A study on Xingkai Lake pine gall rust

The Xingkai Lake pine (Pinus takahasii Nakai) gall rust caused byCronartium quercuum(Berk.) Miyabc: Shirai is a serious stem rust in the northeast region of China. The alternate host is oak (Quercus mongolica Fisch). Germination of both acciospores and urediospores was optimal at 12°C and occurred over a range of temperatures, from 4°C to 32°C. Teliospores germinated optimally at 16–18°C and over a range of 8–28°C. All spores germinated best under natural light and dark conditions. Direct light inhibited germination even when followed by darkness. The incubation periods of urediospores and teliospores in inoculation experiments were 6–16 days and 3–33 days respectively. Anatomical studies ofCronartium quercuum galls showed that rust hyphae freely ramify through the intercellular spaces within parenchymatous tissues of the cortex, phloem, cambium and xylem. Hyphae are perennial; large haustoria arc cylindrical with rounded or blunt ends. Among the 12 fungicides tested for control of the rust, pine-tar, pine-tar: diesel oil (1:1, 1:3, 1:5), 75% Bravo emulsion and 70% Mancozeb emulsion applied to the galls produced satisfactory results.     

Light quality treatments enhance somatic seedling production in three southern pine species

Embryogenic cultures of loblolly pine (Pinus taeda L.), slash pine (Pinus elliottii Engelm.), longleaf pine (Pinus palustris Mill.) and slash pine x longleaf pine hybrids were initiated from immature seeds on an initiation medium containing 13.57 microM 2,4-dichlorophenoxyacetic acid and 2.22 microM benzylaminopurine. Embryogenic cultures proliferated and somatic embryos developed, matured and germinated following a modified protocol and media originally developed for radiata pine (Pinus radiata D. Don.) somatic seedling production. A discrete, light-sensitive pre-germination stage and a later germination (radicle emergence) stage were identified by the differential response of somatic embryos to light of different wavelengths. Different light quality treatments were applied during the pre-germination and germination steps, using cool white fluorescent bulbs or light-emitting diodes (LEDs), or both. In general, red wavelengths provided by LEDs during these steps resulted in higher frequencies of somatic embryo germination (up to 64%) and conversion (up to 50%), longer tap roots and more first-order lateral roots than the standard cool white fluorescent treatments or treatment with blue wavelengths from LEDs. In addition, exposure to red light allowed germination of somatic embryos of some clones that failed to produce germinants under fluorescent light. Germination and conversion were further enhanced by sequential application of cool white fluorescent light and red light, resulting in up to 100% germination and conversion in one experiment. Longleaf pine somatic embryos were especially responsive to the light quality treatments, resulting in the first report of somatic seedling production for this species.     

Effects of seed water content and storage temperature on the germination parameters of white spruce, black spruce and lodgepole pine seed

The effect of seed water content (WC) (2–3, 5–6 and 22–25%, on a fresh weight basis), storage temperature (+4, −20, −80 and −196°C) and storage duration (6, 12, 24, 48 and 60 months) on the germination of white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill.) B.S.P.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed was investigated. Germination of white spruce control (untreated) seeds and seeds adjusted to 2–3% and 5–6% WC declined after 48 months of storage at −80 and −196°C, with a further decline at 60 months at −20, −80, −196°C. Germination remained high when control white spruce seeds and seeds with 2–3, 5–6% WC were stored at +4°C, over all storage durations. Generally, black spruce and lodgepole pine exhibited high germination at all storage temperatures at 2–3% and 5–6% WC as well as the control (untreated) seed, for up to 60 months in storage. Germination declined for all three species when seed was conditioned to 22–25% WC. This loss in germination was partially recovered in white spruce seed stored at +4, −20 and −80°C after storage durations of 24, 12 and 48 months, respectively, and in black spruce seeds stored at −20 and −196°C after storage durations of 24 months. Mean germination time (MGT) was relatively constant for all species, under all conditions, except for seed conditioned to 22–25% WC, where MGT increased for white spruce seed stored 48 months at −80 and −196°C, and for black spruce seed stored 24 months at +4 and −80°C and 60 months at −196°C. These results show that the optimal storage temperatures are 4°C for white spruce, and 4, −20, −80, and −196°C for black spruce and lodgepole pine, and 2–6% water content is optimal for all 3 species at these temperatures.     

Target seed moisture content,chilling and priming pretreatments influence germination temperature response in Alnus glutinosa and Betula pubescens

Abstract

The response of common alder [Alnus glutinosa (L.) Gaertn.] and downy birch (Betula pubescens Ehrh.) seeds to germination temperature was examined following chilling and priming. Seeds of two seed lots of each species were subjected to combinations of chilling (4±1°C) and priming (20°C) treatments in fully imbibed (FI) state or a lower target seed moisture content (TMC) level (30% and 35% in alder and birch, respectively). After treatment, the seeds were allowed to germinate for 56 days at constant temperatures of 7.5, 10, 15, 20, 25 or 30°C. The response to temperature and pretreatment differed between species, but the effect was consistent in each seed lot within each species. In alder, the TMC seeds germinated well across the full range of temperatures, whereas there was an optimum temperature (22–23°C) for seeds given the FI pretreatment. Priming had no significant effect on the germination response of the TMC seeds in alder, but priming greatly improved germination in the FI seeds, especially at the lower germination temperatures (optimum 18–19°C). In contrast, in birch, the TMC seeds germinated better across the full temperature range, but the optimal germination temperature (15°C) was the same for all seed pretreatments. Priming improved germination in both the FI and TMC seeds in birch.     

Effect of post treatment temperature and humidity conditions on fixation performance of CCA-C treated red pine and southern pine

introductionWaterbornepreservativesareamajorcomponentofthewood-treatingindustrybecauseoftheireaseofapplication,lowcost,andthecleanappearanceofthewoodattertreatment.Theuseofchromatedcopperarsenate(CCA)preservativesintheUSAhasgrownfroma14%shareofthewoodpreservativesmarketin1977to73%in1987(Micklewright1993).ThisismainlyduetotheincreasinguseofCCAtreatedwoodasdecksandoutdoorstructures.ThewaterbornepreservativeCCAhasbecomeoneofthemosteffectivetreatmentsforNorthAmericanwoodproduCts,usedinapplic…     

Impact of fixation/drying conditions on fixation rate, teachability and bioefficacy in CCA-C treated red pine and southern pine

Red pine (Pinus resinosia Ait) and southern pine (Pinus spp.) sapwood blocks were pressure treated with CCA-C at retention of 6.4, 2.0, 1.5 kgm^-3 followed by fixation using 11 post-treatment schedules ranging from 50–70 °C and 5 different relative humidity conditions. The effect of these post-treatment schedules on fixation rate, chemical leachability and decay resistant once were evaluated to better understand the effects of fixation/drying conditions on leachability and biodeterioration. Southern pine blocks fixes slightly slower than red pine. Fixation of CCA at high temperature high humidity, essential initially fixation at high humidity for fixation/drying schedules, resulted in lower leaching of chromium and arsenic elements than high temperature low humidity or initially fixation at the high temperature low humidity conditions. Copper leaching was indicated no significant difference under 11 fixation/drying conditions for both species. Weight losses for southern pine byChaetomium globosum was lower than red pine byGloeophyllom trabeum. There were some different capacities of decay resistance for both species under those post treatment conditions.     

Pine growth response to management of the subterranean clover understory

Management of subterranean clover (Trifolium subterraneum L.) understory grown with loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) resulted in differences in both clover yield and pine diameter. Loblolly and slash pines were planted into a subterranean clover pasture in 1984. Suppression of warm season herbaceous vegetation by applying herbicides or disking the site in late summer resulted in significantly greater subterranean clover production than on the control site where no additional understory management was applied. Pine species had no effects on clover yield. The N content of the pine foliage on the blocks managed with herbicide application or disking generally was significantly greater than the control from the 5th through 7th growing seasons (1988–1990). The dbh of the pine trees in the disked and herbicide treatments was greater than the control after the 7th growing season (1990).     

Effects of drought stresses induced by polyethylene glycol on germination of Pinus sylvestris var. mongolica seeds from natural and plantation forests on sandy land

Effects of drought stresses induced by polyethylene glycol (PEG) (0.0%, 10%, 15%, 20%, 25%, and 30%, with four replicates) on germination of Mongolian pine (Pinus sylvestris var. mongolica) seeds produced in plantations (southern Keerqin sandy land) and natural forests (Hulunbeier sandy plain) were observed. The results indicated that the seeds from both provenances did not germinate when PEG concentration was more than 25%. The time of initial germination and that of its completion of stressed seeds from both provenances were delayed when compared with the unstressed seeds. The germination capacity and germination rate of natural seeds were significantly higher than those of plantation seeds for all treatment levels (P < 0.05). The mean growth rates of radicle and hypocotyl from natural seeds were significantly higher than those from plantation seeds at all treatment levels below 20% PEG treatment (P < 0.05). The ratios of radicle to hypocotyl of 20% PEG treatment were significant higher than those of the corresponding controls for both provenances (P < 0.05). These results suggested that Mongolian pine seeds/seedlings had stronger resistance to PEG drought stresses; 10% PGE stress did not significantly influence germination. Natural seeds exhibited more resistance to PEG stress than plantation seeds. It was concluded that drought stress on seed germination might be one cause of obstructed natural regeneration of Mongolian pine plantations on sandy land. It is recommended that natural seeds be used for afforestation, and light drought stress (e.g., 10% PEG stress) may be useful in improving seed germination and the growth of radicles and hypocotyls.     

Swedish lodgepole pine seed orchard crops tested in north-west Russia

Abstract

Tree vitality and height of lodgepole pine (Pinus contorta var. latifolia) originating from the six Swedish seed orchards and native Scots pine (Pinus sylvestris L.) were estimated in three 8-yr-old test plantations established in the Komi Republic (north-west Russia). A randomized row-plot design with 9–13 replicates of each entry was used. In general, the Scots pine tree vitality was better than that of lodgepole pine but these differences were significant only for seed sources of southern origins Larslund, Rumhult, and Österby. On the contrary, the lodgepole pine height growth was faster (6–21%) except for seed sources of southern origins Rumhult and Österby. In comparison with the native Scots pine, lower mean heights (4–10%) were recorded for these seed sources. Among the lodgepole pine seed sources the northern origins had better vitality, while the effect of latitude on the tree height was insignificant.     

Experimental determination and modeling of equilibrium moisture content from the sapwood of Mexican pine (<Emphasis Type="Italic">Pinus pseudostrobus</Emphasis> Lindl.)

A desorption isotherm is a very important basis in the understanding of drying process. In this study, the desorption isotherms from the sapwood of Mexican pine (Pinus pseudostrobus Lindl.) were determined by the gravimetric method (discontinuous control of sample weight) at 30℃ and 50℃. The salt method was used in the range of water activities from 0.11 to 0.89. The results show that the desorption ability of Mexican pine sapwood increased with temperature at a given relative humidity. The experimental data was further simulated with the models, i.e., BET, GAB, Oswin and Henderson models. The GAB, Oswin and Henderson models allow the representation of the entire desorption isotherms. The BET model showed a better fit for water activity lower than 0.35, with a mean relative deviation of 0.0286 at 30℃ and 0.0167 at 50℃. Simultaneously, the BET model gave a better representation of moisture content in the monolayer saturation region. Overall, the GAB model ensured the best simulation of the entire isotherm, while the Henderson model displayed the worst simulation.     

Date of sowing and emergence timing affect growth and development of loblolly pine seedlings

Loblolly pine (Pinus taeda L.) seeds were sown from February to June in Alabama, U.S.A. If sowing was conducted in May or June, seedling emergence was reduced and seedling mortality increased. Seedlings from earlier sowings grew to greater sizes, but seedlings from later sowings grew later into the fall. Within any given sowing date, the earliest seedlings to emerge grew largest. Seedlings from the February sowing formed buds in mid-summer, flushed, and in some instances flushed yet again. However, by early October, not all seedlings from May and June sowings had formed an initial bud.     

Autumn freeze testing of one‐year reciprocal families of Pinus sylvestris (L.)

Reciprocal families of Scots pine, Pinus sylvestris (L.), from a Swedish seed orchard were artificially freeze tested to ‐10°C at the end of the first growth period. The degree of freezing damage was used as an indication of the cold acclimatization achieved at the time of freeze testing. Both one‐year cold acclimatization and one‐year height were mainly additively inherited. Specific combining ability, reciprocal and maternal effects were small. On the family level, freezing damage was non‐significantly correlated with field survival and field height after ten years. One‐year height was positively correlated with 10‐year field height and negatively correlated with field survival on the family level. Within families, plants from early germinated seeds cold acclimated earlier and were higher at the end of the first growth period than plants from lately germinated seeds. The results indicate that conclusions made from first‐year cold acclimatization studies can be influenced by variation in the rate of seed germination and seedling/germinant development.     

Germination and seedling growth of Quercus vulcanica: effects of stratification, desiccation, radicle pruning, and season of sowing

Effects of stratification, desiccation, radicle pruning, and season of sowing on Quercus vulcanica germination and growth were studied to identify optimum nursery procedures for artificial regeneration of this species. Following stratification (0, 2, 4 and 8 weeks), acorns were germinated, and acorn moisture content and germination performance were also determined at various times during desiccation. In early December unsprouted acorns were planted in containers, and in early April sprouted acorns, which had been stored in polyethylene bags at 4 °C, with radicles left intact or with radicles pruned back to 1.0 cm were planted in containers.Stratification for 2 and 4 weeks did not increase germination percentage but significantly increased germination rate. Germination percentage of the seeds dropped when the moisture content of the seeds was reduced by desiccation, and the critical minimum moisture content of the recalcitrant Q. vulcanica acorns was found to be 11–16%. Spring sowing of sprouted acorns altered the morphology the containerized seedlings and caused the formation of significantly more main roots, but resulted in significantly less shoot height and shoot dry weight. Spring-sown sprouted acorns had also a significant advantage over the fall-sown unsprouted acorns in seedling survival, and thus nursery personnel should not be concerned if acorns sprout before sowing.     

Effects of light/darkness, thermal shocks and inhibitory components on germination of Pinus canariensis, Pinus halepensis and Pinus pinea

Knowledge of the germination characteristics of Pinus species can help in the understanding, prediction and management of the regeneration of pine forests. In the Canary Islands, several exotic pines (Pinus halepensis L. and Pinus pinea L.) were planted with Pinus canariensis Chr. Sm. Ex DC, the only native pine species, and there is now an interest in controlling these exotic species to restore the original forest. The main objective of the present study is to determine the germination response of P. canariensis, P. halepensis and P. pinea to different light regimes (darkness and light/darkness), thermal shocks and the presence of inhibitory substances from the leaves and litter of P. canariensis. P. halepensis seeds showed the highest viability and germination rate. Darkness accelerated P. halepensis germination, while exudates accelerated P. canariensis germination. Only treatments of 200 °C for 5 min and 300 °C for 5 min significantly decreased the germination of all three pine species. In the absence of strong differences in germination among species after treatments, the key for fire management or prescribed burning in this case may be the sprouting ability of P. canariensis. A possible management strategy to control the two obligate seeder exotic species could be to use one intense prescribed fire followed by a low-intensity prescribed fire after seed bank germination in the field, so in this way, only P. canariensis could resprout after fire and it would eliminate only the exotic pines in a mixed stand.     

Effects of storage conditions on dormancy and vigor of Picea abies seeds

The dormancy and vigor of Picea abies seeds were studied after five months of storage at 25 and 75% relative humidity (RH) and 5 and 12 °C. Dormancy was evaluated by studying germination response to light and moist chilling at 12 and 21 °C. Dormancy causing germination reduction in the dark was induced in seeds during storage at 25% RH (5–6% moisture content, MC) in darkness. The dormancy was greater when seeds were germinated at 12 than at 21 °C and after storage at 12 than at 5 °C. The effective dormancy relief by light indicates that germination was under phytochrome control. Moist chilling could partly replace light. According to accelerated aging and leachate conductivity tests, dry seeds could be stored at 12 °C for five months without affecting their vigor. After storage at 75% RH (11% MC) and 5 °C, the seeds germinated slowly and incompletely. The decreased germination response to light indicates that other processes than those mediated directly by phytochrome restricted germination of these seeds. The positive germination response to moist chilling suggested that secondary dormancy was induced in the seeds. However, vigor tests gave some evidence of simultaneous decrease of vigor. Storage at 75% RH and 12 °C decreased germination nearly to 0%. Germination of seeds stored at 75% RH could be stimulated by a short accelerated aging period.     

Seedling shoot,needle and bud development in three provenances of Pinus sylvestris and Pinus contorta cultivated in northern Sweden

The patterns of current‐year shoot, needle and terminal bud elongation in seedlings of three Scots pine (Pinus sylvestris L.) and three lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) provenances were compared during the third and fourth growing seasons after planting. Lodgepole pine produced longer shoots and buds than did Scots pine, mainly because lodgepole pine formed more stem units and elongated at a faster rate. Stem unit length and the duration of shoot and bud elongation differed relatively little between species and provenances. Lammas or polycyclic growth occurred in some lodgepole pine provenances, but not in any Scots pine provenance, and was associated with enhanced shoot elongation. Needle elongation commenced earlier, proceeded at a faster rate, and was greater in lodgepole pine than in Scots pine, but ceased about the same time in all species and provenances. The heat sum required to attain 50% of final length was lower for shoots and needles in lodgepole pine than in Scots pine, and for shoots in northern provenances than in southern ones. Mitotic activity in the apical meristem of the terminal bud, which occurred less than one week after the seedlings were free from snow, started and ceased about the same time in each species, but was higher in lodgepole pine than in Scots pine early in the shoot elongation period.     

Freezing temperatures in the root zone—effects on growth of containerized Pinus sylvestris and Picea abies seedlings

Roots of 1‐year‐old containerized seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) were experimentally frozen in December. The seedlings were then grown for 3 weeks in a growth chamber and evaluated with regard to root growth capacity (RGC) and shoot elongation. The subsequent RGC of Scots pine declined as root zone temperatures were lowered from ‐6°C to ‐11°C and from ‐11°C to ‐16°C. Almost no root growth was observed after exposure to ‐20°C. Shoot growth was also negatively affected by low root temperatures but less than root growth. Low root temperatures did not affect Norway spruce as much as Scots pine, although root and shoot growth of Norway spruce were reduced after exposure to the lowest test temperatures (‐16°C and ‐20°C). The length of exposure, ranging between 1 and 8 hours had no effect on subsequent growth.     

Differentiation of seed germination traits in relation to the natural habitats of three <Emphasis Type="Italic">Ulmus</Emphasis> species in Japan

Germination traits of three Japanese Ulmus species, including two summer-fruiting species, U. davidiana var. japonica (UD) and U. laciniata (UL), and an autumn-fruiting species, U. parvifolia (UP), were investigated. Germination tests that controlled light (16 h dark–8 h light/24 h dark) and temperature (alternating 20–30°C/constant 23°C) conditions were conducted just after seed dissemination. Under the preferred (light and alternating temperature) conditions, UD germinated quickly and percentage germination was high (99%), whereas UL and UP germinated moderately to slowly (65.2 and 23.8%, respectively) and the remaining seeds were primarily dormant. When the seeds were exposed to unsuitable conditions for germination, secondary dormancy was induced in all three Ulmus species. Because primary and secondary dormancy of these species was not strict, the existing dormancy could be released by moist conditions and low temperature during the winter. Thus, all three Japanese Ulmus can germinate either just after seed dissemination or in the following spring. Nevertheless, the predominant germination of summer-fruiting UD just after seed dissemination seems to be advantageous for finding safe sites that might become available after a large-scale fluvial disturbance. Similarly, the delayed germination of autumn-fruiting UP until the following spring seems to be advantageous for preventing germination at the end of the growing season. Summer-fruiting UL had a more negative response to favorable light conditions just after seed dissemination, which seems to be advantageous for establishment in canopy gaps. These germination traits seem to be adaptive responses to the dominant disturbance regimes of their natural habitats.     

“Target moisture content” prechill overcomes the dormancy of temperate conifer seeds

Temperate conifer seeds are often considered to be shallowly dormant because a dormancy breakage treatment such as incubation of moist seeds at 4°C (prechilling) for 3–6 weeks improves germination. However, longer prechill durations can induce germination during the cold phase. Since the delicate radicles of prematurely germinated seeds are easily damaged and killed during sowing, potential benefits of extended prechilling are unknown.Described here for the first time is a target moisture content (TMC) prechill. In this dormancy breakage method the seeds are chilled at moisture contents high enough for removal of dormancy but low enough to produce surface dry, free flowing seeds that do not germinate during chilling. The method is a simple, effective and practical way to restrict the amount of water available to seeds from the start of a prechill treatment. The TMC prechill was applied to three conifer species, Douglas fir (Pseudotsuga menziesii (Mirbel) Franco), Lodgepole pine (Pinus contorta Douglas), and Sitka spruce (Picea sitchensis (Bongard) Carrière). All three species benefited from the TMC prechill. Extending the prechill period progressively improved germination by widening the range of temperatures over which germination occurred, raising germination capacity at most temperatures and increasing germination rate at all temperatures. The optimum prechill period combining high germination capacity and low mean germination time was 36 weeks for Douglas fir, from 36 to 76 weeks for Lodgepole pine and 36 or 76 weeks for Sitka spruce depending on incubation temperature. None of the seeds of any of the species germinated during the TMC prechill of up to 76 weeks at 4°C.This work is Crown copyright, reproduced by Kluwer Academic Publishers by permission of the Forestry Commission.     

Agroforestry: southern pines and subterranean clover cultural treatments

Agroforestry research in central Louisiana, USA, examined the effects of agronomic cultural treatments (disk, chemical, hay, and hay-graze) on subterranean clover (Trifolium subterraneum L.) yields and slash pine (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) survival and growth. Cultural treatments appear necessary for successful production of subterranean clover in tame pastures, especially for early fall forage growth. Subterranean clover yields in volunteer swards during spring were highest on the disk and chemical treatments. Generally, pine survival and growth during the first 5 years following tree establishment were not affected by cultural treatments.