Apple Nursery Trees Research Articles

Genome‑Wide Identification and Expression Analysis of SPX Domain-Containing Gene Subfamily in Response to Phosphorus-Solubilizing Bacteria in Apple (Malus domestica)

Phosphate is one of the major elements that significantly affects fruit yield and quality. The aim of the study was to determine whether using phosphorus-solubilizing bacteria could produce high-quality apple nursery trees. Five different treatments were tested on a “Granny Smith” apple cultivar that was grafted onto an M.9 rootstock. These were 100% P, 50% P, 50% P + Bacillus megatarum (plant growth promoting rhizobacteria, PGPR), 0%P, and 0%P + PGPR. The study also identified the SPX gene family, which is essential for plant growth and development and responds to phosphorus (P) stress. A total of 72 SPX genes were identified in different plant species based on structural and phylogenetic analysis. The apple genome contains seven different SPX genes distributed on five of the 17 chromosomes. Gene structure and motif analysis showed that SPX genes show a relatively conserved exon/intron arrangement and motif composition in five different species: apple, strawberry, peach, apricot, and grape. Protein–protein network analysis showed that SPX proteins are closely related to proteins involved in P metabolism in apple. The digital expression profiles of MdSPX genes among 47 apple tissues were characterized to provide insight into their potential functions. RT-qPCR revealed that the expression level of all MdSPXs was significantly downregulated in 50% P + PGPR treatments, indicating that 50% P combined with PGPR is effectively taken up by the plant, saving it from Pi starvation. These results not only confirm the key role of MdSPXs in Pi homeostasis and the Pi signaling pathway but also clarify the importance of Pi-solubilizing bacteria in plant nutrition.

Repeated Applications of a Mixture of Gibberellin A<sub>3</sub> and 6-benzyladenine Increase the Feather Number on Apple Nursery Trees in the Current Year of Grafting

Repeated Applications of a Mixture of Gibberellin A<sub>3</sub> and 6-benzyladenine Increase the Feather Number on Apple Nursery Trees in the Current Year of Grafting

Ramificação lateral em diferentes mudas de macieira pela aplicação de reguladores de crescimento vegetal

Abstract Feathering in apple nursery trees is a critical operation used to increase the quality of planting material. Plant growth regulators (PGR) could be used to form feathers in apple nursery trees. The main goal was to study the impact of different PGR and concentrations on feathering promotion in different nursery apple trees. The study had three different trials where the specific aims were to study the impact of: i) different rates of 6-benzyladenine (6-BA); ii) different PGR (6-BA and 6-BA + GA4+7) on feathering promotion, and; iii) 6-BA on feathering promotion and prohexadione calcium (P-Ca) on trunk thickening under greenhouse conditions. Both 6-BA and 6-BA + GA4+7 were effective inducing feathering in the different cultivars tested. 6-BA reduced final young plants grafted height only in one out of three seasons, reducing an average of 15 and 10 cm on ‘Early Red One’ and ‘Fuji’ apple nursery trees, respectively. P-Ca reduced tree growth rate 4-5 weeks after sprayed, but the difference did not persist until the end of the season. Trunk diameter was not affected by the different plant growth regulators and concentrations tested. 6-BA alone or in combination with GA4+7 is an efficient tool to feathering formation in different nursery apple cultivars and conditions.

Effects of plant growth regulators applications on induction of lateral branching in Oregon Spur apple nursery trees

The study presents the influence of 6-benzayladenine alone and in combination with gibberellic acid on growth and lateral branching of one-year-old ‘Oregon Spur’ apple nursery trees grafted on MM-106 rootstock. Different concentrations of BA and BA+GA3 (200, 300, 400, 500, 600 and 700 ppm) were applied three times at one week interval during second vegetative growth. Investigation reveal that Oregon Spur have strong apical dominance and plant applied with growth regulators resulted in a significant increase in number of feathers (0.58 to 6.18 per tree) compared to untreated control (0.18 per tree). However, BA alone has more significant effect on number of feathers (1.45 to 6.18 per tree) than BA+GA3 (0.58 to 4.35 per tree). Maximum number of feathers (6.18 per tree) has been obtained with 500 ppm BA treatment. This treatment also resulted in more uniform feather length (2.58 short and 2.55 medium length lateral branches per tree) and correct distribution of feathers along the trunk (20.63 cm branching zone) with appropriate average feathers crotch angle (54.74° from vertical). Furthermore, this treatment resulted in 100 per cent feathered trees compared to none in control and 2.88 trunk and mean feather diameter ratio compared to 1.54 in control. Some treatments with BA had a negative influence on the tree height. Whereas, most treatments increased trunk diameter and crotch angle compared to control.

Canker and Wood Rot Pathogens Present in Young Apple Trees and Propagation Material in the Western Cape of South Africa.

Canker and wood rot pathogens cause dieback and, in severe cases, the death of young apple trees. Recently, a higher occurrence of cankers was observed on 1-year-old apple trees in the Western Cape Province of South Africa. This study aimed to assess the phytosanitary status of nursery trees and propagation material as possible inoculum sources for canker pathogens. Thirteen 1-year-old apple orchards showing canker or dieback symptoms were sampled. Certified nursery apple trees were collected from four nurseries as well as scion and rootstock mother plant material. Isolations were made from the discoloration observed in the vascular tissue of the plant parts and from asymptomatic material. Possible canker and wood rot species were identified with PCR and sequence comparisons of the relevant gene regions and phylogenetic analyses. Similar canker and wood rot species were isolated from 1-year-old diseased apple trees, nursery apple trees, and the propagation material. Forty-five fungal species associated with canker or wood rot symptoms were identified. The top five most abundant fungal species found causing disease on commercial 1-year-old trees were also found in high numbers causing latent infection in certified apple nursery trees. These species were Didymosphaeria rubi-ulmifolii sensu lato, Diplodia seriata, Schizophyllum commune, Didymella pomorum, and Coniochaeta fasciculata, with D. rubi-ulmifolii sensu lato being the dominant species in both sampling materials. In all, 65% of certified nursery apple trees, 5% of scion shoots used for budding, and 21% of rooted rootstock cuttings from layer blocks had latent infections of canker and wood rot pathogens. Pathogenicity trials were conducted with isolates of 39 species, inoculated onto 2-year-old branches of 14-year-old Golden Delicious trees. All species caused lesions that were significantly longer than the control. This study confirmed the presence of canker and wood rot pathogens in apple propagation material as well as certified nursery apple trees, which will aid the improvement of management practices in nurseries.

Effects of Brassinosteroid Associated with Auxin and Gibberellin on Apple Tree Growth and Gene Expression Patterns

Brassinosteroid is an important hormone that interacts with auxin and gibberellin to regulate plant growth and development. However, there is currently a relative lack of information regarding brassinosteroid in apple. Previous study confirmed that exogenous brassinosteroid treatments increased growth and endogenous brassinosteroid, auxin, as well as gibberellin levels of apple nursery trees. Here we succeeded to find that exogenous brassinosteroid treatments upregulated the transcript expression of auxin biosynthesis, transport, and positive signal transduction genes as well as gibberellin biosynthesis genes. In contrast, the application of exogenous brassinosteroid downregulated the expression of genes encoding negative regulators of auxin and gibberellin signal transductions. Rapid responses of several brassinosteroid-, auxin-, and gibberellin- related genes to the brassinosteroid and brassinazole treatments inferred the crosstalk of BR and IAA or GA. Furthermore, the expression levels of cell growth-related genes were also enhanced by exogenous brassinosteroid. Auxin and gibberellin treatments also influenced growth of apple tree and enhanced the expression of brassinosteroid- and cell growth-related genes. These results indicate that the growth of apple tree is regulated by the interaction between brassinosteroid, auxin, and gibberellin. Our work opened new avenues for deep portfolio of apple tree growth and laid the foundation for future studies aimed at elucidating the mechanisms regulating hormone interactions-mediated growth in apple trees.

Apple nursery trees and irrigation water as potential external inoculum sources of apple replant disease in South Africa

Apple replant disease (ARD) is a biological phenomenon caused by soilborne agents that include selected species of fungi (Rhizoctonia and ‘Cylindrocarpon’-like), oomycetes (Pythium, Phytopythium and Phytophthora) and nematodes (Pratylenchus). Old orchard soils previously planted to apple or related species are a primary inoculum source of ARD pathogens. In the current study, nursery trees and irrigation water were investigated as potential external ARD inoculum sources in South Africa. Investigations conducted at five nurseries over two years revealed that roots of nursery trees were infested by several ARD agents. In the 2013 sampling year, Pythium irregulare and Pythium ultimum were obtained from trees in five and two of the nurseries, respectively, using isolation studies. Based on isolation studies conducted on individual trees in 2013, 47% and 4% of all surveyed trees contained P. irregulare and P. ultimum, respectively. In the 2014 season, real-time quantitative PCR (qPCR) analyses of root tissue from individual trees demonstrated that all of the nurseries and 95% of trees contained P. irregulare, whereas three nurseries and 41% of trees contained P. utlimum. The only other oomycete pathogens that were detected in nursery tree roots were Pythium spp. complex B2A and Pythium sylvaticum and each only occurred in one nursery in one of the sampling years. For all nurseries in both years, trees were consistently infected with ‘Cylindrocarpon’-like spp. Pratylenchus spp., which were only analysed in 2013, was present in all five nurseries and in 29% of the trees. Infestation levels were high, with 22% of trees having Pratylenchus root densities that exceeded 100 per 5 g of roots. Pythium irregulare was the dominant oomycete pathogen detected in irrigation water samples (31% to 76% of the samples) obtained from 13 orchards over two years on a monthly basis. The ARD pathogens P. ultimum, Phytopythium litorale and Pythium spp. complex B2A were rarely identified in irrigation water, along with five other non-pathogenic Pythium and Phytopythium species. The association of ARD causative agents with nursery trees and irrigation water suggests that these could function as potential ARD inoculum sources that might limit post-plant tree growth.

Feathering ability of apple, pear and cherry nursery trees treated with different branch-inducing methods

Feathering ability of apple, pear and cherry nursery trees treated with different branch-inducing methods

Use of Plant Growth Regulators for Feathering and Flower Suppression of Apple Nursery Trees

The use of highly feathered trees can make high-density apple plantings more profitable through enhanced precocity and increased early yield. Currently, nurseries are asked to provide highly feathered trees with wide branch crotch angles. The use of plant growth regulators (PGRs) can play a key role when it comes to branch induction; however, dose and timing both need to be tested to enhance branching without compromising other tree quality attributes. Over the last 4 years, we have conducted studies of the use of MaxCel® (6-benzyladenine) and Promalin® (a mixture of 1.8% 6-benzyladenine and 1.8% GA4+7) in comparison with Tiberon™ SC (cyclanilide) at several nurseries in NY, WA, DE, Ontario (Canada), and Chile. The best results were obtained with four applications of MaxCel® or Promalin® (400 mg·L−1) beginning when leader growth reached 70 cm above the soil line and reapplied at 10–14 days intervals. Promalin® was a slightly less effective branching agent than MaxCel®. On the other hand, Promalin® stimulated leader growth resulting in improved final tree height, whereas MaxCel® induced the widest branch angles. Overall, we observed good response and quality ratings with ‘Cameo’, ‘Cripps Pink’, ‘Enterprise’, ‘Fuji’, ‘Ambrosia’, ‘Crimson Crisp’, ‘Gingergold’, and ‘Granny Smith’, whereas less quality ratings were observed on ‘Ambrosia’, ‘Cortland’, ‘Goldrush’, ‘Honeycrisp’, and ‘Suncrisp’. Response with ‘Gala’ varied depending on the temperature range. Multiple sprays of Gibberellins (GA4+7, or GA3) at 250 mg·L−1 applied to nursery trees in the late summer inhibited flower bud development and flowering in the orchard the next year. This reduces the risk of fire blight infection in newly planted trees.

Branch induction via prolepsis in apple nursery trees

Branching in fruit trees is mostly cultivar-dependent. However, the branching habit of genotypes might be altered by training methods. This study has been carried out to investigate the tree quality of different methods focused on proleptic and sylleptic branching in the apple nursery. 'Golden Reinders'/'M.9' combination was used as a plant material. Knipboom tree for syllepsis and fruitful tree for prolepsis were chosen. Data were collected for tree quality (branch character, tree height, spur and brindle, tree weight, root: shoot ratio, total leaf area, etc.) and physiological criteria (total carbohydrate, nutrients, etc.). Fruitful tree significantly increased the number of branches (>25 cm) in comparison to knipboom tree. The fruitful tree produced 7.05 branches tree-1 in the first year and 6.97 branches tree-1 in the second year of the trial. The best results for branch crotch angle, spur number, brindle number, trunk diameter and tree height were obtained from fruitful tree treatment in both trial years. Proleptic branching e.g., fruitful which is a new approach in the nurseries found to be a satisfactory method to promote many tree quality and physiological characteristics.

Protection of budding wounds in apple nursery trees from European canker

The fungus Neonectria ditissima can cause European canker in apple nursery trees In this study ten treatments of EMLA 9 rootstocks budded with Royal Gala were examined 5 Treatments included combinations of five budding tapes two budding methods and three fungicidal treatments Fifteen months after inoculation all Tbudded trees had died Chipbudded trees inoculated after tying with either Flexiband type C or plastic precut strips displayed significantly more canker (21 and 22 respectively) than those tied with Buddy tape (11 P

The influence of BA and BA+GA4+7 on formation of sylleptic shoots on one-year-old apple nursery trees

This study presents the influence of BA (6-benzyladenine) and BA+GA4+7 (6-benzyladenine + gibberellic acids 4 and 7) on feathering of one-year-old apple trees of two cultivars Jonagold and Cadel. Different concentrations of BA (300, 600, 1,200 and 1,800 mg L-1) and BA+GA4+7 (500, 1,000, 1,500 and 2,000 mg L-1) were applied, and two treatments for both chemicals were performed. The first treatment was applied at 70-cm height of nursery trees and the second 2 weeks later. Comparison was performed in relation to untreated control. An application of BA and BA+GA4+7 did not affect both rootstock and nursery tree diameter at 10 cm above the grafting union. Nursery trees of cultivar Jonagold were not influenced by treatments applied, whereas in cultivar Cadel, the treatment with BA+GA4+7 decreased apical growth of nursery trees. The development of sylleptic shoots in both cultivars tested was influenced by the type of growth regulator and concentration applied. Treatment with BA at 300 mg L-1 concentration in both cultivars tested did not influence total length and number of sylleptic shoots, as well as the number of sylleptic shoots longer than 20 cm. The most positive influence on all studied parameters was observed on nursery trees treated with the concentration of 1,200 mg L-1 BA. The lowest concentration of BA+GA4+7 (500 mg L-1) caused the low feathering of both studied cultivars. The higher concentrations (1,000, 1,500 and 2,000 mg L-1) similarly increased the number and total length of sylleptic shoots of nursery trees.

The use of ethephon and mixtures of ethephon luith inorganic defoliants to defoliate apple nursery trees

Ethephon alone and in a mixture with inorganic defoliants was used to defoliate apple nursery trees of three cultivars: Yellow Transparent, McIntosh and Jonathan. The mixture of ethephon with copper sulphate or magnesium chlorate defoliated the trees better than ethophon or inorganic defoliants used seperately in twice as high concentrations as in a mixture. The tress defoliated with the mixtures of defoliants suffered less from frost injury than those treated with only the inorganic defoliants.

지표면 멀칭재료가 지온과 사과나무 묘목의 수체생육에 미치는 영향

본 실험은 멀칭용 P.E 필름 종류에 따른 지온변화가 사과 우량 측지묘 생산에 미치는 영향을 구명하고자 실시하였다. 투명 P.E. 필름, 흑색 P.E. 필름 피복구와 대조구로 무피복구를 두고 대목 직경이 9.1~11.0mm인 M.9 대목을 재식하였다. 대목 재식 3주 후에 사과 '시나노 스위트' 품종을 절접하였으며, 6월 중순에는 재식 당년 측지발생을 유도하기 위하여 묘목에 BA를 살포하였다. 생육기인 4월 중순부터 11월 초순까지의 대조구의 지온은 기온보다 약 <TEX>$0.7^{\circ}C$</TEX> 정도 높았고, 피복구의 지온은 대조구보다 약 <TEX>$1{\sim}5^{\circ}C$</TEX> 정도 높았다. P.E. 필름 종류별 지온은 투명 P.E. 필름 피복구가 흑색 P.E. 필름 피복구보다 약 <TEX>$2{\sim}3^{\circ}C$</TEX> 정도 높았다. 기상요소에 따른 지온의 일교차는 흑색 P.E. 필름 피복구가 시험구중 가장 낮았다. 사과 묘목의 생장과 측지 발달에 있어서는 피복구가 무피복구보다 생장이 양호하였다. 우량 측지묘 획득률은 흑색 P.E. 필름피복구가 가장 높았는데, 그 이유는 생육초기 지온이 대조구보다 높게 유지되면서 여름철에 지온이 <TEX>$35^{\circ}C$</TEX>를 넘은 적이 투명 P.E. 필름 피복구보다 많지 않았기 때문으로 추정되었다. This study was conducted to investigate the influence of different polyethylene film (P.E. film) for mulching on the changes in soil temperature and the production of good feathered apple nursery trees. M.9 rootstocks with stem diameter of 9.1~11.0 mm were planted in plots covered with different P.E. film (i.e., transparent P.E. film, black P.E. film, and bare soil as control). Three weeks after planting, the rootstocks were veneer grafted with 'Sinano Sweet' apple cultivar. In the middle of June, BA was sprayed to nursery for inducing feathering during the growing season. The soil temperature of the control was higher than air temperature by about <TEX>$0.7^{\circ}C$</TEX> from mid April to early October, and that of P.E. film mulching was about <TEX>$1{\sim}5^{\circ}C$</TEX> higher than that of the control. The soil temperature under transparent P.E. film was about <TEX>$2{\sim}3^{\circ}C$</TEX> higher than that under black P.E. film. The diurnal range of soil temperature under the black P. E. film was lowest among all treatments. The P.E. film mulching induced better tree growth and feathering than bare soil. Percentage of good feathering apple nursery of black P.E. film was highest among all treatments because the soil temperature unuder black P.E. film in the early growing season was higher than that of the control and the number of days when the maximum soil temperature was over <TEX>$35^{\circ}C$</TEX> in the summer was lower than that under the transparent P.E. film.

わい性台木を用いたリンゴ２年生苗木の側枝発生に及ぼす切り返し，芽かき，ベンジルアデニン散布の影響

近年, 欧州においてリンゴ苗木の品質改善が進みつつあるが, わが国では依然として棒状の苗木が用いられている.本試験では, 'ふじ'などの日本の経済品種を用いて, 側枝の発生した2年生苗木の育成法について検討した.棒状に生育した1年生苗木の切り返し(Pruning)と芽かき(Bud removal)処理による側枝発生の品種間差を検討した結果, マルバカイドウを台木として用いたM.9ナガノ中間台木苗を二重台木法で用いた場合, '芳明', 'らくらくふじ'では平均5&acd;8本の側枝が発生し, 'シナノレッド', '秋映'は側枝の発生が劣ることが明らかとなった.'シナノスイート', 'シナノゴールド'はこれらの品種の中間的な特性であった.棒状に育った'ふじ'の1年生苗木への切り返し(Pruning), 芽かき(Bud removal), BA散布による側枝の発生効果を検討した結果, これらの処理の組み合わせにより平均15本程度の分岐角度の広い側枝がフェザーとして発生し, 円錐形の樹冠が形成された2年生苗木を育成できることが明らかとなった.

IMPROVED FEATHERING ON APPLE NURSERY TREES BY BA APPLICATION

IMPROVED FEATHERING ON APPLE NURSERY TREES BY BA APPLICATION

244 Effects of Fall Urea and Copper Chelate (CuEDTA) Application on Defoliation, Reserve Nitrogen, and Spring Regrowth of `Fuji' Apple Nursery Trees

Bench-grafted `Fuji'/M.26 trees were sprayed with 1% CuEDTA on 31 Oct., defoliated manually on 12 Nov., or allowed to defoliate naturally. Foliar urea at 3% was applied at 14 days and 9 days before CuEDTA treatment. Plants were harvested after natural leaf fall and stored at 2 °C. One set of the plants were destructively sampled for reserve N (expressed as total Kjeldahl N or soluble protein concentration) analysis, and the remaining plants were transplanted into a N-free medium in the spring without any N supply for 40 days after budbreak. CuEDTA resulted in &gt;80% defoliation within 5 days of application. Trees defoliated with CuEDTA had lower reserve N content than naturally defoliated controls, but had higher N than hand-defoliated controls. Foliar urea application before the CuEDTA treatment significantly increased reserve N level in all tree parts, without affecting the efficacy of CuEDTA on defoliation. The extent of spring regrowth was proportional to the reserve N level of the tree. Urea-treated plants, whether hand- or CuEDTA defoliated, had more growth in the spring than hand- or naturally defoliated controls. It is concluded that CuEDTA, as combined with foliar urea, can be used to effectively defoliate apple nursery trees, and increase reserve N level and improve regrowth performance during establishment.

EFFECT OF REPEATED BA (BENZYLADENINE) APPLICATION ON FEATHERING OF ‘IDARED’ APPLE NURSERY TREES

EFFECT OF REPEATED BA (BENZYLADENINE) APPLICATION ON FEATHERING OF ‘IDARED’ APPLE NURSERY TREES

Branch induction on apple nursery trees: Effects of growth regulators and defoliation

Abstract One‐year‐old apple (Malus domestica Borkh.) nursery trees of several cultivars on MM 106 and M 9a rootstock were sprayed once in early summer with benzyladenine (B A) followed by one, two, or three applications of gibberellin (GA4+7) either in 1989 or in 1990. In both years GA4+7applied at the same time or 2 weeks after a B A spray produced more branches and more total growth than controls. In 1990, but not 1989, GA4+7 applied 2 weeks after BA stimulated more branches and more total branch length than when these chemicals were applied together. In 1990 multiple applications of GA4+7 beginning 18 days after B A sprays induced the longest branches, most total branch growth, and greatest branch crotch angles than applications involving a single GA4+7 plus B A spray. In addition in 1989, immature leaves were removed immediately beneath the growing tip on the main stem (LR) once in early summer and sprayed with or without GA4+72 weeks later. Leaf removal treatments did not affect branching.

Branch Induction by Growth Regulators and Leaf Removal in ‘Delicious’ Apple Nursery Stock

Abstract Spur-type ‘Delicious’ apple nursery trees do not naturally branch in the nursery. In several experiments during 2 years, combinations of immature leaf removal (LR), BA, and gibberellins 4 + 7 (GA4+7) at 750 and 1000 mg·liter–1 induced lateral shoot formation of Campbell and Mercier strains of ‘Redchief Delicious’ trees in a commercial nursery. Split applications of BA and GA4+7 at 1000 mg·liter–1 induced more and longer branches than simultaneous applications. GA3 did not substitute for GA4+7 in this response. Removing young shoot tip leaves increased branching only when very young leaves were removed during a period of 2 weeks. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine (BA), gibberellin (GA).