Density Of Resin Canals Research Articles

Variation and genetic parameters of axial resin canal features in clones and families of Pinus radiata

Resin canal features are associated with significant economic losses to appearance grade Pinus radiata timber. This study investigated the variation in resin canal features in young, 2-year-old, P. radiata. Axial resin canal size, density and relative cross-sectional area were determined in twenty families and ten clones from images of microtomed sections, scanned with polarised light to highlight resin canals. Axial resin canal size was generally homogenous with a mean value estimate of 0.02 mm2, and a coefficient of variation of ~ 10%. Estimated mean values for axial resin canal density and relative area were more variable (coefficients of variation ~ 30%) and lower for clones (0.69 canals/mm2 and 1.13%, respectively) than for families (0.90 canals/mm2 and 1.53%, respectively). Narrow-sense heritability (h2) estimates of the studied axial resin canal features in radiata pine at age 2-years-old were ~ 0.30. Modulus of elasticity and longitudinal shrinkage were moderately correlated with axial resin canal density and relative area, while basic density and volumetric shrinkage were independent of axial resin canal features. The study indicated that there could be potential for breeding P. radiata for resin canal features, with the aim to improve the grade yields of appearance grade products.

Resin-Secretory Structures of Boswellianeglecta (Burseraceae) in Borana Administrative Zone, Southern Ethiopia

Boswellia neglecta is a small tree that produces commercially important oleo-resin known as frankincense. This frankincense has been used for varied purposes, and it is a source of income for rural households in southern and south-eastern Ethiopia. Despite the long history of using this species, knowledge on bark anatomy and resin-secretory structures is lacking. In this study, anatomical description of the bark including network and distribution of resin secretory structures were determined; relationship between bark thickness, and axial resin canal characteristics with tree DBH of B. neglecta were assessed in dry deciduous woodlands Borana Administrative Zone, Ethiopia. Twenty-one sampled trees were raandomly selected for this study. The network of resin-secretory structure was investigated from tangential, radial and transversal sections of bark samples using light microscopy. The average density, diameter and total area of axial resin canals were determined from transversal sections of 42 bark samples. The results revealed that the inner bark axial and radial resin canals occurred and that they are interconnected by radial resin canals. Whereas, in the wood, there were no any resin secretory structures. On average, density of functional-axial resin canals is low, reaching 0.33 mm-2. Inner bark thickness linearly increases with tree diameter, but resin canal density was not varying across the inner bark. The total area of axial resin canals was highly significant (p<0.001) positively related to the DBH. The findings of the study will thus lead to new advances in our insights and knowledge on the resin secretory structures of B. neglecta. However, further research is required to introduce new tapping technology for a sustainable resin production.

Colonization and Development ofSirex noctilio(Hymenoptera: Siricidae) in Bolts of a Native Pine Host and Six Species of Pine Grown in the Southeastern United States

AbstractSirex noctilio F. (Hymenoptera: Siricidae) is a major exotic pest of pines (Pinus spp.) in the Southern Hemisphere and has become established in northeastern North America. We investigated the suitability of bolts of six economically and ecologically important U.S. pine species grown in the southeastern United States, including eastern white (P. strobus L.), loblolly (P. taeda L.), longleaf (P. palustris Miller), shortleaf (P. echinata Miller), slash (P. elliottii Engelmann), and Virginia (P. virginiana Miller) pines and its native Eurasian host, Scots pine (P. sylvestris L.), for S. noctilio reproduction. The properties of wood and resin of different pine species were also analyzed for possible correlates to S. noctilio's colonization and reproductive success on bolts. Sirex noctilio completed development on bolts within 4 mo of oviposition activities. Among the seven pine species, S. noctilio completed development in eastern white, Scots, and Virginia pines. Females tended to drill less on bolts with higher area and density of resin canals, as well as higher first 10-ring and radial stripspecific gravity. The resin of eastern white and Virginia pines had distinct extractive profiles, and eastern white pine may have two 3-carene chemotypes in the southeastern region.

Genetic variation for needle traits in Scots pine (Pinus sylvestris L.)

The remnants of the Caledonian Native Pinewood are distributed across a relatively narrow geographic area in the Scottish Highlands yet inhabit a steep environmental gradient in terms of rainfall, temperature and altitude. Previous work based on common garden trials has demonstrated that native pine populations (Pinus sylvestris (L.)) exhibit differentiation in terms of growth, phenology and frost resistance. However, despite their important role in plant fitness, no such information is available on leaf traits, which have shown both plastic and adaptive genetic responses to environmental variation in other species. We analysed a subset of 11 needle characters in 192 saplings grown in a population-progeny common garden trial based on seedlots from eight native pinewoods. Narrow-sense heritability (h 2) was estimated for each trait and found to be particularly high (1.30 ± 0.33) for resin canal density. The majority of the phenotypic variation found was within populations, although interpopulation differentiation was detected for needle length (ΔAICc = 2.55). Resin canal density was positively correlated with longitude (β = 0.45, ΔAICc = 4.23), whereas stomatal row density was negatively correlated (β =−0.12, ΔAICc = 2.55). These trends may reflect adaptation for differences in moisture availability and altitude between eastern and western populations in Scotland.

Alterations of the resin canal system of Pinus pinaster seedlings after fertilization of a healthy and of a Hylobius abietis attacked stand

Changes in resource availability and biotic and abiotic stress may alter the defensive mechanisms of pine trees. The effect of fertilisation on the resin canal structure of Pinus pinaster seedlings established in two trials in NW Spain, one attacked by Hylobius abietis and the other non-attacked, was studied. The leaders of 50 plants were destructively sampled and the resin canal density, the canal area and its relative conductive area in the phloem and xylem were assessed. Experimentally increased nutrient availability significantly decreased resin canal density in the phloem of the seedlings in the two analysed trials, where unfertilised seedlings presented up to 30% more resin canal density than the fertilised seedlings (mean value ± SEM = 0.32 ± 0.02 resin canals mm−2 in the fertilised plants versus 0.45 ± 0.04 resin canals mm−2 in the control plants). Fertilisation had no effect on the resin canal system in the xylem, but significantly increased tracheid size. Significant differences of resin canals among sites were observed mainly in the xylem; the resin canal density was 1.7-fold greater in the attacked site than in the non-attacked site. The similar structure of phloem resin canals in both sites supports that phloem resin canals are constitutive mechanisms of defence in P. pinaster, whereas xylem resin canals would be constitutive mechanisms but also inducible mechanisms of resistance following the attack of pine weevils or bark beetles.

Weevil resistance of progeny derived from putatively resistant and susceptible interior spruce parents

Controlled-cross progeny of interior spruce ( Picea glauca (Moench) Voss × Picea engelmanni Parry ex Engelm.) parents ranked as resistant or susceptible to the white pine weevil, Pissodes strobi (Peck) were screened for resistance to the same insect by augmentation of the trial site with weevils. Progeny from two resistant parents (R × R progeny) sustained significantly fewer weevil attacks (13% of the trees were attacked) in the year following the augmentation, than progeny from susceptible parents (S × S progeny) (68% of the trees were attacked). Progeny obtained by crossing one resistant and one susceptible parent (R × S progeny) sustained intermediate attack levels (47% were attacked). Characteristics of the bark resin canals of the crosses were explored using microscopy techniques. Bark resin canal density was highest in R × R progeny, lowest in S × S progeny and intermediate in R × S progeny. There was a negative correlation between the percentage of trees attacked in each cross and the average density of the outer resin canals for each cross. A discriminant function was developed that distinguished between resistant and susceptible progeny using bark characteristics. The function was characterized by positive coefficients for outer resin canal density and inner resin canal size, and a negative coefficient for bark thickness. Thus, trees with thin bark, large inner resin canals and dense outer resin canals are more likely to be resistant to P. strobi.

The significance of lenticels for successful Pityogenes chalcographus (Coleoptera: Scolytidae) invasion of Norway spruce trees [ Picea abies (Pinaceae)

In this study we tested whether Pityogenes chalcographus L. beetles preferably infest their host tree, Picea abies (L.) Karst., through lenticels or not. In a second step the resin canal system, which is important for defence against bark beetles, was investigated under lenticels and under lenticel-free periderm. Beetle colonisation tests on breeding logs resulted in 93.2% successful invasions through lenticels, 4.2% through lenticel-free periderm, 1.2% through wounds, and 1.4% near branches (n=1,606). Three main reasons why beetles invade preferable sites are discussed, taking the function of lenticels to supply gas exchange of the interior tissues into consideration. First, attractive volatiles are more easily detectable over the lenticels, and this could be a stimulus for the bark beetles to invade their hosts through these structures. Secondly, the very loosely arranged tissues of the lenticel and bigger intercellular spaces in the cortex and secondary phloem under the lenticel permit the beetles easier movement towards the vascular cambium. Thirdly, the total resin canal area of both primary and secondary canals and the number of secondary resin canals were reduced under lenticels. A higher resin canal density beneath lenticels would constitute a barrier to gas movement.

The effect of crown position and tree age on resin-canal density in Scots pine (Pinus sylvestris L.) needles

Resin canals are an important taxonomic characteristic in conifers. In this paper we examined within- and between-needle variation of the cross-sectional number of resin canals in Scots pine (Pinus sylvestris L.). Variation within needles was determined from 12 free-hand sections taken along the whole length of foliage collected from a common crown position. The effect of crown location and tree age on resin-canal density was also examined from the midpoint cross sections of 450 Scots pine needles collected from interior and exterior locations from the top, middle, and bottom of 25 crowns of trees ranging in age from 8 to 70 years. Within-needle resin-canal density varied with needle length. Two resin canals were typical for the basal and the terminal needle cross sections. There were 3.2 and 8.6 resin canals for cross sections taken from 10 and 30% of the needle length from the basal sheath, respectively. Resin-canal density was largest, and relatively constant, between 30 and 80% of the needle length. We found significant differences in the cross-sectional number of needle resin canals, as influenced by crown positions and tree age. Resin-canal density increased with foliage height. Foliage from the top one-third of crowns had significantly more resin canals than foliage from the bottom. Foliage collected from the crown interior (proximal to the stem) had fewer resin canals than samples from the crown edge. Resin-canal density increased from 7.1 to 10.3 as tree age increased from 8 to 70 years. These results suggest that crown position and tree age need to be incorporated into the sampling protocols used to establish species standards in resin-canal density, at least for Scots pine, if meaningful comparisons are to be made.Key words: resin canal, needle age, crown position, needle anatomy, Pinus sylvestris.

A Comment on “Feeding and Oviposition Preferences of White Pine Weevil (Coleoptera: Curculionidae) on Resistant and Susceptible Sitka Spruce Clones in Laboratory Bioassays”

Associations between the density and distribution of cortical resin canals of host trees and their resistance against insects have been the subject of many studies (Stroh and Gerhold 1965; Wilkinson 1983; Tomlin and Borden 1994a, 1994b). None, however, has demonstrated a causal relationship between number, density, or distribution of resin canals and resistance. For demonstrating causal relationships between resistance and its causative factors and identifying distinct mechanisms of resistance, our understanding must advance beyond associations. The premise of Alfaro (1996) constitutes an initial step for exploring a possible causal relationship between the density of cortical resin canals and resistance by proposing and testing a biologically meaningful hypothesis. He examined feeding and partial oviposition patterns on resistant and susceptible young grafts of Picea sitchensis (Bong) Carr. by Pissodes strobi Peck. in a greenhouse experiment and feeding patterns on the terminal and penultimate internodes of lateral branches in petri dishes. The main finding was that feeding and oviposition are several times greater on the penultimate internode of the main stem than on the leader. The author then hypothesized that this pattern could be the result of a higher number of resin canals, a higher proportion of the area being occupied by resin canals, or a higher density of the constitutive cortical resin canals in the leader. In a separate sample of three resistant and three susceptible trees he found that the density of resin canals and the area occupied by them per unit area of the are higher in the leaders than in the corresponding penultimate internodes. From these data he concluded, bark resin canals play an important role in the resistance of spruce to weevils not only within his experiment but also by extrapolation of this inference to explain how resistance may function in the field. …

Wood properties and ring width responses to long‐term atmospheric CO2enrichment in field‐grown loblolly pine (Pinus taedaL.)

Loblolly pine (Pinus taedaL.) were grown in the field, under non‐limiting nutrient conditions, in open‐top chambers for 4 years at ambient CO2partial pressures (pCO2) and with a CO2‐enriched atmosphere (+ 30 PapCO2compared to ambient concentration). A third replicate of trees were grown without chambers at ambientpCO2. Wood anatomy, wood density and tree ring width were analysed using stem wood samples. No significant differences were observed in the cell wall to cell lumen ratio within the latewood of the third growth ring formed in 1994. No significant differences were observed in the density of resin canals or in the ratio of resin canal cross‐sectional area to xylem area within the same growth ring. Ring widths were significantly wider in the CO2‐enrichment treatment for 3 of 4 years compared to the ambient chamber control treatment. Latewood in the 1995 growth ring was significantly wider than that in the ambient control and represented a larger percentage of the total growth‐ring width. Carbon dioxide enrichment also significantly increased the total wood specific gravity (determined by displacement). However, when determined as total sample wood density by X‐ray densitometry, the density of enriched samples was not significantly higher than that of the ambient chamber controls. Only the 1993 growth ring of enriched trees had a significantly higher maximum latewood density than that of trees grown on non‐chambered plots or ambient chambered controls. No significant differences were observed in the minimum earlywood density of individual growth rings between chambered treatments. These results show that the most significant effect of CO2enrichment on wood production in loblolly pine is its influence on radial growth, measured as annual tree ring widths. This influence is most pronounced in the first year of growth and decreases with age.

White spruce resistance to white pine weevil related to bark resin canal density

Examination of the bark from the uppermost lateral branches of white spruce, Picea glauca (Moench) Voss, indicated that trees resistant to attack by the white pine weevil, Pissodes strobi Peck, had significantly higher number and density of vertical resin canals per unit of bark area (mm2) than susceptible trees. The number and density of resin canals were also positively correlated with tree growth rate, an indicator of tree vigor. The density of the resin canals found near the periphery of the bark (outer resin canals) had higher correlation with resistance and growth than inner resin canals. Measurements of resin canals on the bark of lateral branches correlated well with measurements on the bark of the leader of the same tree, indicating that lateral samples could be used to screen white spruce for resistance to weevils. Key words: Picea glauca, Pissodes strobi, pest management, tree genetics.

Feeding and Oviposition Preferences of White Pine Weevil (Coleoptera: Curculionidae) on Resistant and Susceptible Sitka Spruce Clones in Laboratory Bioassays

White pine weevils, Pissodes strobi (Peck), caged on live clones (grafts) of resistant and susceptible Sitka spruce trees, Picea sitchensis (Bong) Carr., and petri dish experiments using cut branches from the same clones demonstrated that P. strobi feeding and oviposition was negatively correlated with the density of resin canals in the bark of the host tree. Weevils in cages containing resistant trees fed and oviposited preferentially in the internode below the leader, where resin canal density was lower (i. e., only the leader and not the entire tree was resistant). However, if given a choice, weevils departed from resistant trees and aggregated on susceptible trees. These experiments indicate that resistance is based on blockage by the tree of the normal preference of P. strobi for feeding and oviposition on the leader. This blockage is probably caused by repellency caused by the high resin concentration in the leader which, under natural conditions, forces the weevils to depart from resistant trees. The interaction of the weevil with other resistance mechanisms is discussed.