period of water scarcity.

Dendroclimatological Analysis of Wild Pear Pyrus Pyraster (L.) Burgsd. From Biedrusko Military Area (West Poland) — Preliminary Study

European wild pear (Pyrus pyraster, syn. Pyrus communis subsp. pyraster L.) is widely distributed in Europe, but rarely studied by dendrochronologists. This preliminary study was aimed to assess the age and effect of climate on tree-ring width in the largest Polish population of P. pyraster, in Biedrusko military area (western Poland). On the basis of samples from 21 trees, a chronology (BIE) was constructed, covering 45 years (1963–2007). Mean tree-ring width in the studied trees is 1.92 mm. The performed analyses (pointer years, correlations, and response function) indicate that tree-ring width is strongly dependent on weather conditions in the year preceding formation of the tree-ring. Annual rings of pear trees were wide after cold and rainy previous summer and after rainy previous October, while in the current year, ring width was affected by insolation in February and temperature in August (positive correlations) and precipitation in May (negative correlation). The low similarity of the ring-width pattern and effect of climate on tree-ring width between this population and a wild pear population from the Bielinek Reserve, located 200 km away, indicate that tree-ring width in this species is strongly dependent on habitat and there is a need to continue dendrochronological analyses.

The Impact of Different Water Regime on Chlorophyll Fluorescence of Pyrus pyraster L. and Sorbus domestica L

The water deficit is considered to be significant cause of photosynthesis defects. Measuring of chlorophyll fluorescence is one of the methods revealing defects in the photosynthetic apparatus. The experiment was established with two woody plant (Pyrus pyraster L. and Sorbus domestica L.) cultivated in two different regimes of the substrate saturation. The measurement of the modulated fluorescence of chlorophyll a was done by FMS1 fluorometer during three-week period between June and September (2012 and 2013). There were analysed selected parameters of chlorophyll fluorescence: Fv/Fm – maximum quantum efficiency of PSII, ΦPSII – effective quantum yield of PSII and RFD – chlorophyll fluorescence decrease ratio. According to the obtained results, Pyrus pyraster has probably higher potential for adaptation to water deficiency. There were recorded the significant decreases mainly in the values of parameter RFD and ΦPSII for Sorbus domestica within duration of experiment with different water regime in both growing seasons 2012 and 2013. The results document a weak sensitivity of the parameter Fv/Fm on changes in the amount of available water in the substrate in both taxa.

Occurrence, Biology and Harmfulness of Byctiscus betulae (L.) (Coleoptera, Rhynchitidae)

In 2012 and 2013, was studied the occurrence, biology and harmfulness ofByctiscus betulae(L.) (Rhynchitidae) on forest woody plants in the Brno region. Leaf rolls were found on 13 species (and 10 genera) of woody plants. Most frequently, they occurred onFagus sylvatica,Tiliaspp. (namely onT. cordata),Salix capreaandPopulus tremula. The beetles hibernate in ground pupal chambers and appear on woody plants in the last decade of April. After hibernation, females live on average seven (males five) weeks, and damage on average 40 (males 25) cm2of leaves. The females create leaf rolls on annual shoots they have gnawed, exceptionally (in 2%) on leaves with damaged petioles. In the rolls onF. sylvatica, they roll on average 5.6 leaves whose total average area is 49.5 cm2and lay on average 5.1 eggs. In the rolls onTiliaspp., they roll on average 3.3 leaves whose total area is 63.2 cm2and lay on average 4.9 eggs. In the rolls onS. caprea, they roll on average 3.3 leaves whose total area is 38.3 cm2and lay on average 3.5 eggs. The maximum number of laid eggs (on average 8.0) was observed in the leaf rolls onVitis vinifera. The average number of eggs in the leaf rolls was decreasing from May to July. The number of eggs was increasing with the increasing total leaf area rolled. The females lay on average 50 eggs. OnP. tremula,S. capreaandPyrus pyrasterthey create about 15 leaf rolls, onF. sylvaticaandTiliaspp. about 10 leaf rolls and onV. viniferaca. 8 leaf rolls. Embryogenesis lasts from 8 to 9 days. Larvae develop over 3 instars and damage ca. 300 mm2of leaves. Coming of age within 4−7 weeks, they leave the leaf rolls from mid-June to the beginning of September.