磷对杉木不同家系苗木生长影响试验研究

对２０个杉木不同家系的苗木进行磷素营养要求试验，１年生苗木盆栽试验结果表明：杉木不同家系苗木对磷素营养反应敏感，２ｇ磷处理使苗高、地径分别增益３．７％—９６．５％、７．４％—６１．１％，４ｇ磷处理使苗高、地径分别增益２．１％—８３．１％、３．７％—５７．９％，杉木苗期需要磷素营养。三明３８、三明６７、三明４８、三明５８四个家系生长比较理想，在０ｇ磷处理下，１年生平均苗高１３．０—１５．９９ｃｍ，平均地径０．２３—０．２７ｃｍ，这４个家系具有更大的生长潜力，２０个家系间对磷素营养要求方面不存在显著的差异。     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica III. Cycles of organic matter and nutrients

Models for cycles for organic matter and nutrients element (N, P, K, Ca and Mg) are presented for the agroforestry systems of cacao (Theobroma cacao) withCordia alliodora orErythrina poeppigiana in Turrialba, Costa Rica.For the models, system reserves (soil, humus, vegetation divided into leaves, branches, stems, fine roots, fruits) and transference between compartments (production and decomposition of litter residues) inputs (fertilizer, rainfall) and outputs (harvests) of the system are considered.The implications of the models are discussed in detail.Aspects of net primary production in the systems studied are considered.N fixation is calculated on the basis of balances. Analysis of soil water showed high variations that coincided with rainfall patterns and pruning of theE. poeppigiana.For part I see Vol. 4, No. 3, 1986 For part II see this issueAgroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesellschaft für Technische Zusammenarbeit), Turrialba, Costa Rica     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica II. Cacao and wood production,litter production and decomposition

During 7 years (1979–1985) cacao harvests (beans and husks) have been recorded for the agroforestry systems ofTheobroma cacao underCordia alliodora andErythrina poeppigiana shade trees. The mean oven dry cacao yields were 626 and 712 kg.ha⁻¹.a⁻¹ cocoa beans underC. alliodora andE. poeppigiana respectively. Harvests have gradually increased over the years and the plantation has now reached maturity. Annual extraction of N, P, K, Ca and Mg in fruits, which is relatively small, was calculated on the basis of chemical analyses. The following average values were found (kg.ha⁻¹.a⁻¹): At the age of 8 years, theC. alliodora trees have reached 26.7 cm diameter (DBH) and 14.0 m in height. Mean annual growth (from age 5 to 7) is 14.6 m³.ha⁻¹.a⁻¹. Natural plant residue production has been measured for 4 years (Nov. 1981–Oct. 1985). UnderE. poeppigiana it has reached a value of 8.91 t.ha⁻¹.a⁻¹ and underC. alliodora 7.07 t.ha⁻¹.a⁻¹. The shade trees have contributed 57 and 47% respectively. Transference and decomposition rates are high and important in the nutrient cycles. The nutrient content of the litter was analysed and corresponding average yearly transfers were (kg.ha⁻¹.a⁻¹): For part I see Vol. 4, No. 3, 1986. Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesselschaft für Technische Zusammenarbeit), Turrialba, Costa Rica     

不同磷效率马褂木种源对磷胁迫的生理反应

低磷胁迫条件下,植物将以一系列形态、生理、生化和遗传机制主动适应胁迫环境,包括根系对生长环境中难溶性磷的活化,有效吸收、运转、分配及再利用等.植物通过改变对养分的需求以维持自身代谢和改变根系形态、生理机能来增强自身活化和吸收养分的强度[1].具有较高的磷素吸收能力是植物耐低磷胁迫的基础[2],研究低磷胁迫条件下植物的生理生化特性对揭示耐低磷机理具有重要意义.以往在农作物方面有过一些研究[3～6],但在林木方面研究不多.本试验以不同磷效率的马褂木(Liriodendron chinense (Hemsl.)Sarg.)6个种源为材料,试图研究低磷营养胁迫下马褂木种源在膜脂过氧化、可溶性蛋白含量、叶绿素含量及酸性磷酸酶活性等方面的差异及与磷效率的关系,为优良耐低磷马褂木种源的选育提供理论依据.     

Tracer methods to assess nutrient uptake distribution in multistrata agroforestry systems

Separate assessment of nutrient uptake by individual plants in mixed cropping with trees is impossible without tracer techniques. The different ¹⁵N-to-¹⁴N isotope ratio of atmospheric and soil N can be used to study the contribution of biologically fixed N to the nutrition of associated trees. In most cases, the assessment of nutrient uptake distribution is an appropriate way of evaluating how to improve the transfer of biologically fixed N. Radioisotopes (e.g., ³²P), stable isotopes (e.g., ¹⁵N) and rare elements (e.g., Sr) can be used to determine relative root activity distribution by applying the tracer to different soil depths or distances from trees. A broadcast application of the tracer instead of point application makes it possibe to calculate uptake values per unit area. The direct determination of nutrient pathways with such robust experiments offers considerable advantages for improving nutrient use efficiency and complementarity in multistrata agroforestry systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica

The agroforestry systems of cacao (Theobroma cacao) under laurel (Cordia alliodora) and cacao under poro (Erythrina poeppigiana) were studied at CATIE, Turrialba, Costa Rica. An inventory was taken of the organic matter and nutrients (N, P, K, Ca, and Mg) separating the species into their compartments (leaves, branches, trunks and roots). Studies of the litter and of the mineral soil (0–45 cm) yielded these results: Patterns of nutrient accumulation are discussed in relation to the characteristics of these agroforestry systems.     

Estimated stocks of organic carbon in mangrove roots and sediments in Hinchinbrook Channel,Australia

Aboveground and belowground root biomasses (Babove and Broot) were measured for young, isolated Rhizophorastylosa on Iriomote Island, Japan. The relationship between these two parameters was significant and given as the equation, Broot(g dry weight) = 0.394 × Babove(g dry weight) – 485 (r = 0.986). Multiple regression analyses also revealed good correlation between diameter and biomass of prop roots (Dprop and Bprop) and between prop root and root biomasses. Consequently, root biomass could be estimated from the measurements of diameter and biomass of prop roots using the multiple regression equation, Broot(g dry weight) = 80.0 ×Dprop(cm) + 0.86 ×Bprop (g dry weight) – 251. The relationship between DBH (diameter at breast height) and prop root biomass was also adequately described using an allometric equation.In Hinchinbrook Channel, Australia, redox potential (measured as Eh) and organic carbon stocks in the top 5cm of mangrove sediments were measured along a 600m transect from the frequently inundated, Rhizophora dominated zone on the creek edge, towards higher grounds, where Ceriops spp. became increasingly dominant. Eh values were about –60mV near the creek edge and increased to 260mV on higher grounds. Organic carbon stocks showed an opposite trend to Eh, with the values decreasing from about 360tCha–1 to 160tCha–1. At 18 sites, representing six different habitats, organic carbon stocks were also measured along with the DBH of mangrove trees. DBH was converted into aboveground biomass and then into root biomass using the equations obtained in the study on Iriomote Island. The average organic carbon stocks in the top 50 cm of sediments, aboveground biomass and root biomass were 296tCha–1, 123 tCha–1 and 52 tCha–1, respectively, and accounted for 64%, 25% and 11% of the total organic carbon stock.     

氮磷钾对绿玉菊生长的影响

采用水培方式,探讨不同浓度水平氮、磷、钾对绿玉菊生长的影响。分析了不同浓度氮、磷、钾处理下绿玉菊的株长、根长、叶绿素含量、丙二醛含量的关系。结果表明绿玉菊的株长和叶绿素含量随氮肥浓度的增加而增长;处理5(含氮7.5mmol.L-1,含磷0.2mmol.L-1,含钾3mmol.L-1)最符合绿玉菊水培生长要求。     

磷素环境与马褂木种源的生长和干物质积累

自然土壤中有效磷含量很低,难以满足植物最佳生长的需要。据统计,在全世界13·19亿hm2的耕地中约有43%缺磷,而我国耕地则有2/3缺磷(何绪生等,1998)。我国南方地区高温多雨,富铝化作用明显,多数土壤呈酸性或强酸性,磷素固定强烈,土壤有效磷含量仅在1~2mg·kg-1(邱燕等,2003)。虽然施用磷肥的效果显著,但其利用率一般不超过10%,多为土壤固定并转变成植物较难吸收的Ca-P、Fe-P和Al-P等(熊毅,1997)。鉴于植物具有将土壤难溶态磷转化为有效态磷并加以吸收利用的能力,通过选育磷高效利用的植物品种来开发土壤中难溶态的磷素资源,可减小对施用磷…     

加杨插条苗对氮磷反应的研究

加杨插条苗对培养液中氮磷营养水平反应敏感,在不同营养条件下,苗木对氮磷钾营养元素吸收、体内氮磷比值(N/P)、水分代谢和蛋白质合成作用等,有不同反应,因而幼苗生长状况表现出较大差异。试验研究结果表明,培养液中氮200ppm、磷60ppm时,加杨插条苗生理指标反应较好,幼苗长势旺盛。