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1.
Quercus petraea was undercut according to the following procedure: undercutting first year once (July, September, November), twice (July and November), or undercutting in two consecutive years (September of year 1 and either July, September or November of year 2). Undercutting decreased height and dry weight of the seedlings compared to uncut control seedlings. Undercutting in September and July in two consecutive years increased the number of first-order lateral roots. Field performance was evaluated by transplanting under two conditions, (a) competition with a mixture of grasses with no irrigation or fertilisation and (b) standard conditions with fertilisation and irrigation first year and no competition with grass. After two growing seasons under competitive conditions, seedlings undercut in September of year 1 had a significantly higher dry weight compared with that of uncut control seedlings. Numbers of lateral roots and field performance under competitive conditions was related when numbers of lateral roots were small, but not when high. Competitive conditions had limited effect on root growth after one growing season, whereas shoot growth was reduced. After two growing seasons both shoot and root growth were reduced in all treatments compared with standard conditions. 相似文献
2.
To assess the effects of seedling spacing on one-year-old seedling morphology in the nursery, seeds of three provenances of Fraxinus angustifolia were sown at five different seedling spacings within rows of two different spacings in the seedbed. Subsequent growth performance of one-year-old seedlings was assessed by planting in the forest. Within row spacings were: 4.3, 5.0, 6.3, 8.3, and 12.5 cm, and there were five rows at 20 cm apart, or three rows at 33 cm apart across the 1.2 m wide seedbeds. Both spacings within and between rows significantly affected shoot height, root collar diameter, root dry weight and shoot dry weight, but not root/shoot ratio. Wider spacings produced larger seedlings, but only the wider spacing within rows significantly increased fine and coarse root mass. Provenances showed significant differences in diameter, root/shoot ratio, and fine and coarse roots, and they also showed interactions with row spacings in height and diameter measurements. One year after outplanting, diameter growth was significantly related to provenance, and diameter growth was 88% greater for trees from 33 cm nursery row spacing than those from 20 cm nursery row spacing. 相似文献
3.
Bigras FJ 《Tree physiology》1997,17(5):311-318
Root systems of 6-month-old, cold-hardened, container-grown black spruce seedlings (Picea mariana (Mill.) B.S.P.) were exposed to 0, -5, -10, -15, -20, or -22.5 degrees C. Freezing-induced damage to fine roots, coarse roots and the whole root system was assessed by various viability tests including leakage of electrolytes, leakage of phenolic compounds, water loss, root and shoot water potentials, and live root dry mass. To assess the long-term effects of freezing-induced root damage, seedling survival and regrowth were measured. Leakage of both electrolytes and phenolic compounds differed among fine roots, coarse roots, and whole root systems. In coarse roots and the whole root system, but not in fine roots, leakage of electrolytes, leakage of phenolic compounds, water loss, and root and shoot water potentials were correlated with percentage of live root dry mass which, in turn, was highly correlated with seedling survival and regrowth. Compared with live root dry mass, electrolyte and phenolic leakage, water loss, and root and shoot water potentials were less well correlated with seedling survival and regrowth. Among the viability tests, electrolyte leakage of the whole root system correlated most closely with seedling survival and regrowth. Under freezing conditions that destroyed less than 50% of each seedling's root system, about 70% of the seedlings survived and subsequent growth was little affected, whereas under freezing conditions that destroyed 70% of each seedling's root system, only about 30% of the seedlings survived and subsequent growth was reduced compared with that of undamaged plants. 相似文献
4.
5.
Coarse and fine root respiration rates of aspen (Populus tremuloides Michx.) were measured at 5, 15 and 25 degrees C. Coarse roots ranged from 0.65 to 4.45 cm in diameter, whereas fine roots were less than 5 mm in diameter. To discriminate between maintenance and growth respiration, root respiration rates were measured during aboveground growing periods and dormant periods. An additional measurement of coarse root respiration was made during spring leaf flush, to evaluate the effect of mobilization of resources for leaf expansion on root respiration. Fine roots respired at much higher rates than coarse roots, with a mean rate at 15 degrees C of 1290 micromol CO2 m-3 s-1 during the growing period, and 660 micromol CO2 m-3 s-1 during the dormant period. The temperature response of fine root respiration rate was nonlinear: mean Q10 was 3.90 for measurements made at 5-15 degrees C and 2.19 for measurements made at 15-25 degrees C. Coarse root respiration rates measured at 15 degrees C in late fall (dormant season) were higher (370 micromol CO2 m-3 s-1) than rates from roots collected at leaf flush and early summer (200 micromol CO2 m-3 s-1). The higher respiration rates in late fall, which were accompanied by decreased total nonstructural carbohydrate (TNC) concentrations, suggest that respiration rates in late fall included growth expenditures, reflecting recent radial growth. Neither bud flush nor shoot growth of the trees caused an increase in coarse root respiration or a decrease in TNC concentrations, suggesting a limited role of coarse roots as reserve storage organs for spring shoot growth, and a lack of synchronization between above- and belowground growth. Pooling the data from the coarse and fine roots showed a positive correlation between nitrogen concentration and respiration rate. 相似文献
6.
《Scandinavian Journal of Forest Research》2012,27(1-4):307-316
The average stump and below‐ground biomass of pine was 1464 g/m2; 4% as fine roots (Ø<1 mm), 18% small roots (Ø=1–10 mm), 49% large roots (Ø>10 mm), and 29% stumps), which comprised 35% of the total biomass in the Scots pine stands. The average root length of pine was 728 m/m2: 71 % of this length was fine roots, 29% was small roots, and less than 1 % was large roots. Most of the fine pine roots (80%) were in the 0–10 cm peat layer. The root biomass of the field layer was 548 g/m2, which comprised 47 % of the total field layer biomass. Characteristic features of the root systems were: high below‐ground/above‐ground ratios, rather low amounts of root biomass, shallow rooting, and relatively thin roots. Hummocks tended to have less roots in the 0–10 cm layer and more roots in the 10–20 cm layer than the hollows. 相似文献
7.
The distribution of fine (<2 mm diameter) and small roots (2–20 mm diameter) was investigated in a chronosequence consisting
of 9-year-old, 26-year-old, 82-year-old and 146-year-old European beech (Fagus sylvatica) stands. A combination of trench wall observations and destructive root sampling was used to establish whether root distribution
and total biomass of fine and small roots varied with stand age. Root density decreased with soil depth in all stands, and
variability appeared to be highest in subsoil horizons, especially where compacted soil layers occurred. Roots clustered in
patches in the top 0–50 cm of the soil or were present as root channels at greater depths. Cluster number, cluster size and
number of root channels were comparable in all stands, and high values of soil exploitation occurred throughout the entire
chronosequence. Overall fine root biomass at depths of 0–120 cm ranged from 7.4 Mg ha−1 to 9.8 Mg ha−1, being highest in the two youngest stands. Small root biomass ranged from 3.6 Mg ha−1 to 13.3 Mg ha−1. Use of trench wall observations combined with destructive root samples reduced the variability of these estimates. These
records showed that variability in fine root distribution depended more on soil depth and edaphic conditions than on stand
age, and suggest that trench wall studies provide a useful tool to improve estimates of fine root biomass. 相似文献
8.
Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) seedlings were grown in containers filled with growth media based on medium-textured sphagnum peat, coarse perlite and fine sand. The seedlings were then planted into fine and coarse sandy soils in 2.2 l pots, which were subjected to two water-content treatments (only one for birch). After the seedlings had grown five weeks in a greenhouse, rooting into the surrounding soil and shoot growth were measured. Addition of perlite and sand to peat medium slightly affected rooting; thus suggesting minor effects on seedling establishment. However, nitrogen concentration of the seedlings varied between growth media and correlated positively with rooting into the soil. The particle size and water content of the soil affected considerably rooting of the seedlings. Seedling height at the time of planting did not affect rooting or shoot growth. The fact that the fewest out-grown roots occurred in the dry fine sandy soil, suggests that dry soil together with high strength and resistance to root penetration reduce rooting and water uptake by container seedlings most and may thus cause water and nutrient stresses to seedlings after outplanting. 相似文献
9.
Influence of ground flora on Fraxinus mandshurica seedling growth on abandoned land and beneath forest canopy 总被引：1，自引：0，他引：1
Jinsong Wang L. Wu Xiuhai Zhao Juan Fan Chunyu Zhang Klaus von Gadow 《European Journal of Forest Research》2013,132(2):313-324
A better understanding of root/shoot interactions influencing seedling growth on abandoned land could yield insight into seedling regeneration and restoration of the abandoned lands. Field work had been conducted for 2 years (2008–2009) to investigate the impacts of neighbouring plants on Manchurian Ash (Fraxinus mandshurica) seedling growth under the canopy of an old secondary forest and on the abandoned land exposed to full solar radiation in North-eastern China. Four different interaction treatments were designed for the study: neither shoot nor root interaction, shoot interaction only, root interaction only, and both shoot and root interaction. The presence of either the shoots or roots of neighbours had a competitive effect, reducing the growth of the target seedlings at each site. The total competitive effect of roots and shoots of neighbouring plants was significantly less than the sum of root and shoot competition separately on the abandoned land, but this difference was not significant beneath the forest canopy. Root competition was more restraining than shoot competition on the abandoned land. Target seedlings adjusted their root morphology and growth rates in response to the competitive effects from different parts of the neighbouring plants. Our results indicated that the root:shoot ratios of the target seedlings at the end of the experiment were affected by neither initial tree size nor the competition from either above- or belowground at either site. The results also highlight the importance of reducing root competition in boosting seedling regeneration and forest rehabilitation on the abandoned land. 相似文献
10.
Paulo Csar Teixeira Roberto Ferreira Novais Nairam Flix Barros Júlio Csar Lima Neves Jos Luiz Teixeira 《Forest Ecology and Management》2002,160(1-3):263-271
Lack of information concerning root growth of trees limits our knowledge of plant development and fertilizer response. The objective of this work was to study root growth dynamics of an E. urophylla forest after harvesting and the supply of nutrients from the roots and the soil to the new sprouts originating from the stumps. About 7-year-old eucalypt trees were felled and the sprouts and roots were sampled at 0, 60, 120, 180, 240, 330 days after harvesting. The roots were separated into fine roots (<1 mm), medium roots (1–3 mm), coarse roots (>3 mm), and taproot. Nutrient supply to sprouts from the old roots and the soil was calculated based on the change in nutrient content of the roots with time and accumulation of nutrients in the sprouts. Fine, medium and coarse root biomass increased with time after harvesting. However, the increase was more pronounced with fine roots. Between harvesting and day 60 of the new growth, all nutrients allocated to the sprouts, excluding potassium, were supplied by the soil. K was the nutrient most dependent on root reserves for the initial growth of sprouts. The contribution of the old roots to N, P, Ca, and Mg accumulation in the sprouts increased between day 60 and 120. At 330 days after harvesting, about 9.2, 23.9, and 12.6% of the N, K, and Mg, respectively, that had accumulated in the sprouts were supplied by the roots, while all P and Ca were supplied by the soil. 相似文献
11.
Alan E. Harvey Deborah S. Page-Dumroese Martin F. Jurgensen Russell T. Graham Jonalea R. Tonn 《New Forests》1996,11(3):255-270
This report documents impacts from manipulations of native forest soils and competing vegetation on development and ectomycorrhizal formation of outplanted western white pine and Douglas-fir in the Inland Northwest. Treatments were: 1) mounding surface horizons with competition left in place, 2) mounding surface horizons with subsequent physical or chemical control of competing vegetation, 3) scalping for control of competing vegetation, and 4) a control, or no postharvest disturbance. Treatments were applied on a low-altitude, relatively harsh site and on a higher altitude, more moderate site. Wich established seedlings, mounding with no competition control generally produced small seedlings (5–15g; both species) with low numbers of ectomycorrhizal short roots (21). Mounding with competition control produced large seedlings (20–48g) with moderate numbers of short roots (25). Scalping produced small seedlings (8–16g) with high numbers of short roots (41). The control also produced small seedlings (8–13g) but with a moderate number of short roots (27). Douglas-fir produced more short roots on the harsh than the moderate site. Western white pine produced high root to shoot ratios (above 0.60) in the mound with competition on the harsh site. Douglas-fir produced very high root to shoot ratios (above 1.0) in both the mound with no competition of the harsh site and in the mound with competition of the moderate site. Throughout, western white pine produced more ectomycorrhizae more rapidly than Douglas-fir. Ectomycorrhizal development and root and shoot weight of both conifers were adversely affected by competing vegetation. 相似文献
12.
Different management practices are commonly applied to increase pasture yield of Mediterranean open woodlands, but the consequences of increasing competition for soil resources with these practices on tree recruitment are still unknown. In a greenhouse study, belowground competition of Quercus suber L. seedlings growing together with natural (OakNP) or improved pasture (OakIP) was evaluated, and their root systems compared with those of seedlings growing in bare soil (OakBS). Two watering levels and two regimes of P2O5 fertilisation were also tested. Because of competition, the OakIP seedlings had their fine root mass density, coarse root length, and shoot mass reduced by up to 40, 36, and 39%, respectively, when compared to OakNP seedlings. OakNP and OakBS seedlings showed similar average root density parameters and shoot mass values, indicating that Q. suber seedlings growing with natural pasture is a low competitive system. High availability of water and phosphorus did not mitigate the strength of competition between herbaceous plants and oak seedlings, and favoured the pasture to the detriment of the trees. Our findings suggest that P2O5 fertilisation and irrigation practices performed to improve herbaceous productivity will negatively influence recruitment of Q. suber seedlings. 相似文献
13.
【目的】探究‘凤丹’牡丹种苗的最适移栽时期,为其丰产栽培技术提供参考。【方法】以3年生‘凤丹’牡丹实生种苗为试验材料,设置8个移栽时期,通过大田对比试验,分析移栽后根系活力、叶片光合性能及生物量的变化;采用主成分分析和综合评价的方法对不同移栽时期的成苗效果进行评价。【结果】移栽期可能通过移栽时气温、土壤温度和移栽后土壤积温等环境因素影响‘凤丹’牡丹新根和植株的发育,适时移栽显著促进牡丹苗体的生长发育。在不同的移栽时期,‘凤丹’牡丹植株生长期间的新根总数、木质化新根数、根系活力、叶面积、叶片SPAD值、净光合速率、枝条粗度、根生物量、枝条生物量、总生物量和壮苗指数均有一定差异,而枝条长度和根冠比没有显著差异。9月29日与11月28日移栽相比,单株木质化新根质量和叶面积分别增加了90.26%和51.22%,根系活力和净光合作用速率分别提高了93.53%和60.98%,单株生物量增加了46.00%。经通径分析、主成分分析和综合评价表明:9月29日移栽的‘凤丹’牡丹成苗效果最好。【结论】本研究依据植株生物量、壮苗指数与移栽期气象环境要素的依赖关系,明确9月中旬至10月下旬,日均气温15~20℃气侯条件,是‘凤丹’牡丹的最适移栽期。 相似文献
14.
Seedlings of Pinus pinea L. growing in plastic containers were treated with seaweed concentrate (SWC). Different concentrations of SWC were applied, 0 to 3 times, to the roots or shoots of the seedlings. Shoot application increased plant weight mainly by increasing shoot growth. This was manifested as increased shoot length and weight and a decrease in the root/shoot ratio. Root drenches did not change the total plant weight but it accelerated root growth and increased lateral root dry weight. Root growth capacity (RGC) tests for both shoot and root applications indicated an increase in root length and some increases in root number when applied as a root drench. This study indicates that root application of SWC improved seedling quality and increased the ability of seedlings to survive transplanting into pots.Abbreviations GC-MS
Gas Chromatography-Mass Spectrometry
- RGC
root growth capacity
- SWC
seaweed concentrate 相似文献
15.
D. S. Thomas 《New Forests》2009,38(3):245-259
Forestry requires low mortality of transplanted seedlings. Mortality shortly after planting is often associated with inadequate
hydration of transplants. Seedlings can be hardened to the drought conditions they may experience after transplanting by exposing
them to controlled drought conditions in the nursery. Eucalyptus pilularis Sm. seedlings were drought hardened by providing nil (severe treatment) or half (mild treatment) the daily irrigation routinely
received (control treatment) for up to two non-consecutive days per week during the last 4 weeks of growth in the nursery.
Drought hardening reduced stem diameter, seedling leaf area, leaf area per root biomass and seedling quality measured by the
Dickson quality index, but increased root:shoot ratio. Hardened seedlings had lower stomatal conductance and leaf water potential
on the days they received less irrigation that the control treatment. Hardened seedlings had greater stomatal conductance
and were less water stressed than seedlings experiencing drought for the first time indicating hardened seedlings had adjusted
physiologically to drought. Survival after transplanting in the controlled drought environment in a glasshouse was enhanced
by the hardening treatments. Non hardened seedlings that had had their upper leaves manually removed immediately prior to
transplanting to reduce leaf area (top-clipped) had similar survival to hardened seedlings. Stomatal conductance and leaf
water potential after transplanting were higher in hardened and top-clipped seedlings than unhardened control seedlings or
vegetative cuttings. Survival in the field trial was over 95% for all treatments, possibly as rain fell within 4 days of planting
and follow-up rain occurred in the subsequent weeks. Neither the hardened or top-clipped seedlings planted in the field trial
had reduced growth, increased propensity to form double leaders or worse stem form than control seedlings when measured at
age 3 years. 相似文献
16.
Roots of 2-year-old black spruce seedlings (Picea mariana [Mill.] B.S.P.) were exposed to freezing temperatures to destroy 20, 40, 60, and 80% of the root systems. For comparison, other root systems were pruned to eliminate the same proportions of roots. Treated and control seedlings were planted in spring 1992 at Forêt Montmorency (the Université Laval forest research station, 50 km north of Quebec City). From 1992 to 1995, survival, shoot height and stem diameter were measured. Mortality mainly occurred in 1993, the year after planting; pruned seedlings showed practically no mortality while seedlings with 20, 40, 60, and 80% of their root systems affected by frost showed mortality rates of 0, 6, 17, and 24%, respectively. Shoot height and stem diameter decreased with increasing root damage when compared to controls. After three years on the planting site, shoot height was reduced by 2, 8, 11, and 18% while stem diameter was reduced by 4, 21, 25, and 24% for 20, 40, 60, and 80% frost damage, respectively. For pruned seedlings, shoot height was increased by 3% at 20% damage and was decreased by 1, 3, and 13% for 40, 60, and 80% root damage while stem diameter was reduced by 1, 4, 8, 19% for 20, 40, 60, and 80% respectively. Use of damaged seedlings on the planting sites should be limited in order to reduce the cost of replacement planting. 相似文献
17.
杉苗移植成活力初步研究 总被引：1，自引：0，他引：1
通过对杉苗出圃定植过程苗木失水、剪根与发根关系的试验分析表明：杉苗水分是定植成活的要素；苗根中１－２ｍｍ粗根对发根最重要；细根失水较快，长途运输杉苗宜剪去部分细根；杉苗失水率在３５％以下可以发根。 相似文献
18.
Stem cuttings of Eucalyptus globulus are used within tree improvement programs and for mass deployment. To be successful, cuttings must perform as well or better than seedlings. The root systems of cuttings are fundamentally different from those of seedlings. If these differences influence growth, the differences and their consequences must be identified and the propagation system manipulated to improve performance of the propagules.Cuttings are only a viable alternative to seedlings as planting stock if the method of propagation does not affect their growth and development adversely. Full-sibling cuttings and seedlings of Eucalyptus globulus were compared under controlled environmental conditions to minimise extraneous sources of variation, and to establish whether changes in growth or development were induced by propagation. On three occasions over a period of eight weeks root-collar diameter, shoot height, leaf and stem weight, shoot/root ratios and root system morphology were measured on cuttings and seedlings. Seedlings were taller than cuttings throughout the experiment, but both plant types had similar height growth rates. Diameter growth rates were lower in cuttings than seedlings, and there were differences in both height and diameter growth rates between families. Root system configuration differed between the plant types. Seedlings had strongly gravitropic tap-roots, with two types of primary roots from which secondary roots emerged. Cuttings had no tap roots, and the main structural components of their root systems were adventitious roots formed during propagation. Cuttings did not develop further structural roots during the experiment, whereas seedlings continued to develop primary roots. Individual primary roots of cuttings were longer and had larger mid-point diameters than those of seedlings, but the total length of primary roots was greater in seedlings. Seedlings also had a greater number and total length of secondary roots. Shoot/root ratios, calculated from a range of functional measures, were higher in cuttings than seedlings. 相似文献
19.
The effect of cutting the tap root on shoot growth and development of lateral roots was observed in seedling Quercus robur L. growing in PVC tubes containing peat and perlite. Cutting the tap root had little effect on shoot height and leaf number although some treatments caused a significant but slight reduction in shoot dry weight and number of branches. Total root dry weight was similar in control and treated plants but distributed differently between the types of root present. The tap root always formed the largest part of the total root dry weight. In control plants most lateral root dry weight was in roots < 1 mm diameter whereas in treated plants most dry weight was in roots > 1 mm diameter. Development of the root system following root cutting was similar for all treatments: new long laterals > 1 mm diameter with relatively few branches, that formed replacement tap roots, developed near the cut end of the original tap root. Fine laterals (< 1 mm diameter) near the root collar continued to grow forming highly branched systems. 相似文献