Mature Cuttings Research Articles

Improved Clonal Propagation through Rejuvenation of Mature Branch Cutting of Four Important Acacia Species

Asexual propagation techniques for producing good quality germplasm for breeding and dissemination purposes have proven difficult for acacia species comprised of mature planting material. The study was conducted to study the effect of rejuvenation on the rooting ability of mature cuttings. Shoots were induced from the lower branch by cutting a part of the mature branch of the crown and leaving it horizontally on the propagation bench under the misting system. Shoots were harvested and further used as stem cuttings to evaluate their rooting ability through the application of rooting hormone. The rooting ability of the cuttings is highly variable among species. The percentage of stem sections producing juvenile shoots was similar for Acacia mangium Willd. (88%) and Acacia auriculiformis A.Cunn. ex Benth. (90%). Only 52% of stem sections were able to produce shoots for Acacia crassicarpa A.Cunn. ex Benth., followed by Acacia aulococarpa A.Cunn. ex Benth. with only 31%. Overall, A. auriculiformis rooted better and recorded the highest mean value for all traits tested. Hormone treatment significantly enhances the rooting ability of A. auriculiformis and A. mangium. However, A. aulococarpa and A. crassicarpa did not respond well to the treatment. Rejuvenated stem cuttings were rooted better than mature cuttings, producing the highest mean value for all traits tested in all species, with or without hormone treatment. Results indicated that it is possible to rejuvenate mature cuttings through bud break in a controlled environment.

Effect of donor plants and rooting medium on stem cutting propagation of faloak (Sterculia quadrifida)

Abstract. Rianawati H, Siswadi. 2020. Effect of donor plants and rooting medium on stem cutting propagation of faloak (Sterculia quadrifida). Trop Drylands 4: 31-35. Faloak (Sterculia quadrifida R.Br.) is a semiarid species and an important medicinal plant from Sterculiaceae family. This species is threatened by overexploitation and low seed production, reducing its population in the wild. Thus, planting is necessary to conserve this species, but limited knowledge exists regarding its propagation. The study was conducted to investigate the effect of donor plants and rooting medium on stem cutting propagation of S. quadrifida. The stem cuttings from S. quadrifida seedlings/juvenile (3.7-8.5 mm in diameter) and S. quadrifida trees/mature plants with two different size of diameter, small diameter (5.8-13.8 mm) and large diameter (15.4-24.4 mm), were planted in three various growth medium (soil, soil+manure of 1:1 ratio, and coco peat). The result showed that the survival rates of stem cuttings from juvenile donor plants and mature plants with large diameter were higher (15%-25%) than the survival rate of mature cuttings with small diameter (0%-5%). However, the rooting medium had no significant effect on the survival rate of stem cutting. Additionally, variables measured at the end of the observation, such as the number of roots/cutting, root length, number of nodes, number of leaves, leaf size were not significantly different among the survived stem cuttings from different treatments.

Improved method for vegetative propagation of mature Pinus halepensis and its hybrids by cuttings

Forest trees possess high genetic diversity and high heterozygosity which allow adaptation to changing environmental conditions. There is a tendency to propagate successful and unique genotypes, which are identified at their mature stage in the forests, for future improvement programs and conservation purposes. However, vegetative propagation of mature forest trees is still a challenge in many conifers. In this study, we focused on improving the rooting of cuttings of mature and old Pinus halepensis and its hybrids. We observed that storage of cuttings before rooting at 4°C for 4 weeks and prolong immersion of cuttings in a solution containing 400 mg/l of indole-3-butyric acid, 5 mg/l of the auxin conjugate 2-(2,4-dichlorophenoxy)propanoic acid-glycine methyl ester, and 0.01% of Amistar fungicide significantly improved rooting of mature cuttings. The active ingredient in Amistar is azoxystrobin, an uncoupler of respiration, which seems to directly promote rooting. Rooted cuttings of selected clones demonstrated unique and uniform growth performance, most likely delivering the intrinsic growth parameters of the mother trees. It was also observed that trees growing under drought stress possess improved rooting ability. By using rooted cuttings, it will be possible to study the relationship between growth rate and adaptation to semi-arid climate conditions. The ability to clonal propagate mature and old P. halepensis trees not only enables vegetative propagation of elite trees for improvement programs, but also provides an opportunity to preserve unique naturally occurring old P. halepensis genotypes.

A leaf bud technique for rapid propagation of cassava (Manihot esculenta Crantz)

The slow rate of multiplication is one of the main constraints on the production of cassava (Manihot esculenta Crantz). This work aimed to evaluate the use of leaf buds for rapid propagation of cassava varieties. Leaf buds were excised from three cassava varieties (BRS Kiriris, 98150-06 and 9624-09) for plantlet generation. The experiment was completely randomized with a 5 (age of mother plant) × 3 (position of the leaf buds on the stems) × 2 (agrochemical treatments) factorial design. Data were collected on leaf sprouting percentage (Spro.Per), plantlet height (Plant.Hei) and total dry mass of plantlets (Dry.Mass.Plant). There was a difference between the three traits for most of the varieties, demonstrating significant effects on the agronomic attributes evaluated. Better agronomic performance (higher sprouting percentage, plantlet height and total dry mass) in plantlets was observed in leaf buds of: i) maturing plants up to six months old; ii) more herbaceous (upper) parts; and iii) plants treated with agrochemicals (fungicides and insecticides). Considering four-month-old plants, three annual cycles, and an 81 % average sprouting, it would be possible to reach an annual multiplication rate of 1:72, which is much higher than that achieved by traditional methods using mature stem cuttings from 12-month-old plants (around 1:5). These results are important because they demonstrate the possibility of using cassava leaf buds to produce high-quality plantlets rapidly for greater multiplication and diffusion of new varieties and cultivation on a larger scale.

Effect of Different Rooting Media on Root Proliferation of Taxus baccata L. Stem Cuttings

Taxus baccata L., an endangered medicinal tree is highly valued for anti-cancer drug ‘Paclitaxel’ which is extracted from its leaves and barks. Reckless exploitation and habitat destruction have greatly reduced its natural population. Its regeneration through seed is also poor, so focus has been paid on vegetative propagation by stem cuttings to augment its natural regeneration. The present study was carried out to evaluate the effect of different rooting media on rooting behavior of Taxus baccata cuttings under poly house conditions. Effect of ten rooting media was studied on rooting of juvenile and mature stem cuttings of Taxus baccata. Six substrates i.e. field soil, forest soil, river sand, FYM, peat and vermi-compost were used for preparation of rooting media. The experiments were laid out in a randomized completely block design. The different rooting parameters were evaluated after six months of planting. The results revealed that the highest value of per cent survived, per cent callused, per cent rooted, mean number of root and mean root length was obtained in both juvenile and mature cuttings planted in Forest soil+ Peat+ FYM (1:1:1) compared to the other rooting media. Not a single cutting survived which was planted in river sand. Mature cuttings planted in Forest soil + River sand + VC (1:1:1) also failed to survive. The media containing peat as substrate significantly improved the rooting of cuttings but due to optimum physico-chemical properties, Forest soil+ Peat+ FYM (1:1:1) proved ideal rooting media for stem propagation of Taxus baccata.

Localized gene expression changes during adventitious root formation in black walnut (Juglans nigra L.).

Cutting propagation plays a large role in the forestry and horticulture industries where superior genotypes need to be clonally multiplied. Integral to this process is the ability of cuttings to form adventitious roots. Recalcitrance to adventitious root development is a serious hurdle for many woody plant propagation systems including black walnut (Juglans nigra L.), an economically valuable species. The inability of black walnut to reliably form adventitious roots limits propagation of superior genotypes. Adventitious roots originate from different locations, and root induction is controlled by many environmental and endogenous factors. At the molecular level, however, the regulation of adventitious root formation is still poorly understood. In order to elucidate the transcriptional changes during adventitious root development in black walnut, we used quantitative real-time polymerase chain reaction to measure the expression of nine key genes regulating root formation in other species. Using our previously developed spatially explicit timeline of adventitious root development in black walnut softwood cuttings, we optimized a laser capture microdissection protocol to isolate RNA from cortical, phloem fiber and phloem parenchyma cells throughout adventitious root formation. Laser capture microdissection permitted high-resolution, site-specific analysis of gene expression that differentiated between participatory and non-participatory root progenitor cells. Results indicated mRNA abundance was altered in all nine rooting-related genes in response to auxin treatment in both juvenile and mature cuttings. SCARECROW LIKE-1 (SCL) had the greatest change in expression in juvenile rooting-competent cells at days 16 and 18, with a 24- and 23-fold increase relative to day 0, respectively. Tissues not linked to root organogenesis had little change in SCL expression at similar time points. AUXIN RESPONSE FACTOR (ARF)6 and ARF8 as well as SHORTROOT expression also increased 2- to 4-fold in rooting-competent tissue. The greatest transcript abundance in rooting-competent cuttings was restricted to root progenitor cells, while recalcitrant cuttings had a diffuse mRNA signal among tissue types.

Strategies to Combat Mycosphaerella Leaf Disease in Eucalyptus globulus Plantations in Northern Spain

Eucalyptus globulus is widely planted in temperate regions to produce pulp for its high performance but few studies of the impact of Mycosphaerella Leaf Disease (MLD) have been documented. This study aimed to explore and provide knowledge on disease in the management of young Eucalyptus globulus stands in the north of Spain. The influences of subspecies, cloning, and fertilization on the degree of severity of the disease were analyzed. The study was conducted with different material plants of Eucalyptus globulus, of Australian origin, from other sources, open-pollinated families, clones, and families of controlled pollination. Each series tested different vegetal material, except for a number of control codes that were used as reference samples for MLD evaluation. Severity, height at which foliage changes from juvenile to adult, total height, and volume were all measured. There were significant correlations in the average MLD severity of families and provenances obtained from the different trials. ANOVA revealed important differences between subspecies of E. globulus. A correlation was found between the percentage of adult leaf and the severity. There were differences in the impact of MLD between plant material non-selected and selected by its tolerance (p < 0.0001). There was a significant effect on the severity between mature cuttings and families from seed non-selected in their tolerance to MLD. Their tolerance was lower than that achieved from seed selected by its tolerance to MLD. Genetic selection was shown as the best strategy since there are individuals exceptionally tolerant to MLD.

An integrated workflow to assess the remaining potential of mature hydrocarbon basins: a case study from Northwest Germany (Upper Jurassic/Lower Cretaceous, Lower Saxony Basin)

Mature hydrocarbon provinces require a high level of geological understanding in order to extend the lives of producing fields, to replace reserves through smaller targets and to reduce the risks of exploring for more and more subtle hydrocarbon traps. Despite a large number of existing wells in the area studied in this paper, the depositional environments and the stratigraphic architecture were still poorly known. In order to improve the geological understanding, we propose a workflow to assess the remaining reservoir potential of mature hydrocarbon areas, integrating cores, cuttings, well-logs, biostratigraphy and seismic data. This workflow was developed for and is exemplified with the northwest of the Lower Saxony Basin (LSB), a mature hydrocarbon province in northwest Germany, but can be applied in a similar fashion to other areas. Systematic integration of lithofacies analysis, chrono- and sequence stratigraphy, combined with electrofacies analysis and modern digital methods like neural network-based lithology determination and 3D facies modelling provides a high-resolution understanding of the spatial facies and reservoir architecture in the study area. Despite widely correlatable litho-units in the Upper Jurassic and Lower Cretaceous in the LSB, complex heterogeneous sedimentary systems can be found in the basin’s marginal parts. Two new play types were determined in the study area, showing a remaining potential for stratigraphic hydrocarbon traps. The results of this exploration scale study also provide the basis for re-evaluations on a field development scale. On a basin scale, this study may encourage further data acquisition and re-evaluations to discover previously unknown reservoirs.

Biochemical Status of Stock Plants and Their Annual Sprouts as a Crucial Key for Successful Adventitious Root Formation

Leafy cuttings of Prunus subhirtella Miq. ‘Autumnalis’ were harvested from mature, semi-mature and juvenile stock plants at four dates during the vegetative period 2011 (on 16th of May, on 30th of May, on 20th of June and on 11th of July) and their auxin levels (IAA, IAA-Asp) and sugar content (glucose, sucrose, sorbitol) were quantified. The IAA and IAA-Asp contents in cutting bases increased over the vegetative period, whereby aspartate values were higher than IAA values. The IAA-Asp values ranged from 6.3 µg g-1 to 22.7 µg g-1 FW and reached two great peaks on 30th of May and on 11th of July. The IAA values ranged from 0.29 µg g-1 to 4.51 µg g-1 FW, reaching a small fall on 20th of June. Significantly higher levels of IAA and IAA-Asp were measured at the base of mature cuttings compared to cuttings of semi-mature and juvenile origin, when the cuttings were harvested on 30th of May and on 11th of July. On the other hand, mature leafy cuttings accumulated significantly less fructose and glucose in their root emergence zone (16.3 g kg-1 DW, 45.2 g kg-1 DW) compared to semi-mature cuttings (26.4 g kg-1 DW, 62.5 g kg-1 DW) and juvenile cuttings (27.3 g kg-1 DW, 73.9 g kg-1 DW). All measured rooting parameters (rooting success, number of main roots and root length) were significantly improved when cuttings of a more juvenile origin (semi-mature and juvenile) were used.

Biochemical Status of Stock Plants and Their Annual Sprouts as a Crucial Key for Successful Adventitious Root Formation

Leafy cuttings of Prunus subhirtella Miq. ‘Autumnalis’ were harvested from mature, semi-mature and juvenile stock plants at four dates during the vegetative period 2011 (on 16th of May, on 30th of May, on 20th of June and on 11th of July) and their auxin levels (IAA, IAA-Asp) and sugar content (glucose, sucrose, sorbitol) were quantified. The IAA and IAA-Asp contents in cutting bases increased over the vegetative period, whereby aspartate values were higher than IAA values. The IAA-Asp values ranged from 6.3 µg g-1 to 22.7 µg g-1 FW and reached two great peaks on 30th of May and on 11th of July. The IAA values ranged from 0.29 µg g-1 to 4.51 µg g-1 FW, reaching a small fall on 20th of June. Significantly higher levels of IAA and IAA-Asp were measured at the base of mature cuttings compared to cuttings of semi-mature and juvenile origin, when the cuttings were harvested on 30th of May and on 11th of July. On the other hand, mature leafy cuttings accumulated significantly less fructose and glucose in their root emergence zone (16.3 g kg-1 DW, 45.2 g kg-1 DW) compared to semi-mature cuttings (26.4 g kg-1 DW, 62.5 g kg-1 DW) and juvenile cuttings (27.3 g kg-1 DW, 73.9 g kg-1 DW). All measured rooting parameters (rooting success, number of main roots and root length) were significantly improved when cuttings of a more juvenile origin (semi-mature and juvenile) were used.

Transient response of Salix cuttings to changing water level regimes

AbstractSustainable water management requires an understanding of the effects of flow regulation on riparian ecomorphological processes. We investigated the transient response of Salix viminalis by examining the effect of water‐level regimes on its above‐ground and below‐ground biomass. Four sets of Salix cuttings, three juveniles (in the first growing season) and one mature (1 year old), were planted and initially grown under the same water‐level regime for 1 month. We imposed three different water‐level regime treatments representing natural variability, a seasonal trend with no peaks, and minimal flow (characteristic of hydropower) consisting of a constant water level and natural flood peaks. We measured sap flux, stem water potential, photosynthesis, growth parameters, and final root architecture. The mature cuttings were not affected by water table dynamics, but the juveniles displayed causal relationships between the changing water regime, plant growth, and root distribution during a 2 month transient period. For example, a 50% drop in mean sap flux corresponded with a −1.5 Mpa decrease in leaf water potential during the first day after the water regime was changed. In agreement with published field observations, the cuttings concentrated their roots close to the mean water table of the corresponding treatment, allowing survival under altered conditions and resilience to successive stress events. Juvenile development was strongly impacted by the minimum flow regime, leading to more than 60% reduction of both above‐ground and below‐ground biomass, with respect to the other treatments. Hence, we suggest avoiding minimum flow regimes where Salix restoration is prioritized.

Adventitious rooting declines with the vegetative to reproductive switch and involves a changed auxin homeostasis.

Adventitious rooting, whereby roots form from non-root tissues, is critical to the forestry and horticultural industries that depend on propagating plants from cuttings. A major problem is that age of the tissue affects the ability of the cutting to form adventitious roots. Here, a model system has been developed using Pisum sativum to differentiate between different interpretations of ageing. It is shown that the decline in adventitious rooting is linked to the ontogenetic switch from vegetative to floral and is mainly attributed to the cutting base. Using rms mutants it is demonstrated that the decline is not a result of increased strigolactones inhibiting adventitious root formation. Monitoring endogenous levels of a range of other hormones including a range of cytokinins in the rooting zone revealed that a peak in jasmonic acid is delayed in cuttings from floral plants. Additionally, there is an early peak in indole-3-acetic acid levels 6h post excision in cuttings from vegetative plants, which is absent in cuttings from floral plants. These results were confirmed using DR5:GUS expression. Exogenous supplementation of young cuttings with either jasmonic acid or indole-3-acetic acid promoted adventitious rooting, but neither of these hormones was able to promote adventitious rooting in mature cuttings. DR5:GUS expression was observed to increase in juvenile cuttings with increasing auxin treatment but not in the mature cuttings. Therefore, it seems the vegetative to floral ontogenetic switch involves an alteration in the tissue's auxin homeostasis that significantly reduces the indole-3-acetic acid pool and ultimately results in a decline in adventitious root formation.

Gene expression profiling in juvenile and mature cuttings of Eucalyptus grandis reveals the importance of microtubule remodeling during adventitious root formation.

BackgroundThe ability to form adventitious roots (AR) is an economically important trait that is lost during the juvenile-to-mature phase change in woody plants. Auxin treatment, which generally promotes rooting in juvenile cuttings, is often ineffective when applied to mature cuttings. The molecular basis for this phenomenon in Eucalyptus grandis was addressed here.ResultsA comprehensive microarray analysis was performed in order to compare gene-expression profiles in juvenile and mature cuttings of E. grandis, with or without auxin treatment on days, 0, 1, 3, 6, 9 and 12 post AR induction. Under these conditions AR primordia were formed only in auxin-treated juvenile cuttings. However, clustering the expression profiles revealed that the time after induction contributed more significantly to the differences in expression than the developmental phase of the cuttings or auxin treatment. Most detected differences which were related to the developmental phase and auxin treatment occurred on day 6, which correlated with the kinetics of AR-primordia formation. Among the functional groups of transcripts that differed between juvenile and mature cuttings was that of microtubules (MT). The expression of 42 transcripts annotated as coding for tubulin, MT-associated proteins and kinesin motor proteins was validated in the same RNA samples. The results suggest a coordinated developmental and auxin dependent regulation of several MT-related transcripts in these cuttings. To determine the relevance of MT remodeling to AR formation, MTs were subjected to subtle perturbations by trifluralin, a MT disrupting drug, applied during auxin induction. Juvenile cuttings were not affected by the treatment, but rooting of mature cuttings increased from 10 to more than 40 percent.ConclusionsThe data suggest that juvenile-specific MT remodeling is involved in AR formation in E. grandis.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-826) contains supplementary material, which is available to authorized users.

Profiling microRNAs in Eucalyptus grandis reveals no mutual relationship between alterations in miR156 and miR172 expression and adventitious root induction during development.

BackgroundThe change from juvenile to mature phase in woody plants is often accompanied by a gradual loss of rooting ability, as well as by reduced microRNA (miR) 156 and increased miR172 expression.ResultsWe characterized the population of miRNAs of Eucalyptus grandis and compared the gradual reduction in miR156 and increase in miR172 expression during development to the loss of rooting ability. Forty known and eight novel miRNAs were discovered and their predicted targets are listed. The expression pattern of nine miRNAs was determined during adventitious root formation in juvenile and mature cuttings. While the expression levels of miR156 and miR172 were inverse in juvenile and mature tissues, no mutual relationship was found between high miR156 expression and rooting ability, or high miR172 expression and loss of rooting ability. This is shown both in E. grandis and in E. brachyphylla, in which explants that underwent rejuvenation in tissue culture conditions were also examined.ConclusionsIt is suggested that in these Eucalyptus species, there is no correlation between the switch of miR156 with miR172 expression in the stems and the loss of rooting ability.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-524) contains supplementary material, which is available to authorized users.

PRODUCTION OF CERTIFIED PLANTING MATERIAL FOR BIOLOGICAL FRUIT PRODUCTION FROM BLACKCURRANT

Basic mother nursery from the blackcurrant cultivars ‘Ometa’, ‘Titania’, ‘Hedda’ and ‘Silvergieters Schwarze’ (Ribes) was put to procedures for biological certification based on complete excluding of mineral fertilizers and use only of permitted means for plant protection. Conversion has started since 2007, and in 2010 a certificate was obtained from the licensed company “Balkan Biocert” for bio-logically certified planting material, with which plantations for biological fruit production can be established. Rooting of mature cuttings from cultivars ‘Ometa’, ‘Titania’, ‘Hedda’ and ‘Silvergieters Schwarze’ took place under the same conditions. The results of the conducted observations showed that the percentage of rooting of the cultivars varied from 70% (‘Hedda’) to 96% (‘Titania’) obtained planting material had acceptable quality.

Microarray analysis revealed upregulation of nitrate reductase in juvenile cuttings of Eucalyptus grandis, which correlated with increased nitric oxide production and adventitious root formation

The loss of rooting capability following the transition from the juvenile to the mature phase is a known phenomenon in woody plant development. Eucalyptus grandis was used here as a model system to study the differences in gene expression between juvenile and mature cuttings. RNA was prepared from the base of the two types of cuttings before root induction and hybridized to a DNA microarray of E. grandis. In juvenile cuttings, 363 transcripts were specifically upregulated, enriched in enzymes of oxidation/reduction processes. In mature cuttings, 245 transcripts were specifically upregulated, enriched in transcription factors involved in the regulation of secondary metabolites. A gene encoding for nitrate reductase (NIA), which is involved in nitric oxide (NO) production, was among the genes that were upregulated in juvenile cuttings. Concomitantly, a transient burst of NO was observed upon excision, which was higher in juvenile cuttings than in mature ones. Treatment with an NO donor improved rooting of both juvenile and mature cuttings. A single NIA gene was found in the newly released E. grandis genome sequence, the cDNA of which was isolated, overexpressed in Arabidopsis plants and shown to increase NO production in intact plants. Therefore, higher levels of NIA in E. grandis juvenile cuttings might lead to increased ability to produce NO and to form adventitious roots. Arabidopsis transgenic plants constantly expressing EgNIA did not exhibit a significantly higher lateral or adventitious root formation, suggesting that spatial and temporal rather than a constitutive increase in NO is favorable for root differentiation.

Effect of temperature, light intensity and growth regulators on propagation of Ansellia Africana from cuttings

Ansellia africana (Orchidaceae) is an important endangered medicinal plant species of South Africa which has been heavily exploited in recent years. Experiments were conducted in growth rooms at different temperatures (16, 26, 36°C) and in a nursery at different light intensities induced by shade cloth densities (200, 400, 600, 800 mol m -2 s -1 light) at the University of Zululand, South Africa. Mature A. africana plants were cut into two lengths, the top leafy shoot and the bottom part with roots (10 – 15 cm in length, 3 - 8 mm diameter). The top leafy or leafless cuttings were used in all the experiments. Bud formation and rooting competence of cuttings were compared by growing cuttings treated with solutions of varying naphthaleneacetic acid (NAA) and kinetin concentrations in river sand. Three types of cuttings were used: a) mature cuttings with both green leaves and an inflorescence, b) mature cuttings with yellow leaves (or leafless) and an inflorescence, and c) young cuttings with green leaves but no inflorescence. The lowest percentage death was recorded in cuttings with both green leaves and an inflorescence in the growth room (10%) and nursery (5%), respectively. The same type of cuttings gave significantly higher (P < 0.05) percentage bud formation in the incubator (18%) and nursery (37%), respectively. NAA was effective in root initiation when applied after bud break. The best results for root number, root length and root dry weight were achieved at NAA concentration of 1 or 2 mg l-1. Optimum conditions for bud formation were temperature of 36°C, light intensity of 200 - 400 mol m -2 s -1 and kinetin concentration of 1 or 2 mg l -1 . A maximum value of 57% was recorded for bud formation in this study. Keywords: Ansellia Africana , cuttings, kinetin, naphthaleneacetic acid, propagation African Journal of Biotechnology Vol. 9(34), pp. 5566-5574, 23 August, 2010

TISSUE ELEMENT CONCENTRATIONS AND MINERAL REMOVAL RATES IN HONEYBUSH TEA II: CYCLOPIA SUBTERNATA

A survey of plantation-grown Cyclopia subternata showed that average concentrations of nitrogen, phosphorus, potassium, calcium and magnesium in the new top growth of mature seedlings and cuttings were 1.59, 0.09, 0.62, 0.32, and 0.17%, respectively. Respective removal rates of these elements at each harvest averaged 13.1, 0.7, 5.1, 2.6, and 1.4 g plant−1. These quantities were equivalent to. 28% to 45% of the total element in the plant. Concentrations in the top growth of sodium, manganese, iron, copper, zinc and boron averaged, respectively, 1459, 34, 143, 7, 9, and 30 mg kg−1. Old top growth dry mass and root dry mass increased with time. Peak new top growth yields from C. subternata plants derived from seedlings and cuttings differed by only 2.2%. At peak production, new growth constituted 15% of total seedling dry mass and 21% of total cutting dry mass.

Ageing delays the cellular stages of adventitious root formation in pine

Summary Vegetative propagation programs internationally are affected by the significant decline of rooting success as trees mature. This study compared the cellular stages of root formation in stem cuttings from 15-week-old (juvenile) and 9-y-old (mature) stock plants of the slash × Caribbean pine hybrid (Pinus elliottii var. elliottii × P. caribaea var. hondurensis). The cellular stages of root formation were the same in both juvenile and mature cuttings, beginning with cell divisions of the vascular cambium forming callus tissue. Within the callus, tracheids differentiated and elongated to form root primordia. Roots in juvenile cuttings developed faster than those in mature cuttings and the juvenile cuttings had a much higher rooting percent at the end of the study (92% and 26% respectively). Cuttings of the two juvenile genotypes had more primary roots (5.5 and 3.3) than the three mature genotypes (0.96, 0.18 and 0.07). The roots of juvenile cuttings were more evenly distributed around the basal circumference when compared with those on cuttings from the mature genotypes. Further work is needed to improve understanding of physiological changes with maturation so that the rooting success and the speed of development in cuttings from mature stock plants can be optimised, hence improving genetic gain.

Development of pre-detection technique for bacterial blight (Xanthomonas axonopodis pv. dieffenbachiae) disease in Anthurium to produce healthy planting materials

Anthurium cut-flowers and potted plants have earned a growing marketing demand both in the local and global markets. Bacterial blight, caused by Xanthomonas axonopodis pv. dieffenbachiae has been of major economic concern among the growers worldwide as the disease could cause heavy losses on Anthuriums and other members of the family Araceae. The disease has the potential of spreading latently exhibiting no symptoms through a range of hosts and this fact makes it a prerequisite to detect the presence of pathogen early. No reliable control method so far has been developed and therefore maintenance of strict crop sanitary measures is of great importance. 100 samples representing 30 nurseries were selected from three of the major producing districts, Gampaha, Kurunegala and Puttlam districts. The pathogen was isolated from the samples using 5% KOH test and yeast dextrose calcium carbonate medium. Isolated pathogen was inoculated to healthy Dieffenbachia cane and leaf slices and after 1 – 2 days, symptoms first developed in cane cuttings while leaves took three days for the development of symptoms. Young, tender leaf and cane slices were observed to be highly susceptible to disease. The mature cane slices and leaf cuttings were found to be resistant to the pathogen, most probably due to the non-specific mechanical impermeability of the tissues. Tender leaf and cane tissues, with their ability to get infected and develop visual symptoms relatively fast, worked best with the technique as they proved to shorten the time taken for the detection. The validity and the precision of the pathogen identification test and therefore, the method, were assessed with an indirect-ELISA pathogen-specific detection step, prior to inoculation of healthy tissues. Pathogen was detected to present in 15 samples from Kurunegala and Gampaha districts. The method confirmed its precision, reliability, cost-effectiveness and application under normal laboratory conditions.