Scion Cultivars Research Articles

Aspects influencing the rootstock - scion performance during long term evaluation in pear orchard

During 1999–2016, the performance of ‘Red Bartlett’, ‘Conference’ and ‘Beurré Alexander Lucas’ grafted on four pear (Pyrus) rootstocks OH × F 69, OH × F 87, OH × F 230, OH × F 333 and on quince (Cydonia) rootstock BA 29 was evaluated at the RBIP Holovousy Ltd. For each combination, trunk cross-section area, cumulative yield, yield efficiency and mean fruit weight were assessed. The growth vigour of the scion cultivars on OH × F rootstocks was similar or slightly higher comparing to the growth on BA 29. Throughout the years, the growth vigor and productivity of the rootstock combinations may change. Less vigorous combinations of rootstock/scion were linked with higher yields in young trees, but usually with just moderate yields in later seasons. By contrast, combinations with higher growth vigour had usually higher yields in the later seasons. This balance is genotype specific, where aside of rootstock an important role is played by the scion cultivar vigour. The bearing precocity may be influenced by the cultivar as well. The results can vary with different climatic conditions and orchard management.

Agrobacterium-Mediated Transformation of Tree Fruit Crops: Methods, Progress, and Challenges.

Genetic engineering based on Agrobacterium-mediated transformation has been a desirable tool to manipulate single or multiple genes of existing genotypes of woody fruit crops, for which conventional breeding is a difficult and lengthy process due to heterozygosity, sexual incompatibility, juvenility, or a lack of natural sources. To date, successful transformation has been reported for many fruit crops. We review the major progress in genetic transformation of these fruit crops made in the past 5 years, emphasizing reproducible transformation protocols as well as the strategies that have been tested in fruit crops. While direct transformation of scion cultivars was mostly used for fruit quality improvement, biotic and abiotic tolerance, and functional gene analysis, transgrafting on genetically modified (GM) rootstocks showed a potential to produce non-GM fruit products. More recently, genome editing technology has demonstrated a potential for gene(s) manipulation of several fruit crops. However, substantial efforts are still needed to produce plants from gene-edited cells, for which tremendous challenge remains in the context of either cell’s recalcitrance to regeneration or inefficient gene-editing due to their polyploidy. We propose that effective transient transformation and efficient regeneration are the key for future utilization of genome editing technologies for improvement of fruit crops.

New cherry rootstock and cultivar interactions directly affect orchard profitability

Due to increased production costs, Wasco County Oregon, USA cherry growers have found it difficult to remain profitable in recent years. Despite production increases in the last 30 years, average yields ha(-1) have actually fallen slightly to 10.5 t ha(-1). A newly developed cost of production study determined that at the average price received (US$ 2.14 kg(-1)), the break-even yield for ‘Bing’ cherries is 14 t ha(-1). New scion and rootstock cultivar releases have provided growers with the means to exceed this economic benchmark. In a rootstock trial in The Dalles, Oregon, ‘Bing’ cherries on ‘Krymsk 5’ rootstock yielded 21.0 t ha(-1) and ‘Krymsk 6’ yielded 21.7 t ha(-1) (5th-8th leaf). A new, productive, dwarfing rootstock series released by Michigan State University, named CoretteTM, consisting of five rootstocks: ‘Cass’, ‘Clare’, ‘Clinton’, ‘Lake’ and ‘Crawford’, also showed potential to significantly increase yields. The average number of flowers per leader cross-sectional area for ‘Bing’ on ‘Gisela 6’ was about 10 flowers cm(-2), but ‘Lake’, ‘Clare’ and ‘Crawford’ all had significantly more flowers with ‘Lake’ producing more than 20 flowers cm-2. However, in order to produce quality fruit, fruit on all five rootstocks were thinned to obtain a standard crop load. No differences in average fruit size were found between the five Corette™ rootstocks and the ‘Gisela 5’ and ‘Gisela 6’ controls in 2012 and 2013. The Krymsk rootstocks produced sufficient yields for growers to exceed all costs of production and the Corette™ rootstocks have similar potential. In addition to rootstock effects on yield, differences between cultivars also have a direct effect on profitability. Newly released cultivars offer growers an alternative to low-producing cultivars. Data from a cultivar evaluation trial in The Dalles, Oregon is presented.

Cherry production in South Africa: status quo and new initiatives

At present the main production area for cherries in South Africa is situated in the Western Cape Province, which represents about 50% of the total 262 ha that has been planted up to 2016. Previously, production centered around the Highveld region in the eastern Free State. The cherry production areas in the eastern Free State are situated at approximately 28°45’ latitude and 27°45’ longitude and 1650 m a.s.l. The Highveld region is part of the summer-rainfall area, with dry winters and below zero temperatures during winter nights. This decline in production in the Highveld region is mainly due to these adverse growing conditions. Production was also negatively affected by using the too dwarfing ‘Gisela 5’ rootstocks that were not suitable for the shallow and sandy soils. Older orchards on Mahaleb rootstock are still producing good average yields in harsh growing conditions. Current initiatives include the use of more yield efficient rootstocks like ‘Maxma 14’ and the low-chilling scion cultivars from the breeding programs in California, USA. The poor rootability of Mahaleb cuttings in the nursery and the shortages of in vitro propagated rootstocks like ‘Maxma 14’, also tempered the planting of new orchards. This problem was overcome by a mass importation of in vitro ‘Maxma 14’ from Italy, optimising the current availability of nursery trees to increase dramatically from 32,000 to 150,000 trees year-1. These new initiatives will have a positive effect increasing the number of ha in non-traditional cherry growing areas in South Africa, such as the Northern Province as well as in the warmer parts of the Western Cape Province.

Effect of rootstock-scion interaction on petiole nutrient content, bud break, and yield of three commercial grape cultivars

An experiment was conducted to study the influence different rootstocks (1103 P, SO4 and Dog ridge) on petiole nutrient content (%), bud break (days) and fruit yield (kg ha−1) of commercial grape varieties (Thompson Seedless, Flame Seedless and Kishmish Chorni). The study revealed that there was often rootstock, scion and rootstock x scion interaction effect on mineral nutrient content, yield components and yield. In general, across scion cultivars higher petiole N content was recorded with Dogridge rootstock at full bloom, while the pronounced effect on increasing petiole K content was recorded with Dogridge at bud differentiation stage. Considerable effect in increasing phosphorus (P) content was recorded with 1103 P which was comparable to own rooted vines during both the stages. Across rootstocks, Thompson Seedless cultivar recorded higher nitrogen (N) and P and Kishmish Chorni recorded higher potassium (K) content. Early bud break was observed with 1103P and own rooted vines among rootstocks and with Kishmish Chorni among cultivars. Yield per vine was higher in Thompson Seedless on own root which was on par with Kishmish Chorni on Dogridge which recorded comparable yields with 1103 P and own rooted vines. Irrespective of the scion varieties, higher bunch weight was recorded on Dogridge.

Advances in fruit crop propagation in Brazil and worldwide-apple trees

Abstract Apple production has been an important economic activity worldwide. The wide dissemination and cultivation of apple trees in several regions of the world is due to the development of propagation techniques from its domestication to the present time. Apple trees can be propagated by seeds, restricted to the use in breeding programs, and multiplied by several methods of vegetative propagation, both for rootstocks and apple scion cultivars. Considering the high technological level currently used in apple crop management, plant propagation plays a very important role in order to enable seedling production with high morphological quality and free of diseases, requiring new advances and propagation improvements in new releases of rootstocks and apple scions.

Effects of Scion Cultivar, Rootstock Age and Hormonal Treatment on Minigrafting of Persian Walnut

The experiment was carried out during 2015-2016, with the aim of investigating the effects of scion cultivar, rootstock age and hormonal treatments on the success of walnut minigrafting. Analysis of results showed that all studied factors were effective on graft-take and survival of minigrafted walnuts and other growth traits of the scions. The highest graft-take was observed on one-year-old rootstocks in hormonal treatments of 20 mg/L BA + 12.5 mg/L IBA for ‘Jamal’ and 80 mg/L BA + 50 mg/L IBA for ‘Chandler’. The highest survival rate was observed on one-year-old rootstocks in control treatment and the lowest was on two-year-old rootstocks in hormonal treatment of 80 mg/L BA + 50 mg/L IBA. The highest growth rate of scion belonged to the scions of ‘Jamal’ on one-year-old rootstocks in hormonal treatment of 20 mg/L BA + 12.5 mg/L IBA and the lowest was in scions of ‘Chandler’ on two-year-old rootstocks in hormonal treatments of 20 mg/L BA + 12.5 mg/L IBA and 80 mg/L BA + 50 mg/L IBA. In addition, diameter of the graft union on two-year-old rootstocks was more than on one-year-old ones. Histological studies showed that increase in the diameter of the graft unit on two-year-old rootstocks was due to dead and necrotic tissues at the upper parts of it which acted as a barrier against passage of water and minerals from the rootstock to the scion and reduced the growth of the scion on two-year-old rootstocks.

Effect of tree type and rootstock on the long-term performance of ‘Gala’, ‘Fuji’ and ‘Honeycrisp’ apple trees trained to Tall Spindle under New York State climatic conditions

In 2006, two 0.3 ha orchard trials were established at two sites (Dressel farm in Southeastern New York State and VandeWalle farm in Western New York State) to compare two tree types (feathered trees and bench-grafted trees) on five rootstocks [three Geneva® rootstocks (G.11, G.16, G.41) with one Budagovsky rootstock (B.9) and one Malling rootstock (M.9T337)] as controls. ‘Gala’ and ‘Fuji’ were used as scion cultivars at Dressel farm and ‘Gala’ and ‘Honeycrisp’ as the scions cultivars at VandeWalle farm. At each location, trees were planted at 3,262 trees ha−1and trained to a Tall Spindle (TS) system. Location, tree type and rootstock interacted to affect tree growth, production and fruit quality of each scion cultivar. ‘Gala’ trees from VandeWalle (Western NY State) were more productive (33% more production) than those from Dressel Farm (Southern NY State), because they produced more fruits per cm−2 and fruit size was bigger. When comparing the two tree types (feathered and bench-grafted) at both locations and across all rootstocks (B.9, G.11, G.16, G.41, and M.9T337), feathered trees were similar in tree size after 11 seasons as bench-grafted ones, except for ‘Fuji’ at Dressel farm where bench-grafted trees were 27% smaller than feathered trees. The bench-grafted trees had lower cumulative yield per hectare, cumulative yield efficiency, and cumulative crop load than the fully feathered trees. Finally, when comparing all 10 tree type × rootstock combinations, for ‘Fuji’, feathered trees with G.11, for ‘Gala’, feathered trees with G.41, and for ‘Honeycrisp’, feathered trees with G.16 were the combinations with the highest cumulative yield, high yield efficiency and crop loads, low biennial bearing, and with slightly significant larger fruits.

The performance of Geneva apple rootstocks in the province of Trento

In spring 2011, six trials of dwarf and semi-dwarf apple (Malus domestica Borkh.) rootstocks to study the performance of yield and fruit quality were established in the province of Trento in two distinct sites: 210 m a.s.l. (S1) and 650 m a.s.l. (S2). ‘Gala’, ‘Golden Delicious’ and ‘Fuji’ were chosen as scion cultivars. The M9 T337 clone was compared to two Geneva® genotypes: G11 and G16. Besides these, other genotypes such as the M9 clone Pajam 2, Supporter® 4 Pi80 and CIV-P21 were also compared to M9 T337. The cultivars did not have the same number of genotypes, therefore a comparison of genotypes in each cultivar and each cultivar in the two localities were compared. Trees were trained as spindle. After 5 years, there were significant differences in growth of trees at the two locations. Trees at S1 had higher trunk cross sectional area than trees at S2. Among the genotypes, tree size was largest with P21 and smallest with M9 T337 and Pajam 2. Likewise, G11 and G16 were higher than M9 T337 in ‘Fuji’ and similar to ‘Golden Delicious’. Instead, in ‘Gala’ G16 was significantly higher than M9 T337. Trees on G11 and G16 had similar yield as M9 T337. Yield efficiency was higher at S2 than at S1. G11 and G16 had similar yield efficiency as M9 T337 in ‘Fuji’ and ‘Golden Delicious’, and lower in ‘Gala’. S2 trees had higher number of fruits and lower fruit weight compared to S1. G11 had higher fruit weight than M9 T337 in all the cultivars while G16 in ‘Gala’ and ‘Golden’ only. G16 had better fruit over color than G11 in ‘Fuji’ and no differences were found between the Geneva rootstocks and M9 T337 in ‘Gala’.

The performance of different rootstocks in varying soil conditions

In 2011, an orchard trial of apple (Malus × domestica Borkh.) rootstocks was established using ’Golden Delicious’ as the scion cultivar. Five rootstock genotypes were planted in previously used rows under different soil conditions: replanted (R), fumigated (F) and free orchard (FOS) soils. The conventional M9 T337 was compared to rootstocks selected by Cornell-Geneva (G.41, G.16 and G.202) and Consorzio Italiano Vivaisti (P21). After five years, tree size was significantly bigger on P21 followed by G.202, G.16 and G.41. M9 T337 had similar vigor as G41. The dwarfed genotypes G.41, G.16 and M9 T337 showed higher yield efficiency over five years than G.202 and P21. Tree size was the highest in FOS followed by trees in F and R soils. Trees on M9 T337 showed a significant growth in FOS compared with trees in F soil. Total shoot growth was higher in FOS and in F soil in the first year only, compared with those in R soil. Trees on P21 showed more shoot growth in two years in F and FOS. G41 increased shoot growth in F only in the first year. Trees in F soil had higher yield only in the second and fourth year than trees in R soil and FOS. Fumigation and FOS did not affect the cumulative yield. Trees on M9 T337 and P21 had lower CY in F soil and FOS respectively.

Effects of apple (Malus×domestica) rootstocks on vigor and yield response on ‘Honeycrisp’

Tree size plays a key role in yield and management, affecting production costs and driving orchard efficiency. Three Budagovsky (B.9, B.10 and B.7-20-20), five Geneva (CG.4814, CG.4214, G.935, G.41 and G.11) and two Malling (M.9T337 and M.26) rootstocks with 'Honeycrisp' as the scion cultivar were used for this trial. The most dwarfing rootstock was B.9, while G.11, B.10, G.41, M.9 and M.26 were slightly larger. The next larger group was CG.4214, G.935 and CG.4814. B.7-20-20 was much more vigorous than all other rootstocks. Higher yields were attained with CG.4814, CG.4214, B.10 and G.41, whereas the lowest values were observed for B.9 and M.26. The most yield efficient rootstocks were B.9, G.11, B.10 and G.41.

Identifying vigour controlling rootstocks for mango

Vigour reduction in many tree crops is an essential element of highly productive, high density systems that is often achieved through rootstocks. Mangoes are large vigorous tropical trees that are traditionally grown at low density as suitable vigour reducing technologies are not commercially available. The aim of this work was to identify rootstock cultivars for mango that reduced scion vigour while maintaining or boosting yields. Ninety rootstocks are being evaluated for their ability to reduce vigour in two Australian mango scion cultivars from the National Mango Breeding Program (NMBP); ‘NMBP-1243’ and ‘NMBP-4069’. The evaluated rootstocks were sourced from a wide genetic range within Mangifera indica and related Mangifera spp. from the Australian National Mango Gene Bank and the Australian Mango Breeding Program. Rootstock-scion combinations were field planted at Walkamin, Queensland, Australia over three years, from May 2014 in randomised incomplete blocks. Tree height, canopy depth, canopy length (along the row), canopy width (across the row), rootstock trunk diameter (10 cm above the ground and 10 cm below the graft point) and scion diameter (10 cm above the graft) were measured every six months as indicators of tree growth and vigour. This is a report on the progress of 29 rootstocks from the May 2014 planting. There was a significant (p<0.05) effect of rootstock on tree height, canopy size and trunk diameter at 24 months. Seven rootstocks were consistently among the 13 lowest vigour trees for tree height, canopy length, canopy width and scion/rootstock trunk diameters, when ranked from lowest to highest vigour. These rootstocks show promise for high-density mango orchard systems. Evaluation is ongoing and will evaluate effect of rootstock on scion flowering and cropping.

Characterization of genome-wide microRNAs and their roles in development and biotic stress in pear.

Using a genome-wide analysis of miRNAs in 'Yali' pear (Pyrus bretschneideri) via the next-generation high-throughput sequencing of small RNAs with a bioinformatics analysis, we found that pbr-miR156, pbr-miR164, pbr-miR399, and pbr-miR482 and their target genes function in viral defense in 'Duli' and 'Hongbaoshi'. pbr-miR160, pbr-miR168, pbr-miR171, and pbr-miR319 and their targets function in auxin signaling pathways in 'Zhongai 4' and 'Zhongai 5'. Successful fruit production in pear (Pyrus spp.) depends on the use of optimal combinations of rootstocks and scions. Deciphering plant-pathogen defense mechanisms and hormone signaling pathways is an important step towards developing pear rootstocks and varieties with improved qualities. In the current study, we combined next-generation sequencing of small RNAs with a bioinformatics analysis to systematically identify and characterize 298 miRNAs in the pear scion cultivar 'Yali' (Pyrus bretschneideri). We also analyzed miRNAs in three rootstock varieties ('Duli', 'Zhongai 4', and 'Zhongai 5') and one scion cultivar ('Hongbaoshi'). We found that pbr-miR156, pbr-miR164, pbr-miR399, and pbr-miR482 are induced following infection with the pear virus Apple stem pitting virus (ASPV), and identified their target genes (pbRPS6, pbNAC, pbTLR, and pbRX-CC, respectively), which participate in viral defense pathways in 'Duli' and 'Hongbaoshi'. Furthermore, we identified pbr-miR160, pbr-miR168, pbr-miR171, and pbr-miR319, and found that the production of these miRNAs was suppressed under low levels of synthetic auxin. The targets of these miRNAs (pbARF, pbAEC, pbSCL, and pbTCP4) respond to auxin signaling pathways in 'Zhongai 4' and 'Zhongai 5'. Our results lay the foundation for breeding improved pear cultivars.

Long-term performance of ‘Gala’, Fuji’ and ‘Honeycrisp’ apple trees grafted on Geneva® rootstocks and trained to four production systems under New York State climatic conditions

In 2006, two 1-ha orchard trials were established at each of two sites (Dressel farm in Southeastern New York State and VandeWalle farm in Western New York State) to compare seven Geneva® rootstocks (‘CG.4210’, ‘G.11’, ‘G.16’, ‘G.41’, ‘G.30’, ‘G.210’, and ‘G.935’) with one Budagovsky (‘B.9’) and three Malling rootstocks (‘M.9T337’, ‘M.26EMLA’ and ‘M.7EMLA’) as controls. ‘Gala’ and ‘Fuji’ were used as scion cultivars at Dressel farm and ‘Gala’ and ‘Honeycrisp’ as the scion cultivars at VandeWalle farm. At each location trees were trained to four high-density systems: Slender Pyramid (SP) (840 trees ha−1), Vertical Axis (VA) (1284 trees ha−1), Slender Axis (SA) (2244 trees ha−1), and Tall Spindle (TS) (3262 trees ha−1). Location, rootstock, and training system, interacted to affect growth, production and fruit quality of each scion cultivar. ‘Gala’ trees from VandeWalle farm were smaller but more productive than those from Dressel farm. In general, the largest trees (in trunk cross sectional area: TCSA) were SP on ‘M.7’ rootstock and the smallest were TS on ‘B.9’ and ‘G.11’. Cumulatively, yield was lowest for trees on SP with ‘M.7’. However, the highest values were on TS with ‘G.11’ for ‘Fuji’, TS with ‘G.41’ for ‘Gala’, and TS with ‘G.16’ and ‘M.9’ for ‘Honeycrisp’. Independent of the cultivar, trees on SP with ‘M.7’ had the highest number of root suckers. When comparing systems which had the same rootstocks, TS trees were the least vigorous ones, but much more productive although, fruit red color was slightly reduced compared to the lower density systems. When comparing dwarfing rootstocks common across several systems, generally, ‘G.16’ trees were the largest, however ‘G.11’, ‘G.41’ and ‘M.9’ were the most productive for ‘Fuji’, ‘Gala’ and ‘Honeycrisp’, respectively.

Effects of sodic water irrigation on growth, physiological relations and ion uptake in two Ziziphus rootstocks

We studied the effects of sodic irrigation on growth, physiological parameters and mineral partitioning in Zizyphus rotundifolia (ZR) and Z. spina-christi (ZS) seedlings used as rootstocks for Indian jujube scion cultivars. Plants grown in normal soils were irrigated with fresh (control) and three kinds of sodic waters having residual sodium carbonate (RSC) levels of 3, 6 and 9 meq/l. Both the species displayed appreciable decreases in fresh and dry weights of shoots and roots at RSCiw level of 9 meq/l. Leaf chlorophyll and chlorophyll fluorescence also decreased with increasing sodicity. While leaf proline content remained unchanged up to RSCiw 3 meq/l, plants treated with 9 meq/l sodic water had nearly twofold higher leaf proline than control indicating that it could play a major role in osmotic adjustment in salt stressed plants. Na+ and Cl- contents increased while K+ and Ca2+ declined in different plant parts with increase in RSCiw. Na+: K+ ratio was higher at a given RSCiw in leaves and roots of ZS and in stems and roots of ZR reflecting better Na+ exclusion by ZR. ZR leaves also had less Cl- than ZS at a given RSCiw. Owing to these adaptive traits, both the species could tolerate RSCiw up to 6 meq/l.

Agronomic and Anatomical Indicators of Dwarfism and Graft Incompatibility in Citrus Plants

Poncirus trifoliata var. monstrosa (T. Ito) Swingle is a rootstock used in Brazilian citriculture for its potential to induce dwarfism and the viability of densified crops. Its recommendation is still restricted due to lack of research on the performance and compatibility of different types of scion under specific conditions of soil and climate. The aim of this study was to correlate plant size and productive efficiency with anatomical indicators of dwarfism or graft incompatibility between citrus scion cultivars and the ‘Flying Dragon’ trifoliate orange (FD) and ‘Rangpur Lime’ (RL) as rootstocks. The experimental design was of randomised blocks with split plots, with the experiment conducted in an orchard from the fourth to the sixth year of cultivation, under localised irrigation. The treatments consisted of two rootstocks (FD and RL) in the plots and five scion cultivars (Tahiti acid lime, and Natal, Navel, Lima Sorocaba and Pera oranges) in the sub-plots, with four replications per treatment. The agronomic performance of the plants was evaluated, together with the characteristics of samples containing the cambial zone and secondary xylem below, above and within the graft region. The FD rootstock gives the smallest size and greatest productive efficiency. The ‘Navel’ orange has good anatomical plasticity, adjusting itself more efficiently to the rootstocks. Visual symptoms of incompatibility between the ‘Pera’ orange grafted onto the FD can be seen at 64 months after planting. Vessel size and frequency, as well as the size and disposition of the cambial zone, are related to dwarfism and graft incompatibility.

Yield performance of apple rootstocks of the Geneva series on replanting soil

Abstract: The objective of this work was to identify rootstocks with competitive agronomic potential to substitute those currently used in Southern Brazil for the Galaxy and Fuji Suprema apple scion cultivars cultivated on replanting soils. The experiment was carried out in the municipality of Lebon Regis, in the state of Santa Catarina, Brazil, from the 2009/2010 to the 2014/2015 crop season, in a randomized complete block design, with four replicates. The yield performance of the 'Galaxy' and 'Fuji Suprema' scions grafted on the G.056, G.202, G.213, G.814, G.896, G.969, M.9, and Marubakaido/M.9 rootstocks was evaluated. G.896 and G.814 stood out due to their superior annual and cumulative fruit yields, as well as to their greater yield regularity, although they showed lower ability of dwarfing the scion. The greatest average fruit weight of 'Galaxy' was obtained on G.056 and G.213. For 'Fuji Suprema', G.969 promoted smaller fruits, whereas the other rootstocks did not differ. All the evaluated rootstocks produced less suckers than Marubakaido/M.9 and less burrknots than M.9 and Marubakaido/M.9. In general, on replanting soil conditions, G.202 is promising among dwarfing rootstocks, mainly for 'Fuji Suprema'. G.056, G.814, and G.896 also stand out, and the two first are more specific for 'Fuji Suprema'.

Leaf nutrient content on seven plum cultivars with grafted by budding or own-rooted trees

Abstract Several studies have been conducted in Brazil with rooting of plum scion cultivars, however, it is not known the performance and benefits of own-rooted trees at field. This study aimed to evaluate the leaf nutrient content (N, P, K, Ca, Mg, Fe, Mn, Zn, Cu and B) in seven Japanese plum cultivars (Prunus salicina) on the 2nd and 3rd year after field planting, whose nursery trees were produced by “T-inverted” budding method over ‘Capdeboscq’ peach (P. persica) or by own-rooted hardwood cuttings. The experimental design was in randomized blocks, factorial 7 x 2 (cultivars x nursery tree types), with five replicates of one tree per plot. We conclude that leaf nutrient content of Japanese plums varies among cultivars; however there is no cultivar that stands out in all macro and micronutrients evaluated. K, Ca and Mn leaf contents, when affected by nursery tree types tested, were always higher in own-rooted trees. However, Mg leaf contents, when affected by nursery tree types tested, were always higher in budded trees on ‘Capdeboscq’ peach. Own-rooted plum trees of ‘Amarelinha’, ‘Blood Plum’, ‘Pluma-7’ and ‘Reubennel’ presented higher Mn leaf contents, in relation to budded trees of these cultivars on ‘Capdeboscq’. Own-rooted ‘Cerejinha’ plum trees have highest K leaf content and also increase the agronomic interpretation class in relation to the budded trees of this cultivar on ‘Capdeboscq’.

Apple rootstock trials at Warsaw University of Life Sciences-SGGW, Poland

valuation of 22 dwarfing and semi-dwarfing apple rootstocks for several scion cultivars was conducted on fertile soil in the years 1995–2010. It was found that most of the new rootstocks performed similarly to M.9 EMLA with respect to vigour, yield, cropping efficiency and fruit mass. These rootstocks would not be, therefore, a good replacement for M.9 in Polish climatic conditions. The most promising rootstock was B 9 and some of its derivatives, e.g., B 146, B 396, P 59 and P 60. However, their suitability may be limited to particular cultivars grown under similar soil conditions.

Yield and fruit quality of grafted tomatoes, and their potential for soil fumigant use reduction. A meta-analysis

Grafted fresh market tomatoes are widely used in commercial production throughout Europe and Asia, and interest among commercial producers in the Americas has increased in recent years. Many field trials have found dramatic net economic return increases relative to non-grafted scion cultivars. However, optimal yields require growing conditions that satisfy the agronomic needs of both rootstock and scion cultivars. Most commercial rootstocks are resistant to multiple soilborne pathogens, allowing grafted plants to maintain high yields in pathogen-infested fields without the use of soil pesticides, including fumigants. Here we comprehensively and quantitatively review, for the first time, all available published trial data on fruit quality and yield of grafted tomatoes. Collectively, 159 publications included 202 different rootstocks, 126 geographic locations, and 1023 experimental treatments. Yield performance varies with the specific rootstock/scion combinations and with the conditions of a given production system. Among 949 heterograft treatments (rootstock/scion of different cultivars), grafted plant yields were not significantly higher in 65% of the cases, yet they averaged a 37% yield increase for all data. In addition, grafted/non-grafted yield ratios in 105 experimental treatments with rootstock ‘Maxifort’ varied dramatically by scion. However, European trials used completely different scions than US trials, so the roles of scion and geographical differences remain unclear. Concerns that grafting might contribute to inferior fruit quality (pH, titratable acidity, total soluble solids, lycopene, vitamin C, firmness, “taste”) seem unfounded in general, though isolated cases show dramatic differences. Grafted tomatoes show promise to reduce the usage of various soilborne pathogen treatments, with 33% of commercial tomato rootstocks either resistant or highly resistant to seven or more common soilborne pathogens. Our approach integrated trial data from around the world, though limitations in available data complicated our analysis of relationships between some experimental variables and fruit yields and quality.