Growth Of Apple Trees Research Articles

Effect of Water-Fertilizer Coupling on the Growth and Physiological Characteristics of Young Apple Trees

China has the largest apple-growing area and fresh fruit production in the world; however, water shortages and low fertilizer utilization rates have restricted agricultural development. It is a major challenge to obtain scientific and reasonable irrigation and fertilization systems for young apple trees in semi-arid regions of northern China. A 2-year field bucket experiment with four irrigation levels of W1 (75–90% Fs, where Fs is the field water holding capacity), W2 (65–80% Fs), W3 (55–70% Fs), and W4 (45–60% Fs), and three fertilizer levels of F1 (27-9-9 g N-P2O5-K2O), F2 (18-9-9 g N-P2O5-K2O), and F3 (9-9-9 g N-P2O5-K2O) was conducted in 2019 and 2020, so as to explore the effects of different water and fertilizer treatments on the growth and physiological characteristics of young apple trees. The results showed that the plant growth, leaf area, and dry matter of young apple trees at each growing period reached maximum values under F1W2, and they showed a positive linear relationship with relative chlorophyll content (SPAD), net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), water consumption, and water use efficiency (WUE). With the growth of young apple trees, water-fertilizer coupling could significantly increase the leaf SPAD of young apple trees. Pn, Tr, and Gs reached the maximum value under F1W1, and although they decreased under F1W2, the water use efficiency increased by 2.3–25.7% and 4.0–23.8% under F1W2 compared with other treatments in two years, respectively. The water consumption of young apple trees increased with the increase of irrigation and fertilizer, and both dry matter and water productivity reached the maximum value under F1W2, which increased by 0.8%, 14.6% in 2019, and 0.6%, 11.1% in 2020 compared with F1W1, while water consumption decreased by 12.2% and 9.4% in both years. In conclusion, F1W2 treatment (soil moisture was controlled at 65–80% of field water holding capacity, and N-P2O5-K2O was controlled at 27-9-9 g) was the best coupling mode of water and fertilizer for young apple trees in semi-arid areas of northern China.

Application of living mulch in rows of the apple trees on several rootstocks – long-term evaluation

The long-term influence of several living mulches on apple tree growth, nutrient status, yield, and fruit quality concerning the year of cover crop sowing in tree rows was evaluated in the Lower Silesia region in the southwestern part of Poland. The estimation was conducted in six apple tree ‘Ligol’ populations differentiated by the rootstock: M.26, M.9, P 60, P 2, P 16, and P 22. In experiment no. 1, one-year-old nursery stock was planted, and perennial living mulches were sown: colonial bent grass (Agrostis vulgaris With.) and white clover (Trifolium repens L.) in the same year and blue fescue (Festuca ovina L.) in the following year. In experiment no. 2, which involved two-year-old stock, the sowing of blue fescue was delayed until the second, third, fourth, and fifth years following orchard planting. The presence of the cover crop significantly affected young tree growth when one-year-old trees were planted. The sowing of the living mulch in the first or the second year after tree planting led to a significant reduction in the cumulative yield obtained from the young trees. The living mulch improved the red coloration of the fruit skin in the young orchard, but it caused a reduction in the mean fruit weight and size. However, it also contributed to decreased nitrogen concentration in the leaves of the apple trees, and the tree tolerance to living mulch increased as the orchard aged. A choice of semidwarf rootstock, postponed sowing of cover crop, and high-quality nursery stock were recognized as the most important factors for fostering apple tree tolerance to living mulches in tree rows.

Hyperspectral Estimation of Chlorophyll Content in Apple Tree Leaf Based on Feature Band Selection and the CatBoost Model

Leaf chlorophyll content (LCC) is a crucial indicator of nutrition in apple trees and can be applied to assess their growth status. Hyperspectral data can provide an important means for detecting the LCC in apple trees. In this study, hyperspectral data and the measured LCC were obtained. The original spectrum (OR) was pretreated using some spectral transformations. Feature bands were selected based on the competitive adaptive reweighted sampling (CARS) algorithm, random frog (RF) algorithm, elastic net (EN) algorithm, and the EN-RF and EN-CARS algorithms. Partial least squares regression (PLSR), random forest regression (RFR), and the CatBoost algorithm were used before and after grid search parameter optimization to estimate the LCC. The results revealed the following: (1) The spectrum after second derivative (SD) transformation had the highest correlation with LCC (–0.929); moreover, the SD-based model produced the highest accuracy, making SD an effective spectrum pretreatment method for apple tree LCC estimation. (2) Compared with the single band selection algorithm, the EN-RF algorithm had a better dimension reduction effect, and the modeling accuracy was generally higher. (3) CatBoost after grid search optimization had the best estimation effect, and the validation set of the SD-EN-CARS-CatBoost model after parameter optimization had the highest estimation accuracy, with the determination coefficient (R2), root mean square error (RMSE), and relative prediction deviation (RPD) reaching 0.923, 2.472, and 3.64, respectively. As such, the optimized SD-EN-CARS-CatBoost model, with its high accuracy and reliability, can be used to monitor the growth of apple trees, support the intelligent management of apple orchards, and facilitate the economic development of the fruit industry.

Evaluating the effects of different nutrient management strategies on apple (malus pumila) in intensive orchards of Kazakhstan. Results from a 4-year study

This article presents the findings of a four-year study in intensive apple orchards in southern Kazakhstan, evaluating different nutrient management strategies on apple trees (Malus pumila). The research aimed to assess the impact of nutrition plans on tree growth, productivity, and fruit quality, considering the region's unique soil and climate. The experiment, established in 2014, covered 1.5 hectares and consisted of Jeromini apple trees grafted onto M9 rootstock. Three treatment groups were established: a control group with no additional nutrition, a group with nutrition based on a generally accepted program, and a group with nutrition tailored to the apple tree's needs with fertigation. Phenological and biometric observations were conducted regularly from 2019 to 2022 to monitor tree performance. Soil and leaf samples were analyzed for nutrient content, and soil properties like pH and salinity were assessed. Statistical analysis was used to identify significant differences among the treatment groups. The research was conducted in intensive apple orchards located in the Turkestan region, known for its grey-brown soil. The climate in the study area was characterized as continental, with hot and dry summers and limited precipitation. Soil samples were analyzed for agrophysical and agrochemical properties, including nutrient levels and trace elements. The results showed that the control group had a decreasing trend in yield, while both the generally accepted program and the tailored nutrition program showed increasing trends in yield, with the latter showing a decrease in 2022. Over the fouryear period, the fruits from the control group exhibited reduced commercial qualities. Our program demonstrated similar sweetness and superior shape and yield compared to the conventional method. However, the storage quality of apples in our program was lower. Nevertheless, considering its positive impact on soil fertility and cost-effectiveness, our program appears to be an optimal choice. The findings of this study provide valuable insights into the effects of different nutrient management strategies on the growth, health, and productivity of apple trees in a garden setting. This information can benefit orchard growers and researchers seeking to optimize nutrient management practices for apple trees. The study also highlights the importance of considering various factors, such as orchard characteristics and environmental conditions, when designing nutrient management strategies for apple orchards.

Response of apple orchard bacteria co-occurrence network pattern to long-term organic fertilizer input

Organic fertilizer substitution is frequently used for increasing the apple yield and soil fertility. However, the effects of organic fertilizer substitution on soil microbial communities and their co-occurrence patterns in apple orchard are still unclear. In the present study, we investigated the soil bacterial communities in apple orchard after 12 years of different fertilization regimes. Soil samples were collected in the four major periods of apple tree growth under four fertilization strategies: no fertilization control (CK), organic fertilizer (M), chemical fertilizer (NPK), and partial substitution of chemical fertilizer with organic fertilizer (MNPK). The soil bacterial community was significantly affected by the fertilization strategy (R2 = 0.22), growth period (R2 = 0.22), and their interactions (R2 = 0.28). The α-diversity (Shannon and Richness indexes) was generally stable in the budding and setting periods of apple tree, but the α-diversity indexes in the swelling and maturing periods were 7.05 % and 7.20 % lower for NPK and MNPK compared with CK and M, respectively. The dissimilarities of the bacterial communities determined based on the Bray–Curtis distances in different growth periods were greater in MNPK than CK, M, and NPK. Network analysis showed that connections between bacterial taxa were more frequent for MNPK, where the number of total links were 130.28 %, 56.86 % and 143.82 % higher than CK, M, and NPK, respectively. The percentage of positive interaction in NPKM was 81 %, which was higher than the other treatments. These results demonstrate that long-term organic fertilizer substitution made the bacterial community more sensitive to environmental changes. More keystone species were detected in the network for MNPK (module and connector hubs = 18), and the complexity and connectivity of the bacterial network increased after long-term organic fertilizer substitution. More modules in the networks for M and MNPK had significant relationships with the soil DON, MBC, and SOC than those in the networks for CK and NPK, indicating that more bacteria in organic fertilizer treatments participated in the C and N turnover. Overall, long-term organic fertilizer substitution made the bacterial community more sensitive to environmental changes, and might stimulated the soil C and N cycles.

The problem of soil fatigue in apple orchardsmonoculture

The article provides an analysis of current domestic and foreign scientific sources regarding the phenomenon of soil depletion in perennial apple orchards, its impact on the growth and productivity of apple trees, and measures to improve the soil’s ecological condition within monocultures. In recent years, there has been an increasing need to establish new apple plantations on land plots after the removal of old orchards. This is influenced by various factors, including the cultivation of intensive short-cycle orchards with necessary infrastructure, economic facilities with access networks situated on privatized lands, the designated use of which cannot be altered. Consequently, establishing new fruit plantations on land previously unused for perennial fruit crops becomes unfeasible. This underscores the necessity of enhancing soil quality indicators, including reducing or entirely mitigating the negative effects of soil depletion on young trees following the removal of old ones. Particular attention is warranted to the adverse impact of cultivating weak-growing varieties on dwarf rootstocks repeatedly. These root systems are located in surface layers of the soil where the majority of the roots from previously grown trees were concentrated. A series of studies have demonstrated the negative influence on plant growth indicators when young trees are grown in the same location as removed orchards. The presence of residual tree roots in the soil suppresses the growth of young plantations, leading to a reduction in stem diameter, shoot growth, and tree height. In global practice, fumigation (chemical and biological), cultivation of specific plant species in interrows for bioremediation with subsequent plowing as cover crops, the application of mineral and organic fertilizers, various biostimulants, and organic additives are often used to minimize the negative effects of soil depletion. Continuous research is being conducted to study various crop varieties, fertilization systems, and agricultural practices aimed at effectively and ecologically safely addressing the issue of soil depletion in specific soil-climatic conditions.

Changes in Growth, Fruit Quality, and Leaf Characteristics of Apple Tree (Malus domestica Borkh. ‘Fuji’) Grown under Elevated CO2 and Temperature Conditions

Changes in Growth, Fruit Quality, and Leaf Characteristics of Apple Tree (Malus domestica Borkh. ‘Fuji’) Grown under Elevated CO2 and Temperature Conditions

The Use of Organic Additives for Replanted Soil in Apple Tree Production in a Fruit Tree Nursery

How soil is used affects its production characteristics in the future. Under ARD (Apple Replant Disease) conditions, replanted soil’s physical, chemical and biological properties deteriorate. Their improvement is possible through, for example, increasing the content of organic matter in the soil. The study aimed to assess the effect of two organic additives for replanted soil on its physical, chemical and biological properties, as well as on the vegetative growth of apple trees of the ‘Gala Schniga SchniCo(s)’ cultivar grafted on M.9 rootstock. The experiment was performed in 2021, in western Poland, on a nursery farm. The trees were planted in pots filled with soil from two stations: soil previously used for the production of apple trees (replanted soil) and nursery material (agricultural soil) unused for production so far. To fertilise it, three different portions of biocarbon and Carbomat Eco soil conditioner were added to the replanted soil. The experiment showed that apple trees grown on replanted soil had fewer side shoots, a smaller leaf area and a lower mass of leaves than those grown on agricultural soil. Furthermore, supplementation of replanted soil with organic additives caused a significant increase in its enzymatic activity and respiration, increased the rate of photosynthesis and improved several parameters determining the strength of vegetative growth in apple trees.

Parameters of apple tree crowns depending on the crown shape and pruning time

The apple tree is a leading fruit crop in Ukraine in terms of production volumes and planting areas and is a valuable food product with a high content of vitamins. In new modern plantings, fruit producers prefer intensive cultivation technologies that ensure the maximum amount of high-quality fruit yield per unit area. The main criterion for solving this problem is the design of plantings: a narrow-row scheme for planting trees and a low-volume crown shape. The purpose of the study was to establish the influence of the pruning period of different types of crown formations on the growth and productivity of apple trees of two varieties: Fuji and Honey Crisp. The study was conducted in the conditions of the central Forest-Steppe of Ukraine (Uman National University of Horticulture). The scheme of planting was 4x1 m, M.9 rootstock, chernozem sod-podzolic soil, drip irrigation. Field, statistical, and computational-analytical methods were used in the course of the study. It was identified that the growth pattern of the examined varieties differed substantially, and crown volume, projection area, and development of the feeding area prevailed in Honey Crisp trees. However, in terms of productivity, the plantings of the Fuji variety substantially exceeded the values of the Honey Crisp variety. Forming a ballerina crown with the removal of overgrown wood in a 25 cm zone on the central trunk above the lower tier of semi-cellular branches provided an increase in the growth activity of the examined trees by 3-5%. A substantial decrease in the values of crown parameters was provided by the formation of the French axis crown – there was a decrease in the crown diameter by 44%, the crown volume – by 67%, and the crown projection area and the development of the feeding area – by 69%. Performing additional summer pruning of trees also helped to reduce growth activity by 6-11%. However, the specific productivity of plantings doubled in plantings with the formation of the French axis and by 45-50% with the introduction of double pruning of trees. It is recommended that agricultural producers investigate the terms of pruning low-volume crown forms, considering varietal characteristics, to create compacted apple stands and increase the intensification of production

High nutrients surplus led to deep soil nitrate accumulation and acidification after cropland conversion to apple orchards on the Loess Plateau, China

Nitrate accumulation in the deep vadose zone poses direct or potential threat of environment and agriculture due to the long hydraulic retention time, especially in areas with limited rainfall. This study explored the primary causes and associated environmental problems of deep soil nitrate accumulation in apple orchards on the Loess Plateau by investigating nutrient (N, P, and K) surplus, deep soil nitrate accumulation and acidification, fertilization habits, and farmer awareness, through a combination of questionnaire and experiment. The results revealed much larger nutrient inputs than outputs, with N, P, and K surpluses 1.8–4.0-fold higher than required for apple tree growth. The huge N surplus caused nitrate accumulation and acidification in deep soil under apple orchards (up to 6 m). Soil nitrate storage in 25-year-old apple orchards within 6 m depth ranged from 5039–14,693 kg ha–1, 4.7–11.7-fold higher than under cropland. In addition, soil pH in 25-year-old apple orchards was 0.31–0.40 lower at 2–4 m depth than that of cropland. Overfertilization was the main contributor to the high cost of apple production, with most farmers unaware that they had overfertilized; the farmers also lacked an environmental conscious. We recommend multiple fertilizations, reasonable ratios of chemical and organic fertilizer, and scientific fertilization guidance to balance the economic benefits and environmental protection of apple orchards. In addition, farmers should be educated on environmental protection to sustainably develop the apple industry on the Loess Plateau.

Wood biochar in soil enhances the promotion of KNO3 on sulfur accumulation in apple trees by regulating root sulfate assimilation

To determine how potassium nitrate (KNO3) effect apple roots and sulfate assimilation in the presence of wood biochar in soil, KNO3 was applied to the root-zone soil without or with 150-day naturally aged wood biochar (1% w/w) in soil. Soil properties, root architecture, root activity, the accumulation and distribution of sulfur (S), enzyme activity, and gene expression related to sulfate uptake and assimilation in apple trees were analyzed. Results showed that KNO3 and wood biochar application exhibited synergistic effects on improving S accumulation and root growth. Meanwhile, KNO3 application increased the activities of ATPS, APR, SAT, OASTL and upregulated the expression of ATPS, APR, Sultr3;1, Sultr2;1, Sultr3;4, and Sultr3;5 in both roots and leaves, and the positive effects of KNO3 addition on both genes and enzyme activity were enhanced by wood biochar. Wood biochar amendment alone promoted the activities of enzymes described above, upregulated the expression of ATPS, APR, Sultr3;1, Sultr2;1, Sultr3;4, and Sultr4;2 in leaves, and enhanced S distribution in roots. KNO3 addition alone decreased S distribution in roots and increased that in stems. In the presence of wood biochar in soil, KNO3 application decreased S distribution in roots but increased that in both stems and leaves. These results indicated that the wood biochar in soil enhances the effect of KNO3 on S accumulation by promoting root growth and sulfate assimilation in apple trees.

ASSVd infection inhibits the vegetative growth of apple trees by affecting leaf metabolism.

Apple scar skin viroid (ASSVd) can infect apple trees and cause scar skin symptoms. However, the associated physiological mechanisms are unclear in young saplings. In this study, ASSVd-infected and control 'Odysso' and 'Tonami' apple saplings were examined to clarify the effects of ASSVd on apple tree growth and physiological characteristics as well as the leaf metabolome. The results indicated that leaf ASSVd contents increased significantly after grafting and remained high in the second year. Leaf size, tree height, stem diameter, branch length, and leaf photosynthetic efficiency decreased significantly in viroid-infected saplings. In response to the ASSVd infection, the chlorophyll a and b contents decreased significantly in 'Odysso', but were unchanged in 'Tonami'. Moreover, the N, P, K, Fe, Mn, and Ca contents decreased significantly in the leaves of viroid-infected 'Odysso' or 'Tonami'. Similarly, the CAT and POD contents decreased significantly in the viroid-infected saplings, but the SOD content increased in the viroid-infected 'Tonami' saplings. A total of 15 and 40 differentially abundant metabolites were respectively identified in the metabolome analyses of 'Odysso' and 'Tonami' leaves. Specifically, in the viroid-infected 'Odysso' and 'Tonami' samples, the L-2-aminobutyric acid, 6″-O-malonyldaidzin, and D-xylose contents increased, while the coumarin content decreased. These metabolites are related to the biosynthesis of isoflavonoids and phenylpropanoids as well as the metabolism of carbohydrates and amino acids. These results imply that ASSVd affects apple sapling growth by affecting physiological characteristics and metabolism of apple leaves. The study data may be useful for future investigations on the physiological mechanisms underlying apple tree responses to ASSVd.

Effects of Dwarfing Interstock Length on the Growth and Fruit of Apple Tree

There is no report on the effect of the length of Jizhen 2 interstock on the growth and fruit quality of Tianhong 2 apple trees, which are usually grown in Baoding, Hebei Province, China. We surveyed the tree size, branch types, fruit set, fruit quality and root parameters of 3–5-year-old ‘Tianhong 2/Jizhen 2/Malus × robusta Rehder’ apple trees, to study the effects of dwarfing interstock length on the growth of the tree’s aboveground parts and roots, as well as fruit yield and quality. The tree height and the stem girths of the interstock and scion decreased as interstock length increased, and the dwarfing degree of the apple trees gradually increased. Trees with an interstock length of 30 cm had the fewest long branches, the most short branches, and the greatest proportion of short branches. An interstock length of 30 cm provided the highest fruit-set rate, the highest yield per tree and per unit cross-sectional area, the highest single fruit weight, the highest soluble: acid ratio, the highest color brightness (L*), and better red skin coloration (higher a*) of the fruit skin. The root length density, root surface area density, and root volume density exhibited two growth peaks in a year, during the slow growth period when spring and autumn shoots are stopped. Root length density, root surface area density, and root volume density decreased with interstock length. Root death peaked during the growth peak period of the autumn shoots, and root length density of dead roots and root turnover frequencyincreased with the interstock length. A 30 cm length was the most suitable for the Tianhong 2 apple trees when the Jizhen 2 was used as the interstock.

Integration of root architecture, root nitrogen metabolism, and photosynthesis of ‘Hanfu’ apple trees under the cross-talk between glucose and IAA

Sugars and auxin have important effects on almost all phases of plant life cycle, which are so fundamental to plants and regulate similar processes. However, little is known about the effect of cross-talk between glucose and indole-3-acetic acid (IAA) on growth and development of apple trees. To examine the potential roles of glucose and IAA in root architecture, root nitrogen (N) metabolism and photosynthetic capacity in ‘Hanfu’ (Malus domestica), a total of five treatments was established: single application of glucose, IAA, and auxin polar transport inhibitor (2, 3, 5-triiodobenzoic acid, TIBA), combined application of glucose with TIBA and that of glucose with IAA. The combined application of glucose with IAA improved root topology system and endogenous IAA content by altering the mRNA levels of several genes involved in root growth, auxin transport and biosynthesis. Moreover, the increased N metabolism enzyme activities and levels of genes expression related to N in roots may suggest higher rates of transformation of nitrate (NO3--N) into amino acids application of glucose and IAA. Contrarily, single application of TIBA decreased the expression levels of auxin transport gene, hindered root growth and decreased endogenous IAA content. Glucose combined with TIBA application effectively attenuated TIBA-induced reductions in root topology structure, photosynthesis and N metabolism activity, and mRNA expression levels involved in auxin biosynthesis and transport. Taken together, glucose application probably changes the expression level of auxin synthesis and transport genes, and induce the allocation of endogenous IAA in root, and thus improves root architecture and N metabolism of root in soil with deficit carbon.

Выращивание саженцев яблони сибирской в Чурапчинском улусе РС(Я)

The article presents the first experimental data on the cultivation of the Siberian apple tree in the conditions of the alas of Yakutia on the example of the school district of the MBOU "Ozhulunskaya secondary school". Long-term results of research (2017-2022) confirmed the plasticity of this crop in terms of the biological trait of winter hardiness. So, during the cold winter of 2021, the sum of the minimum temperatures is minus 5554.7 ° С. In January, the minimum temperature reached minus 54 °C. The provision of moisture during the growing season was at the hydrothermal coefficient (hereinafter HTC) an average of 0.62 over 5 years. In the course of the research, the landing site was chosen open, well warmed by the sun. The soil scheme of the planting pit for the apple tree was established to a depth of 50 cm. The growth and development of the Siberian apple tree was recorded. The main phenological phases of apple tree development under alas conditions against the background without irrigation were determined. Accounting for the height of the Siberian apple tree showed that the maximum growth of the main trunk falls on the age of 5, which is 53 cm of growth. At the same time, the height of the apple tree reached 123 cm. By the age of 6, the growth reaches 37 cm and the height of the apple tree is 169 cm. It was planned to establish a fruit and berry garden in the alas permafrost zone. To increase the durability of a tree, its winter hardiness should be increased. An important factor is agricultural technology, but the basis of longevity is the right choice of the location of the apple tree itself, then the rootstock, the base of the tree. The winter hardiness of the Siberian apple tree in the conditions of the alas of the Churapchinsky district showed a satisfactory assessment after the first overwintering of 2 seedlings, one remained with excellent winter hardiness in the next 4 years of research. In the future, the selected seedling without shelter can serve as forms of adapted material for landscaping gardens and parks, obtaining high-quality apple fruits. Keywords: SEEDLINGS, SIBERIAN APPLE TREE, WINTER HARDINESS, ALAS, GROWTH AND DEVELOPMENT OF SIBERIAN APPLE TREE

Effect of different dwarfing interstocks on the vegetative growth and nitrogen utilization efficiency of apple trees under low-nitrate and drought stress

• Two new interstocks were studied in apple cv. ‘Tianhong 2’. • Apple dwarfing interstocks varied in their responses to nitrate deficiency and drought stress. • ‘SH40’ had the best vegetative growth and N utilization efficiency, followed by ‘J1’ and then ‘J2’. We developed apple plants that are better adapted to growth in high-density orchards in dry areas with low-nutrient soil. One-year-old ‘Fuji’ apple cultivar ‘Tianhong 2’ on ‘ Malus. robusta’ rootstock was cultivated with ‘SH40’, ‘Jizhen 1’, or ‘Jizhen2’ dwarfing rootstock as an interstock bridge to investigate the effects on vegetative growth and nitrogen utilization efficiency under different water and nitrate conditions. The results showed reductions in several growth indices, including plant height, trunk diameter, total dry weight, relative growth rate, chlorophyll content, and net photosynthesis rate, for all interstocks under low-nitrate and drought conditions. The smallest reductions occurred with ‘SH40’ and the highest with ‘Jizhen2’. When subjected to drought, ‘SH40’ showed the minimum and ‘Jizhen2’ the maximum reduction in 15 N accumulation and utilization. Additionally, ‘SH40’ had the highest nitrogen content and uptake flux, regardless of the nitrogen level. These findings suggest that the high tolerance of ‘SH40’ to drought and low-nitrogen stress recommend its use as an interstock.

Chemical fumigants control apple replant disease: Microbial community structure-mediated inhibition of Fusarium and degradation of phenolic acids

Fusarium and phenolic acids in apple replant soil have deleterious effects on soil, which affects the growth of young replanted apple trees. Here, we studied the effects of different chemical fumigants (metham sodium, dazomet, calcium cyanamide, 1,3-dichloropropene, and methyl bromide) on Fusarium and phenolic acids in soil. The chemical fumigants disturbed the apple replant soil microbial community to different degrees in the order from highest to the lowest as methyl bromide > 1,3-dichloropropene > dazomet > metham sodium > calcium cyanamide. Compared with the control, the total numbers of Operational Taxonomic Unit (OTU) were 104.63 % and 9.38 % lower in the methyl bromide and calcium cyanamide treatments, respectively while the average contents of Fusarium were 88.04 % and 59.18% lower in these treatments, respectively. Higher disturbance degrees resulted in a slower recovery rate of the soil microbial community, which facilitated the transformation of the soil into a disease-suppressing state. During the recovery process, the roots recruited Streptomyces OTU2796 and Bacillus OTU2243, which alleviated Fusarium-induced stress via the synthesis of polyketones and macrolides. The roots also recruited Sphingomonas OTU3488, OTU5572, and OTU8147, which alleviated phenolic acid-induced stress through the degradation of benzoate and polycyclic aromatic hydrocarbons.

Changes to bacterial communities and soil metabolites in an apple orchard as a legacy effect of different intercropping plants and soil management practices.

Intercropping is an important soil management practice for increasing orchard productivity and land-use efficiency because it has beneficial effects on soil microbial communities and soil properties. However, there is relatively little information available regarding the effects of different crops/grasses on soil microbial communities and soil metabolic products in apple orchards in arid and semi-arid regions. In this study, we showed the microbial communities of apple, intercropping plants, and sandy waste soil, using the third-generation PacBio SMRT long-read sequencing technology. Our results also revealed that the microbial communities and soil metabolic properties differed significantly between apple and the sandy waste soil and the intercropping plants. Intercropping could significantly enrich diverse microbial species, microbial nitrogen, and microbial carbon of soil. Moreover, intercropping with licorice showed better effects in recruiting beneficial microbes, compared to grass and pepper, significantly enriching species belonging to some well-known taxa with beneficial effects, including Bacillus, Ensifer, Paenibacillus, Rhizobium, and Sphingomonas. Thus, intercropping with licorice may improve apple tree growth and disease resistance. Furthermore, Bradyrhizobium and Rubrobacter were included among the keystone taxa of apple, whereas Bacillus, Chitinophaga, Stenotrophobacter, Rubrobacter, and Luteimonas were the keystone taxa of the intercropping plants. The results of our study suggest that intercropping with licorice is a viable option for increasing apple orchard productivity.

Evaluation of Apple Chlorotic Leaf Spot Virus Impact on Fruit Yield and Vegetative Growth in Apple Cultivars ‘Antonovka’ and ‘Gita’

Abstract The negative influence of pathogens on plant development is well known. However, the negative impact depends on various factors: cultivar and rootstock resistance, nutrition, the environment, the virulence, and concentration of pathogens in the plant tissue. The evaluation of apple chlorotic leaf spot virus (ACLSV) influence on apple tree growth and production was performed at Institute of Horticulture (LatHort) from 2012 to 2020. Virus-free and ACLSV-infected trees from the traditional cultivar ‘Antonovka’ and new scab resistant cultivar ‘Gita’ were evaluated on dwarfing rootstock B.396. The presence of four common apple viruses (apple mosaic virus (ApMV), ACLSV, apple stem grooving virus (ASGV), apple stem pitting virus (ASPV)) was assayed in the planting year and repeated at the end of the study period. The vigour of planting material, growth, yield, and yield efficiency were compared between virus negative and ACLSV-infected trees. During eight growing seasons (2013–2020), no statistically significant negative impact of ACLSV infection on tree growth or yield was observed for the cultivars. A larger canopy volume was observed for ACLSV-infected trees (p = 0.01), but the cumulative yield per canopy volume was equivalent between virus-negative trees and ACLSV-infected trees (p = 0.07).

Subsurface irrigation with ceramic emitters: Evaluating soil water effects under multiple precipitation scenarios

China's Loess Plateau is the optimal and largest region of growing apple trees in the world. Subsurface irrigation with ceramic emitters (SICE) is an energy-efficient and water-saving approach for fruit trees in arid and semi-arid regions. Climate change, which is shifting annual precipitation regimes, is challenging the existing irrigation scheduling. However, little is known about how annual precipitation change affect the irrigation scheduling with SICE. Therefore, simulations with HYDRUS-2D and validation experiments in apple orchard were used to study the effects of the event- and annual-scale precipitation and ceramic hydraulic conductivity of emitter (CHC) on soil water dynamics. Results indicated that annul precipitation slightly affected the irrigation volume, however precipitation events had a significant effect on emitter discharge; the outflow was 22.7% and 49.7% lower in soil than in air with CHC of 0.017 and 0.077 m d−1. There was a significant positive correlation among CHC, irrigation volume and deep percolation. Precipitation and CHC both have a significant effect on the soil water content in apple orchards, the average SWCs of wet year were 17.8%− 24.7% higher than normal and dry year, the average SWC was 0.154 and 0.191 cm3 cm−3 with emitter hydraulic conductivities of 0.017 and 0.077 m d−1, respectively, in 2010. SICE could provide a stable soil water environment for apple trees in different precipitation years. Apple trees could be continuously irrigated by SICE until July, and irrigation could be stopped when the average SWC exceeds 0.20 cm3 cm−3 after July in Loess Plateau. This work may assist orchard managers in adapting their orchards by SICE to meet apple growth under future climate change conditions.