Root Suckers Research Articles

Local adaptation through genetic differentiation in highly fragmented Tilia cordata populations.

We assessed the level of geographic differentiation of Tilia cordata in Denmark based on tests of 91 trees selected from 12 isolated populations. We used quantitative analysis of spring phenology and population genetic analysis based on SSR markers to infer the likely historical genetic processes within and among populations. High genetic variation within and among populations was observed in spring phenology, which correlated with spring temperatures at the origin of the tested T. cordata trees. The population genetic analysis revealed significant differentiation among the populations, but with no clear sign of isolation by distance. We infer the findings as indications of ongoing fine scale selection in favor of local growth conditions made possible by limited gene flow among the small and fragmented populations. This hypothesis fits well with reports of limited fruiting in the investigated Danish T. cordata populations, while the species is known for its ability to propagate vegetatively by root suckers. Our results suggest that both divergent selection and genetic drift may have played important roles in forming the genetic patterns of T. cordata at its northern distribution limit. However, we also speculate that epigenetic mechanism arising from the original population environment could have created similar patterns in regulating the spring phenology.

Recovery of Baikiaea forest of southwestern Zambia from shifting cultivation and its implications for sustainable management

We studied the dominant species by age category of re-growth, and how subsistence forest use through shifting cultivation impacted on the floristic composition of Baikiaea forest. For re-growth stands, variable sampling method was adopted in data collection while in mature stands, a sample plot size of 50 m × 50 m was used at each of three study sites. Distribution of species by age categories showed that shrub, herb, and grass species were abundant in young re-growth stands while woody vegetation became common with increasing age of the re-growth stand. Hierarchical clustering for common woody species showed several species associations with age categories and also with relatively undisturbed woodland. Common regeneration mechanisms of key woody species were mainly by seed (48%), coppicing (40%) and root suckers (12%). The young re-growth stands of 6–10 and 11–15 years were characterized by B. petersiana, B. massiensis, Combretum zeyheri, and Guibourtia coleosperma. Older stands (16–20 years after abandonment) were characterized by B. plurijuga, Pterocarpus antunesii, and Baphia massiensis, thus closely mimicking the relatively undisturbed forest whose dominant key woody species were B. plurijuga, P. antunesii, and G. coloesperma. There were many stems in younger stands (2–5 years) and fewer stems in older re-growth stands of 16–20 years after abandonment following shifting cultivation. Older re-growth stands (16–20 years) were similar to undisturbed stands (P < 0.005). The similarity between re-growth stands of 16–20 years and control stands demonstrates the recovery of Baikiaea forest over time after cessation of shifting agriculture. Baikiaea forest requires some disturbance to perpetuate the dominant species and begins to show signs of recovery from shifting cultivation within 16–20 years after abandonment. This is contrary to assertions that this ecosystem could take up to about 100 years for abandoned fields to begin showing signs of recovery

Leaf gas exchange and isoprene emission in poplar in response to long-term experimental night-time warming and summer drought in a forest-steppe ecosystem

Climate change projections forecast an average warming in mean temperature and an associated change in the distribution and intensity of rainfalls. At the manipulation experiment in Kiskunság, Hungary, we aimed to study the effect of the soil drought and night-time warming conditions projected for the coming decades on leaf gas exchange, including photosynthetic rates and isoprene emission rates and on isoprene synthase expression levels of Populus alba sprouts (root suckers). During the years 2010 and 2011, warming treatment increased the air temperature 0.35 °C on average whereas drought treatment reduced the soil moisture by 13% on average in relation to control plots. The results highlighted important seasonal differences. Photosynthesis was limited by stomatal closure in summer and also isoprene emission and isoprene synthase expression levels were lower in summer than in autumn for all treatments. As a consequence, a negative relationship was found between temperature, ranging from 25 °C to 35 °C, and isoprene emission throughout all the study period and treatments. Results also showed significant treatments effects on isoprene parameters but only in July 2011. Isoprene emission decreased with drought, and isoprene synthase expression levels decreased with night-time warming. A positive relationship was found between isoprene emission and leaf internal carbon in drought treated poplar plants, which contrasted with our findings for control and warming treated plants. These results indicated either a change in the regulation of pyruvate distribution between isoprene synthesis and respiration under drought or a utilization of alternative carbon sources for isoprene emission.

Clonal variation in root suckering ability of hybrid aspen (Populus tremula L. × P. tremuloides Michx.)

ABSTRACTCurrent information on the root sucker ability of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) is in most cases based on clone mixtures. In this study, we could separate the performance among clones by using two experimental sites with monoclonal plots of the crossing. The natural regeneration was followed for 2 years after harvest of the formerly planted stands, clear-cut at 22 and 25 years of age, respectively. We found that clonal differences were present in the number of root suckers produced per area unit and their biomass production. However, all included clones produced sufficiently many root suckers for a successful regeneration. To receive a more complete evaluation of the root sucker dynamics for future selection on the clonal level, further studies are needed where vitality, self-thinning and effects of thinning measures are coupled to the goal of the aspen forestry.

Analysis of growth of recruits of natural regeneration of Sorbus torminalis (L.) Crantz - a rare European forest tree species

Abstract: We compared growth and survival of wild service tree (Sorbus torminalis [L.] Crantz) recruits of different origin (generative: seedlings; vegetative: root suckers) established in a fenced plot at the Forest District of Krzyz (north-western Poland). Total height, annual growth of the dominant shoot, stem diameter at root collar, number of first-order branches, and mortality were measured every year over the period 2011-2015 (5 years). In 2011, a total of 382 multi-age recruits originated both from seeds (212) and root suckers (170) were recorded. Five-year mortality was higher in the generative progeny (12.3% - only youngest seedlings) as compared with vegetative recruits (2.9%). The growth rate of individuals markedly increased with height as absolute values, but slightly decreased in terms of relative growth. Statistical analysis revealed that the effect of the recruit origin on growth was noticeably weaker than that of age, defined in terms of development (height) classes. The origin of recruits had a major effect on the annual growth of the dominant shoots and a minor (though significant) effect on stem diameter and the number of first-order branches. Overall, the analysis of growth rate showed that generative recruits grow faster than the vegetative ones. Our results highlight the importance of stimulating the generative regeneration and protecting seedlings as a conservation strategy for Sorbus torminalis.

Biomass, nutrient content and energy yield of short-rotation hybrid aspen ( P. tremula x P. tremuloides ) coppice

Abstract In Nordic and Baltic countries short-rotation management of various tree species for pulpwood and energy is gaining increased interest. The sprouting, biomass production, nutrient uptake and heating value of coppiced hybrid aspen were studied over three years in southern Finland. The 26-year old mother stand was clearcut and coppiced. Half of the 12 study plots were fertilized with nitrogen. Allometric equations relating the dry weight of wood and bark to tree height were developed to estimate bark and wood biomass. After the first growing season, 99% of the sprouts were root suckers. The 833 mother trees produced 182,100 sprouts ha−1. The number of living sprouts decreased to 41,400 ha−1 at the end of the third growing season. After the third growing season, nitrogen fertilization had increased biomass by 20% to 28.6 Mg ha−1. The mean annual increment (MAI) on N-fertilized plots was 9.5 Mg ha−1. The nitrogen fertilized stands had 133 kg N, 17 kg P, 113 kg K, 117 kg Ca and 18 kg Mg bound in their leafless above-ground biomass per ha. Fertilization had increased the amount of N, P, K, Ca and Mg bound in the stands by 52, 4, 28, 7 and 2 kg ha−1 respectively. The amount of micronutrients bound in the stand per ha was much smaller (259 g B, 380 g Fe, 830 g Mn, 1512 g Zn, 63 g Cu, 13 g Cd). The effective heating value of hybrid aspen bark was higher than that of wood and the heating value of shoots decreased with age. The heating value of three-year-old shoots was 18.608 MJ kg−1.

Biological Flora of the British Isles: Neottia cordata

Abstract This account presents information on all aspects of the biology of Neottia cordata (L.) Rich. (Lesser Twayblade; Listera cordata (L.) R. Br.) that are relevant to an understanding of its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, reproductive characteristics, herbivores, history and conservation. Neottia cordata is an inconspicuous orchid, confined to humid heathlands and woodlands rich in bryophytes in the British Isles. Neottia cordata is a polycarpic, perennial herb with populations maintained predominantly by vegetative reproduction from root suckers. The main perennating organ is a short rhizome that produces two new internodes each year. The long adventitious roots are mainly colonized not only by mycorrhizal basidiomycetes from the Sebacinales (clade B, Serendipitaceae) but also by several other fungal groups. The species flowers from mid‐April to August depending on latitude and altitude. The flowers possess a sensitive rostellum that releases a viscid fluid when touched, ensuring that the pollinia are glued to the pollinator. The flowers produce nectar and are pollinated mainly by fungus gnats (Mycetophilidae and Sciaridae). Between 60% and 80% of open flowers set fruits. Neottia cordata is classified as Least Concern in Great Britain. It is still locally abundant in north and west Scotland but has declined elsewhere, especially at lower altitudes, because of burning on grouse moors, drainage of swamps and cutting of wet forests. It is likely to have been under‐recorded throughout its range, particularly in earlier surveys, due to its inconspicuousness.

Regeneration dynamics of planted seedling-origin aspen (Populus tremuloides Michx.)

Aspen (Populus tremuloides Michx.) is a foundational tree species of the North American boreal forest. After disturbance, clonal aspen stands quickly achieve canopy closure by sending up numerous clonal shoots (root suckers) from their lateral root system. Controlled aboveground disturbance will commonly induce prolific root suckering and thereby increase stem density in clonal aspen stands, but it is unclear if increases in stem density will be observed in planted seedling-origin aspen stands. The objectives of this study were to determine (1) overall root suckering response of planted aspen to aboveground disturbance; (2) if different cut heights of the stem or infliction of root damage impact the number of root suckers produced. We found that planted aspen regenerated readily after disturbance, averaging five root suckers per cut tree. However, individual response was highly variable, ranging from zero to 29 root suckers per root system. Of the cut trees, 75% produced at least one root sucker and 60% produced at least one stump sprout. Cutting trees close to the soil surface produced more root suckers than leaving a 25 cm stump. While root system size (mass and length) was well correlated with aboveground measures of planted aspen, root suckering was not related to root system size. As a result of increased forest reclamation efforts in the boreal forest region the planting of aspen has become a more common practice, necessitating a better understanding of the regeneration dynamics and root suckering potential of these planted and seedling-origin aspen forests.

Change of clonal frequency in the second root sucker generation of hybrid aspen

Abstract Two hybrid aspen (Populus tremula L. × P. tremuloides Michx.) trials in southern Sweden were used for studies of clonal composition in the second of two root sucker regenerations. Trial 1 was established in 1998 and originally included eight clones randomly distributed in four plots, each having 10 × 10 positions. Trial 2 was planted in 1957, with 150 seedlings from each of 25 full sib families randomly planted. Genotyping, using six SSR markers, was performed on wood samples collected from the second root sucker generation in each trial. Results from trial 1 clearly indicated a reduction in the genotypic diversity of the second sucker generation. All eight clones were still present, but at significantly different frequencies, with some close to zero. In trial 2, a total of 210 clones were found, genetically matched to 21 families, implying a rather marginal reduction in genetic variation. The clonal structure was mostly aggregated, but at the same time intermixing of ramets from different clones was quite common. The root suckers had, on average, spread 15 m from the stumps of the previous sucker generation of the same clone and the maximum distance was 49 m. The results indicate a change in clone frequencies over generations in root sucker stands of hybrid aspen. Hybrid aspen reforestation with seedlings originating from several unrelated families will retain genetic variation better in future sucker generations compared to clonal reforestations in which few clones are used. It is appropriate to use a higher number of clones than the normal five to eight used in Sweden today, in order to prevent future clone-specific damage as a result of reduction of clone diversity after several root sucker generations.

Beech shearing/high-stumping to control understory interference

The research evaluated opportunities for cutting off small understory beech root suckers at 0.6-0.9 m above ground. By six years (pilot test) after cutting with lopping shears in a closed-canopy uneven-aged northern hardwood stand, 91% of high stumps lacking a residual live branch had died. Of those cut above the lowest living branch, all survived. In a later operational trial by contract crews using chainsaws two growing seasons before a selection system cutting, 75% of high stumps without a residual live branch had died by the fifth year. Of stumps cut below the lowest living branch and that initially sprouted, only 7% had a live sprout by the sixth year. Among high stumps cut above the lowest branch, 84% survived.

Physiological differences between root suckers and saplings enlarge the regeneration niche in Eucryphia cordifolia Cav.

Many clonal plants produce vegetative recruits that remain connected to the parent plant. Such connections permit resource sharing among ramets, explaining the high survival rates of vegetative recruits during establishment under suboptimal conditions for sexual regeneration. We propose that differences in the regeneration niches of sexual and vegetative recruits reflect different physiological adjustments caused by parental supply of resources to the ramets. We conducted ecophysiological measurements in saplings and root suckers of Eucryphia cordifolia Cav., a tree species of the temperate rainforest of southern South America. We compared the following traits of saplings and suckers: gas exchange at the leaf level, crown architecture, daily crown carbon balance, biomass allocation to above-ground tissues (leaf-to-stem mass ratio, leaf mass area and leaf area ratio), xylem anatomy traits (lumen vessel fraction, vessel density and size) and stem ring width. We also correlated the growth rates of saplings and suckers with relevant environmental data (light and climate). Saplings showed morphological, architectural and physiological traits that enhance daily crown carbon balance and increase water-use efficiency, in order to supply their growth demands while minimizing water loss per unit of carbon gained. The radial growth of saplings diminished under dry conditions, which suggests a strong stomatal sensitivity to water availability. Suckers have low stomatal conductance, likely because the carbon supplied by the parent plant diminishes the necessity of high rates of photosynthesis. The low responsiveness of sucker growth to temporal changes in water availability also supports the existence of parental supply. The physiological differences between sexual and vegetative recruits satisfactorily explain the ecological niche of E. cordifolia, with saplings restricted to more closed and humid sites.

Genet diversity, genetic structure, and trait expression of trembling aspen (Populus tremuloidesMichx.) after clear-cut harvesting and post-harvest soil treatments

Trembling aspen is a fast growing, broadly distributed tree in North America that reproduces by root suckers (clonally) and by seeds (sexually). Since timber harvesting can affect both reproduction pathways by changing the soil properties, we assessed genet diversity, genetic structure, and phenotypic trait expression of trembling aspen populations after clear-cut harvesting in a long-term soil productivity study site in Michigan. A total of 323 stems in replicated plots having heavy soil compaction and surface organic matter (OM) removed, and the untreated controls, were analyzed at microsatellites and for phenotypic traits. Overall, higher spatial aggregation of ramets from the same genet, a greater spatial separation of different genets, and a very good phenotypic separation among genets was observed in the treatment plots. In contrast, for plots with spatially intermixed clones phenotypic separation was much lower. Genetic differentiation was high between individual plots, but soil compaction and OM removal had little effect on genetic differentiation and diversity. One treatment plot was strongly differentiated phenotypically, but not genetically, from all other plots. Consequently, microenvironmental and genetic differences should be considered when forest management effects on trait expressions and productivity are analyzed. Overall, heavy soil compaction and OM removal in fine-textured soil seemed to have restricted the spread of aspen clones.

Productivity and sustainability of hybrid aspen (Populus tremula L. × P. Tremuloides Michx.) root sucker stands with varying management strategies

Hybrid aspen (Populus tremula L.×P. tremuloides Michx.) has recently been introduced commercially in the Nordic and Baltic forestry. The hybrid is suitable for biomass production under high latitude conditions and the productivity is promising. Regeneration may be based on vigorous root sucker sprouting. Management strategies for root sucker stands are important for the outcome, but are still under development. Our study examined dynamics, productivity and sustainability of root sucker generations with three different management regimes: 4-year rotation (4YR), 8-year rotation (8YR) and intended 16-year rotation (8+YR), which was halfway in this study. Thinning measures were performed in the two longest rotations, i.e. corridor cleaning in 8YR, and corridor cleaning followed by thinning to ca 1100–1200 stems ha−1 in the 8+YR rotation. The study comprised a mid-term evaluation eight years after clear cutting of the initial planted stand.Total woody biomass production during eight years was 98.3, 92.6 and 87.2MgDMha−1 in the 4YR, 8YR and 8+YR treatments, respectively, but without significant differences. Mean annual increment (MAI) raised rapidly and reached a level of 10–12MgDMha−1year−1 in all regimes two years after clear cutting. Stem diameter development was strongly promoted by thinning measures and height development was also positively affected by reduced stand density.Sustainability in biomass production is essential when relying on sprouting after harvest. We could not see any productivity decline in the two consecutive 4-yearcycles included.Thinning measures often cause a decreased production until canopy closure is reached, but our study showed no decrease, which may be due to the very rapid growth of root sucker stands. The root sucker number was 77,000–124,000ha−1 after the first season. Self-thinning was reached after one year leading to a rapid reduction in living shoots in unthinned plots where the share of dead shoots constituted 46–56%, but only 5.0–9.1% of biomass, at the end of the 4-year rotations.We concluded that different management strategies affected biomass production weakly, but influenced diameter development strongly, which suggests a large flexibility where different management strategies may be selected for various purposes without substantial initial loss of biomass.

Evaluation Results of Finnish Apple Rootstocks in Latvia

Abstract A trial was established in 2011 with five rootstocks - MTT1, MTT4 and control B.9 (1.5 × 4 m, five replications with two trees), MTT5 and control MM.106 (2.5 × 5 m, six replications with two trees), and two cultivars - ‘Auksis’ and ‘Gita’. The evaluated parameters were: tree general condition, flowering, and yielding intensity (points), number of root suckers, average yield (kg·tree-1), yield per trunk cross section area (g·cm-2), average fruit mass (g), and amount of non-standard fruits (%). A randomised fruit sample from each cultivar-rootstock combination was put into storage, and a panel taste was performed once each season. A snowless winter occurred in 2013/2014, when soil froze to 1.5 m depth, which was critical for MM.106. Other rootstocks did not show injury. The best results were obtained for MTT4, which was similar to that of M.26 in Finland. Its vigour was similar to MM.106, and start of bearing to B.9. Rootstock MTT5 was initially grouped with medium vigour MM.106, as having 60-80 % of vigour of ‘Antonovka’ seedlings in Finland. Yet in our trial, it had vigour and start of bearing was similar to that of B.9 or slightly larger, depending on cultivar; it has a tendency to form root suckers. MTT1, ranged with B.9 in Finland, had too weak vigour. The most promising cultivar-rootstock combination was ‘Gita’ on MTT4.

Yale Behavioral Intervention Team (BIT) Model study: Results from the Two-year Implementation of a Proactive CL Psychiatric Service at the Yale New Haven Hospital

Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) has recently been introduced commercially in the Nordic and Baltic forestry. The hybrid is suitable for biomass production under high latitude conditions and the productivity is promising. Regeneration may be based on vigorous root sucker sprouting. Management strategies for root sucker stands are important for the outcome, but are still under development. Our study examined dynamics, productivity and sustainability of root sucker generations with three different management regimes: 4-year rotation (4YR), 8-year rotation (8YR) and intended 16-year rotation (8+YR), which was halfway in this study. Thinning measures were performed in the two longest rotations, i.e. corridor cleaning in 8YR, and corridor cleaning followed by thinning to ca 1100–1200 stems ha−1 in the 8+YR rotation. The study comprised a mid-term evaluation eight years after clear cutting of the initial planted stand.Total woody biomass production during eight years was 98.3, 92.6 and 87.2 Mg DM ha−1 in the 4YR, 8YR and 8+YR treatments, respectively, but without significant differences. Mean annual increment (MAI) raised rapidly and reached a level of 10–12 Mg DM ha−1 year−1 in all regimes two years after clear cutting. Stem diameter development was strongly promoted by thinning measures and height development was also positively affected by reduced stand density.Sustainability in biomass production is essential when relying on sprouting after harvest. We could not see any productivity decline in the two consecutive 4-year cycles included.Thinning measures often cause a decreased production until canopy closure is reached, but our study showed no decrease, which may be due to the very rapid growth of root sucker stands. The root sucker number was 77,000–124,000 ha−1 after the first season. Self-thinning was reached after one year leading to a rapid reduction in living shoots in unthinned plots where the share of dead shoots constituted 46–56%, but only 5.0–9.1% of biomass, at the end of the 4-year rotations.We concluded that different management strategies affected biomass production weakly, but influenced diameter development strongly, which suggests a large flexibility where different management strategies may be selected for various purposes without substantial initial loss of biomass.

Early regeneration response to aggregated overstory and harvest residue retention in Populus tremuloides (Michx.)-dominated forests

Recent emphasis on increasing structural complexity and species diversity reflective of natural ecosystems through the use of retention harvesting approaches is coinciding with increased demand for forest-derived bioenergy feedstocks, largely sourced through the removal of harvest residues associated with whole-tree harvest. Uncertainties about the consequences of such approaches prompted us to examine the combined impacts of aggregated overstory retention and harvest residue retention on the composition and density of regeneration following biomass harvests on four operational-scale (40 ha) study areas dominated by Populus tremuloides Michx. in northern Minnesota. Whole-tree harvest had no statistically significant effects on initial (2-year) regeneration densities, including root suckers, sprouts, and seedlings relative to conventional, stem-only harvest. The density of shrub stems was also unaffected by harvest residue retention. Despite having a lower mean leaf area index than intact forest controls, aggregates maintained comparable densities of the four most common tree species, individually, as well as all tree species combined. The composition of regeneration within aggregates differed from surrounding harvested areas as expected, but this increase in complexity at the stand scale was achieved without diminishing P. tremuloides densities in the edge area (0–5 m) surrounding aggregates 2 years after harvest. These initial findings suggest even small aggregates of overstory reserves may achieve basic objectives related to structural complexity and sustaining shade-tolerant tree species in harvested units without compromising regeneration objectives for less tolerant species.

Molecular Identification and Karyological Analysis of a Rampant Aspen Populus tremula L. (Salicaceae) Clone.

A rampant highly heterozygous aspen (Populus tremula L.) clone “Meshabash” has been revealed in course of population genetic diversity analysis in a native stand in the Republic of Tatarstan, Russia. Here we report the results of karyological analysis showing that this highly vigorous clone is diploid (2n = 38) while typically triploid aspen demonstrates increased growth rate and resistance to aspen trunk rot caused by fungus Phellinus tremulae. By means of DNA identification of a series of model trees using 14 SSR loci we outlined the area occupied by this clone (at least 1.94 ha) and demonstrated that its ramets constitute 40 out of 48 genotyped trunks on the plot with the maximal distance between ramets 254 m. Since aspen is able to regenerate after cutting or die-off of maternal tree by root suckers at a distance up to 20–35 m this assumed that current stand appeared as a result of such spreading from an ortet tree during at least 5 generations. Trunk rot damage in the wood of model trees indicated low influence of this pathogen on viability and performance of the studied clone that can be associated with its extreme heterozygosity level (0.926) exceeding all the studied trees in this research plot and in three other control samples.

The effects of population size on genetic parameters and mating system of sandalwood in Gunung Sewu, Indonesia

We combined feld observations with isoenzyme analysis to compare population demographic and its effects on genetic diversity and mating systems, among six populations of sandalwood in Gunung Sewu, Indonesia, during March to August 2015. This endangered economic-important species was originated from the southeastern parts of Indonesia, but is recently occured as new landraces in Gunung Sewu, Java island. The observed heterozygosity varied from Ho 0.184 to 0.385 in parents, and from Ho 0.083 to 0.348 in offspring levels, based on the degree of clonality and genetic base. Most of genetic variation is distributed within populations, and only 2.7% were presented among populations, that was indicated by the low DST and FST value (HT 0.30; HS 0.276; DST 2.4%; FST 7.98%). A dendrogram indicated a grouping of populations into three clusters. However, there were seemed to be no association between geographical and genetic distance. Genetic depletion occured due to (i) clonality events as result of heavy-exploitation and/or natural disturbance which induced root suckering, (ii) genetic drifts and bottleneck effects, (iii) the founder effects due to parental low diversity, and (iv) the alteration on mating systems to be more inbreeders. Some of the results confrmed a “reproductive assurance prediction” while some others were contradicting this. It seemed that genetic diversity and mating systems are not much affected by population size, but more by the parental heterozygosity and the degree of clonality. Our results emphasized the importance of populations’ genetic base or parental genetic diversity to naturally maintain the genetic and evolutionary processes under equilibrium conditions.

Efecto de la combinación Adara-M2624 y otros siete portainjertos sobre las características del dosel de dos variedades de cerezo

Se estudió la influencia de los portainjertos SL64, MxM60, MxM14, CAB6P, Weiroot 13, GiSeLa® 5 y GiSeLa® 6 y Adara-Mariana 2624, sobre el comportamiento vegetativo de las variedades de cerezo Bing y Celeste, durante 9 años después de la injertación, en las condiciones agroclimáticas locales. El diseño experimental fue por bloques completos al azar, con seis repeticiones de cuatro plantas por unidad experimental. Las variables fueron: área de sección trasversal de la variedad (AST), relación AST variedad-filtro, altura, volumen de dosel, índice de vigor y densidad de sierpes. El tamaño del dosel fue influido principalmente por el portainjerto y, en menor medida, por la variedad e interacción. En las condiciones del ensayo, SL64 fue el más vigoroso, seguido por MxM60 como vigoroso. Los MxM14, CAB6P y Adara-M2624 fueron semivigorosos; W13, semienanizante; G6, enanizante y G5, muy enanizante. GiSeLa® 5, GiSeLa® 6 y Weirrot 13 mantuvieron el VDct por debajo del máximo disponible, mientras que el de MxM14 y Adara-Mariana 2624 fue controlado sólo con poda. La variedad Bing fue más vigorosa que Celeste. Las combinaciones de portainjertos muy enanizantes con variedades de vigor medio resultaron en árboles demasiado débiles, y viceversa, plantas con excesivo vigor. Los W13, CAB6P y Adara-M2624 formaron sierpes.

Generative developments and pomological traits of apple (Malus x domestica Borkh.) scion cultivars canopy on dwarf clonal rootstocks in dry temperate ecosystem of north-west Himalayas

The investigations were undertaken to study the generative developments of thirteen scion cultivars grafted onto four dwarfing rootstock clones viz., EMLA.111, EMLA.7, MM.111 and BUD.9 for pomological traits in dry temperate ecosystem of north-west Himalaya of India. Comparing scion cultivars after 7 years of planting, the survival was recorded maximum for ‘Gale Gala’ grafted onto EMLA.111 and the poorest for ‘Oregon Spur-II’ grafted onto BUD.9 rootstock clone. EMLA.111 and EMLA.7 performed very well with “Gale Gala” and ‘Golden Spur’ with regard to agro-morphometric traits and elevated yield efficiency. The growth vigor of trees grafted onto EMLA.111 and EMLA.7 was larger than those on BUD.9. After seventh harvest season, the rootstock and scion cultivar significantly affected TCSA, TCV, CA, root suckering, yield efficiency and fruit size. Maximum TCSA, TCA and CA were recorded in scion cultivar grafted onto EMLA.111. The greatest root suckering was developed from EMLA.111 (Gibson Golden) and EMLA.7 (Red Gravenstein, Sparton), and the least in EMLA.111 (Gale Gala). Correlation analysis of different attributes representing the pomological traits also resulted in a significant association at alpha=0.05 attribute pairs. PCA of pomological and fruit quality traits was also worked out to evaluate the differences among scion cultivars tested on different dwarfing rootstock clones. PC4 accounted for 93.9% (pomological traits) and 80.6% (fruit quality) of the cumulative variance of scion cultivars studied. PCA-F1 had the highest positive loadings from plant height, tree girth, TCSA, and TCV followed by PCA-F2 (fruit yield and cumulative fruit yield). Further, no significant differences were obtained when the calculated factor scores of PCA-F1, PCA-F2 and PCA-F3 for fruit quality attributes were analyzed. The study inferred that the ability of the rootstock clones to perform better than current commercial standards, while, promoting orchard health and productivity with enhanced insect-pest and disease resistance.