Significant Effect Of Rootstock Research Articles

Seasonal trends in leaf and fruit nutrient concentrations of apple (Malus x domestica Borkh.) grafted on different clonal rootstocks and their effect on fruit quality

Effective nutrient management necessitates monitoring of nutrient requirement, extent and timing of nutrient supply during the fruit development. To achieve a good nutrient balance and its impact on fruit quality, study of nutrient dynamics is of utmost importance as it provides an intriguing stratagem to control tree nutrient status. The research aimed at investigating seasonal patterns of nutrient concentrations in leaves and fruits of apple (Malus × domestica Borkh.) cv Silver Spur on various clonal rootstocks (MM106, M4 and M9) during the year 2019–2020 and their impact on fruit quality. For this purpose collection of leaf and fruit samples commenced from one month after full bloom (May 15) until harvesting (September 18) at an interval of twenty one days and samples were evaluated for both macro and micro-nutrients {Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Boron (B)} and quality characteristics. In general, concentration of N, P, K and B declined continuously in both leaf and fruit toward the end of fruit maturation, whereas leaf Ca and Mg augmented along the cycle, however fruit Ca and Mg increased up to first fruit development stage and then decreased again signifying nutrient dilution along growing season and its effect on fruit quality. With respect to rootstocks, semi-vigorous rootstock MM106 recorded higher values for leaf and fruit nutrient concentrations as compared to dwarf M9 and semi-dwarf M4 rootstocks specifying a significant effect of rootstocks on nutrient absorption.

Influence of rootstock genotype on individual metabolic responses and antioxidant potential of blood orange cv. Tarocco Scirè

In fruit crops, tree rootstock plays a relevant role in the tolerance of biotic and abiotic factors, various qualitative traits and biochemical profiles of the juice. In this work, the fruit quality characteristics of sweet orange Tarocco Sciré grafted onto ten rootstocks were evaluated. Analyses were performed on the fruit juice, coupling the quantification of phenolic compounds (anthocyanins, flavanones, flavones and hydroxycinnamic acids) through hyphenated chromatographic techniques and the assessment of antioxidant potential (measured in vitro). The study was conducted for two consecutive years in which the different minimum temperatures recorded during fruit ripening determined a higher accumulation of polyphenols, especially anthocyanins (63.6 %), and higher levels of antioxidant activity (48.92) in the colder year. The analyses allowed the identification and quantification of 24 phenolic compounds (6 anthocyanins, 5 flavanones, 1 flavone and 12 hydroxycinnamic acids). The results highlighted a significant effect of both rootstocks and the environment (and their interaction) on the metabolic profile of the juice, with low temperatures being directly involved in juice pigmentation and significant differences among the rootstocks within each year of analysis. In addition to temperature, a significant effect of rootstocks on the metabolic profile of the juice was revealed, with C35 and Bitters being the most effective in enhancing anthocyanin accumulation in the fruit of the grafted variety.Altogether, the data presented shed light on the significant role exerted by the rootstock on fruit quality, providing useful insights to guide the selection of rootstocks in novel implants.

Rootstock Affects Floral Induction in Citrus Engaging the Expression of the FLOWERING LOCUS T (CiFT)

In Citrus, flower induction represents the transition from vegetative to reproductive growth. The regulation of flower induction is mainly triggered by exposure to low temperatures and water-deficit stress, which activates the signaling cascade leading to an increased expression of the citrus orthologs of the FLOWERING LOCUS T (CiFT). In this study, the relationship between rootstock and flower induction under Mediterranean field conditions was investigated by monitoring the expression levels of the floral promoter CiFT2 in leaves of the pigmented sweet orange “Tarocco Scirè” grafted onto “C35” citrange and “Swingle” citrumelo rootstocks. The latter two are known to confer, respectively, high and low yield efficiency to the scion. In both rootstock/scion combinations, CiFT2 showed a seasonal expression with a peak during the inductive period in January triggered by cold temperature. The “Tarocco Scirè”/”C35” citrange combination showed the highest expression levels for CiFT2; this increased expression was correlated with yield and a higher number of flowers in the following spring, suggesting a significant effect of rootstocks on flower induction mediated by the overexpression of the CiFT2 gene.

Scion × Rootstock Response on Production, Mineral Composition and Fruit Quality under Heavy-Calcareous Soil and Hot Climate

Since there are many different factors which affect peach orchard profitability, it is necessary to conduct long-term studies to find the best scion/rootstock combination within the constraints imposed by local climate and economic conditions. The influence of six peach-almond hybrids (“Adafuel”, “Adarcias”, Garnem”, “GF 677”, “PADAC 9902-01” and “Rootpac 70”); one P. persica × P. davidiana hybrid: “Cadaman”; five hexaploid plums (“Adesoto 101”, “PM 44 AD”, “PM 105 AD”, “PM 150 AD”, and “Penta”); three plum × peach-almond hybrids (“PADAC 04-01”, “PADAC 04-03” and “PADAC 99-05”), and one plum x almond hybrid (“Rootpac R”) on agronomic, basic fruit quality parameters, and flower and leaf mineral nutrients of the “Big Top” nectarine was tested. The highest vigor was induced by “Adafuel”, while the lowest vigor was exhibited by “PM 105 AD”, although the latter did not differ from the rest of the rootstocks. Yield efficiency was higher for “Adesoto 101” and lower for “Adafuel”. Regarding the soluble solids content (SSC), “PADAC 04-01” rootstock induced the highest average content, although it did not differ from “Adarcias”, “Adesoto 101”, “PADAC 99-05”, “PM 105 AD”, and “Rootpac R”. In addition, significant effect of rootstock was found on the flower and leaf mineral analysis traits evaluated. The medium (“Adarcias”, “Adesoto 101”, “PM 105 AD”) to high vigorous plum based hybrid rootstocks (“PADAC 04-01”, “PADAC 99-05” and “Rootpac R”) showed the tendency to induce a better fruit quality, based on higher concentration of SSC, and other yield attributes, demonstrating their commercial interest as new rootstocks for peaches. Considering its overall performance, “PADAC 04-01” appears as a new promising rootstock alternative to peach-almond hybrids on heavy and calcareous textured soils.

Influence of rootstocks on the chemical composition of the fruits of plum cultivars

This paper presents the chemical composition of the fruits of three European plum cultivars (‘Cacanska Rana’, ‘Cacanska Lepotica’, and ‘Cacanska Najbolja’) grafted on four rootstocks (Myrobalan, ‘Pixy’, ‘Fereley’, and ‘St. Julien A’). The rootstock/cultivar combinations significantly influenced the content of most of the phenolic compounds in the plum skin and flesh. The total anthocyanin content in the skin ranged from 1.87 to 7.33 mg cyanidin-3-glucoside g−1 fresh weight. The major phenolic compound in the skin was rutin, which ranged from 95 to 238 mg kg−1, while in the flesh, cinnamic acid and catechin were dominant. The total sugar content in the fruit ranged from 66.2–147 mg g−1. The highest glucose and fructose contents were in ‘Cacanska Lepotica’, then in ‘Cacanska Najbolja’, and the lowest were in ‘Cacanska Rana’ cultivar. The highest contents of glucose and sucrose were found in fruits from trees grafted on Myrobalan rootstock, and the lowest in fruits from trees grafted on ‘St. Julien A’ rootstock. The rootstocks significantly influenced the potassium, calcium, and copper contents in the plum fruit. The results of this study demonstrate the significant effect of rootstocks on the phenolic and sugar profiles, and on the mineral content of the plum fruits.

INFLUENCIA DEL FRÍO INVERNAL Y PORTAINJERTOS EN LA BROTACIÓN Y FLORACIÓN DEL MANZANO ROYAL GALA

El manzano (Malus sylvestris var. domestica) se cultiva en gran diversidad de ambientes, con diferentes portainjertos y cultivares, por lo que la caracterización de la respuesta de la planta en cada una de las combinaciones ambiente-cultivar portainjerto es importante para entender el comportamiento del árbol en su entorno. Con el objetivo de explorar la influencia del frío invernal expresado en unidades frío (UF) acumuladas durante ese periodo y de portainjertos sobre la apertura de yemas y floración del manzano, se seleccionó un huerto con la variedad Royal Gala injertada sobre 12 portainjertos diferentes. En los inviernos 2010-2011 y 2014-2015 se calcularon las unidades frío y posterior a ésto, el porcentaje de yemas abiertas y los grados día (GD) requeridos para el inicio (5 %) y durante el evento de floración (de 5 a 95 %) para cada una de las combinaciones cultivar/ portainjerto. La apertura de yemas y el evento de floración de Royal Gala se midieron periódicamente en porcentaje relativo de ocurrencia y se relacionó con UF y portainjerto. Posterior a un invierno con baja acumulación de frío (524 UF) abrió el 72.6 % de yemas, la floración inició a los 236 GD y se completó en 117 GD, mientras que posterior a un invierno con 830 UF abrió el 96.7 % de yemas, la floración inició a los 146 GD y se completó en 129 GD. Se detectó influencia significativa del factor frío invernal para la apertura de yemas y para los GD acumulados al inicio de la floración e igualdad estadística para la duración de la floración. No se detectó efecto significativo de portainjerto ni interacción significativa entre frío invernal y portainjerto.

INFLUENCIA DEL FRÍO INVERNAL Y PORTAINJERTOS EN LA BROTACIÓN Y FLORACIÓN DEL MANZANO ROYAL GALA

The apple tree (Malus sylvestris var. domestica) is grown in a wide variety of environments, with different rootstocks and cultivars; thus, the characterization of the response of the plant in each of the environmentcultivar- rootstock combinations is important to understand the tree behavior in its environment. In order to explore the influence ofwinter cold expressed in chill units (CU) accumulated during the winter period as well as rootstocks on bud breaking and blooming of apple trees, an apple orchard with the Royal Gala cultivar grafted on 12 different rootstocks was selected. During the winter periods of 2010-2011 and 2014-2015 CU were calculated and after that, the percentage of open buds and the day degrees (DD) required for the beggining (5 %) and during the flowering event (from 5 to 95 % ) for each of the environment-cultivar-rootstock combination were registered. The bud opening and blooming of Royal Gala were periodically measured in percentage of occurrence and related to CU, DD and rootstock. After a winter with low chill units accumulated (524 CU) there was 72.6 % of bud breaking, blooming began at 236 DD and was completed with 117 GDD, while after a winter with 830 CU there was 96.7 % of bud breaking, blooming began at 146 DD and was completed with 129 DD. Significant difference for winter cold factor was detected on bud breaking and DD accumulated at the beginning of blooming and statistical equality for the duration of blooming period. No significant effect of rootstocks or significant interaction between CU and rootstocks were detected.

Fine root dry matter relative to mango (Mangifera indica) tree scion size grafted on size-controlling rootstocks, is negatively related to scion growth rate

The effects of mango rootstock cultivars on scion vigour may be predicted by scion growth rate being negatively related to fine root dry matter/scion trunk cross sectional area. Knowledge of root dry matter (DM) allocation, in relation to differing vigour conferred by rootstock cultivars, is required to understand the structural relationships between rootstock and scion. We investigated the mass of roots (four size classes up to 23 mm diameter) by coring proximal to five polyembryonic mango rootstock cultivars known to differ in their effects on the vigour and productivity of scion cultivar ‘Kensington Pride’, in a field trial of 13-year-old trees. Significant differences in fine (<0.64 and 0.64–1.88 mm diameter) and small (1.88–7.50 mm) root DM contents were observed between rootstock cultivars. There was a complex relationship between the amount of feeder (fine and small size classes) roots and scion size (trunk cross sectional area, TCSA), with intermediate size trees on rootstock MYP having the most feeder roots, while the smallest trees, on the rootstock Vellaikulamban had the least of these roots. Across rootstock cultivars, tree vigour (TCSA growth rate) was negatively and significantly related to the ratio of fine root DM/scion TCSA, suggesting this may be a useful indicator of the vigour that different rootstocks confer on the scion. In contrast non-ratio root DM and scion TCSA results had no significant relationships. The significant rootstock effects on orchard root growth and tree size could not be predicted from earlier differences in nursery seedling vigour, nor did seedling vigour predict root DM allocation.

Effect of rootstocks on tree growth, yield, quality and leaf mineral composition of lemon (Citrus limon (L.) Burm.)

The present study aimed to evaluate the horticultural performance of lemon cv ‘Kagzi Kalan’ on eight rootstocks under typical subtropical conditions for maximizing the production and fruit quality. The experiment was conducted on five years old Kagzi Kalan lemon plants budded on eight rootstocks. The variables collected over two successive years included vegetative growth, fruiting density, fruit quality, and leaf nutrient concentrations. Results revealed a significant effect of rootstocks on all the variables studied. Tree height and canopy volume were found higher on rough lemon and RLC-4 rootstocks, while trunk cross sectional area was higher on Billikichlli and RLC-4 rootstocks than other rootstocks. RLC-4 and Attani-2 rootstocks had higher fruiting density, while it was lowest on Troyer citrange. RLC-4 produced heaviest fruits, while trees on rough lemon and RLC-4 had significantly higher juice recovery. RLC-4 and Karna Khatta improved TSS and acid contents in the fruit juice. RLC-4 and Troyer citrange proved their superiority in terms of higher ascorbic acid content. Foliar N concentration in scion cultivars was found higher on RLC-4, rough lemon and Attani-2 rootstocks, while the foliar K content was higher on RLC-4 and rough lemon. Jatti Khatti was more efficient in accumulating Mg in leaf tissues, whereas Troyer citrange restricted accumulation of Na in leaf tissues. Sour orange was more capable of accumulating Cu and Zn in leaf tissues, while other rootstocks had similar uptake of Cu. Karna Khatta, rough lemon and RLC-4 absorbed more Fe, while the foliar Mn content was highest on rough lemon rootstock. Troyer citrange appeared poor performer in terms of fruiting density and nutrient concentration. A positive significant correlation was found between leaf Ca concentration and canopy volume. Hence, considering growth performance, fruit quality and nutrient concentration, RLC-4, rough lemon and Karna Khatta rootstock could be suggested for lemon under alike ecological conditions.

Agronomical Parameters, Sugar Profile and Antioxidant Compounds of “Catherine” Peach Cultivar Influenced by Different Plum Rootstocks

The influence of seven plum rootstocks (Adesoto, Monpol, Montizo, Puebla de Soto 67 AD, PM 105 AD, St. Julien GF 655/2 and Constantí 1) on individual and total sugars, as well as on antioxidant content in fruit flesh of “Catherine” peaches, was evaluated for three years. Agronomical and basic fruit quality parameters were also determined. At twelve years after budding, significant differences were found between rootstocks for the different agronomic and fruit quality traits evaluated. The Pollizo plum rootstocks Adesoto and PM 105 AD seem to induce higher sweetness to peach fruits, based on soluble solids content, individual (sucrose, fructose and sorbitol) and total sugars. A clear tendency was also observed with the rootstock Adesoto, inducing the highest content of phenolics, flavonoids, vitamin C and relative antioxidant capacity (RAC). Thus, the results of this study demonstrate the significant effect of rootstock on the sugar profile and phytochemical characteristics of peach fruits. In addition, this work shows the importance of the sugar profile, because specific sugars play an important role in peach flavour quality, as well as the studied phytochemical compounds when looking for high quality peaches with enhanced health properties.

INFLUENCE OF PLUM ROOTSTOCKS ON THE DYNAMIC OF DRY MATTER IN THE ANNUAL SHOOTS OF CULTIVAR 'VICTORIA'

This paper reports on rootstock influence on plum tree winter-hardiness. Dry matter dynamic during winter in one-year-old shoots of plum trees was evaluated on Prunus domestica 'Victoria' plum (2n=6x=48) in 2008-2009, 2009-2010 and 2010-2011 in Pūre HRC, Latvia. Sixteen rootstocks ('St. Julien A', 'Brompton', 'Ackermann', 'Pixy', GF8/1, G5/22, GF655/2, 'Hamyra', 'St. Julien INRA2', 'St. Julien d'Orleans', 'St. Julien Noir', 'Brompton', 'Wangenheims Zwetche', 'St. Julien Wadenswil', 'Myrobalana', Pr. Cerasifera var. divaricate were planted in 2001 for comparison. Samples were taken 5 times over the wintering period and dry matter content (mg g-1) was determined. Dry matter content during 3 wintering periods showed significant increase during December and January. No significant effect of rootstock was recorded. The most fluctuating content of dry matter in one-year shoots was observed for trees grafted on 'Myrobalana' (496-541 mg g-1). More stable contents were detected in trees grafted onto Prunus cerasifera (495-507 mg g-1) and ‘Pixy’ (503-516 mg g-1). These results would suggest that the latter rootstocks are suitable for the more variable winter weather conditions.

Videira 'Syrah' sobre diferentes porta-enxertos em ciclo de inverno no sul de Minas Gerais

O objetivo deste trabalho foi avaliar a influência de porta-enxertos sobre as características agronômicas, ecofisiológicas e qualitativas da videira 'Syrah' manejada por meio da técnica da dupla poda. As videiras foram enxertadas nos porta-enxertos 'SO4', '110 Richter' e '1103 Paulsen', e sustentadas em sistema espaldeira sem irrigação. Foram avaliadas as características ecofisiológicas, de produção e de composição físico-química das bagas maduras em três safras (2007, 2008 e 2010). Os porta-enxertos não exerceram influência sobre o potencial hídrico de base, que apresentou valores próximos a -0,2 MPa, o que indica que não houve restrição hídrica no solo ao final da maturação (junho). Também não houve diferença significativa quanto à produção. O porta-enxerto '1103 Paulsen' conferiu menor vigor, menor taxa fotossintética e melhores resultados de maturação, para as safras com menores precipitações. Os porta-enxertos '110 Richter' e 'SO4' apresentaram maior vigor nas condições meteorológicas de 2010 e as maiores taxas fotossintéticas para o mesmo período. As condições meteorológicas tiveram efeito significativo na maturação tecnológica e fenólica, com os melhores resultados para os anos mais secos. O porta-enxerto '1103 Paulsen' fornece melhor equilíbrio entre vigor e produção, o que aumenta a qualidade da uva.

Effect of Three Apple Rootstocks on the Population of the Small Red-Belted Clearwing Borer,Synanthedon myopaeformis

Experiments were conducted in Ash-Shoubak area of Jordan from June 2003 to September 2005 to study the effect of three apple rootstocks on the development of the small red-belted clearwing borer, Synanthedon myopaeformis (Borkh.) (Lepidoptera: Sesiidae), under field conditions. Mondial Gala apple trees grafted on the dwarfing rootstock M9 and the semi-dwarfing rootstock M26 were equally infested, whereas those grafted on MM106 showed significantly lower infestation levels. S. myopaeformis bore into burr knots that develop below a graft union on rootstocks and girdle the tree. There was a significant effect of rootstock on the numbers of burrs present, and the percentage of burr knots infested by S. myopaeformis, with M106 having significantly fewer burrs, and a lower percent infested.

Relative resistance of newly released apple rootstocks to Phytophthora cactorum

New rootstocks from series SJM (St-Jean-Morden) and SJP84 (ST-Jean-1984) have been evaluated for agronomic qualities since 1970 and 1975, respectively. As a result of the evaluation, seven and nine rootstocks from the SJM and SJP84 series, respectively, were selected. However, these were not evaluated for crown rot resistance. Excised shoot assay was used to evaluate resistance of 22 apple rootstocks to crown rot caused by Phytophthora cactorum (Leb. and Cohn.) Schroet. The pathogenicity of four isolates of P. cactorum to apple rootstocks was confirmed using the same excised twig assay. For both tests, relative lesion length was used as a measure of susceptibility. The analysis of variance showed that there was a significant effect of rootstocks, isolate and the interaction between rootstock and isolate. In general, apple rootstocks were more susceptible to isolate PC04-02 followed by isolates PC04-03 and PC04-01 and less susceptible to isolate PC04-04. The selection SJM189 was the least susceptible to P. cactorum and SJP84-5162 and SJM15 were the most susceptible suggesting that these rootstocks may not be suitable in orchards with favourable conditions to P. cactorum infection. Excised twigs of the SJP84-5180, SJP84-5189, SJP845174, O.3, SJP84-5230, O.3A, SJP84-5198, SJM167 and M.44 showed low to moderate susceptibility, whereas, rootstocks SJP845231, SJM150 and M.26 showed moderate susceptibility to P. cactorum. Rootstocks SJM188, SJP84-5217, MM.111, SJM127, SJP84-5218 and MM.106 showed high susceptibility to P. cactorum. The present results confirmed that none of the released or commercial rootstocks are completely resistant to P. cactorum and an integrated approach including resistance, chemical control and cultural practices is recommended to manage P. cactorum in apple orchards. Key words: Apple breeding, crown rot, Malus domestica Borkh., root rot

Transpiration efficiency and carbon-isotope discrimination of grapevines grown under well-watered conditions in either glasshouse or vineyard

This paper describes variation in transpiration efficiency ‘W’ (where W = dry matter produced/water transpired) among grapevine genotypes grown under well-watered conditions in either a glasshouse or a vineyard. Nineteen genotypes were grown in a glasshouse where growth and transpiration were measured. W ranged from 2.5 to 3.4 g dm/kg H2O transpired. Carbon-isotope discrimination (Δ) of laminae dry matter ranged from 20.8 to 22.7%o and there was a negative relationship (R2= 0.58) between W and Δ. A large proportion of variation in W could be attributed to variation in stomatal conductance. Genotypic variation in photosynthetic capacity was also an important component of variation in W. In a second experiment, lamina Δ was measured for mature field-grown Shiraz and Chardonnay, grown either on their own roots or grafted to five different rootstocks, and maintained at three sites under well-watered conditions. At all sites and regardless of rootstock, the laminae of Chardonnay had Δ values 1 to 2%o lower than Shiraz. There was also a 1 to 2%o variation among the sites. Rootstock variety affected Δ values inconsistently and by a maximum of 0.5%o. Leaf gas exchange measurements were performed at a single site on sun-exposed leaves of Chardonnay and Shiraz on either their own roots or 1103 Paulsen, a moderate to high vigour rootstock. There was no significant effect of rootstock on leaf gas exchange and photosynthetic rates did not differ between scion varieties. However, Chardonnay had a 20% lower stomatal conductance and a 1.4-fold higher ratio of CO2assimilation/H2O transpiration (A/T) indicating a potentially higher W, at a leaf level, for Chardonnay compared with Shiraz. We conclude that photosynthetic capacity was also higher for Chardonnay. Δ values, predicted from the Ci/Ca ratio calculated from leaf gas exchange measurements, did not differ significantly from measured values for laminae Δ. This similarity for Δ, in conjunction with the fact that the lower Δ of Chardonnay was reflected in a higher A/T ratio, suggests that Δ may be a reliable predictor of comparative W under vineyard conditions.

Rootstock effects on scion growth and reproduction in 8-year-old grafted loblolly pine

Contributions of sites, rootstocks, and scion clones (and the interactions between these factors) to scion growth and reproduction were studied in loblolly pine (Pinus taeda L.). Twenty-five full-sib families were used as rootstocks. Six scion clones were grafted on them in all combinations. Study sites were three seed orchards in the southeastern United States; trees were measured 8 years after grafting. Scion elongation, diameter at breast height (DBH) of the main leader, crown diameter, cone counts, and number of male and female strobili were measured at all sites. Crown diameter and tree height were combined into a crown volume index. Highly significant differences existed among scion clones for all traits. When analyzed over all three sites, the only trait with significant rootstock effects was DBH. There were significant rootstock × scion interactions for total scion elongation, crown volume index, and DBH and significant site × scion interactions for strobili counts and cone count. In analyses by clone, rootstock effects were expressed differently in the different clones. There were significant rootstock effects for three traits in each of three clones and no effects at all in two clones. For all traits the largest variance component was for either site or scion clone. Components for rootstocks were small or zero. These results show that the scion clone and site have more control on scion growth and reproduction of grafted loblolly pine than the rootstock. The study did not identify full-sib families that (as rootstocks) would signficantly reduce scion elongation or signficantly increase cone production, for all six scion clones at all three sites.

ROOTSTOCK EFFECTS ON NORTHERN SPY APPLE LEAF COMPOSITION

Leaf samples collected during the 1988-90 seasons were analyzed to evaluate influence of selected rootstock clones on the composition of Northern Spy apple leaves. Rootstocks included 17 elite selections from the Geneva breeding program plus M.9, M.26, M.7, MM.106 and MM.111 as references. Rootstock selections were grouped according to relative vigor and compared with appropriate references. Significant rootstock effects were more frequent in the two smaller tree-size groups. Each of the 10 elements analyzed exhibited significant rootstock effects in two or more vigor groups. No rootstock selection consistently resulted in higher or lower concentrations of all elements when compared with the reference rootstock of similar vigor.

An Exploratory Study of Reciprocal Apple Rootstock and Scion Hardiness with Two Methods of Assessment

Root hardiness for the apple (Malus domestica Borkh.) rootstocks M.26, MM.106, MM.111, M.7A, and M.7EMLA at - 8 and - 11C and trunk survival for the tender cultivar Gravenstein and the hardy cultivar Wealthy at -25 and -35C were evaluated both destructively (tissue examination) and nondestructively (regrowth measurement the following season). No differences in root survival were detected at -8C by either method; at - 11C, MM.111 rated better than the others, while regrowth was higher on M.26, MM.111, and M.7A than on MM.106 or M.7EMLA. Root survival did not differ for the scions at either temperature, but regrowth was greater for `Gravenstein' than Wealthy' at both temperatures. Trunk tissue survival at -25C was consistently lowest for scions on M.7EMLA, and regrowth was less than on M.26 and MM.111. At -35C there were no significant rootstock effects. For the scions, lateral wood tissue survival at -25C was highest for Wealthy', but the weight of the new growth did not differ. At -35C bark tissue survival and regrowth was greater for Wealthy' than for `Gravenstein'. Evidence is presented in support of the occurrence of reciprocal effects. Correlation between the two methods was highest for root exposure at - 11C and for the assessment of trunk bark.

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.

The relative effects of rootstocks and calcium sprays on the appearance of internal breakdown and superficial scald of ‘Red Delicious’ apples during storage

The 2-year investigation involved storing fruit samples from each tree in a trial of 8 rootstocks with the locally selected ‘Lalla Red Delicious’ to see how the storage characteristics were modified by rootstock and/or calcium sprays. The 6 spray applications of calcium made a significant reduction in the incidence of internal breakdown in both years, although the magnitude of the response varied from rootstock to rootstock in 1976. There were no significant rootstock effects in 1975, and in 1976 they were eliminated where calcium sprays were used. In the absence of calcium sprays in 1976, apples from ‘M. 16’ produced significantly more internal breakdown than those from any of the other stocks, with ‘MM. 107’ producing the second highest level. At the other end of the scale, apples from ‘MM. 110’ had the lowest incidence, closely followed by ‘M. 1.’ The remaining 4 stocks (‘11 immune’, ‘M.13’, ‘M.25’ and ‘Seedling’) gave intermediate readings and were not significantly different from each other. The calcium spray treatments also significantly reduced the incidence of superficial scald with all rootstocks. The main rootstock effect observed was that apples from ‘MM. 110’ and ‘M. 1’ had significantly less scald than from 5 of the other 6 rootstocks.