The resistance of plants of Juglans nigra varieties to the influence of the low temperature

The results of research on the influence of low temperatures on the structural parts of shoots of three varieties and a hybrid of domestic and foreign selection of black walnut in the conditions of cultivation of the Liso-steppe and Polissya of Ukraine are highlighted. It was found that the core of the shoot, depending on the year of vegetation, and the buds were damaged the most by low temperatures on average during three years of research. The most resistant to low temperatures were the tissues of the bark and cambium, of the varieties — plants The highlight of the garden. This variety can be used for breeding work for winter hardiness to obtain stable forms.

Определение содержания мирицитрина в коре ореха черного методом ВЭЖХ

Разработана методика количественного определения мирицитрина в коре ореха черного (Juglans nigra L.) методом ВЭЖХ. Содержание доминирующего флавоноида — мирицитрина (мирицетин-3-O-α-L-рамнопиранозид) в коре ореха черного варьирует от (3,10 ± 0,18) до (3,18 ± 0,14) %. Ошибка единичного определения мирицитрина в коре ореха черного с доверительной вероятностью 95 % составляет ± 5,81 %.

Competitive Advantage of Geosmithia morbida in Low-Moisture Wood May Explain Historical Outbreaks of Thousand Cankers Disease and Predict the Future Fate of Juglans nigra Within Its Native Range

Bark beetles vector symbiotic fungi and the success of these mutualisms may be limited by competition from other microbes. The outcome of fungal competition is strongly influenced by the physical and chemical conditions of the wood they inhabit. These conditions are in turn subject to climatic variation. In particular, wood moisture content (MC) influences fungal competition and, therefore, could help determine environmental suitability for thousand cankers disease (TCD) caused by Geosmithia morbida and its vector Pityophthorus juglandis. We conducted competition experiments in Juglans nigra wood that was naturally or artificially colonized by G. morbida and other fungi over a range of wood MC expected across prevailing United States climatic conditions. G. morbida outcompeted antagonistic fungi Clonostachys and Trichoderma spp. at <5% equilibrium moisture content. Aspergillus spp. outcompeted G. morbida at low moisture in wood from Indiana. We fit a logistic regression model to results of the competition experiments to predict survival of G. morbida across the United States. Expected survival of G. morbida was highest in historical TCD epicenters and accounted for the low incidence and severity of TCD in the eastern United States. Our results also predict that under future climate scenarios, the area impacted by TCD will expand into the native range of J. nigra. Given its role in emergent forest health threats, climate change should be a key consideration in the assessment of risks to hardwood resources.

Juglone: a versatile natural platform for obtaining new bioactive compounds

: Juglone is a metabolite produced by several species of plants, in particular Juglans nigra. Additionally, juglone is a 1,4-naphthoquinone that has several biological actions. Antimicrobial, antifungal, sedative, oxidizing, antihypertensive, and especially anti-proliferative actions have been described for juglone. This justifies that 1,4-naphthoquinone is a privileged structure for Medicinal Chemistry, and it is useful for the development of new prototypes with varied actions. In this work, we make a profound review of juglone synthesis methodology, the biological actions of juglone, and mainly the synthesis and pharmacological actions of juglone derivatives. We hope that the potent biological actions described for these derivatives in this review will stimulate the continuous design, synthesis, and pharmacological evaluation of new juglone derivatives.

Structure of black walnut (Juglans nigra L.) stands on sandy soils in Hungary

Understanding the various processes and relationships that take place in forest ecosystems is generally possible only through long-term observations. This is especially true of the biological production of forests, through the in-depth exploration of their structure. In Hungary the black walnut (Juglans nigra L.) is one of the most valuable exotic tree species, mainly because of its very valuable wood, with fine tissues and unique colour, for furniture industry. Generally, the species is established by manual seeding, and can also be regenerated well by coppice shoots, but not by natural seeding. Black walnut regularly produces seeds from the age of 25–30 years and its rotation age is 70–80 years. It is also used outside forests due to the very decorative stem and crown shapes. In this paper, out of the stand structure factors, the relationships between age and height (r² = 0.7205), age and diameter (r² = 0.7719), age and number of stems per ha (r² = 0.3485) as well as between diameter and number of stems per ha (r² = 0.4595), all considered important for cultivation technology, were examined (based on the data collected in 34 black walnut stands, age of 7 to 67 years). We also analysed the diameter distributions in two black walnut stands with tending operations, reporting them as a case study. Its future role may be increased mainly on sandy soils of better quality, therefore the more accurate exploration of the structure of black walnut stands growing under such conditions can be considered as gap-filling.