Root damage affects nitrogen uptake and growth of young Fuji/M.26 apple trees

Summary

Effects of root damage during the transplant process on growth and nitrogen (N) uptake were studied with one-year-old bench-grafted Malus domestica Borkh ‘Fuji’ on M.26 rootstock apple nursery plants. Plants were potted after grafting and grown outside for one season. At the end of the season uniform trees were selected and randomly divided into four groups. One group of plants were moved into a 2°C cold room with soil and container intact (IR Treatment). Plants in other groups were removed from pots and stored as bareroot in the same cold room for three months. In the spring, bareroot plants were either: (1) transplanted with about 10% of the root system damaged during transplant (TP Treatment and Control-CK); or (2) root pruned by 25% (by volume) prior to transplant (RP treatment). Five trees from each treatment received 1 g of ¹⁵NH₄¹⁵NO₃ at 12, 41 and 76 d after repotting. Control (CK) trees received no N. Trees were harvested 10 d after each N application, and plant growth and total N and ¹⁵N content of different tissues were determined. Root pruning reduced plant total biomass and root biomass at the first two harvests, but the plants from the RP treatment had highest total plant biomass and root biomass at the third harvest. There was no significant difference in the new stem and leaf growth among IR, RP and CK treatments at harvests but the TP treatment reduced new shoot biomass. Plants with intact roots (IR) had the higher total N content while control plants (CK) had the lowest. Root pruning reduced ¹⁵N uptake rate at the first two harvests but promoted it at the third harvest. Our results suggest that plant growth and nutrient uptake was suppressed by root pruning/damage during transplanting only in the early season, and the negative effects on growth and N uptake were offset later in the season by compensative root regeneration.     

短截修剪程度对‘红灯’甜樱桃~(13)C和~(15)N分配利用的影响

以2年生‘红灯’(Prunus avium L.‘Hongdeng’)/东北山樱(Cerasus sachalinensis Kom.)为试材,研究了不同短截程度对13C和15N分配和利用的影响。结果表明,新梢生长期,短截处理修剪促进了碳水化合物向根系分配,极重度短截处理使叶片和新梢中13C分配率分别减少了29.15%和7.3%,粗根和细根中13C分配率增加了46.65%和48.43%。随着时间的推移,短截处理的叶片和新梢的13C分配率均显著高于对照,多年生枝干的13C分配率随短截程度的增加而减小,根系的13C分配率以中短截最低,极重度短截最高。各处理15N利用率从高到底依次为中度短截对照极重度短截,在新梢停长期差别最大,3个处理15N利用率分别为6.91%、5.54%和3.60%;多年生枝干15N分配率随短截程度的增加而减小,短截处理叶片和新梢的15N分配率随短截程度的增加而增加。     

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.     

Effect of pruning and plant spacing on the growth of cherry rootstocks and their influence on stem water potential of sweet cherry trees

Summary

The aims of this work are to describe the effects of pruning and planting density on growth and water relations of ungrafted and grafted sweet cherry trees. A trial with cherry rootstocks ‘Prunus avium’, ‘CAB 11E’, ‘Maxma 14’, ‘Gisela 5’ and ‘Edabriz’ was begun in 1997. Pruning severities were applied to the rootstocks (0, 30, 60 and 90% of the vegetative growth was removed corresponding to P1, P2, P3 and P4 treatments, respectively) after planting to two plant spacings (S1 = 0.25 × 1.0 m and S2= 0.45 × 1.5 m). Canopy, root growth and leaf water potential (ψ_leaf) were quantified throughout the growing season. Pruning significantly affected root length and root weight of the rootstocks. Uncut plants (P1) showed a heavier and expanded root biomass (231 g and 108 m) than the intensively pruned plants (P4) (187 g and 75 m). The greater root biomass was obtained with the spacing/pruning combination, S1/P1 (285 g), and the smaller with S1/P4 (180 g) and S2/P4 (176 g). ψ_leaf varied significantly between the rootstocks and plant spacing but not with pruning. ‘Maxma 14’ and ‘P. avium’ attained the lowest values of midday ψ_leaf, –2.28 and –2.04 MPa, but the highest values of predawn ψ_leaf, –0.29 and –0.25 MPa, respectively. Generally, with high density (S1), the rootstocks exhibited lower predawn and midday ψ_leaf. In 1998, cultivars ‘Burlat’, ‘Summit’ and ‘Van’ were grafted onto rootstocks and a trial was installed in 1999. Predawn and midday stem water potential (ψ_stem) on cherry trees, measured in 2002, were affected significantly by the rootstock/genotype combination. Cultivars grafted on ‘P. avium’ and ‘Maxma 14’ showed the less negative midday ψ_stem, –1.36 and –1.42 MPa respectively, so these rootstock genotypes perhaps induced a higher drought resistance to the scion. Recorded data show that the scion-rootstock interaction with regard to production performance under water deficits may be an important consideration in cherry tree planting strategies.     

Grundlagen der Reaktion von Apfelbäumen auf Wurzelschnitt – eine Übersicht

Root pruning in order to reduce shoot growth is characterized by inconsistent results and has unavoidable side effects. The theoretical basis for reliable predictions of apple tree's responses to root pruning is still largely missing. Here it is proposed that root pruning primarily interferes with the plant's mechanism of growth control: Reduced provision of cytokinins by the roots → reduced activity of shoot gibberellins → limited shoot growth and reduced auxin formation by the shoots → less inhibition of root growth and less shoot competition for carbohydrates → renewed root formation, cytokinin supply by the roots and shoot gibberellin activity → probably renewed shoot growth. Obviously, the initially reduced activity of gibberellins is crucial for the reduction of shoot growth and the various side-effects of root pruning. It depends – next to the extent and timing of root pruning – on the endogenous and external growing conditions. If these are optimal, the effect of root pruning is very limited as renewed root formation and vigorous root growth subsequently soon abolish the reduction of gibberellin activity. For a general recommendation of root pruning as part of a strategy of growth control, the prerequisites are missing.     

The effect of container shape on the development of roots and canopy of woody plants

The branching and spread of roots in containers was studied in a shallow rooting plant (Erythrina corralodendrum) and in a deep-rooting plant (oak, Quercus ithaburensis). In the Erythrina, the weight of the roots was found to decrease towards the base of the container. Sixty percent of the root system was laterals, which were evenly distributed throughout the container. In the oak, a higher root weight was found in the lowest third of the container than in the 2 upper thirds. Lateral roots comprised 14% of the complete root system, mostly in the base of the container. Severe pruning of oak roots resulted in a ratio of main-root/lateral roots comparable to that found in unpruned Erythrina.The growth and distribution of roots of plants with different growth characteristics in containers of various shapes, e.g. deep and narrow, or shallow and wide as compared to regular shape containers, were studied. Thus, in Ficus retusa, which has a shallow root system, the development of roots was stimulated in a shallow and wide container, but roots and canopy were restricted in a deep and narrow container. In Pistacia lentiscus, which has a deep root system, planting in a shallow and wide container resulted in retarded canopy and roots, while growing the same plant in a narrow and deep container showed a stimulated root growth. In Dodonea viscosa, whose root system is naturally deep and tends to spread laterally, a slight retardation of the root development was found when it was grown in a shallow and wide container. When grown in a deep and narrow container, canopy and root growth were stimulated.The study indicated that growth tends to be stimulated when there is a mutual matching between the natural growth pattern of roots and the shape of their container.     

除草剂对毛桃幼苗生长与光合的影响

以毛桃[Prunus persica（L.）Batsch.] 1年生幼苗为材料,研究土施除草剂对其生长发育、根系结构以及光合作用等的影响。结果表明：土施百草枯后,毛桃幼苗根系细胞电解质渗透率在初期显著升高,随后受损伤程度减轻;处理后40 d叶片蒸腾速率升高,叶片水分利用率、地上部干物质量显著降低。施用草甘膦对幼苗外部形态影响较明显,处理后7 d,幼叶变黄、向上卷曲,根系细胞电解质渗透率始终显著高于清水处理对照;处理后40 d,根总体积、总根长、总表面积以及根尖数显著减少,叶片净光合速率、气孔导度、蒸腾速率下降,植株干物质积累量也显著降低,表明草甘膦可通过根部传导危害地上部,桃园应尽量避免草甘膦等内吸性除草剂的使用。     

Rootstock and pruning effects on first season dry weight distribution in delicious apple trees

Redchief Delicious apple trees on MM. 106 and M.9 rootstocks were left unpruned, dormant headed at planting, or summer headed 12 weeks after planting, to investigate pruning and rootstock effects on dry weight distribution between roots and shoots during the first growing season. Dormant heading stimulated new shoot dry weight and reduced new root dry weight during the first six weeks after planting. However, by 12 weeks differences in new root dry weight and new shoot dry weight were insignificant. Summer heading resulted in a significant increase in new shoot growth and decrease in new root growth. This caused the root/shoot ratio in headed trees to return to the unpruned value within six weeks after summer heading. New root growth was reduced over a longer time by dormant heading trees on MM. 106 than those on M.9. New shoot growth was increased longer in trees on M.9. Allometric constants (K) of new shoot growth relative to new root growth were significantly changed by dormant heading with both rootstocks. Summer heading had the greatest effect on K values by shifting growth heavily toward new shoots. Root/shoot ratios in all treatments for both rootstocks showed no differences 24 weeks after planting.     

Root influence on shoot development in tea (Camellia sinensis (L.) O. Kuntze) following shoot pruning

The physiological interaction between the factors controlling the development of new shoots in pruned tea plants was investigated in an experiment using a widely cultivated TRI clone growing at low elevation in Sri Lanka. The functional importance during new shoot growth of root reserves, feeder roots and leaves and buds on unpruned branches (lung-shoots) is critically evaluated. A scheme for their interaction is presented, which highlights the need to maintain feeder roots alive during new shoot development, for which a large proportion of both reserve and current assimilates seem to be utilized. Mature leaves on lung-shoots, besides supplementing carbohydrate supply by current photosynthesis, may also serve to maintain the flow of metabolites from feeder roots to developing shoots and also function as ‘sinks’ for excess, toxic levels of root metabolites. Removing all mature leaves, as is done during ‘clean pruning’, leads to the depletion of reserves below the critical level for feeder root survival, resulting in death of feeder roots and failure of new buds to form shoots.     

Effects of growing and storage temperatures on growth and tuber yield of caladium

Growth of caladium (Caladium × hortulanum) plants was followed during ca. 7 months under prevailing summer conditions in Israel. Weight of daughter tubers increased exponentially with time. Growth ceased when mean night temperatures fell below 12°C in mid-November. Caladium is a plant which is sensitive to low temperatures, and when tubers were stored at temperatures below 20°C, subsequent sprouting rate was slowed. Storing tubers at 2°C for longer than 7 days reduced yield of daughter tubers, but shorter storage resulted in an improved crop. This was apparently a result of selective damage to the central bud, removing its apical dominance and releasing lateral buds from inhibition.Although chilling damage was evident when growth was considered, none of the accepted physiological processes normally associated with chilling injury, including electrolyte leakage, ethylene and CO₂ production, was correlated with it in caladium.     

芘对萝卜幼苗生长和一些生理特性的影响

采用土培方法探讨芘对萝卜幼苗生长和一些生理特性的影响。结果表明:芘对萝卜种子出苗率无影响,对幼苗株高、根长和叶面积有显著抑制作用;芘处理的萝卜幼苗叶片内叶绿素a、叶绿素b含量显著下降,丙二醛(MDA)含量、电解质渗透率显著提高,除超氧化物歧化酶(SOD)活性一直降低外,过氧化物酶(POD)、过氧化氢酶(CAT)活性均呈现先升高后下降的趋势。     

Impact of Mononychellus progresivus and Oligonychus gossypii (Acari: Tetranychidae) on cassava growth and yield in Central Africa

Growth of cassava was investigated in Central Africa (Congo) on crops attacked by two phytophagous mites: Mononychellus progresivus and Oligonychus gossypii. Change and distribution of dry matter in leaves, stems and roots were monitored for the 24 month crop cycle on infested and mite-free plants. Leaf dry matter increased during the rainy season and decreased during the dry season. Stems contain the reserves used for initiating plant growth after the dry season. Dry matter increased in the roots which form true storage organs. At the start of the second year of cultivation, one third of the root biomass was used to support the recovery of plant growth and development. Mite densities fewer than 50 mobile forms per leaf (maximum number of mites) were not sufficient to cause significant loss of leaf, stem and root dry matter. Nevertheless the mites diverted part of the biomass allocated to the roots thereby reducing the efficiency of storage root production in the infested plot.     

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.     

Light quality affects in vitro adventitious rooting and ex vitro performance of cherry rootstock Colt

The effect of light quality on in vitro rooting of cherry rootstock “Colt” was studied to evaluate adventitious root development, ex vitro acclimatization and plant growth performance. Adventitious rooting was dependent on the light quality to which the microcutting were exposed. Highest number of roots per microcuttings was recorded under dichromatic light (blue + red). This response could be ascribed to the control of a strong synergistic interaction between phytochromes and blue light photoreceptors. Red light was more effective on root elongation than blue light. In this response a strong synergistic interaction between phytochromes and blue light photoreceptors was suggested. The effect of light quality on the number of root/explant affected the plant during acclimation, scoring the highest level of plant survival in the blue-, red- and blue + red-exposed plantlets. The light quality effect was also observed under greenhouse culture conditions, as shown by growth parameters at the end of six months in plants growth. No specific role was observed for the photoequilibrium of phytochrome. The results reported in this work show that plantlets exposed to different light quality, during the in vitro rooting phase, retain the light quality effects in the subsequent plant acclimatization and greenhouse plant growth phase.     

Carbohydrate dynamics in roots,stems, and branches after maintenance pruning in two common urban tree species of North America

The ability of plants to tolerate stress is determined in part by the carbon allocated to their reserves. We studied two common urban tree species in northeastern North America, Acer saccharinum (Silver maple, native) and Acer platanoides (Norway maple, exotic), to assess the dynamics of non-structural carbohydrate (NSC) concentrations immediately following a maintenance pruning of 30% of the tree crown. NSC concentrations were measured by high-performance liquid chromatography in branches, main stems, and root tissues for both pruned and un-pruned trees at three intervals during the growing season. NSC concentrations in tree organs of A. platanoides were 75% higher than in A. saccharinum. Maintenance pruning did not have any significant depletion effect on carbohydrate concentrations in the tissues of either species. Yet, there was a significant increase in the NSC concentrations in un-pruned branches of pruned trees of A. platanoides at the end of the growing season, but no effect was observed in A. saccharinum. Higher levels of carbohydrates after pruning in woody plant tissues suggested that A. platanoides may have compensatory mechanisms that allow this species to respond better to maintenance pruning than A. saccharinum.     

Growth and stability of deep planted red maple and northern red oak trees and the efficacy of root collar excavations

Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and stability, with and without root collar excavation, for red maple [Acer rubrum L. Red Sunset^® (‘Franksred’)] and Northern red oak (Quercus rubra L.) planted at grade or 30-cm below grade. Sleeves to prevent soil-trunk contact were installed around trunks on a subset of deep trees. Root collar excavations were made during the 6th growing season for both species and trees were grown for an additional 4 and 3 growing seasons for red maples and Northern red oaks, respectively. Within two weeks of root collar excavations, pulling tests compared the effect of treatments on stability of red maples. Deep planting generally slowed growth of red maple but had no clear effect on Northern red oak. Root collar excavation had no lasting effect on growth of either species. Approximately 55% of deep red maples and 33% of deep Northern red oaks had roots crossing and in intimate contact with buried trunks, suggesting a potential for future girdling roots. Approximately 25% of deep maples had substantial adventitious rooting. All deep Northern red oaks had new roots emerging just above the first original structural roots but none were clearly adventitious. Trunk sleeves had no effect on growth for either species. Neither deep planting nor root collar excavation resulted in a loss of tree stability compared to trees planted at grade, although failure patterns varied among treatments. Overall, the biggest long term concern for deep-planted trees is the potential for girdling root formation.     

平邑甜茶幼苗生长、根构型及吸收特性的容器调控

 以平邑甜茶[Malus hupehensis (Pamp.) Rehd.] 幼苗为材料, 研究了栽培容器形状对幼苗新梢生长、幼苗根构型特征及根系营养吸收特性的影响。结果显示, 生长在“深窄盆”中的幼苗新梢生长量最大, 主根粗, 侧根多且短, 毛细根丰富, 对钙及锌的吸收能力较强, 但根系活力及根系对磷、铁的吸收能力较弱; “等高径盆”中幼苗新梢生长量小, 根冠比接近1, 主根细短、一级侧根少且粗长, 对钾的吸收能力较强; “浅宽盆”幼苗根冠比最大, 一级侧根数量、长度和粗度居中, 二级侧根粗长, 根系活力及根系对磷、铁的吸收能力较强, 但对钾、钙及锌的吸收能力弱。     

Chemical control of side shoots in the tomato

23 compounds, comprising a range of methyl esters, long-chain acids, alcohols and hydrocarbons, and four commercial products were tested as chemical pruning agents to control side shoot growth in the tomato. When applied in the form of emulsions as sprays to the whole plant, a number of these compounds killed lateral buds less than 6–8 mm in length and no subsequent regrowth occurred. Damage to other parts of the plant frequently occurred, but this could be reduced considerably by confining the spray treatment to the leaf axils, avoiding run-off of the emulsion down the stem, and by thoroughly wetting the plant with water 20 min after the application. The commercially available pruning agent Off-Shoot-O gave the most successful control of lateral bud growth with least damage to the rest of the plant, and it is suggested that the careful use of this compound at certain stages of growth may have advantages over manual pruning.     

Interactions between N,P and C mobilisations during spring growth of a semi-evergreen shrub (Ligustrum ovalifolium L.) grown in containers with different fertilisation schedules

Container-grown Ligustrum ovalifolium L. plants were used to determine the influence of nutrient availability on the mobilisation of carbon (C), nitrogen (N) and phosphorus (P) during spring growth. During the spring of the second growing season, plants either received no fertiliser, or were fertilised early (starting 17 days after bud break) or late (starting 3 months after bud break). Nutrient composition of different plant tissues was determined at several times during the second growing season from bud break to the end of elongation. Time of fertilisation did not influence aerial dry weight until flowering was completed. Plants that received no fertiliser or were fertilised late had greater root dry weight than plants that received fertiliser early. Fertilised plants had a second flush of growth after flowering completed. Nitrogen and phosphorus mobilisation occurred from bud break to the end of elongation (3 months). Nutrient mobilisation was effective in each perennial organ: root, trunk, ligneous stems and old leaves. However, the role of old leaves as storage organ was minor compared to evergreen tree leaves. Carbon mobilisation only occurred on the 1st month following bud break, before elongation. C-starch accumulation was observed in unfertilised plants even when the C-starch quantities in early fertilised plants were very low at the end of elongation, mainly in roots. In spite of fertilisation supplies, N and P quantities did not increase after elongation in the early fertilised plants, probably in relation to C insufficiency in roots to sustain N and P absorption and assimilation. By contrast, in late fertilised plants, high C quantities in roots were mobilised for N and P uptake and assimilation, which allowed both second growth flush and storage of N and P in perennial organs. The mobilisation of nutrients before and during elongation revealed the nutritional autonomy of shrubs, which could allow fertiliser use efficiency to be increased and environmental impacts to be minimised by delaying spring fertilisation. Nevertheless, the shrub ability to valorise fertilisation supplies for sustaining growth or nutrient storage restoration required sufficient C-starch quantities in roots. The starch accumulated in roots before late nutrient supply can be used for these objectives.     

持续低温胁迫下甜樱桃枝条电导率变化研究

用电导法测定了5个甜樱桃和1个酸樱桃的枝条细胞在经历持续低温胁迫的过程中电解质渗出率(即电导率)的变化,研究了5个甜樱桃品种的抗寒性。结果表明:所有樱桃品系的枝条细胞在接受持续-20℃低温胁迫处理过程中,细胞电解质渗出率先升高后降低,即细胞在接受临界致死温度附近的低温胁迫过程中,在一定的较短时间内细胞的自身恢复能力会快速提高。比较各品种之间电解渗出率的相对大小与分析细胞自身恢复能力情况得出,酸樱桃CAB、红艳和龙冠的抗寒力相对较强,是抗寒性较强品系、品种,红蜜、红灯和茉莉抗寒力相对较弱,是抗寒性较弱品种。