Evaluating the interaction between genotype and water stress in the hybrid poplar – Septoria musiva pathosystemThis note is one of a selection of papers published in the Special Issue on Poplar Research in Canada.

2007 ◽  
Vol 85 (11) ◽  
pp. 1098-1102 ◽  
Author(s):  
Jared M. LeBoldus ◽  
Peter V. Blenis ◽  
Barb R. Thomas

Septoria musiva , the causal agent of Septoria canker, has caused widespread damage to plantations of hybrid poplar across North America. A greenhouse experiment was conducted to evaluate the size of interactions between the genotype factors of (i) clone, (ii) isolate, and (iii) the clone–isolate interaction and the environmental factor of water stress. Four clones of hybrid poplar were inoculated with four isolates of S. musiva and subsequently exposed to two levels of water stress (stressed and unstressed). Tree height, root collar diameter (RCD), and disease severity were measured 56 d after inoculation. Water stress reduced height and RCD growth by approximately 30% but did not affect disease severity (P = 0.258). Of the explained variability, 97.5% was attributable to genotype effects (89% from clone, 0% from isolate, and 8.5% from clone–isolate interaction). The remaining 2.5% of the variation was accounted for by the genotype – water stress interaction. These results suggest that clonal effects will be more important determinants of disease severity under greenhouse conditions than genotype – water stress interactions.

1997 ◽  
Vol 87 (4) ◽  
pp. 381-388 ◽  
Author(s):  
D. L. Maxwell ◽  
E. L. Kruger ◽  
G. R. Stanosz

Septoria musiva causes leaf spot and canker diseases of trees in the genus Populus, and is one of the most damaging fungal pathogens of hybrid poplar in eastern North America. The effect of host water stress on Septoria canker development was studied in two separate greenhouse experiments. Hybrid poplar clones NM6, NC11396, and NE308 were stressed by withholding water until predawn water potential fell below −1.0 MPa. Stems were treated by removing a leaf and applying agar plugs that were either colonized by S. musiva (inoculated) or sterile (control) to the wound. Cankers on inoculated water-stressed trees were significantly larger than those on nonstressed trees. A leaf disk assay also was conducted three times with the NM6 and NE308 trees. We cut two disks from each of 120 stressed and 120 well-watered trees, placing them on water agar in 24-well tissue culture plates. A conidial suspension was applied to one disk in each pair and sterile water to the other. Inoculated disks from water-stressed trees developed less necrosis than those from well-watered trees. These results demonstrate that environmental influences on host condition must be considered in evaluating resistance of clones proposed for widespread culture of hybrid poplar.


Plant Disease ◽  
2010 ◽  
Vol 94 (10) ◽  
pp. 1238-1242 ◽  
Author(s):  
Jared M. LeBoldus ◽  
Peter V. Blenis ◽  
Barb R. Thomas

Most artificial inoculations of Populus spp. stems with Septoria musiva have required host wounding to induce canker development; in the absence of wounds, frequencies of cankers have been low. Three greenhouse inoculation experiments were conducted to demonstrate the reliability and repeatability of an inoculation method that did not require wounding. In the first, 16 clones of hybrid poplar were inoculated with three isolates of S. musiva to compare responses following wounding and inoculation with mycelium (wound inoculation) with responses following inoculation of nonwounded trees by spraying with a conidial suspension (spray inoculation). Stem disease severity among clones following spray inoculation was correlated with stem disease severity following wound inoculation. A significant clone–isolate interaction was detected with spray inoculation but not wound inoculation. In the other two greenhouse experiments, 29 clones of hybrid poplar and 69 clones of Populus balsamifera were inoculated with a spore suspension mixture of three isolates. In both cases, the experimental error was similar to that obtained in previous experiments, in which trees were wound inoculated, and was adequately small to permit detection of differences in responses among clones. Ultimately, field studies will be needed to determine the best inoculation method for predicting stem responses to this pathogen under field conditions. However, relative to wound inoculation, spray inoculation of nonwounded trees has the advantage of yielding faster results, permitting inoculation with a mixture of isolates, and not circumventing potential mechanisms for resisting penetration. The ability to infect stems without wounding creates opportunities for numerous types of epidemiological and disease control studies that are difficult to conduct with wound inoculation.


Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1146-1150 ◽  
Author(s):  
Jared M. LeBoldus ◽  
Peter V. Blenis ◽  
Barb R. Thomas ◽  
Nicolas Feau ◽  
Louis Bernier

A greenhouse inoculation experiment and field study were conducted to determine the cause of an outbreak of Septoria musiva cankers on Populus balsamifera in a northern Alberta plantation. Four clones of P. balsamifera, five clones of putatively resistant P. deltoides, and one susceptible hybrid poplar clone, Northwest, were inoculated with seven isolates identified as S. musiva. Four of the isolates were from P. balsamifera in Alberta and the others were from P. deltoides in Quebec. Results indicated that disease severity was similar for Alberta and Quebec isolates (P = 0.243) and that P. balsamifera had the greatest mean disease severity (x-bar = 4.20), P. deltoides had the lowest (x-bar = 2.76), and Northwest was intermediate (x-bar = 3.45). A genetic analysis comparing six polymorphic polymerase chain reaction restriction fragment length polymorphism loci and the mitochondrial small subunit ribosomal DNA sequences of the seven isolates indicated that the Alberta population was made up of at least three distinct genotypes. Canker incidence and age on Northwest and 56 different clones of P. balsamifera in a plantation were recorded. Canker incidence (P = 0.726) and the canker age distributions (P = 0.994) were similar for the two species. In conclusion, contrary to what has been reported in the literature, P. balsamifera appears to be quite susceptible to Septoria canker.


2007 ◽  
Vol 64 (1) ◽  
pp. 23-29
Author(s):  
José Geraldo de Araújo Carneiro ◽  
Deborah Guerra Barroso ◽  
Luis Maurício da Silva Soares

Seedlings compete for nutrients, water and light. The available area for each seedling affects their behavior related to requirements for these resources. This experiment evaluated the influence of five plant densities on the growth of bare root Pinus taeda, L. seedlings in a nursery after outplanting. The analyzed characteristics were: height (H), root collar diameter (D), H/D ratio, and dry matter weight. Higher densities stimulated H growth and the lowest densities increased D average and dry matter weight and lowered the H/D ratio. Seedlings were distributed by H, D and H/D classes. Higher densities had a larger number of seedlings in larger H classes. Larger numbers of seedlings with larger D and lower H/D ratios were found in lower densities. Ten months after outplanting the seedlings grown in lower densities had higher survival percentages and growth. Some saplings of standardized heights were uprooted with the objective of studying their root systems. The lowest densities stimulated higher numbers of first and second order roots as well as fresh and dry matter weights of thin roots with mycorrhizae presence. In both parts of the experiment, the density of 278 seedlings m-2 yielded equivalent averages as compared to the lowest densities.


CERNE ◽  
2011 ◽  
Vol 17 (2) ◽  
pp. 189-193 ◽  
Author(s):  
Thais Galhardo Godoy ◽  
Sebastião Carlos da Silva Rosado

The objective of this study was the selection of superior genotypes for growth traits, correlating them to initial height growth in the field, at age eight months. A random block design was used in the nursery, with eight clones, three replicates and four plants per plot. And a random block design was also used in the field, with eight clones, four replicate blocks and nine plants per plot. Data being analyzed in the nursery at age 120 days included: height of field seedling, at age eight months (Hc), height of nursery seedling (Hm), root collar diameter (Dc), shoot diameter (Db), shoot dry matter (PMSPA), root dry matter (PMSR), total dry matter (PMST), ratio of shoot dry matter to root dry matter (PMSPA/PMSR), Dickson quality index of root collar diameter (IQD-Dc), Dickson quality index of shoot diameter (IQD-Db). Analyses of variance showed that significant genetic differences exist among clones for all traits and, given the high heritability values found, the estimated genetic gains were generically very high. As for predicted indirect genetic gain, selection in nursery seedlings for Dc, PMSPA/PMSR, IQD-Dc provided the highest values of indirect gain in field seedling height.


2019 ◽  
Vol 11 (10) ◽  
pp. 277 ◽  
Author(s):  
Meire Pereira de Souza Ferrari ◽  
Mayara dos Santos Queiroz ◽  
Matheus Marquezini de Andrade ◽  
Jessica Rezende Trettel ◽  
Hélida Mara Magalhães

This study aimed to evaluate the in vitro growth and biochemical activity of Curcuma longa explants using different MS medium formulations and growth regulators. In all the experiments, plants were grown in MS medium supplemented with agar (6.5 g L-1) and pH adjusted to 5.8. In the first assay, the MS culture medium at 70% strength, supplemented with 30 g L-1 of sucrose, and without the addition of activated carbon, resulted in the highest number of shoots. The sucrose concentration of 60 g L-1, combined with the addition of actived charcoalin half-strength MS medium, resulted in the increased root dry mass, root collar diameter, and relative chlorophyll index. In the second assay, the highest root collar diameter and dry matter of shoots and roots were found in the MS medium supplemented with 4.44 BAP, 0.46 KIN, and 1.08 NAA. The MS medium with 8.88 BAP, 0.92 KIN, and 2.16 μM NAA resulted in the highest number of shoots (7.75), number of leaves (35), and shoot length (88.57 mm). The antioxidant activity was significantly higher in the treatments that resulted in better plantlets growth performance, demonstrating that the antioxidant activity is related to other factors such as a possible role of growth regulators on the elicitation of compounds in plants. Superoxide dismutase had a high enzymatic activity in both assays, whereas the enzymatic activity of catalase and ascorbate peroxidase was dependent on the culture media used.


Author(s):  
Şemsettin Kulaç ◽  
Özge Yıldız

In this study, in order to help the mass production of seedlings, the effect of fertilization on the morphological development of hornbeam leafy European hophornbeam (Ostry carpinifolia Scop) seedlings were investigated. For this, seedlings, which were obtained from the seeds coming from different European hophornbeam populations (Düzce-Yığılca, Antalya-Finike, Antalya-Akseki, Kastamonu-Şehdağ ve Adana-Saimbeyli) from various parts of Turkey, were used. European hophornbeam seedlings were treated with different fertilizers, including urea, ammonium sulphate, compound fertilizer 15-15-15 and 20-20-0, and 6-9 months Osmocote release fertilizer, and effects of these fertilizers on the morphological characters were investigated. Fertilization contained the same amount of nitrogen, and was made in three different ways; (1) mixing with habitat, (2) topical application and (3) liquid application. The development of germinated European hophornbeam seeds, which were spring-sowed in the same medium were monitored during the vegetation period. At the end of vegetation period, seedlings were removed from the soil and morphological characteristics of root (seedling length, root collar diameter, root length, fresh root and stem weight of the seedlings, dried root and stem weight of the seedlings and bud number) were measured. As a result, it was observed that fertilization positively affects the development of seedlings and depending on the fertilization type the seedlings of European hophornbeam populations were found to exhibit different improvements/growing. In addition, 6-9 months Osmocote release fertilizers were determined to be the best fertilizers affecting the morphological (diameter and height) development of European hophornbeam populations effectively, and among the populations, Düzce and Kastamonu populations showed the best improvement/growing.


2013 ◽  
pp. 39-50 ◽  
Author(s):  
Vladan Ivetic ◽  
Zoran Davorija ◽  
Dragica Vilotic

Most commonly used morphological attributes were correlated with nutrient concentration in order to standardize quality assessment of two-year-old hop hornbeam (Ostrya carpinifolia Scop.) seedlings. Diameter has proven to be the best single morphological indicator of seedling quality given its strong positive correlation with all other observed morphological attributes. Seedling dry mass (shoot and root dry mass) and Dickson Quality Index can be considered the most comprehensive indicators of hop hornbeam seedling quality. However, the measuring of mass is destructive and requires a certain amount of time. The absence of strong correlations between physiological and morphological attributes of two-year old seedlings of hop hornbeam suggests the need for further research. The only significant correlation between physiological and morphological attributes (weak and positive) was recorded between the potassium concentration in root and root collar diameter after the second growing season.


1992 ◽  
Vol 70 (11) ◽  
pp. 2265-2270 ◽  
Author(s):  
Zhijun Liu ◽  
Donald I. Dickmann

Repeated progressive drought and flooding stress were imposed on hybrid poplar clones Populus × euramericana 'Eugenei', and Populus tristis × Populus balsamifera ‘Tristis’ grown in pots in a greenhouse under two nitrogen levels. In both clones the rate of leaf initiation was promoted only in high-N plants subjected to minimum water stress. Water stress alone did not retard the rate of leaf initiation, but it significantly reduced leaf expansion of 'Eugenei', whereas only flooding led to smaller leaves in 'Tristis'. The addition of N stimulated leaf expansion, leaf chlorophyll and N concentrations, and leaf and stem biomass production across soil moisture levels, but the greatest effect of N was associated with minimum water stress. High N altered carbon allocation towards the aboveground portions, leading to lower root to shoot ratios. High N also appeared to stimulate initiation of fine roots. Soil moisture determined the amount of biomass that accumulated in roots, with highest root production in well-watered pots and lowest in flooded pots, with the droughted treatment in between. Leaves became thinner as soil moisture decreased from flooding. Stem biomass of 'Tristis' declined more under flooding than under drought, whereas 'Eugenei' displayed a greater reduction of stem biomass in droughty than in flooded soil. Key words: water stress, nitrogen, leaf and root morphology, root to shoot ratio, biomass, Populus, flooding.


2017 ◽  
Vol 16 (2) ◽  
Author(s):  
M.E.A. Borba ◽  
G.M. Maciel ◽  
E.F. Fraga Júnior ◽  
C.S. Machado Júnior ◽  
G.R. Marquez ◽  
...  

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