Bud development and dormancy in slash and loblolly pine. I. Speed of budbreak and second year height as related to lifting date

Slash and loblolly pine 1-0 seedlings were lifted from the nurserybed in late November, mid-December, late December, and mid-February. The buds of the seedlings were classified as set or growing two weeks prior to lifting and were re-examined upon lifting. For both species, buds that had set remained set whereas those that were classified as growing showed an decreasing trend of setting from November through December. A subset of seedlings was potted and maintained in a greenhouse to determine rate of budbreak; the remainder were field planted. In the greenhouse, loblolly pine broke bud fastest and slowest when lifted in mid-February and mid-December, respectively. The rate of slash pine budbreak increased over successive lifting dates. In the field, loblolly pine lifted in mid-December exhibited the highest percentage of growing seedlings; these seedlings were also tallest after one year in the field. Field-planted slash pine had the highest percentage of growing seedlings when lifted in late November. However, seedlings lifted in mid-December were tallest after one year.     

Phenological variation in height and diameter growth in provenances and families of loblolly pine

The phenology of 5- and 6-year old loblolly pine (Pinus taeda L.) trees was studied over two different growing seasons (1993 and 94) in southwest Georgia. These trees were from 7–9 open-pollinated families from each of four different provenances planted at two locations. The provenances were: Atlantic Coastal Plain (eastern SC), Gulf Hammock (north FL), Lower Gulf (south AL, MS) and Upper Gulf (north AL, MS). Provenances did not vary as to when height growth started in spring, but showed very significant differences for the date of growth cessation in fall. The Gulf Hammock source grew the most and also had the longest height growth period, while the Upper Gulf source was first to stop height growth and had the least annual height increment. Provenances were also significantly different for the date of cessation of diameter growth (a difference of 22 days between Gulf Hammock and Upper Gulf), and the order of cessation was the same as for height. Families within provenances were significantly different for date of cessation of height growth and diameter growth. When family means were considered across provenances, there was a correlation of 0.69 (p-value = 0.0001) between annual height increment and date of height growth cessation. There was a weaker association between faster growth and a longer growing season within provenances.     

美国火炬松优良家系对三种叶斑病的抗性的初步评价

从美国引进1批火炬松1代种子园优良家系，在福建洋口林场和南屿林场种植4a，评价各家系在自然情况下对松针褐斑病Lecanosticta acicola、松赤枯病Pestalotiopsis furnrea和松落针病Lophodermium pinastri的抗病性。评价结果显示，多数家系对赤枯病和落针病有不同程度感病性，而大多对褐斑病有一定抗性。综合评价对3种病害的抗性，以来自美国亚拉巴马州的AL-8和MG—3家系表现较好；分别来自我国广东仙菊和福建五一林场的对照湿地松和马尾松家系表现最好。     

Tissue culture method affects ex vitro growth and development of loblolly pine

Loblolly pine (Pinus taeda L.) propagules initiated adventitiously from cotyledons and via axillary-fascicular micropropagation from epicotyls were compared to seedlings grown from the same open-pollinated seedlot. Greenhouse and early field results indicate that unlike tissue culture propagules of cotyledon-origin, propagules originating via axillary-fascicular micropropagation from epicotyls do not display early reduced growth relative to seedlings. Further, axillary-fascicular micropropagules derived from cotyledon-origin adventitious shoots displayed early reduced growth. Early reduced growth and other differences between tissue culture propagules and seedlings previously observed in field plantings appear to be inherent to the cotyledon system of propagation and do not necessarily occur when other tissue culture procedures are used for propagation.     

Durability of selected mulches,their ability to control weeds,and influence growth of loblolly pine seedlings

Several mulches of natural, synthetic, or blends of natural and synthetic fibers were tested around newly planted loblolly pine (Pinus taeda L.) seedlings on a sheared and windrowed site in central Louisiana, USA. The vegetation was primarily winter annuals, some residual grasses and forbs, and sparse woody regrowth. Study 1 was rotary mowed just prior to planting in March 1992, and 35 mulches and an untreated check were established. In Study 2, 15 mulches and an untreated check were established in a 1-year-old rough in March 1993. In both studies, a single loblolly pine seedling formed each plot established in a randomized complete block design, with 10 blocks as replicates. Each block was planted with a separate open-pollinated loblolly pine family.Nearly all mulches had deteriorated to some extent after three growing seasons. Synthetic mulches were generally more durable than the natural or natural/synthetic mulches. Mulching eliminated the established vegetation and germinants, and vegetation did not readily reestablish following the deterioration of a mulch. The soil seed bank apparently was not sufficient to regenerate areas that were once covered with mulch and many of the natural materials deteriorated into a fibrous cover that acted like a natural litter layer. Both of these residual weed control effects -- insufficient soil seed bank and formation of a fibrous cover -- were important in stopping vegetation from reestablishing after a mulch had deteriorated. After three growing seasons, the loblolly pine seedlings generally grew better if mulches were used.     

Bud development and dormancy in slash and loblolly pine. II. Effects of ethephon applications

Ethephon application on four dates did not induce budset in slash and loblolly pine seedlings. Ethephon promoted slash pine budbreak by 11 days when applied in mid-November and delayed loblolly pine budbreak by 8 days when applied in late November. Mid-November and early February applications of ethephon promoted height growth of both species.     

Effect of magnetic treatment on seed germination of loblolly pine (Pinus taeda L.)

Based on preliminary experiments, the speed of germination (SG) was in general increased for Pinus taeda L. seeds treated with a static magnetic field (B = 150 mT) for 10, 30 and 60 min. Negative impact was obtained for seeds treated with SMF for 24 h and 48 h. Mean germination time (MGT), the SG, and time required to obtain 10%, 25%, 50%, 75%, and 90% of seeds to germinate (T₁₀–T₉₀) were calculated. Results showed a reduction of the MGT and T₁₀–T₉₀ for seeds treated with SMF for 10, 30, and 60 min; therefore, the germination speed was increased. Among various magnetic treatments, loblolly pine seeds treated with S3 (SMF60 min) yielded the peak performance.     

Somatic Embryogenesis and Plantlet Regeneration in Callus Cultures Derived from Mature Zygotic Embryos of Slash Pine

1TheworkwassupportedbyChineseNationalHighTechnologyDevelopmentProgram"863project"IntroductionSomaticembryogenesishasagreatpotentiaIforrapidProPaationofsuPCriorconifcrspccics.ThefirstreportonsomaticembryogenesisandplantlctrcgencrationinconifersPeCieswasach…     

Two-year development of southern pine seedlings and associated vegetation following spray-and-burn site preparation with imazapyr alone or in mixture with other herbicides

Eight herbicide combinations containing imazapyr alone or in mixture with glyphosate, triclopyr, or picloram+2,4-D were applied July–August 1991 at each of three upland sites in the southeastern U.S., with or without a subsequent broadcast burn in September. Seedlings of loblolly (Pinus taeda L.) or slash (P. elliottii Engelm. var. elliottii) pine were planted that winter. Second-year (August 1993) vegetation responses indicate that broadcast burning, in combination with herbicides, was associated with increased abundances of grasses, forbs, and shrubs and decreased abundances of vines and hardwood trees. In the presence of burning, imazapyr-in-mixture treatments were associated with a high abundance of grass (53% cover) and a mean size of pines less than that of seedlings growing in imazapyr-alone treatments. In the absence of burning, imazapyr-alone treatments were associated with a high abundance of blackberry (21% cover), an average height of hardwoods (131 cm) exceeding that of pines (71 cm), and a mean size of pines less than that of trees growing in imazapyr-in-mixture treatments. Hardwood height in the absence of burning was less when imazapyr was combined with glyphosate (75 cm) than with triclopyr (102 cm). Regardless of the presence or absence of burning, size of pines and abundance of shrubs and hardwoods did not differ between imazapyr rates of 0.56 and 0.84 kg acid equivalent/ha or among herbicides applied in mixture with imazapyr.     

火炬松体细胞胚胎发生和干化体细胞的氧化物酶活性(英文)

培养于附加2,4-D、BA和KT的愈伤组织诱导培养基上的火炬松成熟合子胚在培养3-9周后形成白色、半透明、有光泽的粘性愈伤组织。这类愈伤组织形成于成熟合子胚的子叶,但当用NAA或者IBA代替愈伤组织诱导培养基中的2,4-D时,它的诱导频率明显降低。这种粘性愈伤组织在分化培养基上形成体细胞胚。体细胞胚经过去50μm ABA和8.5%PEG600处理后成为耐干化胚。扫描电镜观察表明,萌发处理36小时后,耐干化胚恢复到干化处理之前的状态且大小和形态正常,而不耐干化胚不能恢复到干化处理之前的状态且表面撕裂。过氧化物酶活性的分析结果表明,耐干化胚有更高的过氧化物酶活性。耐干化胚的高过氧化物酶活性可能与催化H2O2的分解和保护体细胞胚免受氧化的伤害有关。     

抗生素对火炬松的器官发生植株再生的影响(英文)

本文研究了氨苄青霉素、羧苄青霉素和头孢霉素等3种抗生素对火炬松愈伤组织的生长和分化及不定芽生根的影响。结果表明,头孢霉素最有利于愈伤组织的诱导和生长,羧苄青霉素最有利于芽的分化,氨苄青霉素降低了不定芽的生根频率。所有试验的3种抗生素提高愈伤组织的形成和芽再生,但降低了芽的生根频率。这些结果表明,选择合适的抗生素对优化火炬松遗传转化体系有重要作用。图3表4参25。     

Planting cost,survival, and growth one to three years after establishing loblolly pine seedlings with straight,deformed, or pruned taproots

To provide an objective approach for comparing various planting methods likely to differ in cost, seedling performance, and cost efficiency, loblolly pine (Pinus taeda L.) seedlings were dug-hole or slit planted with either straight, deformed, or pruned taproots, and planting rate (seconds per seedling) and three-year survival and growth of seedlings were measured. The per-hectare cost of dug-hole planting seedlings to ensure straight taproots ($273) was over five times that of slit planting seedlings with intentionally deformed or pruned taproots ($50). Although third-year pine survival did not differ significantly among treatments (74% to 87%), yield index was 58% higher for seedlings dug-hole planted with straight taproots (1152 dm³ stem volume/ha) versus that for seedlings slit planted with deformed or pruned taproots (730 dm³/ha). Third-year cost efficiency (yield index ÷ planting cost) of slit planted seedlings with deformed or pruned taproots (11.7 dm³/$) was over three times that of dug-hole planted seedlings with straight taproots (3.5 dm³/$). These short-term results suggest that the higher values of yield index resulting from straight-root planting do not justify its considerably greater cost.     

Seasonal shoot and needle growth of loblolly pine responds to thinning, fertilization, and crown position

The impacts of thinning, fertilization and crown position on seasonal growth of current-year shoots and foliage were studied in a 13-year-old loblolly pine (Pinus taeda L.) plantation in the sixth post-treatment year (1994). Length of new flushes, and their needle length, leaf area, and oven-dry weight were measured in the upper and lower crown from March through November. Total shoot length was the cumulative length of all flushes on a given shoot and total leaf area per shoot was the sum of leaf areas of the flushes.

By the end of June, first-flush foliage reached 70% of the November needle length (14.3 cm) and 65% of the final leaf area (15.0 cm²). Cumulative shoot length of first- and second-flush shoots achieved 95% of the annual length (30.3 cm), whereas total leaf area per shoot was 55% of the final value (75.3 dm²). Fertilization consistently stimulated fascicle needle length, dry weight, and leaf area in the upper crown. Mean leaf area of upper-crown shoots was increased by 64% six years after fertilization. A significant thinning effect was found to decrease mean leaf area per shoot in the crown. For most of the growing season, the thinned-fertilized trees produced substantially more leaf area per shoot throughout the crown than the thinned-nonfertilized trees. These thinned-fertilized trees also had greater needle length and dry weight, longer first flush shoots, and more leaf area per flush than trees in the thinned-nonfertilized plots. Needle length and leaf area of first flush shoots between April and July were linearly related to previous-month canopy air temperature (T_a). Total shoot length strongly depended on vertical light gradient (PPFD) within the canopy, whereas shoot leaf area was a function of both PPFD and T_a. Thus, trees produced larger and heavier fascicles, more and longer flush shoots, and more leaf area per shoot in the upper crown than the lower crown. We conclude that thinning, fertilization, and crown position regulate annual leaf area production of current-year shoots largely by affecting the expansion of first flush shoots and their foliage during the first half of the growing season.     

Micropropagation of loblolly pine by somatic organogenesis andRAPD analysis of regenerated plantlets

IntroductionOrganogenesis and somatic embryogenesis haveben regarded as the in vitro system of choice withthe Pbtenhal for eventual mass propagation of superior and gen6tically engineering forest tree genotypesIn both conal6rous and hardwood (Gupts et al. 1991,Becwar et al. 1995). Somatic embryogenesis andorganeqenesis have been induced from more than 30ired speCies in conifers, but plant regeneration viaSOmahc embryogenesis and organogenesis remainsdffeutt cd a low rqeneration frequency (A…     

不同造林技术措施对湿地松幼林生长影响的研究

在湖南攸县设置了反映湿地松人工林造林各主要技术环节的试验林体系,以研究不同造林技术措施对湿地松幼林生长的影响。经对试验林固定样地进行连续7年定期、定位观测及统计分析表明:在湿地松人工造林的各项主要技术措施中,立地选择、良种选择和造林密度是影响幼林生长的最重要因素,幼林抚育对湿地松幼林生长有较明显影响,而整地方式与规格对幼林生长无明显影响。     

Leaf traits in relation to crown development, light interception and growth of elite families of loblolly and slash pine

Crown architecture and size influence leaf area distribution within tree crowns and have large effects on the light environment in forest canopies. The use of selected genotypes in combination with silvicultural treatments that optimize site conditions in forest plantations provide both a challenge and an opportunity to study the biological and environmental determinants of forest growth. We investigated tree growth, crown development and leaf traits of two elite families of loblolly pine (Pinus taeda L.) and one family of slash pine (P. elliottii Mill.) at canopy closure. Two contrasting silvicultural treatments -- repeated fertilization and control of competing vegetation (MI treatment), and a single fertilization and control of competing vegetation treatment (C treatment) -- were applied at two experimental sites in the West Gulf Coastal Plain in Texas and Louisiana. At a common tree size (diameter at breast height), loblolly pine trees had longer and wider crowns, and at the plot-level, intercepted a greater fraction of photosynthetic photon flux than slash pine trees. Leaf-level, light-saturated assimilation rates (A(max)) and both mass- and area-based leaf nitrogen (N) decreased, and specific leaf area (SLA) increased with increasing canopy depth. Leaf-trait gradients were steeper in crowns of loblolly pine trees than of slash pine trees for SLA and leaf N, but not for A(max). There were no species differences in A(max), except in mass-based photosynthesis in upper crowns, but the effect of silvicultural treatment on A(max) differed between sites. Across all crown positions, A(max) was correlated with leaf N, but the relationship differed between sites and treatments. Observed patterns of variation in leaf properties within crowns reflected acclimation to developing light gradients in stands with closing canopies. Tree growth was not directly related to A(max), but there was a strong correlation between tree growth and plot-level light interception in both species. Growth efficiency was unaffected by silvicultural treatment. Thus, when coupled with leaf area and light interception at the crown and canopy levels, A(max) provides insight into family and silvicultural effects on tree growth.     

Crown characteristics of juvenile loblolly pine 6 years after application of thinning and fertilization

Total foliage dry mass and leaf area at the canopy hierarchical level of needle, shoot, branch and crown were measured in 48 trees harvested from a 14-year-old loblolly pine (Pinus taeda L.) plantation, six growing seasons after thinning and fertilization treatments.

In the unthinned treatment, upper crown needles were heavier and had more leaf area than lower crown needles. Branch- and crown-level leaf area of the thinned trees increased 91 and 109%, respectively, and whole-crown foliage biomass doubled. The increased crown leaf area was a result of more live branches and foliated shoots and larger branch sizes in the thinned treatment. Branch leaf area increased with increasing crown depth from the top to the mid-crown and decreased towards the base of the crown. Thinning stimulated foliage growth chiefly in the lower crown. At the same crown depth in the lower crown, branch leaf area was greater in the thinned treatment than in the unthinned treatment. Maximum leaf area per branch was located nearly 3–4 m below the top of the crown in the unthinned treatment and 4–5 m in the thinned treatment. Leaf area of the thinned-treatment trees increased 70% in the upper crown and 130% in the lower crown. Fertilization enhanced needle size and leaf area in the upper crown, but had no effect on leaf area and other variables at the shoot, branch and crown level. We conclude that the thinning-induced increase in light penetration within the canopy leads to increased branch size and crown leaf area. However, the branch and crown attributes have little response to fertilization and its interaction with thinning.     

马尾松不同家系光合特性的研究

对马尾松１０个家系光合特性的研究表明：（１）不同家系在叶绿素含量，叶绿素ａ／ｂ值，气孔密度，孔径，生物量等方面存在明显差异。（２）生物量和叶纱含量，气孔密度有明显的相关，两者对生物量的贡献达９５％以上；生物量和净光合速率存在一定的正相关。     

Effects of different overwinter storage regimes on shoot growth and net photosynthetic capacity in Pinus Sylvestris Seedlings

Seedlings of Pinus sylvestris were cold‐stored for three or six months at ‐4°C or 2°C or overwintered outdoors. Dry weight development and net photosynthetic capacity were then measured during a 60‐day cultivation period in a controlled environment. In all storage regimes the longer storage period gave a faster growth initiation. Photosynthetic recovery was faster for seedlings stored at 2°C than at ‐4°C, due to better recovery of stomatal conductance. The results suggest that there is little difference in seedling development between storage temperatures of ‐4°C and 2°C whereas outdoor storage might cause certain negative effects on subsequent growth of seedlings. This result is discussed with regard to the present winter climate.     

Root wrenching and lifting date of slash pine: Effects on morphology,survival, and growth

Slash pine (Pinus elliottii Engelm.) seedlings were subjected to three wrenching treatments: One root wrenching in early August; Three root wrenchings in early August, September, and October; and No wrenchings. Seedlings were then lifted on five dates between November and February based on the number of chilling hours accumulated. All wrenched seedlings had reduced shoot dry weight, smaller shoot-root ratio, and smaller stem diameter and height. These morphological differences translated into improved survival as well as increased diameter and height growth when measured one and two years after planting. Only seedlings wrenched three times demonstrated improved root fibrosity. Furthermore, only multiple wrenched stock showed greater resistance to drying imposed prior to planting. At the time of lifting, seedlings lifted latest had greater stem diameter, increased root dry weight and number of root tips, and improved shoot-root ratio. However, no survival differences were detected across lifts, and those seedlings lifted earliest demonstrated the best height and diameter growth.This paper is Journal Series No. R00695 of the Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611.