Apple rootstock studies: growth of trees on three clonal rootstocks planted with or without roots

Trees of Cox's Orange Pippin on M.IXa, M.26 and MM. 106 were planted either normally with roots or without roots to simplify the planting operation. Pruning treatments were superimposed, the trees being cut back at planting, left unpruned the first year and cut back the second year, or left entirely unpruned. All trees survived. After two growing seasons the trees were lifted and weighed. Removal of all roots before planting reduced shoot growth, trunk girth increment, final tree weight and incremental weight. However, on all rootstocks, trees planted without roots and left unpruned were similar in size when lifted to those planted with roots and cut back at planting in the orthodox manner.

In a complementary trial lasting one season Cox's Orange Pippin trees on M.26 were planted with or without roots. All trees were cut back at planting, and four times of planting were compared. The mid-April planting included trees that had been stored at 2.8 °C and trees that had been bedded-in outdoors. There were no tree losses attributable to removal of the roots before planting. Removing the roots at planting again reduced growth and weight of tree at lifting. Month of planting had no effect upon shoot growth or trunk girth increment.

The results are discussed, together with their practical implications in relation to mechanical tree planting for high density orchards.     

Performance of ‘Discovery’ apple on M.9, M.26 and MM.106 rootstocks at two densities

Summary

The apple rootstocks M.9, M.26, and MM.106 were evaluated for their efficiency in bringing ‘Discovery’ apple trees into production. The experiment, carried out over a ten- year period compared two planting densities at 1666 and 3333 trees per ha. Tree vigour differences between rootstocks were measured in term of trunk growth, tree volume, weight of branches pruned off and final weight of the above-ground parts of the trees. Fruit production is presented both as total yield and as the weight of first class fruit. Fruit colour development is also shown. Cropping efficiency is calculated and presented in relation to the different vigour measurements. The results confirm that ‘Discovery’ is slow to come into production. M.9 was the most productive rootstock, but due to vigour differences MM.106 gave the same yields per tree, although the latter had the lower yield efficiency. M.26 performed poorly; its vigour was similar to M.9 but it produced the lowest yields.     

Rootstock influence on ‘delicious’ and ‘golden delicious’ apple fruit quality at harvest and after storage

The influence of 9 rootstocks (M2, M7, M25, M26, MM104, MM106, MM109, MM111 and seedling) on fruit quality at harvest and after storage of ‘Wellspur Delicious’ (WS) and ‘Goldspur’ (GS), and of 3 rootstocks (M7, M26 and MM106) on fruit quality of ‘Red King Delicious’ (RK) and ‘Golden Delicious’ (GD) apple (Malus domestica Borkh.) was evaluated during a 4-year period. Fruits from trees on M26 were larger, developed earlier color and soluble solids (SS), and maintained higher levels of acidity (at harvest and during storage) in comparison with other rootstocks. Fruit from trees on M2 tended to have high SS. Fruit color from trees on MM104, MM106 and MM109 tended to be comparatively poor. There were significant rootstock effects on SS, starch, acidity, color, circumference, weight and box size.     

Root and shoot growth of newly-transplanted apple trees as affected by rootstock cultivar,defoliation and time after transplanting

Summary

An experiment with Malus demonstrated that a large proportion of the transplanted root system was lost through death and decomposition soon after transplanting in the open ground. Mortality of the roots was not influenced by the rootstock cultivars or by defoliation but increased significantly with time. In the first month, shoots of maiden trees of Malus transplanted in June when in-leaf grew, but roots did not. Subsequently, most of the new roots on the rootstock M.9 regenerated from the rootstock stem, whereas with MM.106 the old coarse roots (>2.0 mm diameter) initially present at planting were most important. Root growth occurred in concert with shoot growth such that a functional balance was maintained as shown by the existence of a constant root length:leaf area ratio over a large part of the growing season. Following transplanting, the trees appear to re-establish their optimal ‘functional’ ratio by way of a co-ordinating pattern of growth tending to correct any disturbance to the ratio resulting from transplanting. Defoliation in the early establishment phase caused only a temporary initial reduction in the root growth, but reduced all the shoot growth variables measured and increased the root length:leaf area ratio throughout the growing season.     

Crown rot (Phytophthora cactorum) of apple in Britain: Observations on natural outbreaks,and experiments on artificially inducing the disease in the field

Crown rot (Phytophthora cactorum) of apple came to prominence in Britain in the 1960s following the introduction of certain new types of clonal rootstock. Observations on crown rot outbreaks over the period 1976 to 1984 were as follows: only rootstocks MM.104 and MM.106 were affected; infection occurred in the bark of the rootstock axis below soil level; lesions caused girdling, and sometimes appeared above soil level and spread down the main roots to a limited extent; infection occurred during the growing season but disease development ceased with the onset of winter and did not resume the following year; trees on MM. 104 were susceptible throughout the life of the orchard while trees on MM. 106 were susceptible only during the establishment years; disease outbreaks occurred sporadically. Crown rot was induced experimentally on trees grafted on MM. 104 and on M.25 in field trials by irrigating for four to six weeks through inoculum applied to the base of the trees. No crown rot occurred on grafted MM.106 or on other grafted rootstocks in the same trials, although lesions developed above soil level on a few trees. The limited experimental data indicated that MM.104 was liable to attack throughout the growing season. The importance of environmental influences on the susceptibility of rootstocks to crown rot is discussed.     

Dormant and Summer Pruning Compared by Pruning Young Apple Trees Once on a Succession of Dates

Rooted cuttings of Malus sylvestris (L.) Mill. var. M.VII were permitted to grow from a single shoot. This was cut back to 3 cm. and the utilization of the subsequent increment, as leaves, stem and root, was determined. Different batches were treated on 7 occasions–June, July, August and December of the 1st year of the bud’s growth and March, April and June of the 2nd year. Also two further batches were cut back in the 2nd year (June and July) to the base of the 2nd year’s shoots. The growth to the end of the 1st and 2nd years was compared with that of unpruned controls.

In most cases pruning reduced the subsequent increment. Following dormant pruning (December, March, April) this reduction was associated with fewer growing shoots, although the leading shoots might be longer than comparable shoots on the controls. The reduction in increment after pruning leafy shoots was attributed to the loss of leaf and to shortening the effective growing season. Such leafy pruning was equivalent to the loss of ½ to ? of the growing season.

The relative distribution of increment (i.e. increment of the part as a fraction of the total increment) to leaf, stem and root was little affected by pruning. The main effect of pruning occurred within the stem region, where the fraction utilized by the old stem decreased, and by the new stem correspondingly increased, so that the total stem fraction changed very little. A small effect following pruning leafy shoots was that the leaf fraction increased slightly and the new stem decreased.

It is concluded that the different effects of dormant and summer pruning may be attributed to the relative importance at different times of the year of bud inhibition and curtailment of the growing season.     

Response of secondary bloom of ‘Bartlett’ pear (Pyrus communis L.) to pruning

Summary

Type V secondary bloom of pear (Pyrus communis L.) is associated with pruning and is frequently infected by fire blight (Southwick et al., 2000). The goal of this research was to determine which pruning practices would most likely be associated with subsequent Type V secondary bloom. Pruning date, shoot age, type of pruning cut and shoot orientation were varied and effect on Type V secondary bloom assessed. In both 1998 and 1999, dormant pruning was more likely to result in Type Vs than summer pruning or pruning one month after harvest. Pruning one week after harvest in 1998 was as likely to lead to Type Vs as dormant pruning, but was less likely in 1999. The likelihood that Type Vs would occur was lowest from 49 to 89.d from full bloom (DFB) and at 175 DFB in 1998. The lowest likelihood of Type Vs in 1999 was found on shoots pruned at 83 or 185 DFB. The likelihood for Type Vs rose with increasing shoot age from one to four years, but there was no difference between three- and four-year old shoots. In 1998, stub cuts (severe heading) were more likely to have Type Vs than head cuts when pruning two year old shoots, but not for one year old shoots. In 1999, type of pruning cut had an inconsistent effect on the likelihood for Type Vs and was not the same for each shoot age. NAA applied to summer pruned shoots completely prevented Type Vs from occurring and almost completely stopped Type Vs when applied to dormant pruning cuts. Summer pruning from 50 to 90 DFB or pruning one month after harvest and the application of NAA to pruning wounds may be strategies for reducing the occurrence of Type V secondary bloom.     

Effects of tree age at planting,root manipulation and trickle irrigation on growth and cropping of apple (Malus pumila) cultivar Queen Cox on M.9 rootstock

Summary

The apple cultivar Queen Cox on M.9 rootstock cropped more precociously when planted as two year old trees than when planted as one year old trees, even though there were no significant differences in the sizes (leader height and branch length) of the trees at the time of planting. However, the two year old trees had larger root systems at planting. As the trees aged, those planted as one year olds grew more vigorously and bore higher cumulative yields than those planted as two year olds. Annual root pruning of the trees, commencing 15 months after planting, reduced extension shoot growth, crown volume and grubbing weights (final fresh weights of scions) severely. In some seasons root pruning increased the number of spur and terminal floral buds produced and also the final sets and yield efficiencies on the treated trees. Planting trees within semi-permeable fabric membranes also reduced extension shoot growth and tree size, but less severely than the root-pruning treatment. Root restriction increased the efficiency of fruit set and yields and also improved the grades of fruits produced. Trickle irrigation treatments increased shoot growth and tree fresh weight at the time of grubbing, but had inconsistent and small effects on fruit set and yields. Interactions between tree age at the time of planting and the root manipulative treatments were significant.     

Polar transport of [3H]-IAA in apical shoot segments of different apple rootstocks

Summary

The polar transport of [³H]-indole-3-acetic acid in apical shoot segments of clonal apple rootstocks (M.27, M.9, M.26, MM.111 and MM.104) was investigated in the UK using a donor-receptor system. The month in which the experiment was undertaken had a significant influence on the uptake and transport of [³H]-indole-3-acetic acid activity; uptake and transport were greater in June and July (faster extension growth period) than in August (slower extension growth period). Shoot segments from dwarfing rootstocks (M.27 and M.9) showed smaller uptake and less transport of [³H]-indole-3-acetic acid than those from invigorating rootstocks (MM.111 and MM.104). [³H]-indole-3-acetic acid was transported to the agar receptors through shoot segments from all the rootstocks in June and July; those from dwarfing rootstocks showing lower levels of transport than those from invigorating ones. However, in August, [³H]-indole-3-acetic acid activity from the agar receptors was detected only from shoot segments of invigorating rootstocks, which continued to produce extension growth slowly, when dwarfing rootstocks had already ceased shoot extension growth. These results are discussed with reference to the effects of apple rootstocks on the size of scions.     

Light penetration,growth, and fruit productivity in ‘Fuji’ apple trees trained to four growing systems

The study was conducted to document the range in soil nutrients, trunk and shoot growth, leaf characteristics and nutrient content, flower bud characteristics, yield, fruit quality, disease occurrence, light penetration, and shoot bark color in a 15-year-old ‘Fuji’ apple (Malus × domestica Borkh.) orchard on M.26 rootstocks trained to four growing systems. SS trees naturally growing had greater width and volume than the LT lightly heading, MLT heavily heading, and S trees thinning and bending. LT trees had more upward terminal shoots at old branches, large numbers of lateral shoots, and longer total shoot length. Leaf [N], [P], and [K] were the lowest for the MLT trees. SS and S trees had greater flower bud density and fruit yield, but LT trees had poor fruit color and less soluble solids and firmness. Percent light penetration into the canopy was the highest with the S system but not different from MLT or SS. The lowest was for the LT system, however, it was not statistically different from MLT or SS.     

Effects of growth retarding treatments on apple tree growth,fruit maturation and fruit abscission

SUMMARY

Eight days after petal fall in 1991, mature 'Delicious'/MM. 106 apple trees and four days after petal fall in 1992, mature 'McintoshVMM. 106 were ringed, scored, root pruned (1 m from the trunk, two sides, 30 cm deep), or treated with ethephon (500 mg 1¹). Only ringing and scoring reduced vegetative growth. Ethephon advanced fruit maturation and fruit abscission, but root pruning did not affect the trees or fruit significantly. Mature 'Cort-land'/M.7a apple trees were root pruned 8 d after petal fall in 1991 and/or at full bloom in 1992. Root pruning reduced shoot growth, even in the year after treatment. Fruit abscission was reduced in 1991 and 1992 by root pruning in 1991, but root pruning in 1992 had no impact on abscission, in 1992. In an additional experiment, mature 'Mcintosh'/ MM.106 were root pruned 4 d after petal fall in 1991 or root pruned both in 1991 and at full bloom in 1992. Growth and preharvest fruit abscission were reduced in both the year of root pruning and the year after.     

The Relationship Between Growth Vigour of Rootstock and Phenolic Contents in Apple (Malus × domestica)

The aim of the study is to determine the effect of different growth vigorous rootstocks on phenolic compounds in leaves of apple. For this purpose it was used the leaves of cultivar ‘Red Chief’ grafted on dwarf (M9), semi-dwarf (M26) and semi-vigorous (MM106) rootstocks. During mid-July, the leaf samples were taken from the middle part of annual shoots. Phenolics of the leaves were determined by HPLC analysis. While significant differences among the rootstocks for p-hydroxybenzoic acid, eriodictyol, ferulic acid and p-coumaric acid were detected, these differences were insignificant for gallic acid and quercetin. It was shown that semi-vigorous rootstocks (MM106) had higher phenolic contents in total than the other two dwarf rootstocks. In addition, apigenin-7-glucoside, chlorogenic acid, caffeic acid, rosmarinic acid, epicatechin, syringic acid, catechin, rutin, resveratrol, hesperidin, naringenin, luteolin, apigenin and acacetin could not to be detected. Data showed that there is the relationship between growth vigour and phenolic contents of apple leaves. Especially, p-hydroxy benzoic acid and p-coumaric acid contents were higher in semi-vigorous rootstock than in dwarf rootstock.     

Effect of plant growth promoting rhizobacteria on young apple tree growth and fruit yield under orchard conditions

The effects of rootstocks (M9 and MM 106), cultivars (Granny Smith and Stark Spur Golden) and growth promoting rhizobacteria (OSU-142, OSU-7, BA-8 and M-3) on the tree growth and yield at apple (Malus domestica Borkh) trees were studied in a clay loam soil in the eastern Anatolia region of Turkey in 2002–2004. Plant growth promoting rhizobacteria (PGPR) were capable of producing indole acetic acid (IAA) and cytokinin, but three of them (OSU-7, BA-8 and M-3) were also able to dissolve phosphate. Maximum shoot number of apple trees was found after inoculation with BA-8 followed by OSU-7 and M-3. All the inoculated PGPR strains contributed to the increase in fruit yield of apple when compared to control but it was strongly depended on rootstocks, cultivars and treatments. Plant growth responses were variable and dependent on bacterial strains, rootstock and cultivar and growth parameters evaluated of young apple trees. Newly planted apple trees inoculated with OSU-142, OSU-7, BA-8 and M-3 PGPR increased average shoot length by 59.2, 18.3, 7.0 and 14.3% relative to the control and fruit yield by 116.4, 88.2, 137.5 and 73.7%, respectively. Bacterial inoculation increased shoot diameter from 7.0 to 16.3% when compared to control. The production of plant growth hormones has been suggested as one of the mechanisms by which PGPRs stimulate young apple sapling growth. The growth-promoting effect appears to be direct, with possible involvement of the plant growth regulators indole-3-acetic acid and cytokinin. In view of environmental pollution due to excessive use of fertilizers and high costs of the production of fertilizers, PGPR strains tested in our study have potential to be used for the sustainable and environmentally benign horticultural production.     

着色系富士苹果在矮化自根砧上的生长和结果表现(1980—1986)

在苹果矮化密植栽培中,良好的砧穗组合,对早果、丰产、优质起着决定性的作用。本项工作以着色系富士品种嫁接于6种营养系矮化自根砧上,通过6年的观察表明,长富6号与M26砧木是较理想的砧穗组合,能够达到3年结果、5年丰产的要求。此外,MM系的106、104、111等组合亦优于对照M7,而MMl06组合上的果实品质最佳。     

Apple Rootstock Studies: Fifteen Years’ Results with Malling-Merton Clones

The field performance of 27 apple rootstock clones, including M.XXV and all the Malling-Merton ones is reviewed over a fifteen-year period. Three scion varieties were used, Cox’s Orange Pippin, Jonathan and Ellison’s Orange, and the trials were planted both on loam and on sand soil types.

None of the new clones made trees as small as those on M.IX, their vigour ranging from that of M.VII to that of M.XVI. MM.106 made trees similar in size and cropping to those on M.VII on the loam soil, but on the sand they were smaller. MM.I06, unlike M.VII, was free from the suckering habit. Trees on MM.III and M.Il were similar in size but Cox on MM.III yielded 20% more fruit over the whole period of the trial and during the years 11 to 15. Trees on MM.I04 were heavy-bearing and larger than those on M.Il and MM.III. In the very vigorous group, MM.Iog cropped heavily but was poorly anchored. Trees on M.XXV were superior in this respect and cropped more heavily than those on M.XVI. Cox and Ellison were unthrifty on 829, but the Jonathan trees behaved normally. Jonathan on MM.102 showed severe interveinalleaf scorch symptoms of magnesium deficiency and cropping was poor.

Many of the new rootstocks fell into similar vigour groups. It is suggested that, in other apple-growing areas of the world, other rootstocks besides MM.104, MM.106, MM.III and M.XXV, which were selected .for English conditions, should be tried experimentally. The data presented suggest MM.1O1, MM.103, MM.110, MM.115 and MM.116 as worthy of local study in addition to the four others.     

Relationships among mineral nutrition,ethylene and post-harvest physiology in apples on six rootstocks

The relationships among several mineral elements of August-sampled leaf October-harvested fruit, maturity and post-harvest quality factors of ‘Starkspur Golden Delicious’ apple trees grown on Seedling, Malling (M) 1, Malling Merton (MM) 106, M 7, Oregon Apple Rootstock (OAR 1) or M 26 in a high-density orchard during 1980–1982 were evaluated. Positive correlations were found between leaf N, K and P and fruit N, K and P, respectively, in most rootstocks. Leaf Ca did not correlate with fruit Ca; thus leaf analysis cannot be recommended for estimates of fruit Ca. Both leaf and fruit N positively correlated with fruit green color and negatively with fruit soluble solids in all rootstocks. Fruit Ca and fruit P were both negatively correlated with fruit soluble solids at harvest and after 6 months of 0°C storage for all rootstocks. The ratio of fruit $\text{N}\text{Ca}$ was positively correlated with internal ethylene in MM 106, M 7 and OAR 1, while fruit $\text{K}\text{Ca}$ ratio was positively correlated with titratable acidity in all rootstocks. Fruit Ca showed negative correlations with bitterpit, storage rot and field internal ethylene, but positive correlation with firmness. Yield was positively correlated with leaf and fruit N, Ca and Cu but slightly negatively correlated with B of those tissues. Higher yield was associated with lower leaf K concentrations. Fruit green color was negatively correlated with soluble solids and titratable acidity. Fruit dry matter was highly positively correlated with soluble solids and titratable acidity in MM 106, OAR 1 and M 26. Soluble solids at harvest were strongly predicted by pre-harvest dry matter.     

Effects of Seasonal Changes in Shoot Growth on the Amount of Unsuberized Root on Apple and Plum Trees

Measurement of the white root, visible through glass panels, from young apple and plum trees showed that production of new white root was reduced during periods of intense shoot growth. On the apple trees maximum quantities of white root occurred in May, at about the time of full bloom, and again in August or September after shoot growth had ceased. In contrast, on some of the plum trees with only a few weak shoots, maximum white root was recorded in June and only small amounts of new white root were present during the remainder of the year. The effect of branch pruning was to stimulate more intense shoot growth: the more intense the shoot growth the greater and more prolonged was the reduction in new white root production in mid-summer. The interpretation of these results in terms of the physiological relationship between root and shoot is discussed.     

双主干并棒树形对矮化自根砧苹果幼树生长和结果的影响

为了探究双主干并棒（Bibaum?）树形‘富士’系苹果在中国渭北黄土高原地区的生长和结果表现，以 M9-T337 矮化自根砧长枝型‘富士’系‘富姬酷’（‘Fujiko’）为试材，调查了并棒形（1.2 m × 3.5 m）与高纺锤形（1.0 m × 3.5 m）幼树树体生长、枝（梢）类组成、成花率、果实品质和产量等指标。结果表明：并棒形树高、干径小于高纺锤形，砧木粗度大于高纺锤形，2016 年东西方向冠幅（行间冠幅）及平均冠幅小于高纺锤形；单株枝量及单位面积枝量 2016 年高纺锤形较高，2017 年无差异；并棒形2016—2017 年间树高、干径、砧木粗度以及单位面积枝量的年增长速率大于高纺锤形；并棒形 2016 年中枝（5 ~ 15 cm）比例、果台副梢长枝比例高于高纺锤形，2017 年营养长枝（> 30 cm）比例低于高纺锤形，同时并棒形 2018 年枝梢成花率高于高纺锤形；两种树形果实品质及单位面积产量无差异，并棒形单株果实数量、2017 年单株产量以及 2016—2017 年单位面积产量在增长速率大于高纺锤形。综合认为，矮化自根砧‘富士’系幼树采用并棒树形，可以显著削弱树体高度，减小行间冠幅，树体生长及枝量增长速度快，长枝比例低，易成花，果实产量上升潜力大。     

Response of watersprout growth to fruit load and intensity of dormant pruning in peach tree

Watersprout occurrence and growth were investigated over a two-year period in an early maturing peach cultivar (Alexandra) under different intensities of dormant pruning for fruited and defruited trees. A preliminary study focused on identifying the laws that determine the probability of presence and occurrence of watersprouts in relation to watersprout-bearing shoot (WBS) length. The increase in watersprout probability of presence and occurrence resulting from greater WBS length illustrated the high capacity of peach for sprouting. Watersprout lengths were measured, as well as the lengths of young shoots, one-year-old fruit-bearing shoots (FBSs) and older branches considered as WBS in order to evaluate total shoot growth within the tree. Watersprout number and total length tended to be higher under severe dormant pruning and in fruited trees than under light dormant pruning and in defruited trees. This stimulation of watersprout length appeared to compensate for the concomitant lower total length of young shoots, resulting in a constant overall vegetative growth rate for the whole tree. In the second year of the experiment, watersprouts were either removed by summer pruning or not in order to evaluate watersprout incidence on the rest of the tree. After light and severe watersprout removal (WSR), the annual diametrical growth of FBS tended to be higher and lower, respectively, compared to trees not submitted to summer pruning. Light WSR might favour light interception in the centre of the canopy, thus improving assimilate production and allocation to FBS, whereas severe WSR could prevent carbohydrate export from watersprouts to FBS. Under our conditions, the limit at which WSR intensity became detrimental for FBS diametrical growth appeared to be after approximately 75% of the watersprouts were removed. Severe WSR appeared likely to improve fruit diameter, whereas it had no significant impact on the percentage of soluble solids.     

Auxin transport capacity in relation to the dwarfing effect of apple rootstocks

SUMMARY

Basipetal auxin transport in shoots obtained from dwarfing (M.9) and less-dwarfing (MM.Ill) apple rootstocks was compared by measuring the distribution of ¹⁴C-[carboxy]-labelled indole 3-acetic acid supplied to the ends of shoot segments. Auxin was transported at a greater velocity in MM.111 than in M.9 in both woody and non-woody segments, and was effectively blocked by 2,3,5-triiodobenzoic acid. The velocities of transport were approximately 8 mmh-¹ in M.9,and 13 mmh-¹ MM.111. There was relatively little transport in the acropetal direction, and there were no significant differences between the two rootstocks in total auxin uptake. Chromatographic analysis suggested that the metabolismof the auxin supplied followed similar patterns in both rootstocks. It is proposed that the slower auxin transport in M.9 results from a lower capacity for auxin efflux from transporting cells. A limiting auxin transport capacity could explain the reduced cambial activity and subsequent xylem formation in the dwarfing M.9 rootstock, and thus make an important contribution to the dwarfing effect.