马尾松切根育苗技术

马尾松常规育苗苗木主根发达,侧根少,影响造林成活率。采用砂床催芽,芽苗截根定距移栽,８月底或９月初苗期切主根和侧根,抑制主根生长,促进侧根根系发育,提高苗木质量和造林成活率;并节约良种,降低育苗成本,是培育壮苗的主要技术措施。     

湿地松切根育苗及其造林对比试验

通过对湿地松不同切根处理、不同深度切根的育苗及其切根苗造林等试验,探讨幼苗切根对苗木质量、造林成活率及幼林生长的影响。试验表明:湿地松育苗采取芽苗截根移栽,8月底苗期切主根和侧根,切根深度9~11 cm,苗木质量最优,造林成活率可达98.7%,幼林生长各项指标表现最好,并提前郁闭成林,降低成本,经济效益显著。     

黧蒴栲芽苗截根移栽育苗及造林成效研究

为了提高黧蒴栲苗木质量和造林成活率,利用随机区组设计开展了黧蒴栲芽苗截根移栽、截根苗造林对比试验.结果表明：黧蒴栲芽苗截根处理对苗高、主根长、一级侧根数、叶干重、茎枝干重、根器官干重有极显著影响,对苗木地径、一级侧根长度有显著影响.芽苗截根处理后苗木高度增加17.51％、地径增加13.72％.不同剪叶处理方式对黧蒴栲苗木造林成活率有极显著影响,芽苗截根苗造林以剪叶75％效果最好,造林成活率达95.86％,而未剪叶苗造林成活率为57.69％;应用芽苗截根苗造林可提高造林成活率17.0％～24.0％,增加当年树高、地径生长量分别为18.22％、15.44％.     

国外针叶树切根育苗技术

为了克服传统的针叶树育苗中存在的问题，国外的许多国家对切根育苗技术进行了多年的试验，研究表明，切根苗在抗性、造林成活率和幼苗期的生长量等方面好于移植苗。切根苗的育苗密度为每平方米２００～２５０ 株；初次切根时间在土温最适宜苗木根系生长的６～７ 月，切主根长度以８～１２ｃｍ 为好；振荡在切主根后的每３～４ 周进行一次，深度以１５ｃｍ 最好。切侧根７ 月末至８ 月初，通过切根技术可培育出根系发达的优质苗木，解决了留床苗、移植苗中存在的苗木质量差和窝根的弊病。     

湿地松芽苗切根育苗技术

通过芽苗切根移栽技术处理，湿地松一年生苗木质量明显提高：主根长度减少42％，侧根数量增加83％，菌根发达，使造林成活率提高29．3％，当年新梢生长量增加12．4％。处理间比较结果，芽苗切根后保留根长度3cm为最好。     

芽苗切根移植对南酸枣苗木及造林当年生长的影响

在贵州三都进行了芽苗切根移植育苗对南酸枣1年生苗木及造林当年生长效应的研究,结果表明:1)芽苗切根移植育苗能提高苗木单株和群体质量,与常规育苗相比,芽苗切根移植育苗对苗木径生长量的提高、长5cm的侧根数量的增加及地径标准差的降低达极显著水平,对苗木高生长的提高和对高径比值、苗高标准差的降低达显著水平;2)芽苗切根移植苗造林优于常规苗造林,当年生树高、胸径生长差异达极显著水平;3)芽苗切根移植苗的高径生长节律与常规育苗一致,但各个时期的苗木高、径生长速度有差异,主要表现为缓慢生长期比常规育苗慢,快速生长期又比常规育苗快,径生长尤其突出。     

火炬松双截育苗试验观察

火炬松（ＰｉｎｕｓｔａｅｄａＬ．）主根明显且具有深根性。通过截根后，一方面可促使苗木多生侧根，扩大根系吸收面积，提高苗木质量，另一方面，造林时能防止窝根、坐根，提高造林成活率，既能方便操作提高工效，又不增加整地深度。截顶后尚可防止苗期枯梢病流脂等现象     

火炬松,湿地松芽苗截根菌根化育苗技术研究

火炬松，湿地松芽苗截根菌根化育苗，能促进苗木根系的发育，苗木生长好，质量高，可使造林成活率达９８％以上，一级苗出苗率达９５％。     

马尾松条播切根育苗研究

马尾松属深根性用材树种,常规育苗情况下,苗木主根发达,侧根稀少,裸根苗上山造林成活率低。采用切根育苗技术,在8月初切断主根,抑制主根生长,可控制苗木主根徒长和苗木高生长,防止松苗秋天抽梢,促进侧根与须根生物量成倍增加,提高苗木质量和造林成活率。     

火炬松、湿地松芽苗截根菌根化育苗技术研究

火炬松、湿地松芽苗截根菌根化育苗，能促进苗木根系的发育，苗木生长好，质量高，可使造林成活率达９８％以上，一级苗出苗率达９５％。     

Early root morphology of jack pine seedlings grown in different types of container

Abstract

This study compared the effects of container type on early root system morphology of jack pine (Pinus banksiana Lamb.) seedlings to determine impacts of container type on root characteristics that may be important for tree stability. Seedlings were grown for one season in Multipots®, Ventblocks®, Copperblocks®, Starpots® and Jiffy® pellets, and for a second season in sand culture in pots. After the first growing season, roots that had grown between Jiffy plugs were cut using a knife, either “early”, in September, or “late”, in November. Seedlings produced in non-pruning containers, Multipots and Ventblocks, had more vertical structural roots, less even root distribution and high shoot:root mass after a second season. Seedlings grown in pruning containers, Copperblocks, Starpots and Jiffy pellets, had more horizontal structural roots and more evenly distributed roots. Jiffy seedlings had high shoot:root mass after pruning, but ratios decreased to low levels similar to Starpots and Copperblocks after a second season in pots. Early pruning of Jiffy seedlings removed less root mass than late pruning, but total live root mass of early and late pruned seedlings was similar after the potting trial. Pruning containers thus produced structural root forms with more desirable characteristics for tree stability. These characteristics were evident after the first season and persisted after the second season in the potting trial.     

不同断根处理对云南拟单性木兰苗木生长影响的研究

不同断根处理对云南拟单性木兰苗木生长影响的研究结果表明:切断苗木的侧根会对苗龄为5年生的云南拟单性木兰苗木地上部分的生长产生负效应而有利于促进新侧根的萌发,其影响程度与断根的强度有关。其苗木经断根处理后新根萌发较快,50天左右有新的侧根生出,其中以切断云南拟单性木兰大苗的全部侧根于切口喷200 mg.L-1的ABT生根粉的A处理的生根效果最好。断根3个月后每株苗木萌发的新侧根平均数为138.8根,根长≥5 cm的侧根平均数为38.4根,侧根深度达32 cm,最长侧根长度14.4 cm,其苗木的新根萌发已经较为充分,可以出圃种植而能保证有高的成活率。     

Influence of root pruning and cutting interval ofLeucaena hedgerows on performance of alley croppedrabi sorghum

The influence of root pruning and cutting interval ofLeucaena hedgerows on alley croppedrabi sorghum was investigated. Paired (60 cm)Leucaena hedgerows spaced 6.6 m wide were subject to either root pruning, using a country plough during mid-kharif season, or no root pruning. The cutting frequency ofLeucaena hedgerows ranged from one month to six months during therabi cropping period. The effect on soil moisture, crop growth, yield and yield components ofrabi sorghum was examined.Root pruning ofLeucaena hedgerows increased grain and stover yields of the alley croppedrabi sorghum by 33 and 17%, respectively, over root not pruned hedgerows. Similarly, shorter cutting intervals (one and two months) increased crop yields as compared with longer cutting intervals (three and six months). The growth (height and dry matter) of the crop was similarly influenced. Soil moisture studies indicated that the competition between crop and hedgerows was considerably reduced by the root pruning. The results clearly showed that the competition between hedgerows and arable crop can be reduced considerably by root pruning and frequent cutting (at one to two months interval) of the hedgerows.     

杉木起苗后不同处理方法对根生长势的影响

苗木品质的好坏直接影响到造林的成败。在起苗到造林的过程中 ,由于对苗木处理不当 ,苗木地上或地下部分常易遭受损伤 ,或丧失水分 ,从而影响苗木的生活力 ,甚至导致造林失败。研究上述不良现象对苗木品质的影响 ,为起苗到造林过程中的苗木保护提供依据具有重要意义[1] 。1　材料与方法1.1　材料杉木 [Cunninghamia lanceolata( Lamb.) Hook.]1年生播种苗于 1999年 3月 2 0日随机起自安徽省宣州市敬亭山绿化管理处苗圃。起苗后立即按国标 [2 ] 的要求测定苗高、地径、长度≥ 5 cm侧根数等形态指标。测定时 ,发现 3级以下的苗木随时剔除。…     

Root architecture in relation to tree-soil-crop interactions and shoot pruning in agroforestry

Desirable root architecture for trees differs between sequential and simultaneous agroforestry systems. In sequential systems extensive tree root development may enhance nutrient capture and transfer to subsequent crops via organic pools. In simultaneous systems tree root development in the crop root zone leads to competition for resources.Fractal branching models provide relationships between proximal root diameter, close to the tree stem, and total root length or surface area. The main assumption is that a root branching proportionality factor is independent of root diameter. This was tested in a survey of 18 multipurpose trees growing on an acid soil in Lampung (Indonesia). The assumption appeared valid for all trees tested, for stems as well as roots. The proportionality factor showed a larger variability in roots than in stems and the effects of this variabilily should be further investigated. A simple index of tree root shallowness is proposed as indicator of tree root competitiveness, based on superficial roots and stem diameter.Pruning trees is a major way to benefit from tree products and at the same time reduce above-ground competition between trees and crops. It may have negative effects, however, on root distribution and enhance below-ground competition. In an experiment with five tree species, a lower height of stem pruning led to a larger number of superficial roots of smaller diameter, but had no effect on shoot:root ratios or the relative importance of the tap root.     

Effects of oak root pruning in forest nurseries on potential pathogen infections

Despite the general practice of root pruning, little is known about the potential impact of reducing shoot/root systems of oak seedlings in this way on their future susceptibility to pathogens, for example Cylindrocarpon spp., Fusarium spp., Ilyonectria spp., Pythium spp. Phytophthora spp. or Rhizoctonia spp. In this study, root‐pruned and non‐pruned seedlings of Quercus robur grown under controlled conditions were inoculated with aggressive and less‐aggressive pathogens. Results indicated, in contrast to our initial assumption, that pathogens significantly reduced lateral root biomass more in non‐pruned seedlings, the extent of the response depending on the pathogens species. In response to pathogen pressure, pruned seedlings tended to attain a higher dry stem mass fraction, but lower dry leaf mass fraction. Pathogens also suppressed leaf mass in total root dry mass fraction (dry leaf mass/total root dry mass ratio, in g × g^?1) more in pruned than in non‐pruned seedlings. These results suggest differences in growth between non‐pruned and pruned seedlings in response to pathogen stress. In nurseries, root pruning of oak trees may enhance the reduction in leaf mass in lateral roots mass fraction resulting from pathogen infections, which may decrease seedling quality. It is therefore important to ensure a low level of inoculum of soil‐borne pathogens to minimize the risk of seedling infection.     

A review of belowground interactions in agroforestry, focussing on mechanisms and management options

This review summarises current knowledge on root interactions in agroforestry systems, discussing cases from temperate and tropical ecosystems and drawing on experiences from natural plant communities where data from agroforestry systems are lacking. There is an inherent conflict in agroforestry between expected favourable effects of tree root systems, e.g. on soil fertility and nutrient cycling, and competition between tree and crop roots. Root management attempts to optimise root functions and to stimulate facilitative and complementary interactions. It makes use of the plasticity of root systems to respond to environmental factors, including other root systems, with altered growth and physiology. Root management tools include species selection, spacing, nutrient distribution, and shoot pruning, among others. Root distribution determines potential zones of root interactions in the soil, but are also a result of such interactions. Plants tend to avoid excessive root competition both at the root system level and at the single-root level by spatial segregation. As a consequence, associated plant species develop vertically stratified root systems under certain conditions, leading to complementarity in the use of soil resources. Parameters of root competitiveness, such as root length density, mycorrhization and flexibility in response to water and nutrient patches in the soil, have to be considered for predicting the outcome of interspecific root interactions. The patterns of root activity around individual plants differ between species; knowing these may help to avoid excessive competition and unproductive nutrient losses in agroforestry systems through suitable spacing and fertiliser placement. The possibility of alleviating root competition by supplying limiting growth factors is critically assessed. A wide range of physical, chemical and biological interactions occurs not only in spatial agroforestry, but also in rotational systems. In a final part, the reviewed information is applied to different types of agroforestry systems: associations of trees with annual crops; associations of trees with grasses or perennial fodder and cover crops; associations of different tree and shrub species; and improved fallows. This revised version was published online in June 2006 with corrections to the Cover Date.     

Trees on farms in Bangladesh: 5. Growth of top- and root-pruned trees in wetland rice fields and yields of understory crops

Growth of trees and seasonal yields of understory crops were measured over a 5-year period for 4 crops grown under 17 tree species at 8 × 8 m spacing in wetland rice fields. All tree species grew well in rice fields, at rates comparable to their growth in forest plantations. Top and root pruning reduced average tree girths by up to 19% and average tree volumes by up to 41%, depending on intensity of pruning. The crops monitored were Oryza sativa, Triticum aestivum, Corchorus olotorius, and Lens culinaris. Crop yields under the trees averaged 93% of the corresponding yields outside the tree canopy. The most important factor affecting the yields of undercrops was tree size (height and/or girth). Differences among tree species and the interaction with species of undercrops were not significant after controlling for tree size. Pruning of roots and branches significantly improved crop yields under trees by amounts proportional to the intensity of root or top pruning. This revised version was published online in June 2006 with corrections to the Cover Date.     

Above- and below-ground biomass dynamics in a sole cropping and an alley cropping system withGliricidia sepium in the semi-deciduous rainforest zone of West Africa

A considerable amount of data is available about above-ground biomass production and turnover in tropical agroforestry systems, but quantitative information concerning root turnover is lacking. Above- and below-ground biomass dynamics were studied during one year in an alley cropping system withGliricidia sepium and a sole cropping system, on aPlinthic Lixisol in the semi-deciduous rainforest zone of the Côte d'Ivoire. Field crops were maize and groundnut. Live root mass was higher in agroforestry than in sole cropping during most of the study period. This was partly due to increased crop and weed root development and partly to the presence of the hedgerow roots. Fine root production was higher in the alleys and lower under the hedgerows compared to the sole cropping plots. Considering the whole plot area, root production in agroforestry and sole cropping systems was approximatly similar with 1000–1100 kg ha^–1 (dry matter with 45% C) in 0–50 cm depth; about 55% of this root production occured in the top 10 cm. Potential sources of error of the calculation method are discussed on the basis of the compartment flow model. Above-ground biomass production was 11.1 Mg ha^–1 in sole cropping and 13.6 Mg ha^–1 in alley cropping, of which 4.3 Mg ha^–1 were hedgerow prunings. The input of hedgerow root biomass into the soil was limited by the low root mass ofGliricidia as compared to other tree species, and by the decrease of live root mass of hedgerows and associated perennial weeds during the cropping season, presumably as a result of frequent shoot pruning.     

Tree root characteristics as criteria for species selection and systems design in agroforestry

This literature review presents information about the role of tree root systems for the functioning of agroforestry associations and rotations and attempts to identify root-related criteria for the selection of agroforestry tree species and the design of agroforestry systems. Tree roots are expected to enrich soil with organic matter, feed soil biomass, reduce nutrient leaching, recycle nutrients from the subsoil below the crop rooting zone and improve soil physical properties, among other functions. On the other hand, they can depress crop yields in tree-crop associations through root competition. After a brief review of favourable tree root effects in agroforestry, four strategies are discussed as potential solutions to the dilemma of the simultaneous occurrence of desirable and undesirable tree root functions: 1) the selection of tree species with low root competitiveness, eventually supplemented by shoot pruning; 2) the identification of trees with a root distribution complementary to that of the crops; 3) the reduction of tree root length density by trenching or tillage; and 4) the use of agroforestry rotations instead of tree-crop associations. The potential and limitations of these strategies are discussed, and deficits in current understanding of tree root ecology in agroforestry are identified. In addition to the selection of tree species and provenances according to root-related criteria, the development of management techniques that allow the manipulation of tree root systems to maximize benefit and minimize competition are proposed as important tasks for future agroforestry research.