Partitioning sources of rooting potential in plum hardwood cuttings

SUMMARY

Rooting of leafless winter hardwood cuttings of the plum rootstock Prunus insititia ‘Pixy’ increased as the location from which the shoots were taken from within specially grown stockplants decreased in height above ground, associated with a parallel reduction in shoot thickness. However, the actual height of the least-ready-rooting crown cuttings had no effect on rooting, suggesting that relative rather than absolute position is important. Rooting was unaffected by bark-ringing and trunk incision distal to the shoot position, suggesting that such treatments did not interfere with a basipetally translocated root promotor which might have accounted for improved rooting of cuttings in the lower parts of the hedge. The rooting of crown cuttings above a bark ring was reduced considerably compared with that of cuttings from normal bushes, and this was associated with increased thickness of shoots distal to the ring. Delaying pruning in spring until after growth had started resulted in thinner crown shoots compared with those from plants pruned normally while dormant, and the rooting of these thinner crown shoots was much higher than that of the normal crown cuttings. It was shown by covariance analysis that shoot thickness accounted for part of the rooting response but could not account for the total effect due to shoot position within the bush, ringing, or time of pruning. Competence to root appears to develop independently in individual shoots, modified by a shoot thickness factor which favours the subordinate shoots induced in the shoot hierarchy of severely pruned hedges.     

Rooting potential in plum hardwood cuttings: I. Relationship with shoot diameter

The length of the annual shoots produced on hedges of the plum rootstock Prunus insititia ‘Pixy’ was determined more by the duration of their growth than by their growth rate. The most dominant shoots from the distal part of the framework grew for more than 16 weeks while weak shoots from lower down the framework stopped growing in half that time. There was a curvilinear relationship between shoot length and the proximal diameter of the cutting prepared from it, for shoots from various sources comprising different levels of winter pruning and different parts of the framework of the bush. The extent to which rooting potential was expressed was determined by the management of the rooting medium. When this was too wet, cutting bases developed necrosis which was particularly prevalent in the thinner cuttings. This problem was avoided by planting cuttings with their bases on rapidly draining sand rather than in granulated bark. Under these circumstances percentage rooting decreased with increasing cutting thickness. Before necrosis was controlled in this way rooting increased with increasing proximal stem diameter up to 6-8 mm, reflecting the susceptibility of thin cuttings to over-wet conditions.     

Rooting response of plum hardwood cuttings to IBA in relation to treatment duration and cutting moisture content

The rooting response of plum rootstock hardwood cuttings to 50, 500 and 5000 ppm IBA was influenced by the duration of treatment in the auxin solution, 18 min, 30 sec and 5 sec being needed to achieve similar levels of rooting at the respective concentrations.

A delay between collection and IBA treatment of cuttings, resulting in a partial water deficit, caused an increase in IBA uptake which was associated with increased rooting. For Myrobalan B a delay of 22 hours at 60 °F (15.5 °C) and 50% RH, leading to a 10% moisture loss, was optimal.     

银杏硬枝插穗不同处理方法生根成活率试验

试验设5个处理,采用春采和冬储两种采穗方式,用自制高分子.激素水凝胶生根膜和ABT1号生根粉100mg/kg溶液对银杏硬枝插穗进行处理。试验结果表明银杏春采插穗涂自制高分子.激素水凝胶生根膜露地与地膜覆盖扦插育苗生根成活率无显著差异,较冬储插穗浸ABT生根粉100mg/kg溶液露地、地膜覆盖扦插可显著提高插穗生根成活率。     

Differentiation of the dynamic variables affecting rooting ability in juvenile and mature cuttings of cherry (Prunus avium)

Summary

The rooting potential of four types or origins of Prunus avium cuttings from the same mature trees (over 20 years-old) was compared using a mist propagation bed during early Summer (June). The cuttings originated from juvenile sucker shoots of the current and previous year, and mature crown shoots (current year’s lateral ‘long-shoots’ and multi-year terminal ‘short shoots’). The morphological differences in inter-node length, stem diameter and leaf area between the four cutting types were highly significant (P = 0.05), leading to large differences in cutting volume and, so it is argued, to assimilate reserves. Juvenile cuttings rooted well (65% and 77% rooting for hardwood and softwood shoots, respectively), while mature cuttings rooted poorly (4% and 7% for mature hardwood and softwood cuttings, respectively). Leaf abscission was significantly more frequent in mature hardwood cuttings (16 – 78%) than in the other cutting types (1.6 – 9%) at the end of the propagation period. Leaf loss resulted from two processes: abscission and leaf rotting. Physiologically (i.e., in carbon assimilation, leaf transpiration and stomatal conductance), the four cutting types were not significantly different early in the post-severance period (day-4); but, by day-22, stomatal conductance was lowest in mature hardwood cuttings that still had leaves. At this time, the most physiologically-active unrooted cuttings were from juvenile hardwood and mature softwood shoots. The extent of physiological and morphological variability between cutting types and their probable impact on processes affecting rooting ability is complex and highly interactive. Consequently, it is not possible to explain the causes of the variation in rooting ability between juvenile and mature cuttings, although this study suggests that the constraints to rooting are likely to reflect physiological differences between the different cutting types. It is concluded that, to resolve the debate about factors that affect the rooting ability of juvenile and mature cuttings (i.e., ontogenetic vs. physiological ageing), there is a need to achieve morphological and physiological comparability in the tissues.     

Effect of xylem blockage on stem resistance and water potential in Triplochiton scleroxylon K. Schum. cuttings

Summary

Cuttings of the tropical hardwood species Triplochiton scleroxylon K. Schum. may be extremely difficult to root, depending on the physiological status of the parent plant and propagation conditions. This study examined the importance of xylem blockage in limiting the water supply to unrooted stem cuttings. Stem resistance was greatest in Node 1 cuttings (youngest node) of stock plants, and decreased basipetally. Resistance increased to a maximum, and water potential reached a minimum, 6 d after transfer to rooting medium.The primary site of blockage occurred within 1 mm of the stem base, suggesting an excision-induced wounding response. Histological studies revealed that gums of carbohydrate origin were deposited in some protoxylem elements near the stem base. The influence of these factors in determining cutting survival is discussed.     

Flower production in Gerbera: I. Correlations between shoot,leaf and flower formation in seedlings

Flower production of seedling plants of Gerbera was shown to be positively correlated with the number of lateral shoots and with the number of leaves per flower. The most productive plants were those which formed 2–5 lateral shoots during the first year and had a $\text{leaf}\text{flower}$ ratio of 2–4. The number of lateral shoots at the moment the first flower bud became visible was strongly correlated with the number of lateral shoots after 1 year.There was a positive correlation between the number of lateral shoots and total number of leaves, but hardly at all between total leaf number and flower production, as the $\text{leaf}\text{flower}$ ratio increased with the number of lateral shoots.     

Relationships between sap flow,hydraulic conductivity,and the anatomical characteristics of stems and roots in apple rootstocks of different vigour

Summary

To find a useful parameter that could be related to the degree of rootstock vigour, for rootstock breeding programmes, sap flow, hydraulic conductivity, and the anatomical characteristics of stems and roots were measured in 1-year-old trees of apple rootstocks of different vigour. Sap flow was less active in dwarfing rootstocks than in invigorating rootstocks, when taking leaf area into account, under a controlled temperature of 20ºC with the root zone at 15ºC. The hydraulic conductivities of stems and roots were not consistent with the degree of dwarfing.The hydraulic conductivity of the stem appeared to be related to the diameter and density of the large vessels in the xylem. On the other hand, the phloem-to-xylem ratio in roots with diameters of 1.5 – 2.0 mm, was closely-related to sap flow and the degree of dwarfing. The phloem-to-xylem ratio decreased as the degree of vigour increased. Moreover, the phloem-to-xylem ratio was considered to be related to the ability of roots to absorb and transport water, which was expressed as the root-specific sap flow. Therefore, the phloem-to-xylem ratio could be a useful index for evaluating the potential of apple trees as dwarfing rootstocks.     

改良高干开心形富士苹果树冠不同层次相对光照强度分布与枝叶的关系

以12 a生富士苹果(Malus domestica Borkh cv.Red Fuji)为试材,研究了改良高干开心形树冠不同层次相对光照强度的分布、季节动态变化与枝叶数量间的关系。结果表明,树冠相对光照强度从上部到下部逐渐降低,同一冠层内相对光照强度从内膛到外围逐步增加;树冠最上层5—10月呈平稳趋势,而中下部5—7月呈下降趋势,7月份后趋于稳定;小于30%的相对光照强度的树冠体积在年生长周期内逐渐增加:5—6月份为15%,7—8月27%,9—10月30%。新梢的空间分布研究表明,>30 cm的长枝(梢)、15～30 cm的中长枝(梢)、5～15 cm中枝(梢)和小于5 cm的短枝(梢)分别集中分布在冠层高度2.0m以上、1.5～2.5m、1.0～2.0m和1.0～2.5m冠层内;生长季总枝量100.39万条/hm2,长、中长、中和短梢占总枝量的比例分别为6.44%、5.52%、14.40%、73.64%,多于6片叶的短梢占总短枝量的42.08%。应用多元统计分析的方法建立了树冠相对光照强度与枝(梢)叶量关系的回归方程,相对光照强度值与累计枝梢数量和叶面积系数呈负指数关系,苹果优质生产和最佳利用光能的群体结构参数为总枝(梢)量小于96万条/hm2,叶面积系数控制在3.9以下,长、中、短梢比例分别为10.91%、13.70%和75.39%。     

Isoelectric focusing of proteins and some enzymes from secondary phloem of cherry grafting-combinations. II. Proteins in spring

Buffer-soluble proteins in secondary phloem surrounding the xylem in grafting-unions of P. avium/P. avium, P. avium/P. cerasus and P. avium/P. fruticosa combinations were extracted and isoelectric-focused in spring. The total number of proteins as well as their concentrations were found to be generally lower in spring than in winter. In all graft combinations, except Hed./(F 12/1) and Hed./Cer. W 11, the number of proteins in the sections adjacent to the graft union was reduced. However, Hed./(F12/1) showed a rise to a maximum in the section below the union. The proteins of rootstock sections located at a greater distance from the union were relatively high in 3 combinations (Hed. on Frut., Cer. W 10 and F 12/1) as compared to those of the scion, whereas the other combinations did not show marked differences in this respect.     

Carbohydrates and their effects on the growth and establishment of Tilia and Betula: II. The early season movement of carbohydrates between shoots and roots

^l4C applied as labelled ¹⁴CO₂ was shown to move from leaves and shoots to roots of young Betula transplants as early as two weeks after budburst, approximately one week before the first visible signs of new root growth. Similar translocation in young transplanted Tilia was not noted until four weeks after budburst, again about one week before the onset of new root growth, which begins later after budburst in this species. The maintenance of a basal stem girdle over the period between planting and approximately eight weeks after budburst severely inhibited new root growth in both genera and also reduced individual leaf area and extension shoot growth. Carbohydrate content within the roots of both species declined in the first month after budburst. Girdling had no effect upon Tilia root carbohydrate content but severely reduced that of Betula. Total carbohydrate content of Betula shoots and leaves increased in the month following budburst, whereas that of Tilia declined slightly. Defoliation one month after budburst also reduced new root growth of both species in the subsequent month; shoot growth of Tilia, but not Betula, was reduced by defoliation. The results are discussed in relation to transplanting success with Tilia and Betula.     

Studies in Iron Deficiency of Crops: II. The Interrelationships of Iron and Potassium in the Potato Plant

Attempts to reduce the growth of Lord Lambourne apple trees without adversely affecting cropping by using mild strains of single viruses or mycoplasmas were not successful. Of the five different infections used only rubbery wood significantly reduced tree size, but two infections (spy epinasty and decline and rubbery wood) reduced crop weight over an eight-year period. None of the treatments affected the skin colour, time of ripening or the seed number of the fruit.     

Bitter Rot of Apples: II. Seasonal Variations in The Development and Sporulation of Cankers of Gloeosporium SPP. Inoculated into Apple Branches

Two-year-old potted trees of Cox’s Orange Pippin, Laxton’s Superb and Worcester Pearmain were grown in controlled environment chambers at Long Ashton during 1960 and 1961, and subjected to four types of winter temperatures : 1, a long, cold winter ; 2, a severe autumn and mild spring ; 3, a mild autumn and severe spring ; 4, a short, mild winter ; 5, natural winter.

The order of bud break was treatment 2 followed by 4, then I and lastly 3. The time of bud break was more strongly influenced by the date of winter chilling than by its intensity, but the intensity influenced the temperature at which bud break became possible. On I-year-old wood the number of leafy rosettes developing increased with the length of the chilling period.

Because of limitation of space and the consequent small number of trees used, no firm conclusions could be drawn, but flower bud production and rate of spur development from bud break to full bloom appeared to be favoured by a mild autumn. An early and severe autumn apparently increased flower bud abscission at green cluster, but no effect of treatments could be determined in the final yields of fruit.     

Variation in stomatal behaviour and gas exchange between mid-morning and mid-afternoon of north–south oriented grapevines (Vitis vinifera L. cv. Tempranillo) at different levels of soil water availability

A 3-year study was conducted to examine leaf gas exchange response of Vitis vinifera L. (cv. Tempranillo) grapevines growing in the central Iberian Peninsula as a function of soil water availability. Net CO₂ assimilation rate (A), stomatal conductance (g_s) and transpiration (E) of leaves were measured at the east and west side of vines planted in north/south orientated rows. Soil water availability was varied by three different irrigation treatments at 0.45, 0.30 and 0.15 of ETo and a fourth non-irrigated treatment. Approximately 60% of the variation in g_s over 3 years was due to changes in soil water content (θ_v); the correlation between the two was closer when examined on a season by season basis. Net CO₂ assimilation rates were significantly correlated with g_s. Stomatal conductance decreased by approximately 25–30% when measured 15:00 h (west side of vines) compared to 09:00 h (east side of vines); reductions in A were even greater than those in g_s. Leaf E increased approximately by 15–25% from morning to afternoon. The reduction in A and g_s from morning to afternoon was observed even in irrigated vines but absolute differences increased with decreasing soil water. This occurred when maximum daily g_s was less than 200 mmol m⁻² s⁻¹. These responses indicate that in hot areas training systems and row orientation, which minimize exposed leaf, area in the afternoon should be recommended.     

Studies on The Effects of Light Quality on The Growth and Development of Plants: II. Formative Effects in Lycopersicon Esculentum and Pisum Sativum

Diffuse and surface-growing bacteria are the two main types of non-pathogenic contaminants in the carnation cultured-cutting test. Wiping the base of the cutting with 10 % Stergene before sterilization decreased fungal contaminants. A medium containing o.o1% crystal violet was used to isolate Verticillium cinerescens from infected plants. It allowed growth of fungi and pathogenic Gram-negative bacteria from stem sections, but prevented growth of Gram-positive contaminants. This medium decreased bacterial contamination in the cutting test, especially from surface bacteria.     

Molybdenum as a Plant Nutrient: II. The Effects of Molybdenum Deficiency on Some Horticultural and Agricultural Crop Plants in Sand Culture

For 12 genotypes of red raspberry, the expression of various fruiting lateral characteristics at different node positions on the cane is described by regression techniques. There was much variation in the expression of these characteristics in 1975. Lateral length and lateral node number usually increased towards the cane base; but in some genotypes the rate of increase was not constant and declined towards the base giving a curvilinear relationship. Reproductive characteristics such as fruit number were often constant for all cane node positions. These relationships differed in 1976 and 1977 but usually genotypes changed in a similar way. Where genotypes changed in a dissimilar way it was related to cane height in the previous year. Some factors which influence these developmental patterns and the possible role of the timing of floral initiation in determining them are discussed together with some practical implications.     

Studies of Fruit Development in Relation to Plant Hormones: II. The Effect of Naphthalene Acetic Acid on Fruit Set and Fruit Development in Apples

The experiments described in this paper were designed. (1) to investigate the mechanism whereby α-naphthalene acetic acid (NAA), applied as a spray to apple trees between full bloom and two to four weeks after petal-fall, reduces the crop ; and (2) to assess the possible value of this substance as a blossom- and fruit-thinning agent.

Spraying open flowers with NAA before pollination was found to induce incompatibility between the pollen tubes and the stylar tissue, and it is considered that this may account for the reduction in set which results from spraying trees at full bloom with NAA. Applied after petal- fall, the spray caused the abortion of a large proportion of the developing seeds and this, in turn, led to an abnormally large drop of young fruitlets. The seeds appeared to be susceptible to damage by NAA only as long as the endosperm was in the free nuclear stage, a condition which, in most varieties of apple, persists until about the third week after petal-fall. As a thinning agent, NAA has the disadvantage that it tends to retard fruit growth. This effect is particularly marked when the spray is applied later than two weeks after petal-fall, and frequently offsets any increase in fruit size which might have resulted from thinning. Earlier application of the spray may, in certain varieties, cause a permanent stunting of the foliage. In the strongly biennial Miller’s Seedling, none of the thinning treatments, using NAA on individual branches, resulted in the differentiation of fruit buds in the " on ” year.     

Multi-model comparison on the effects of climate change on tree species in the eastern U.S.: results from an enhanced niche model and process-based ecosystem and landscape models

Context

Species distribution models (SDM) establish statistical relationships between the current distribution of species and key attributes whereas process-based models simulate ecosystem and tree species dynamics based on representations of physical and biological processes. TreeAtlas, which uses DISTRIB SDM, and Linkages and LANDIS PRO, process-based ecosystem and landscape models, respectively, were used concurrently on four regional climate change assessments in the eastern Unites States.

Objectives

We compared predictions for 30 species from TreeAtlas, Linkages, and LANDIS PRO, using two climate change scenarios on four regions, to derive a more robust assessment of species change in response to climate change.

Methods

We calculated the ratio of future importance or biomass to current for each species, then compared agreement among models by species, region, and climate scenario using change classes, an ordinal agreement score, spearman rank correlations, and model averaged change ratios.

Results

Comparisons indicated high agreement for many species, especially northern species modeled to lose habitat. TreeAtlas and Linkages agreed the most but each also agreed with many species outputs from LANDIS PRO, particularly when succession within LANDIS PRO was simulated to 2300. A geographic analysis showed that a simple difference (in latitude degrees) of the weighted mean center of a species distribution versus the geographic center of the region of interest provides an initial estimate for the species’ potential to gain, lose, or remain stable under climate change.

Conclusions

This analysis of multiple models provides a useful approach to compare among disparate models and a more consistent interpretation of the future for use in vulnerability assessments and adaptation planning.