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Fazio G.,U.S. Department of Agriculture | Wan Y.,Apple Inc | Kviklys D.,Lithuanian Institute of Horticulture | Romero L.,Ciudad Universitaria s n Campus 1 31310 | And 3 more authors.
Journal of the American Society for Horticultural Science

The ability of certain apple rootstocks to dwarf their scions has been known for centuries and their use revolutionized apple (Malus × domestica) production systems. In this investigation, several apple rootstock breeding populations, planted in multiple replicated field and pot experiments, were used to ascertain the degree of dwarfing when grafted with multiple scions. A previous genetic map of a breeding population derived from parents 'Ottawa 3' (O.3) and 'Robusta 5' (R5) was used for quantitative trait locus (QTL) analysis of traits related to scion vigor suppression, induction of early bearing, and other tree size measurements on own-rooted and grafted trees. The analysis confirmed a previously reported QTL that imparts vigor control [Dw1, log of odds (LOD) = 7.2] on linkage group (LG) 5 and a new QTL named Dw2 (LOD = 6.4) on LG11 that has a similar effect on vigor. The data from this population were used to study the interaction of these two loci. To validate these findings, a new genetic map comprised of 1841 single-nucleotide polymorphisms was constructed from a cross of the dwarfing, precocious rootstocks 'Geneva 935' (G.935) and 'Budagovsky 9' (B.9), resulting in the confirmation and modeling of the effect of Dw1 and Dw2 on vigor control of apple scions. Flower density and fruit yield data allowed the identification of genetic factors Eb1 (LOD = 7.1) and Eb2 (LOD = 7.6) that cause early bearing of scions, roughly colocated with the dwarfing factors. The major QTL for mean number of fruit produced per tree colocated with Dw2 (LOD = 7.0) and a minor QTL was located on LG16 (LOD = 3.5). These findings will aid the development of a marker-assisted breeding strategy, and the discovery of additional sources for dwarfing and predictive modeling of new apple rootstocks in the Geneva apple rootstock breeding program. Source

Robinson T.,Cornell University | Hoying S.,Cornell University | Kviklys D.,Lithuanian Institute of Horticulture | Reginato G.,University of Chile
Acta Horticulturae

A replicated field trial was planted in 1999 at Olcott, New York, where we compared six peach training systems [Open Center (384 trees/ha), Quad-Vee (538 trees/ha), Tri-Vee (905 trees/ha), Bi-Vee (1583 trees/ha), Central Leader (1098 trees/ha) and Fusetto (1922 trees/ha)] with 3 cultivars ['Allstar' (yellow peach), 'Blushing Star' (white peach) and 'Flavortop' (nectarine)] all on Bailey seedling rootstock. Tree size (trunk cross-sectional area) after 10 years was negatively correlated with planting density. The Central Leader and the Slender Spindle systems which had the least pruning at planting, had the highest yield in the 2nd year while all of the other four V-shaped systems, which required severe heading at planting, had very low 2nd year yield. Cumulative yields and cumulative crop value after 10 years were positively related to planting density; however, each of the 3 Vshaped systems had higher yield and crop value than expected from their density while the 2 central leader systems had lower cumulative yield and crop value than predicted from their density. Maximum cumulative crop value was at a tree density of 1,300-1,500 trees/ha. Average fruit size was negatively related to planting density. After removing the effect of crop load, adjusted fruit size (independent of crop load) was still negatively related to tree density with the highest density systems producing the smallest fruit size even when adjusted for crop load. © ISHS 2012. Source

Kviklysa D.,Lithuanian Institute of Horticulture
Acta Horticulturae

In 2002-2007 the effect of planting height of the graft union on apple tree growth and productivity on 4 rootstocks was investigated. The experiment was carried out with cultivar 'Auksis' on M.26, M.9, P 22 and P 59 rootstocks planted at of 0, 10, 20 and 30 cm heights of the graft union above ground. Increased planting height on all rootstocks reduced tree growth. Significant differences for M.26 appeared at the height of 20 cm, for P 22 and P 59 at 10 cm. Growth of trees on M.9 rootstock was reduced gradually with increasing planting height. Total fruit yield per tree on P 22 was not affected by planting height. Trees on P 59 budded higher then 10 cm gave lower yield. Yield of trees on M.26 increased with increasing planting height up to 20 cm then decreased when they were budded higher. Yield of trees on M.9 was gradually reduced when planting height increased. Tree yield efficiency index on M.9 and M.26 rootstocks was increased as planting height increased up to 20 cm then showed a tendency to decrease when trees were planted higher. Average fruit weight decreased for M.26 and M.9 rootstocks at 30 cm, for P 59 and P 22 rootstocks at 10 cm planting height. Source

Lepsis J.,Pure Research | Bite A.,Pure Research | Kviklys D.,Lithuanian Institute of Horticulture | Univer N.,Estonian University of Life Sciences
Acta Horticulturae

Apple rootstock trials were carried out in Lithuania, Latvia and Estonia in the frame of the project "Baltic Fruit Rootstock Studies". Local cultivar 'Auksis' on rootstocks P22, P59, P61, P62, P66, P67, PB-4, Pu¯re 1, B.9, B.396, M.9 and M.26 were planted in 2005. Different climatic and soil conditions were characteristic for the trial locations. The soils were an Epicalcari-Endohypogleyic cambisol with high content of nutrient elements in Lithuania; a brown soil with residual carbonates with medium high nutrient concentrations in Latvia; and a sandy loam with medium high nutrient concentrations in Estonia. Climate conditions became more severe in the direction from Lithuania towards Estonia. The most vigorous growth and the highest yield were recorded in Lithuania. The rootstock effect on tree growth had a similar tendency, but some differences were found in each location. The rootstocks P22, P59, P61 and PB-4 appeared to be more dwarfing than M.9. The growth rate of trees on B.396, B.9, P62, P67, P66 and Pu¯re 1 was similar to those of trees on M.9. Effect of rootstocks on cumulative yield and fruit weight was modest. Wintering ability of rootstocks was different in every location. Unsatisfactory wintering ability in Latvia and Estonia was observed for the trees grafted on rootstocks P61, P22 and M.9. Rootstock P 67 had good evaluation results for several parameters. Source

Kviklys D.,Lithuanian Institute of Horticulture | Robinson T.,Cornell University
Acta Horticulturae

Seven-year old potted 'Empire' apple trees on M.9 rootstock were treated with one of 9 temperature regimes for a 10 day period when fruitlets were between 7 and 16mm at Geneva, NY. When fruit size was 7 mm, trees were placed in one of three glasshouses with different day/night temperature regimes (15/7.5°C; 22/15°C; 29/22.5°C). A second control group of trees was maintained outside. Light intensity in the glasshouses averaged 30-35% of outside light. The trees were maintained in the glasshouses for an initial 5 days and then removed for application of chemical thinners (either 7.5 mg Napthaleneacetic acid (NAA)·L -1 + 1240 mg Carbaryl· L -1 or 100 mg Benzyladenine (BA)·L -1 + 1240 mg Carbaryl·L -1) when fruits were 12 mm in diameter. A third group of trees was untreated. Trees in the field were also sprayed with either NAA + Carbaryl or BA + Carbaryl or left unsprayed. Following the application of chemical treatments, the glasshouse trees were reassigned to one of the three temperature regimes and placed again in the glasshouse rooms for 5 days. At the end of the 5 days treatment period the trees were moved back to the field for the rest of the season. Fruit set was more affected by temperatures after application of chemical thinners than temperatures before application. High temperatures for 5 days post chemical treatment had a large negative effect on fruit set. Cool temperatures for 5 days post chemical treatment had a positive effect on fruit set compared to the set at intermediate temperatures. We also estimated carbohydrate supply to the growing fruitlets by using the temperature and light levels of each glasshouse room and outside values using the Lakso carbohydrate supply/demand model. Carbohydrate balance during the 5 days after application of chemical thinners was positively related to fruit set. The addition of chemical thinners reduced fruit set at all carbohydrate balance levels but for each chemical there was a linear relationship between carbohydrate balance and fruit set. Source

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