Optimum timing of gibberellin A4/7 sprays to promote cone production in jack pine seedlings

Three-year-old jack pine (Pinus banksiana Lamb.) seedlings in pots were sprayed with gibberellin A_4/7 solution during the 1989 growing season. Unsprayed and sprayed controls, and seedlings sprayed with gibberellin A_4/7 at three concentrations (200, 400 and 600 mgL^-1) were tested in each of five different treatment periods based on jack pine morphogenesis. Each spraying period consisted of five weekly applications between May and October. Trees produced significantly more pollen cones than the two controls when sprayed at 400 or 600 mgL^-1 during July and early August. Spraying at 600 mgL^-1 during May–June and June–July produced significantly more seed cones than the two controls, as did spraying at 400 or 600 mgL^-1 during July and early August. The best treatment for both pollen- and seed-cone production was weekly spraying at 400 or 600 mgL^-1 gibberellin A_4/7 from early July, which coincided with the end of terminal shoot elongation, through early August, which coincided with microsporophyll initiation in the pollen-cone buds and initiation of the potential seed-cone buds.     

Elevated temperature during reproductive development affects cone traits and progeny performance in Picea glauca x engelmannii complex

Two temperature regimes were applied during reproductive development of seed and pollen cones of interior spruce (Picea glauca (Moench) Voss and Picea engelmannii (Parry) complex) to determine temperature effects on the adaptive traits of progeny. In Experiment 1, identical crosses were made on potted interior spruce using untreated pollen followed by exposure to a day/night temperature of 22/8 or 14/8 degrees C with a 12-h photoperiod during the stages of reproductive development from post-pollination to early embryo development. Frost hardiness and growth of progeny from seed produced in the two temperature treatments were measured over a 4-year period. Elevated temperature significantly affected both seed-cone development and the adaptive properties of the progeny. Seed cones exposed to the 22/8 degrees C treatment reached the early embryo stage in 53 days versus 92 days in the 14/8 degrees C treatment. Seed yields, cotyledon emergence and percent germination were also significantly enhanced by the 22/8 degrees C treatment. Progeny from seed produced in the higher temperature treatment showed significantly reduced spring and fall frost hardiness, but the elevated temperature treatment had no significant effects on time of bud burst, growth patterns or final heights. In Experiment 2, single ramets of the same clone were subjected to a day/night temperature of 20/8 or 10/8 degrees C during pollen cone development, starting from meiosis and ending at pollen shedding. The two populations of pollen were then crossed with untreated seed cones. Compared with pollen cones exposed to the 10/8 degrees C treatment, pollen cones exposed to the 20/8 degrees C treatment during development reached the shedding stage 2-4 weeks earlier, whereas pollen yields, in vitro viability and fertility (seed set) were significantly lower; however, the resulting progeny displayed no treatment differences in frost hardiness or growth after 1 year. Results suggest that seed orchard after-effects could be caused by temperature differences between orchard site and parent tree origin and that this effect acts on maternal development. Gametophytic (pollen or megagametophyte or both) and early embryo (sporophytic) selection are possible mechanisms that may explain the observed results. Although the effects are biologically significant, they are relatively small and do not justify changes in current deployment strategies for seed orchard seed.     

华北落叶松传粉生物学的研究

本文研究了华北落叶松雌雄球花在树冠上的分布和树冠周围花粉密度变化规律、传粉机制、胚珠接收花粉量及结实状况等。雌球花主要分布在树冠中上部2－4龄枝上，雄球花分布范围较广，且常与雌球花混生；树冠周围花粉密度与雄球花的分布密切相关，中部最大，依次向上下两端减少。依据雌球花形态特征的变化，可将传粉期为5个阶段，整个期间无传粉滴出现，由球被顶端大裂片的珠被毛接收花粉。最佳传粉期约为2天。胚珠平均接收4粒花粉，虽然胚珠接收的花粉数与饱满种子的产量有一定的关系，但并不是造成空粒的主要原因。此外，讨论了不同授粉方式对种子产量的重要意义。     

Seed-cone receptivity and seed production potential in white spruce

Three to five ramets were selected from each of five white spruce clones for the study. Seed cones (megastrobili) were pollinated once and some were sampled at the different stages of development to study the pollination mechanism, seed-cone receptivity, and seed production potential.The proximal end of a seed cone emerged from the bud scales and was the area to be receptive first. As the seed cones continued to develop, the margins of the cone scales became reflexed to increase the surface area and to funnel pollen along the margins of two adjacent scales onto the micropylar arms. Pollen was transferred to a deep depression in the nucellus and it germinated in the depression a weel after pollination. Another week later the micropyle was sealed by the ingrowth and divisions of the cells in the micropylar canal. Receptivity of a seed cone lasted for about 10 days and the end of receptivity was signalled by the closure of cone scales.The optimal receptivity appeared to occur when seed cones approached the end of receptivity and this coincided with the peak of pollen shedding. It was evident that seed cones pollinated at this stage produced the most filled seeds, an average of 41.6 from a seed production potential of 88 seeds per cone. Total cone scales averaged 67.7 per cone of which 43.6 scales were fertile and located at the mid-portion of a cone.     

榆林沙区班克松物候及年生长规律观测

对榆林沙区2009年引种栽培的班克松进行了连续3年的物候及年生长规律观测。结果表明:班克松在榆林沙区4月上旬芽膨大,4月下旬至5月下旬主梢、枝生长旺盛,年平均生长量主梢47.7cm、侧枝19.9cm,6月中下旬芽完全形成。4月底至6月中旬针叶生长,平均2.63cm。雄球花5月初散粉高峰期,雌球花4月底5月初授粉。5月上中旬幼果形成,二年球果4月底至5月底生长迅速,平均纵径34.15cm,横径17.13cm,9月中旬球果成熟。     

In situ forcing of pollen maturation in Jack pine and Japanese larch male cones

Paper bags equipped with a polyethylene window were placed on branchlets 6 and 9 weeks before the time of pollen dispersal of Japanese larch and Jack pine, respectively. This technique produced a localized greenhouse effect around the branchlets, accelerating male cone development. For Jack pine trees, buds in bags with the window oriented upward had the shortest maturation time. In fact, it was possible to collect these pollen cones about 11 days before the unbagged control without decreasing the production of pollen. The mean germination rate of the pollen from the bags with the window pointed upward, however, was significantly lower than the control, by about 15%. Buds in bags with the window oriented downward had an accelerated development of about 9 days (compared to the control) but did not experience a decrease in pollen production or quality. This same technique caused the abortion of male cones of the Japanese larch trees. Thermal probes in the bags enabled us to follow the progression of temperature inside and outside the bags during the development of the male cone in each species. They revealed that the bags increased mean temperature, daily temperature range, and degree-day accumulation, and that this effect was most pronounced for Jack pine, when the polyethylene window was oriented upward.     

Promotion of seed production in Douglas-fir grafts by girdling + gibberellin A4/7 stem injection,and effect of retreatment

Twelve- to 17-year-old Douglas-fir grafts, which in 1985 received no treatment, stem girdles only (G), or girdles plus stem injection of gibberellin A_4/7 (G + GA) at vegetative bud burst, were in 1987 retreated with G + GA or left untreated. Tree were untreated in 1986 and cone production the following year was very sparse. G + GA treatment in 1987 increased the 1988 production of seed cones from 465 to 1600 per tree, with a comparable increase in frequency of grafts producing a heavy crop of pollen cones. However, induction treatments applied in 1985 adversely affected seed- and pollen-cone production in 1988, independent of treatment in 1987. Cone size, total and filled seed per cone, and seed germination were little affected by treatment either year. Treatment with G + GA in 1987 only maximized the production of filled seeds (48 100/tree), although G + GA in both 1985 and 1987 (31 200/tree) was still highly effective relative to no treatment in either year (14 700/tree). The G + GA treatment adversely affected tree condition more severely than previously (or since) experienced, probably as a consequence of grafts also being subjected to prolonged late-summer droughts during each of the treatment years.     

Reduced fertilization capacity of SO2-fumigated Picea omorika-pollen

Dry pollen of Picea omorika was fumigated with 820 μg/m³ SO₂ for 3 , 4 , or 5 days. Few or no adverse effects occurred during subsequent in vitro germination: germination percentage was not affected at all, and reduction of the pollen tube length was only 10% in pollen exposed for 5 days. Nevertheless pollination with fumigated pollen resulted in reduced seed production. 41% fewer seeds per cone were produced, and only 33% were filled seeds, compared to 70% filled seeds of the control. Seed-weight was reduced from 3.6 g per thousand in the control to 3.0 g per thousand, when cones were pollinated with pollen fumigated for 5 days. Similar but less striking effects were found with pollen fumigated for 3 or 4 days.     

Effect of flowering phenology,date of cone collection,cone-storage treatment and seed pretreatment on yield and germination of seeds from a Douglas-Fir seed orchard

The effects of reproductive phenology, date of cone harvest, cone storage and seed pretreatment on yield and germination of seeds from a Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seed orchard were studied. Flowering phenology (early, intermediate or late) had no discernible effect on seed maturation. Higher germination and yields of filled seeds were obtained from cones collected in mid-August, approximately 2 weeks prior to cone opening, than from cones collected just as they began to open. Seeds extracted immediately following harvest germinated better than those from cones stored for 2 months. Seeds from all treatments were dormant and responded to prechilling by exhibiting increased germination rates. The implications of these findings for cone-crop management are discussed.     

Production of a new generation of seeds through the use of somatic clones in controlled crosses of black spruce (Picea mariana)

To assess the potential to integrate somatic clones (SC) of desired characteristics in production of high genetic quality seed, controlled crosses between different SCs of black spruce (Picea mariana (Mill) B.S.P.) were used to assess their suitability for the production of viable pollen, cones, seeds and seedlings. These SC produced male and female strobili at an early stage. Pollen, cones and seeds produced were characterized (mass, size, germination); their characteristics were similar to those produced by trees in natural forests or seed orchards. A maternal effect was demonstrated for the cone size and seed mass. Although seeds had excellent germination rates, the somatic biparental crosses were divided into three distinct groups with different germination curves using the Weibull function. Seeds from controlled crosses between different SC enabled the production of high morpho-physiological quality seedlings in a forest nursery. Using black spruce as a model, we showed, for the first time, that SC can be used as seed producers. These encouraging results open new perspectives on the tangible integration of somatic embryogenesis (SE) in the chain of seed, vegetative propagation (cuttings and SE) and production of plants for high productivity plantations. Controlled crosses can be made between SC with the desired characteristics (fewer large branches, fewer nodes, good growth, high wood density, performance, improved yield, etc.), vegetative propagules produced and deployed to clonal tests. After elimination of the worst performing SC, clonal tests can be converted into seed orchards that produce a new generation of seeds of high genetic quality. This will allow the rapid introduction of new materials in elite breeding programs of forest species.     

Influence of female cones on the vegetative growth of Pinus contorta trees

Branches of Pinus contorta Dougl. bearing two-year-old female cones initiated fewer lateral buds than vegetative branches. However, the number of lateral shoots that differentiated and grew was not reduced on female cone-bearing branches. Neither the number nor the weight of female cones influenced the length of the terminal shoot. The total length of all lateral shoots was positively associated with the weight of two-year-old female cones. Branch units with two-year-old female cones produced significantly more total dry weight in the current year than vegetative branch units. There was, however, no significant reduction in the dry weight of terminal and lateral shoots. Branches bearing female cones allocated between 17 and 45% of the current year's dry weight to two-year-old cones and between 1 and 5% was allocated to one-year-old female cones. Female cones therefore apparently do not reduce the photosynthetic potential of trees. The influence of female cones compared with male cones on the growth of trees is discussed.     

Influence of male cones on early season vegetative growth of Pinus contorta trees

On average, branches of Pinus contorta Dougl. bearing male cones had 35 fewer needle pairs than equivalent vegetative branches, and significantly fewer differentiated primordia (i.e., male cones + needle pairs + sterile cataphylls). It was estimated that the formation of male cones results in a 27-50% reduction in the number of needles per male cone-bearing branch. In early spring, branches bearing male cones had on average 23% (0.44 g) more dry weight than vegetative branches. On average, 95% of the dry weight of male cone-bearing branches was allocated to the terminal shoot (54% of which was male cones) and 5% to the lateral shoots. By comparison, vegetative branches allocated 85% of their total dry weight to the terminal shoot and 15% to the lateral shoots. These findings suggest that male cones may reduce the photosynthetic potential of the trees which bear them.     

Effect of feeding by the western conifer seed bug, Leptoglossus occidentalis, on the major storage reserves of developing seeds and on seedling vigor of Douglas-fir

The impact of feeding by the western conifer seed bug (Leptoglossus occidentalis Heidemann) on storage reserves of developing seeds of Douglas-fir (Pseudostuga menziesii (Mirb.) Franco) was studied by caging nymphal and adult seed bugs on cones during late-season development, and nymphs on cones during early, mid- and late-season development. Analysis of the major storage reserves of partially damaged seeds revealed that late-season feeding by each life stage and feeding by nymphs at all three stages of cone development significantly reduced the amounts of lipid and buffer-insoluble (crystalloid) protein in seeds at harvest by up to 78 and 97%, respectively. Seeds showing light to moderate damage on radiographs did not exhibit a reduction in the amount of buffer-soluble (matrix) protein. Seeds damaged by feeding during early development compensated in part by continuing to synthesize lipid and crystalloid protein. Light or moderate damage to mature Douglas-fir seeds exposed to L. occidentalis in the laboratory reduced seedling emergence by > 80%, but the seedlings that emerged successfully appeared to suffer no adverse effects when grown under standard nursery conditions.     

Effects of cone-induction treatments on black spruce (Picea mariana) current-year needle development and gas exchange properties

Both drought and root pruning (RP) increased the number of cones induced when black spruce (Picea mariana (Mill.) B.S.P.) grafts were injected with gibberellins A(4/7) (GA), but their effects on predawn shoot water potential and current-year needle development differed. Drought decreased predawn shoot water potential (Psi(pd)), but only during the period when irrigation was withheld, and it had no effect on the growth or gas exchange properties of current-year needles. Conversely, root pruning had little effect on Psi(pd), but it resulted in trees with smaller current-year needles that had lower nitrogen and chlorophyll concentrations and reduced rates of gas exchange up to the later stages of shoot elongation compared with needles of control trees. These findings are discussed in relation to potential effects on the development of induced cones in the following growth cycle.     

Impact and control of the cone tortricid Pseudococcyx tessulatana (Staudinger), damaging the cone crop of a selected clone of cypress (Cupressus sempervirens L.) in Italy

The green cypress (Cupressus sempervirens) is of great interest for ornamental, reforestation and windbreak use in the whole Mediterranean basin. In Italy, seed material selected for resistance to the fungus Seiridium cardinale is produced in seed orchards by controlled crosses of parent trees. The insect pest showing the highest impact on seed cone production is Pseudococcyx tessulatana (Lep.; Tortricidae), which attacks cones during the initial growth period as well as full-grown cones. The impact on the seed cone crop of the tortricid was estimated on a clone patented for its resistance to cypress canker (Agrimed 1). The attack was inversely related to the cone crop, as it concerned 36.7?% of cones in 1999 (high crop year) and the 66?% in 2000 (low crop year). In both years, about 90?% of the surveyed branches revealed cones attacked by P. tessulatana by the 1^st life-cycle larvae, whereas only 40?% of branches were also attacked by the larvae of the 2^nd life cycle. The highest attack rate per branch was always observed on branches bearing a low number of cones. The potential of two control methods against P. tessulatana to protect cones which result from crossing a mother tree “Agrimed 1” with selected father trees was also evaluated in 2000. The protection given by a sleeve surrounding the branch was almost complete (0.4?% cone mortality), whereas a cone mortality of 24.3?% was observed on branches treated by the insecticide diflubenzuron. Sleeves appear to be useful to protect branches on which special crosses were done, but are expensive and time-consuming and may favour the attack of the mealybug Planococcus vovae inside the sleeve. The insecticide application may represent a valid alternative, especially when protection should be directed toward a high number of branches.     

日本落叶松种子园优良家系球花分布规律及花量调查

对日本落叶松种子园优良家系雌雄球花数量及在树冠上的分布规律进行调查分析。结果表明:日本落叶松雄球花在树冠垂直方向上分布差异极显著,下层和中层的数量显著多于上层,所占比例为83.39%,水平方向上南面的雄球花多于其他方向;雌球花在树冠不同冠层的分布无显著差异,中、上层的雌球花数量比下层多,东、南方向多于西、北方向;雄球花多着生在2,3 a生枝上,雌球花多着生在3,4 a生枝上,1 a生枝条上无花;不同无性系间雌雄球花数量差异显著,356号无性系的雌雄球花数量均为最多。     

Pollen development and multi-nucleate microspores of <Emphasis Type="Italic">Populus bolleana</Emphasis> Lauche

Populus bolleana is a variety of P. alba, commonly used in poplar breeding programs in China. Developmental biology that involves staminate flowers, microsporogenesis and microgametogenesis ofP. bolleana is essential for Populus improvement in cross breeding for better characteristics in sexual reproduction. Flower morphology and pollen development were described and illustrated using anatomical, sectioning and stain-clearing techniques. The results show that microsporocytes undergo a regular meiotic process, but some multi-nucleate microspores occur at the microspore stage. It takes five days for microsporocytes to develop to mature pollen by forcing flower branches under greenhouse conditions. Additionally, an important relationship was found between stages of meiosis and anther colors. Microspore tetrads formed when the anther color turned yellow, whereas, when the pollen matured, the anther was red and the tapetum degenerated completely. When mature pollen grains are formed, flower buds develop into male catkins. In the end, filament elongated and pollen grains were released from dehisced anthers.     

沙冷杉结实特性的观测

以沙冷杉为材料,对其结实特性进行观测,结果表明:在城市人工栽培条件下,初次结实年龄为40～45 a,与野生植株基本相同,初次结实株率为31.3%;充足的光照可使结实植株和球果数量增加,温度对其无明显影响.球果着生于2 a或3 a生枝条基部,以2 a生枝条基部居多;多集中分布在树冠上部的枝条上.果鳞开裂至有种子与果鳞脱落...     

Seed cone abortion and full seed production in an indoor seed orchard with potted grafts of Picea abies

Abortion of seed cones and production of full seeds have been recorded in an indoor‐potted Norway spruce (Picea abies (L.) Karst.) seed orchard at Biri nursery in Norway. Seed cone buds aborted their normal development at much higher frequencies (22–45%) inside isolation bags than in an open‐air (4–12%) greenhouse environment. The grafts had been induced to flower the year prior to seed cone development. Treatment with gibberellin A_4/7 in conjunction with heat reduced the proportion of aborted, isolated flowers (13%) compared to treatment with heat alone (22%) in a clonally balanced material. The production of full seeds per cone increased from 3 in 1987 to 50 in 1991. The full seed production is discussed in relation to methods and timing of pollen forcing. It is anticipated that 1 kg of seeds could be produced annually in a 1250 m² greenhouse.     

山茶花粉生活力及贮藏条件初探

以山茶两种开放程度花朵（初开和盛开）的花粉为试材,采用无机酸法和联苯胺染色法研究了花朵开放程度和贮藏条件对花粉生活力的影响.结果表明：无机酸法不适于山茶花粉生活力的测定,联苯胺染色法能快速地检测山茶花粉的生活力.实验结果表明,两种花粉生活力随着贮藏时间的增加呈逐渐下降的趋势.花朵的开放程度对花粉的生活力影响不大,而贮藏条件对其影响显著：室温（13℃～25℃）下,两种山茶花粉贮藏12 d后生活力完全丧失;冷藏（2℃）条件下,盛开花粉贮藏26 d后生活力完全丧失,而初开花粉生活力完全丧失需要30 d.