Stability of Transgene Inheritance in Progeny of Field-Grown Pear Trees over a 7-Year Period

Breeding woody plants is a very time-consuming process, and genetic engineering tools have been used to shorten the juvenile phase. In addition, transgenic trees for commercial cultivation can also be used in classical breeding, but the segregation of transgenes in the progeny of perennial plants, as well as the possible appearance of unintended changes, have been poorly investigated. We studied the inheritance of the uidA gene in the progeny of field-grown transgenic pear trees for 7 years and the physical and physiological parameters of transgenic seeds. A total of 13 transgenic lines were analyzed, and the uidA gene segregated 1:1 in the progeny of 9 lines and 3:1 in the progeny of 4 lines, which is consistent with Mendelian inheritance for one and two transgene loci, respectively. Rare and random deviations from the Mendelian ratio were observed only for lines with one locus. Transgenic seeds’ mass, size, and shape varied slightly, despite significant fluctuations in weather conditions during cultivation. Expression of the uidA gene in the progeny was stable. Our study showed that the transgene inheritance in the progeny of pear trees under field conditions occurs according to Mendelian ratio, does not depend on the environment, and the seed vigor of transgenic seeds does not change.

Mechanism of Excessive Nitrogen Fertilization Aggravates the Damage of Cacopsylla Chinensis to Pear

Cacopsylla chinensis (Hemiptera: Psyllidae) is one of the most important pests on pear trees. Although nitrogen fertilization is known to often benefit the performance of many herbivores including psyllids, physiochemical and molecular mechanisms of how psyllids respond to excessive nitrogen application remain unclear. Study showed that nitrogen fertilizer concentrations significantly impacted phenolic acids compositions in pear leaves, there was an upward trend in ferulic acid concentration when increasing nitrogen fertilizers. The increased ferulic acid concentration accelerated the C. chinensis development. Moreover, high nitrogen fertilization also caused a significant increase in psyllid honeydew secretion and several amino acids concentrations in honeydew. The increased amino-acid content in pear leaves under high nitrogen fertilization improved the feed intakes of psyllid, however decreased more significantly the expression levels of several C. chinensis genes in amino-acid synthesis pathways. The mechanism of excessive nitrogen fertilization aggravating the damage of C. chinensis to pear trees was defined preliminarily.

Application of ImageJ Software in the assessment of flowering Intensity and growth Vigor of pear Trees

The study evaluated the possibility of using the image acquisition and processing method with ImageJ software for estimating growth vigor and flowering intensity of ‘Conference’ pear trees. For assessing flowering intensity, manual counting of flower clusters and taking of photographs of the trees were conducted at full bloom. Tree vigor was estimated by manually measuring the total length of the central leader and shoots of individual trees. The trees were photographed from the same distance using a hand-held camera. The calibration model for assessing the vigor or flowering of trees by image analysis was based on measurements and photographs taken for nine selected trees differing in the total length of shoots or in the number of flower clusters. Then, a quality assessment of the model was carried out on 26 nonselected trees. Image processing was performed using ImageJ software. High regression coefficients were obtained between the surface area of petals measured on the photographs and the number of inflorescences counted (r2 = 0.98); however, observations carried out in the following year indicate the need for individual calibration of estimation models in each evaluation season. Subsequently, the quality of estimating the flowering intensity of pear trees was assessed using a previously determined calibration model. Mean absolute percentage error (MAPE) values ranged from 14.0% to 21.8%, depending on the measurement time. In the assessment of tree growth vigor, a high correlation (r2 = 0.98) was also obtained between the actual length of shoots measured individually for each tree and the values obtained by analyzing the photographic image, where the MAPE error was 12.9%.

Response of Pear Trees’ (Pyrus bretschneideri ‘Sinkiangensis’) Fine Roots to a Soil Water Regime of Regulated Deficit Irrigation

A field experiment was conducted to evaluate the effects of regulated deficit irrigation (RDI) on the fine root redistribution of mature pear trees in 2009 and 2010. The experiment consisted of four RDI treatments: MRDI-1 and SRDI-1, in which the trees received irrigation replacing 60% and 40% of pan evaporation (Ep) during Stage 1 (cell division stage), and MRDI-1+2 and SRDI-1+2, in which the trees received irrigation replacing 60% and 40% of Ep during Stage 1+2 (cell division and slow shoot growth stage). All the RDI-treated trees received irrigation replacing 80% of Ep (full irrigation) in other stages, and the control trees were fully irrigated during the whole growth season. The results showed that the fine root length density (RLD) of mature pear trees was reduced by water stress. The resumption of full irrigation boosted fine root growth. The RLD of the SRDI-1-treated trees in the irrigated zones recovered in early July, they maintained water and nutrient absorption during the fruit enlargement stage, and the final fruit yield was significantly improved. The RLD of trees in the irrigated zones with MRDI-1 and MRDI-1+2 recovered in July and September, respectively, but there were no significant differences in fruit yield between the MRDI-1, MRDI-1+2, and the control. This indicates that the fruit yield was not negatively or positively impacted by the redistribution of moderate water stress applied during either Stage 1 or Stage 1+2.

The influence of foliar fertilization of maiden pear trees and soaking the root system of the rootstocks in hydrogel with the addition of Trifender WP preparation on the growth of maiden quince trees in a nursery

The comparison of the influence of foliar fertilization with four preparations on the growth of ‘Conference’ maiden pear trees growing on MA quince rootstock was conducted in a nursery in a three-year period. The evaluation was conducted on the basis of maidens growth parameters and the state of their leaf minerals content as well as on photosynthetic activity of the maiden trees. The preparations used in the experiment affected the improvement of some growth parameters studied, especially the stem diameter and fresh mass of the maidens. Biopuls Original turned out to be the best preparation as it improved significantly three out of five studied growth parameters. A varied impact of the preparations used on the content of micro and macro-elements in leaves was detected. All tested preparations positively influenced the leaves area index of maiden trees except for Blackjak preparation. Photosynthetic intensity of maiden pear trees nourished through leaves was significantly smaller in comparison with the control. Only plants treated with Biopulus Original were characterized by a higher concentration of CO2 and its level in intercellular space. The aim of the second experiment was to check the influence of the application of Trifender WP preparation with hydrogel on the growth of ‘Champion’ maiden quince trees at the stage of planting the rootstocks into a nursery. A better branching of the rootstocks was obtained after the use of the preparation with hydrogel and the hydrogel alone. The trees in these combinations were also characterized by bigger fresh and dry mass of the leaves. The influence of Trifinder WP applied in connection with hydrogel was the best.

Fitomonitorizarea intensităţii fotosintezei, respiraţiei şi transpiraţiei la pomii de păr

The paper presents the results regarding the phytomonitoring of physiological processes in pear trees. The modern RTM-48A phytomonitor was used, which allowed the measurement of indices in the form of a film-phytodiagram that allows the diagnosis of the properties of genotype and physiological con-dition of plants. The light saturation curve for photosynthesis in pear plants was determined as a result of the evaluation of the intensity of photosynthesis, respiration, transpiration, stomata conductivity as a func-tion of temperature, humidity and CO2 content in the air. The minimum value of light at which the photo-synthesis process is initiated has been established. As the light intensity increases (1/3 of the total light) the intensity of photosynthesis increases after the essential optimization of the process has taken place.

The use of mulching material in the cultivation of apple and pear in a small plastic greenhouses

This article presents the results of studies that were conducted in a small-sized film greenhouse for growing аpple and pear seedlings according to different planting schemes with mulching between rows with black span bond and matting. It was found that mulching between rows creates more favorable conditions for growing plants. The temperature regime of the soil improves, especially at the depth of the root layer. The row spacing soil is less compacted, since multiple loosening and weeding are not required. The mulching materials used freely pass water and mineral elements dissolved in it. Black woven matting is recognized as the best material for mulching between rows of apple and pear trees in a small film greenhouse. The applied schemes of planting winter grafts of apple and pear trees and mulching of row spacing made it possible to completely abandon the use of intensive manual labor on weeding and loosening the soil. Using three-line planting instead of one-line planting allows to significantly increase the yield of planting material per unit area.

Features of the root system of pear trees on different rootstocks in Crimea

В статье представлены результаты исследований состояния насаждений шести сортов груши (Изумрудная, Изюминка Крыма, Мария, Мрия, Отечественная, Таврическая), привитых на три подвоя крымской селекции (КА 53, КА 86, КА 92) в сравнении с контролем (Бере Арданпон /ВА 29) в зависимости от архитектоники корневой системы. Анализ полученных данных дает возможность классифицировать деревья по силе роста в зависимости от подвоя и сорта. Наиболее рослыми являются комбинации сортов Изумрудная, Бере Арданпон, Отечественная на подвоях ВА 29, КА 53 и КА 86. Сорта Изюминка Крыма и Мария, а также подвой КА 92, относятся к группе слаборослых, что подтверждается биометрическими показателями. Площадь сечения штамба 11-летних деревьев в группе сильнорослых сорто-подвойных комбинаций составляет 79,2-81,1 см, у слаборослых - 64,2-68.8 см. На силу роста, помимо указанных факторов, влияет также развитие корневой системы. Цель исследований - установление зависимости роста и развития деревьев груши на разных подвоях от состояния корневой системы. Основным отличием подвоев крымской селекции является хорошо развитая корневая система. Результаты раскопки корней всех сортов на ВА 29 показывают, что основная их масса расположена на глубине 10-40см. Отдельные корни уходят вглубь до 1,7-2,0 м. Основная корневая система подвоев серии КА занимает почвенные горизонты 20-65 см, проникая в глубину до 2,5 м. Более развитая корневая система деревьев груши повышает также засухо- и хлорозоустойчивость деревьев, увеличивает их якорность и повышает продуктивность. Следовательно, при закладке интенсивного сада груши необходимо подбирать сорто-подвойные комбинации, устойчивые к био- и абиотическим условиям произрастания и обладающие умеренной силой роста. Выбор перспективных подвоев для интенсивного садоводства предусматривает необходимость изучения структурно-морфологических особенностей корневой системы. The article presents the study results of stand condition of plantings of six pear varieties (‘Izumrudnaya’, ‘Izyuminka Kryma’, ‘Maria’, ‘Mriya’, ‘Otechestvennaya’, ‘Tavricheskaya’), grafted on three rootstocks of Crimean selection (KA 53, KA 86, KA 92) in comparison with the control (‘Bere Ardanpon’ / BA 29) depending on the root system architectonics. Analysis of the data obtained makes it possible to classify trees according to the growth power depending on the rootstock and variety. The most strongly-grown are combinations of varieties ‘Izumrudnaya’, ‘Bere Ardanpon’, ‘Otechestvennaya’ on rootstocks BA 29, KA 53 and KA 86. The varieties ‘Izyuminka Kryma’ and ‘Maria’, as well as KA 92, belong to the group of weakly-grown, as confirmed by biometric indicators. Basal area of the trunk of 11-year-old trees in the group of strongly-grown variety-rootstock combinations is 79.2-81.1 cm, in the weakly-grown group - 64.2-68.8 cm. The strength of growth, in addition to above mentioned factors, is also influenced by the root system development. The aim of the research is to establish the dependence of growth and development of pear trees using different rootstocks on the root system condition. The main difference of Crimean rootstocks is a well-developed root system. The results of digging up the roots of all varieties on BA 29 show that their basic weight is located at a depth of 10-40 cm. Separate roots go down to 1.7-2.0 m. Basic root system of KA-series rootstocks occupies soil layer of 20-65 cm, penetrating to a depth of 2.5 m. A more developed root system of pear trees also increases the drought and chlorosis resistance of trees, improves their anchoring and productivity. Consequently, when starting an intensive pear garden, it is necessary to select variety-rootstock combinations, resistant to biotic and abiotic growing conditions and having a moderate growth power. The choice of promising rootstocks for intensive gardening involves the necessity to study structural and morphological features of the root system.

Adaboost-Based Machine Learning Improved the Modeling Robust and Estimation Accuracy of Pear Leaf Nitrogen Concentration by In-Field VIS-NIR Spectroscopy

Different cultivars of pear trees are often planted in one orchard to enhance yield for its gametophytic self-incompatibility. Therefore, an accurate and robust modelling method is needed for the non-destructive determination of leaf nitrogen (N) concentration in pear orchards with mixed cultivars. This study proposes a new technique based on in-field visible-near infrared (VIS-NIR) spectroscopy and the Adaboost algorithm initiated with machine learning methods. The performance was evaluated by estimating leaf N concentration for a total of 1285 samples from different cultivars, growth regions, and tree ages and compared with traditional techniques, including vegetation indices, partial least squares regression, singular support vector regression (SVR) and neural networks (NN). The results demonstrated that the leaf reflectance responded to the leaf nitrogen concentration were more sensitive to the types of cultivars than to the different growing regions and tree ages. Moreover, the AdaBoost.RT-BP had the best accuracy in both the training (R2 = 0.96, root mean relative error (RMSE) = 1.03 g kg−1) and the test datasets (R2 = 0.91, RMSE = 1.29 g kg−1), and was the most robust in repeated experiments. This study provides a new insight for monitoring the status of pear trees by the in-field VIS-NIR spectroscopy for better N managements in heterogeneous pear orchards.