共查询到20条相似文献，搜索用时 296 毫秒
1.
针对海南木麻黄人工林出现无性系品种单一,生产力退化,防护效能衰退等问题,通过选用63个木麻黄优良无性系为试验材料,并进行7年的试验观测,筛选出适应海南不同地区的优良品种。33号、28号、17号、14号、4号、21号和34号等7个无性系具有较强的抗风与抗涝性,经强台风的袭击后仍保持95%的保存率;而1号、53号、54号、41号和10号等5个无性系具有较强的耐高温和耐旱性,在西部典型的干旱地区,保存率为85%以上;21号、34号和17号等3个无性系较为适合海南东部地区种植的优良无性系,7年生综合评价指标平均每亩蓄积量达16.3 m3～17.4m3;西部干旱地区优良无性系为41号、38号;北部砖红壤地区的优良无性系为9号、3号、36号、38号。 相似文献
2.
3.
为明确不同施肥处理对平榛幼苗生长的影响，以平榛幼苗为研究对象，设计9个不同施肥组合，清水为对照，采用方差分析、多重比较等方法，对不同施肥处理的平榛幼苗进行统计和分析。结果表明：不同施肥处理对平榛幼苗生长和苗木质量有显著地影响。不同处理的平榛幼苗苗高、地径、叶片数、根数、根长均高于对照，以N2P2K3处理的苗木生长指标最优，苗木质量最好。在平榛育苗过程中要科学合理进行施肥，在生长季选用10 g/m施尿素+10 g/m磷酸二氢钾+15 g/m硫酸钾的氮磷钾配比肥进行叶面喷施，促进苗木生长，提升苗木质量。 相似文献
4.
5.
6.
7.
8.
15个中粒种咖啡无性系的主要农艺性状观测 总被引：1，自引：1，他引：1
对15个中粒种咖啡无性系的主要农艺性状进行观测和综合评价,筛选出24-2号、兴28、兴29、26号、6号、24- 1号等产量高、农艺性状优良的无性系,建议生产上推广种植。 相似文献
9.
分别以国内美洲黑杨优良无性系228—379为母本,进行天然杂交育种;以国外引进的美洲黑杨优良无性系PE-3—71、PE-19—66、S307—26为父本,I-72、I-69杨为母本,进行人工杂交育种。通过对杂种的苗期选择、无性系测定、无性系基因型与环境互作的区域化试验,从生长量、形质指标、生理生化指标、木材材性、环境适应性、抗逆性、胶合板制作与制浆造纸性能等方面,采用单性状评价、多性状综合选择的方法,选育出适宜培育杨树胶合板材和纸浆材的优良新品种—鲁林1号、鲁林2号、鲁林3号杨。 相似文献
10.
11.
为进一步选择伊犁州适生杨树无性系,采用随机区组试验,对8个杨树无性系1年生扦插苗进行苗高和地径的生长节律研究。结果表明:各无性系苗高和地径生长均为“S”形生长曲线,各无性系之间差异不显著;171、LX-1和TL-3的苗高年生长量均高于对照,分别为362.90、305.79和303.94 cm,较对照增加21.27%、2.19%和1.56%,TL-3和LX-1达到了显著水平,171达到了极显著水平;171、DX-08-8和TL-3的地径年生长量均高于对照,分别为2.26、1.93和1.92 cm,较对照增加36.90%、16.73%和16.33%,均达到极显著水平。无性系171和TL-3苗期在本地表现出较好的适应性,1年生苗年生长量均优于本地良种日本白杨。 相似文献
12.
The use of municipal sewage sludge as a fertiliser could be a more adequate means of disposal of this residue than its transport to the dump. The objective of this experiment was to evaluate the effects of different doses of sludge and sowing a mixture of cocksfoot (Dactylis glomerata) and clover (Trifolium repens) on pasture production, botanical composition of the pasture, forage quality, and changes in soil chemical properties. Treatments applied were: (1) no fertilisation (L0), (2) fertilisation with 26 Mg ha–1 of sewage sludge with no sowing (L40), (3) fertilisation with 26 Mg ha–1 of sewage sludge and sowing with 25 kg of Dactylis glomerata L. cv Artabro (Dg) and 3 kg Trifolium repens cv Huia per hectare and (4) 52 Mg ha–1 of sewage sludge with no herbage sowing (L80). Plots were established in a silvopastoral system with Pinus radiata D. Don at a density of 1666 trees ha–1 (3 × 2 m). The improvement of soil fertility due to organic fertiliser application and the use of Dactylis glomerata increased the production and quality of pasture as well as reduced the risk of fire and erosion, as grasses dominated shrubs. Fertilisation with sewage sludge in soils of acid origin increased the concentration of copper in the pasture and, if cocksfoot was not sown, the levels of this element exceeded the maximum tolerable dietary levels for sheep. On the other hand, fertilisation also increased the levels of zinc in pasture, but values were not above toxic limits for sheep, horses and cattle.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
13.
Theee trials to evaluat the potential of alley cropping in maize production on the low fertility, acidic soils in Northern Zambia are described. Leucaena leucocephala, Gliricidia sepium, Sesbania sesban, Albizia falcataria, Fleminga congesta, and Cassia spectabilis, were grown in alley crops with hybrid maize and soybean. All trials received recommended rates of P and K fertiliser; N fertiliser was applied at three rates as a subplot treatment. One trial received lime before establishment.Only in the limed trial was there a significant improvement in maize yields through alley cropping; when no N fertiliser was applied, incorporation of Leucaena leucocephala prunings resulted in an increase of up to 95% in yields, with a smaller improvement being produced by Flemingia congesta. There was a significant correlation between the quantity of prunings biomass applied and the proportional increase in maize yields over the control treatment. It is suggested that the lack of effect of most of the tree species on crop yields was due to low biomass production.An economic analysis showed that alley cropping with limed Leucaena was only profitable when fertiliser costs were high in relation to maize prices. However, lime is both expensive and difficult to obtain and transport for most small scale farmers in the region, and is therefore not a practical recommendation. It is suggested that future alley cropping research should focus on screening a wider range of tree species, including other species of Leucaena, for acid tolerance and higher biomass production. 相似文献
14.
This paper reports for progress of research onGliricidia sepium conducted by the Humid Zone Programme (HZP) of the International Livestock Centre for Africa (ILCA) at Ibadan in Southwest
Nigeria in the period 1982–1986. It examines the biological characteristics of the species, with respect to growth, flowering
and seed production, and analyses its potential for improving crop production (through soil fertility maintenance) and livestock
production (through production of improved fodder). Integration ofGliricidia into cropping systems is necessary for optimum realisation of its crop improvement quality. The alley farming system is presented
in the paper as one means of achieving sustainability in crop production through integration of trees, such asGliricidia, into cropping systems. The use ofGliricidia in Intensive Feed Gardens, for production of leguminous fodder is also described as an alternative production system. The
paper finally reports on experiences with local farmers in on-farm research and development for the integration ofGliricidia andLeucaena into local farming systems. It ends with a suggestion for more research, targetted specifically at improvement of the species
and its utilisation. 相似文献
15.
This paper reports for progress of research onGliricidia sepium conducted by the Humid Zone Programme (HZP) of the International Livestock Centre for Africa (ILCA) at Ibadan in Southwest Nigeria in the period 1982–1986. It examines the biological characteristics of the species, with respect to growth, flowering and seed production, and analyses its potential for improving crop production (through soil fertility maintenance) and livestock production (through production of improved fodder). Integration ofGliricidia into cropping systems is necessary for optimum realisation of its crop improvement quality. The alley farming system is presented in the paper as one means of achieving sustainability in crop production through integration of trees, such asGliricidia, into cropping systems. The use ofGliricidia in Intensive Feed Gardens, for production of leguminous fodder is also described as an alternative production system. The paper finally reports on experiences with local farmers in on-farm research and development for the integration ofGliricidia andLeucaena into local farming systems. It ends with a suggestion for more research, targetted specifically at improvement of the species and its utilisation. 相似文献
16.
Gudeta Weldesemayat Sileshi Elias Kuntashula Patrick Matakala Philip O. Nkunika 《Agroforestry Systems》2008,72(2):87-101
Pest management research within the context of agroforestry is in its infancy, and it is often difficult to say when a particular
pest justifies investment in research to establish facts. Understanding the potentials and drawbacks of farmers’ indigenous
ecological knowledge (ethnoecology) may form the basis for constructive collaboration between farmers, agroforestry scientists
and extension staff. Therefore, the objectives of the study were to (1) assess farmers’ knowledge and perceptions of pests,
(2) prioritize pest problems that limit tree planting and maize production based on farmers’ own criteria and (3) to identify
farmers’ indigenous pest management practices for priority pests. Data were collected using community meetings, individual
interviews and direct observation by the first author. The farmers involved in this study in eastern Zambia had over ten years
of experience, while most of the farmers in Mozambique and parts of southern Malawi were new to agroforestry. Farmers perceived
insects as the major causes of tree mortality, followed by drought, bush fires and browsing by livestock. Among the biological
constraints to maize production, insects (particularly termites and stalk bores) and weeds (particularly Striga asiatica) were more important in farmers’ minds than crop diseases. Fundamentally, the farmers’ perception of the causes of tree mortality
and crop pests agreed with researchers’ perceptions and the literature. Both termite and witch weed problems were associated
with low soil quality, and farmers use various indigenous control practices to control these pests. Some farmers did not know
the causes of tree mortality, and hence do not take action. Farmer’s perception of tree mortality was found to be a function
of operator-specific variables such as sex, level of education and years of experience with tree species. 相似文献
17.
Ethane production was evaluated as a method for assessing freeze damage to loblolly pine (Pinus taeda L.) seedlings by comparing it to the widely used electrolyte leakage method. Paired measurements, first ethane production and then electrolyte leakage, were conducted on the pooled needle samples at temperatures between 0° and –12°C. Ethane production rates increased in a linear fashion with decreasing temperatures between 0° and –12°C for both Virginia Coastal Plain (R2=0.80) and Marion County, Florida (R2=0.87) seed sources. The Florida seedlings were consistently 2° to 4°C higher than the Virginia seedlings at a given ethane level. Electrolyte leakage expressed as Index of Injury initially increased with decreasing temperatures, but then leveled off at or decreased below –8°C. The log-log linear regression of ethane production against Index of Injury indicated good correspondence for both seed sources (Virginia – R2=0.81; Florida – R2=0.91). Ethane production appears more rapid and to require less sampling than does electrolyte leakage while producing comparable results to the electrolyte leakage method. 相似文献
18.
Temporal variation of leaf area index (LAI) in two young Norway spruce stands with different densities was monitored during
eight consecutive growing seasons (1998–2005). We focused on: (1) LAI dynamics and above-ground mass production of both spruce
stands and their comparison, (2) leaf area duration (LADU), crop production index (CPI) and leaf area efficiency (LAE) evaluation,
and (3) thinning impact on the above-mentioned parameters. Also, we tried to deduce the most effective LAI value for the Norway
spruce forest investigated. The LAI values of both spruce stands showed a typical seasonal course. To describe the LAI dynamics
of the stand, we recommend taking LAI measurements within short time intervals at the time of budding and needle expansion
growth (i.e., in early spring) and close to the LAI peak, when the twig growth has been completed. The reason was that after
reaching the seasonal maximum, no significant differences between subsequently obtained values were found in the following
2 months. Therefore, we recommend this period for the estimation of seasonally representative LAI values, enabling the comparison
of various spruce stands. The maximum hemi-surface LAI value reached 12.4. Based on our results, the most effective LAI values
for maximum above-ground biomass production were within the range of 10–11. We found an LAI over these values to be less effective
for additional production of above-ground biomass. In forest practice, thinning intensity is mostly described by percentage
of stocking reduction. We want to show that not only thinning intensity, but also the type of thinning is important information.
The type of thinning significantly affected the stand above-ground biomass increment, canopy openness, stand LAI and LAI efficiency.
The stimulating effect of high-type thinning was observed; the LAE as well as the CPI increased. Low-type thinning had no
such effects on LAE increments compared to the high-type thinning with similar intensity.
相似文献
19.
The occurrence of heart splitting during the crosscutting of logs was discussed in relation to the released strain on Eucalyptus spp. logs. The strains released in the longitudinal and tangential directions were measured by the strain-gauge method and were correlated with the length of the heart split measured on the same logs. There were differences in the longitudinal strain; however, no significant correlation was found with the diameter that could be converted to a mean annual increment (i.e., a relation with the growth rate). The initial splits expand with the time after felling. The longer the initial split, the longer is the length 1 week after felling. The split length was significantly smaller at the butt end of the first log of every tree than at the other end, but there were no significant differences between the split length at the top of the first logs and at either end of the second logs, although there were differences among individual trees. The length of the heart split correlated with the released strain near the pith, which was estimated using Kublers equation. The longitudinal released strain measured on the surface of logs is a good indicator of the heart splitting when crosscutting logs.Part of this paper was presented at the 52nd Annual Meeting of the Japan Wood Research Society 相似文献
20.
木材产量是营林工作的终极目标,光合作用是叶绿体利用光合有效辐射将CO_2和H_2O同化为有机物质生产过程,探寻影响产量宏观指标的微观光合特征值,是杨树无性系育种工作的重要内容。为此,对湘林—90等7个杨树新、老无性系进行苗期光响应曲线测定,将暗呼吸速率等5个光合特征值与其主伐阶段的材积生长量作相关分析和逐步回归。在光合特征值中,暗呼吸速率与光补偿点呈紧密负相关关系;模拟光合作用白昼CO_2净同化总量与10年生材积生长量关系最为紧密,影响最大。按多元线性回归标准回归系数判断,各光合特征值对材积生长影响力的排序为:模拟光合作用白昼CO_2净同化总量光合速率光响应曲线实测值之和暗呼吸速率光补偿点光饱和点时最大光合速率。模拟光合作用白昼CO_2净同化总量或光合速率光响应曲线实测值之和可以作为杨树育种苗期选择的重要指标。 相似文献