Soil fertility management for reclamation of Imperata grasslands by smallholder agroforestry

Imperata cylindrica grasslands are widely believed to indicate poor soil fertility. Soil fertility improvement may have to be an important component of a reclamation strategy. Data for Sumatra, Indonesia indicate, however, that Imperata occurs on a broad range of soil types and is not confined to the poorest soils. A direct role of Imperata in soil degradation cannot be ascertained. In many instances, however, Imperata soils are low in available P and effective N supply. The use of rock phosphate in combination with erosion control (fertility traps) and legume cover crops can be effective in restoring soil fertility. Case studies for a number of sites in Sumatra have confirmed the practical possibility of reclaiming grasslands for food and tree crops.     

The Imperata grasslands of tropical Asia: area, distribution, and typology

The rehabilitation or intensified use of Imperata grasslands will require a much better understanding of their area, distribution, and characteristics. We generated estimates of the area of Imperata grasslands in tropical Asia, and suggested a typology of Imperata grasslands that may be useful to define the pathways toward appropriate land use intensification. We conclude that the area of Imperata grasslands in Asia is about 35 million ha. This about 4% of the total land area. The countries with the largest area of Imperata grasslands are Indonesia (8.5 million ha) and India (8.0 million ha). Those with the largest proportion of their surface area covered with Imperata are Sri Lanka (23%), the Philippines (17%), and Vietnam (9%). Laos, Thailand, Myanmar, and Bangladesh evidently all have similar proportions of their land area infested with Imperata (about 3 to 4%). Malaysia (< 1%), Cambodia (1%), and the southern part of China (2%) have but a minor proportion of their total land area in Imperata. The species was found widely distributed on the full range of soil orders. It occupied both fertile (e.g. some of the Inceptisols and Andisols) and infertile soils (Ultisols and Oxisols) across a wide range of climates and elevations. Imperata lands fall into four mapping scale-related categories: Mega-grasslands, itmacro-grasslands, meso-grasslands, and micro-grasslands. The mega-grasslands are often referred to as sheet Imperata. They are the large contiguous areas of Imperata that would appear on small-scale maps of say 1:1,000,000. We propose that this basic typology be supplemented with a number of additional components that have a key influence on intensification pathways: land quality, market access, and the source of power for tillage. The typology was applied in a case study of Indonesian villages in the vicinity of Imperata grasslands. We propose an international initiative to map and derive a more complete and uniform picture of the area of the Imperata grasslands. This should include selected studies to understand conditions at the local level. These are critical to build the appreciation of change agents for the indigenous systems of resource exploitation, and how they relate to local needs, values and constraints.     

Early effects of four fast-growing tree species and their planting density on ground vegetation in Imperata grasslands

Ground vegetation development was studied under young plantations of Acacia mangium, A. crassicarpa, Gmelina arborea and Paraserianthes falcataria on an Imperata grassland site in South Kalimantan, Indonesia. The study was based on two separate trials: 1) a species trial with a spacing of 3×3 m, and 2) a spacing trial with progressively decreasing planting density. Both trials were established by use of intensive site preparation, NPK-fertilization, and weeding during the first year. Two years after planting and one year after the last weeding, ground vegetation in the first trial was dominated by Imperata cylindrica grass and shrubs Chromolaena odorata and Clibadium surinamense. In the open area (control) only Imperata grass appeared. Significant differences in total ground vegetation biomass (t ha^–1) between the tree species were as follows: G. arborea (0.2) A. mangium (1.4) A. crassicarpa (4.2) < P. falcataria(9.6) open area (11.4). The early results from the spacing trial showed similar trends in the hardwood species' abilities in Imperata suppression. Highly significant linear relationships existed in regression analysis between the distance between planted trees and the ground vegetation biomass as follows: G. arborea (r²=0.75), A. mangium (r²=0.95), A. crassicarpa (r²=0.97), P. falcataria (r²=0.96). Tree species and their planting density should thus be critically considered in forest plantation establishment on Imperata grasslands, since ground vegetation development plays a decisive role in fire susceptibility, maintenance requirements and the promotion of native species in plantations.     

Fallow enrichment of a traditional slash/mulch system in southern Costa Rica: comparisons of biomass production and crop yield

The slash and mulch system of frijol tapado or covered bean is a pre-hispanic system of bean production found throughout much of Central America. However, land use pressures have forced farmers to shorten the traditional fallow period, thus resulting in decreasing productivity. A potential solution is to enrich the fallow by using leguminous nitrogen-fixing trees. The enriched fallow systems evaluated in this study include both single and mixed species treatments: 1) Erythrina poeppigiana; 2) Calliandra colothrysus; 3) Gliricidia sepium; 4) Inga edulis; 5) Inga edulis and Erythrina poeppigiana; 6) Inga edulis and Calliandra calothrysus; and 7) Inga edulis and Gliricidia sepium. Biomass production of the fallow vegetation is shown to be of greater quality and quantity in all fallow enrichment treatments. However, bean yields did not show a significant response to the fallow enrichment treatments.     

Indigenous livelihood systems in industrial tree-plantation areas in West Kalimantan, Indonesia: Economics and plant-species richness

An integrated tree plantation approach combining indigenous livelihoods and industrial wood production is being implemented in West Kalimantan, Indonesia. In this study the economics of land-use was investigated in villages within the plantation scheme. The effect of three alternative land-use scenarios and costs and benefits of each land-use type were studied using linear programming. The scenarios were based 1) on the current land-use, 2) on the integrated tree plantation system with incentives and government regulations, and 3) on a financially optimal land-use distribution. Additionally, plant species richness in different land-use types was surveyed. The scenarios had different kinds of effects on villages varying in respect to their possibilities for land-use intensification. In villages with extensive land use, establishment of tree plantations without any land-use regulations increased the potential economic return on land, resulting in conversion of natural and man-made semi-natural forests into swidden fields. In villages with more sedentary agriculture, the plantation scheme did not create pressures towards remaining forests even in the case of financially optimal land-use distribution. Incorporation of land-use regulations prevented further deforestation but also decreased households' economic returns. The results also showed that conversion of Imperata grasslands to any other land-use increased species richness. Incentives, restrictions or regulations aiming at conserving natural and semi-natural forests are needed to ensure conservation of biodiversity and long-term improvements in local livelihoods. It can be concluded that tree plantations can be combined with other land-use practices: They can improve the economic return on land without further degradation of the environment.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of cutting position on rooting and shoot growth of two poplar clones

One-year-old shoots from stooling beds of Populus × deltoides Walker and Populus jackii Northwest were collected in late fall to determine the effect of cutting position on rooting and growth of hardwood poplar cuttings. Cuttings with a minimum diameter of 9.0 mm were obtained from basal, middle and distal locations on the poplar shoot. Rooting and shoot growth were assessed in the greenhouse and under field conditions. Walker poplar cuttings collected from basal portions of the shoot and planted in the field had 87.6% rooting and 103.8 cm growth compared to 78.8% and 103.4 cm and 67.6% and 88.8 cm for middle and distal locations respectively. For Northwest rooting and growth under field conditions was 84.4% and 94.7 cm for basal, 78.4% and 90.5 cm for mid and 64.4% and 84.3 cm for distal locations. Rooting in the greenhouse was superior to the field. Walker cuttings had fewer roots and buds per cutting than Northwest, however, growth of Walker in the field was superior.     

Absolute configuration of arylglycerol-β-aryl ethers obtained by asymmetric reduction of the correspondingα-ketonic compound with intactFusarium solani cells

When (±)--oxo-guaiacylglycerol--(vanillic acid) ether (1) is degraded byFusarium solani M-13-1, the-ketone is initially reduced to giveerythro andthreo guaiacylglycerol--(vanillic acid) ethers (2), arylglycerol--aryl ethers, both of which are enantiomerically pure. The absolute configuration in each2 was determined by Mosher's method; the products were converted to,-di-(R)--methoxy--trifluoromethylphenylacetates (MTPA esters) (3) oferythro (-)- andthreo (+)-veratrylglycerol--(methyl vanillate) ethers (3), whose¹H nuclear magnetic resonance (NMR) spectra were examined and compared with those of four di-(R)-MTPA ester (3) diastereomers from chemically synthesizederythro (±)-3 andthreo (±)-3. To assign the- and-MTPA-OCH₃ peaks, the¹H NMR scans of several compounds that have substructures of 3 and their 3,4,5-trimethoxyphenyl analogues were examined. When a racemic alcohol reacts with (R)-MTPA to give a pair of (R)-MTPA ester diastereomers, the value was defined as the absolute value of the difference in the¹H chemical shifts of the peak between the diastereomers. It was found that the values of-MTPA-OCH₃ were larger than those of-MTPA-OCH₃ owing to a shielding effect of the veratryl ring located on the-MTPA-OCH₃, and that the-MTPA-OCH₃ peaks in the 3,4,5-trimethoxyphenyl compounds shifted downfield relative to those in the veratryl compounds. On the basis of the¹h NMR data of (R)-MTPA esters, the absolute configuration of the four chemically prepared diastereomers (3) were determined. The catabolicerythro 3 [fromerythro (-)-3] andthreo 3 [fromthreo (+)-3] were identical to (R, S, R)-erythro 3 and (R, S, S)- threo 3, respectively. An hydrogen species in the fungal reduction would attack the-ketone fromre-face of both (R)-1 and (S)-1, givingerythro (S, R)-2 andthreo (S, S)-2, respectively.Part of this paper was presented at the 33rd Lignin Symposium, Tsukuba, November 1988     

Effect of rhizobial inoculation methods and host plant provenances on nodulation and growth of <Emphasis Type="Italic">Acacia senegal</Emphasis> and <Emphasis Type="Italic">Acacia nilotica</Emphasis>

The purpose of this work was to determine the most efficient methods of inoculation to significantly improve nodulation and growth of Acacia senegal and Acacia nilotica, grown under greenhouse conditions. Our results showed that inoculation using dissolved alginate beads containing rhizobia significantly improved the growth of both acacia species better than the growth of plants in other treatments. The experiment with A. nilotica was conducted in two unsterilised soils from different areas. Plants grown in soil from Bel Air were well-nodulated and showed better growth than plants grown in soil from Sangalkam. However, no difference between these soils was shown between the several methods of inoculation and their effect on the nodulation and growth of plants. An interaction between A. senegal and A. nilotica provenances and the effect of inoculation with rhizobia was also demonstrated. Bel Air provenance of A. senegal, Dahra and RIM provenances of A. nilotica grew best of several provenances tested. These results suggest that (1) it may be possible to improve growth and yield of A. senegal and A. nilotica by careful selection of each symbiotic partner; and (2) nursery-grown seedlings of A. senegal and A. nilotica should be inoculated, just after sowing, with dissolved alginate beads containing a mixture of selected rhizobia. Résumé. Lobject de notre travail était de déterminer la méthodologie dinoculation la plus efficace pour améliorer significativement la nodulation et la croissance dAcacia senegal et dAcacia nilotica poussant dans des conditions de serre. Nos résultats ont montré que linoculation utilisant des billes dalginate dissoutes améliorait significativement la croissance des deux espèces dAcacia par rapport à celle des plantes des autres traitements. Lexpérience avec A. nilotica a été faite dans deux types de sol non stériles. Nous avons observé que les plants poussant dans le sol de Bel Air étaient plus nodulés et mieux développés que ceux poussant dans le sol de Sangalkam. Cependant, aucune différence significative entre les deux sols na été mise en évidence en termes deffet des différentes méthodologies dinoculation sur la nodulation et la croissance des plantes. Il a aussi été démontré lexistence dune interaction entre les provenances dA. senegal et dA. nilotica et leffet de linoculation avec rhizobium. Cest ainsi que les provenances Bel Air dA. senegal, Dahra et RIM dA. nilotica ont le mieux poussé parmi les différentes provenances testées. Lensemble de ces résultats suggèrent: ⁽¹⁾ il devrait être possible daméliorer la croissance et la production dA. senegal et dA. nilotica par une sélection des deux partenaires symbiotiques; ⁽²⁾ Les jeunes plantules dA. senegal et dA. nilotica produites en pépinière devraient être inoculées juste après le semis avec des billes dalginate dissoutes contenant un cocktail de souches sélectionnées.     

A new diterpene dimer from the bark ofChamaecyparis obtusa

This paper describes characterization of diterpenes of the bark of Japanese cypress,Chamaecyparis obtusa (S. and Z.) Endl, without the resinous stem canker to learn the difference between the cypress bark affected with the canker. A diterpene dimer and two diterpenes, 6,12-dihydroxyabieta-8,11,13-trien-7-one and 6,12-dihydroxyabieta-5,8,11, 13-tetraen-7-one, were firstly isolated from Japanese cypress. The dimer, 6-(abieta-6,8,11, 13-tetraenyl-12-oxy)-7-methoxyabieta-8,11,13-trien-12-ol, was a new compound. It is a terpene indicative ofC. obtusa not infected with the resinous stem canker. Five known diterpenes were also isolated.     

Effects of stilbenes from bark of <Emphasis Type="Italic">Picea glehnii</Emphasis> (Sieb. et Zucc) and their related compounds against feeding behaviour of <Emphasis Type="Italic">Reticulitermes speratus</Emphasis> (Kolbe)

The effects of stilbene glucosides and related compounds on termite feeding behavior were investigated using paper disc methods against the subterranean termite Reticulitermes speratus. The stilbene-rich fraction and isorhapontin (3-methoxy-3,4, 5-trihydroxystilbene-3--d-glucoside) from bark extracts of Picea glehnii showed avoidance by termites in choice tests. In the no-choice tests using compounds purified from the stilbene-rich fraction, the largest feeding deterrent effect was observed for piceid (3,4,5-trihydroxystilbene-3--d-glucoside), followed by isorhapontin, and astringin (3,3,4,5-tetrahydroxystilbene-3--d-glucoside), at the concentrations from 0.63 to 2.5µmol/disc. No change in activity was observed at retentions of more than 5.0µmol/disc. When the activities of isorhapontin and its aglycone derivative (isorhapontigenin: 3-methoxy-3,4,5-trihydroxystilbene) were compared with that of taxifolin (3,3,4,5,7-pentahydroxyflavanone) in the no-choice test, the stilbenes exhibited a larger antifeedant potential. Methylation of isorhapontigenin increased its termiticidal activity.Part of this study was presented at the 32nd Annual Meeting of the International Research Group on Wood Preservation, 2001     

Mapping the territory: agroforestry awareness among Washington State land managers

There is growing interest in research to develop potential agroforestry models for temperate climates. In Washington State, recent studies and anecdotal information suggest that agroforestry is already employed by land managers, and if so, this experience should inform future research efforts. Because this population is not well defined, a mail survey was designed to: 1) Assess Washington land manager awareness of agroforestry, 2) assess perceptions of agroforestry as a land management tool, 3) assess the perceived potential opportunities or obstacles for land managers to practice agroforestry, and 4) identify landowner groups believed to be practicing agroforestry in Washington State.Three groups of land managers were surveyed: employees of the Soil Conservation Service (SCS), Washington State University Cooperative Extension Service (WSUCE) and OTHER, consisting of university faculty, private land managers, State and Federal land managers and owners of small natural resource businesses.Agroforestry was not a new concept for most (94%) respondents, further 55% of those familiar with agroforestry were practicing agroforestry or providing advice to landowners who were practicing agroforestry. Use in (government mandated) soil conservation plans on farmland (100% of all respondents) was the most frequently cited potential application for agroforestry in the state followed by range and pasture land and managing non-commercial forest land (both 84%), use on commercial forest plantation (83%) and fruit and nut orchards (61%).Diversifies land use (25%), enhanced productivity (18%), aesthetics (13%) and income diversity (13%) were the four most frequently cited potential advantages to practicing agroforestry. Lack of information (28%), lack of technical assistance (18%), establishment costs (14%) and not an established practice (14%) were the most frequently identified potential obstacles to practicing agroforestry. Respondents suggested there is great potential for application of agroforestry throughout the state, and non-industrial private forest land owners were selected for future study of this potential.     

Structure of xylan from culms of bamboo grass (Sasa senanensis Rehd.)

Xylan prepared from culms of kumaizasa (Sasa senanensis Rehd.), a representative species of bamboo grass, was hydrolyzed with-xylanase ofStreptomyces olivaceoviridis E-86. Four arabinoxylo-oligosaccharides and two glucuronoxylo-oligosaccharides were isolated from the enzymatic hydrolysate of the xylan by chromatography on a charcoal column, a Dowex 1-x8 column, a Toyo-pearl HW-40S column, and a LiChrospher 100 NH₂ column and on preparative paper chromatography. The results of the structural analyses of the saccharides showed that the isolated oligosaccharides had the structures of 3²--l-arabinofuranosyl-xylobiose, 3²--l-arabinofuranosyl-xylotriose, 3²--[-d-xylopyranosyl-(1 2)-l-arabinofuranosyl]-xylobiose, 3³--[-d-xylopyranosyl-(1 2)-l-arabinofuranosyl]-xylotriose, 2³--4-O-methyl-d-glucuronosyl-xylotriose, and 2³--d-glucuronosyl-xylotriose. From the structural analysis of the oligosaccharides derived from the xylan, kumaizasa xylan was concluded to be a kind of arabinoglucuronoxylan having not only stubs of singlel-arabinose and singled-glucuronic acid but also stubs of disaccharide units such as-d-xylopyranosyl-(1 2)-l-arabinofuranose.     

Holzangriff durch Larven der AmpferblattwespeAmetastegia glabrata Fall.(Hym., Tenthredinidae)

Zusammenfassung Die Altlarven 2. Generation der AmpferblattwespeAmetastegia glabrata Fall. sind im Obstbau als Schädling bekannt. Die Schäden entstehen bei dem Versuch der Larven, in Früchten Puppenkammern anzulegen.Üblicherweise verpuppen sich die Larven in den trockenen Stengeln der Nährpflanzen(Polygonaceae) oder anderem trockenem oder verholzten Pflanzenmaterial.Es wird über einen gesicherten Fall berichtet, in demAmetastegia glabrata-Larven in verarbeitetem Nutzholz (Plakattafel) schädlich geworden sind. Ein weiterer Fall konnte nicht völlig geklärt werden; jedoch waren auch hier Blaltwespen-Larven in einer Wohnung in verarbeitetes Nutzholz (Türrahmen) eingedrungen.Nach dem geringen Umfang der Schäden, die nur durch die Anlage kurzer Puppenkammern in weichen Holzteilen entstehen, istAmetastegia glabrata in die Gruppe der gelegentlichen Holzzerstörer einzureihen. Allerdings kann durch diese Art völlig gesundes Holz im Freiland angegriffen werden.Holzschutzsalze vom U-Typ genügen zur Vorbeugung nicht. Vorbeugungs- und Bekämpfungsmaßnahmen werden besprochen.

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Summary Attack on wood by larvae of the dock sawfly Ametastegia glabiata Fall. (Hym., Tenthiedinidae) Normally the mature larvae of the last brood of the dock sawfly bore themselves for pupation into dry stems of plants.By the gnawing efforts in certain years of appearance in masses, however, they may attack fruit too, especially apples, and cause considerable damage by numerous gnawing spots.Besides these known injuries on fruitA. glabrata has now been stated in two cases as an occasionally dangerous animal to dry timber too.The damage caused is described by word and picture; preventive and curative measures are discussed.

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Résumé Attaque du bois par des larves de la Tenthrenidé Ametastegia glabrata Fall. (Hym., Tenthredinidae) Normalment les larves adultes de l'A. glabrata se forent dans les tiges sèches des plantes pour la mé tamorphose.Cependant aussi des fruits, surtout des pommes, sont attaqués par le ronger pendant les anées quand ces insectes paraîssent en masse. Des dommages considérables sont provoqués aux points d'attaque nombreux.A côté de ces dommages connus aux fruits l'A. glabrata a été constaté en deux cas comme causeur de dommage par occasion en bois sec de construction.Les dommages sont décrits et figurés; des methodes preventives et curatives sont discutées.

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? Ametastegia glabrata Fall. (Hym., Tenthredinidae) . , , , . Ametastegia glabrata Fall. ( ) . , .

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Mitteilung aus dem Holzschutzlaboratorium der Farbenfabriken Bayer AG., Werb Uerdingen     

Eucalyptus planting as a response to farm management problems faced by ‘on-site’ and ‘off-site’ farmers

The success of the green revolution in the fertile and agriculturally surplus plains of western U.P. in north India led to labour shortages, and increased opportunities for off-farm investments by landowners, requiring their time and energies away from farming. These changes impelled landowners to adopt strategies which saved family labour and supervision time in cultivation. Many off-site farmers, and such on-site farmers who had a high ratio of owned land to male members in the family, resorted to tree farming, mainly eucalyptus. On the other hand, farmers in eastern U.P., with small holdings, subsistence orientation and cheap labour, showed little enthusiasm for planting eucalyptus. Based on field investigation in six villages, this paper argues that woodlot planting of eucalyptus emerged as an attractive option for landowners facing management and labour problems in western U.P., as tree farming allowed saving in family labour time and permitted greater flexibility in the timing of operations. About 60% of the total trees planted were by this category of management-constrained farmers.     

Traditional fallows in Latin America

Traditional fallow systems of Latin America have not been extensively studied from either a socioeconomic or biophysical viewpoint. Only in the past decade have some of these systems — modified shifting cultivation in the Amazon, the bracatinga (Mimosa scabrella) fallow of southeastern Brazil, the babassu (Attalea spp.) system of the Amazon margins, and short bush fallows mostly for Phaseolus bean (the so-called frijol tapado) — received any attention. Over the past century, traditional cultivators have adopted several legumes such as Mucuna spp., Lathyrus nigrivalis, Canavalia spp., and Senna guatemalensis as green manures or managed fallows in food crop production systems, which have recently been the object of studies by social and biological scientists. Longer, monospecific fallows involving woody legumes have been studied to varying degrees. The legumes include Senna guatemalensis, Mimosa tenuiflora, and Gliricidia sepium. Systems in which crop production is alternated with animal grazing of secondary vegetation include the caatinga of Northeast Brazil, the espinales of Chile, the matorrales of northern Mexico, and the chaco of Argentina, Paraguay, and Bolivia. A classification is proposed depending on the nature of the species (woody or nonwoody) and their composition (mono- or multispecies) and land management (burned or not). Much work is still needed in more complete characterization, determination of economic importance and potential, understanding the relationships among components, studies of nutrient cycling, and verification of the effects of shorter fallow periods of these systems.This revised version was published online in November 2005 with corrections to the Cover Date.     

Inhibition ofTrichoderma cellulase activity by a stilbene glucoside fromPicea glehnii bark

The stilbene glucoside isorhapontin (5,4-dihydroxy-3-methoxystilbene-3--D-glucoside) is the major constituent of the ethyl acetate extracts fromPicea glehnii bark. Isorhapontin inhibited the hydrolytic activity ofTrichoderma cellobiohydrolase I (CBH I) for both bacterial microcrystalline cellulose and the soluble cellooligosaccharide celloheptaitol. The inhibitory effect for celloheptaitol, however, was more drastic than that for bacterial microcrystalline cellulose. The hydrolytic activity of the CBH I core domain for celloheptaitol was also inhibited by isorhapontin to a similar extent, suggesting that the interaction between isorhapontin and the core domain of CBH I is the reason for this phenomenon. The inhibition of CBH I activity by isorhapontin showed mixed noncompetitive and uncompetitive types in a concentration of the inhibitor of less than 125M. TheK _i andK _i values were estimated to be 57.2 and 33.3M, respectively. Whereas isorhapontin strongly inhibited CBH I activity, its aglycone isorhapontigenin (3-methoxy-3,5,4-trihydroxystilbene) showed almost no inhibition. Consequently, both the stilbenic and the-glucosidic structures in isorhapontin are essential for the inhibitory effect on CBH I activity. Isorhapontin also inhibited the activity ofTrichoderma endoglucanase I for celloheptaitol, whereas almost no effect was observed for the activities of both endoglucanases II and III.An outline of this work was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Die Übertragung des Enationenvirus der Erbse durch verschiedene Morphen der BlattlausartenMacrosiphum euphorbiae (Thomas) undAcyrthosiphon pisum (Harris)

Zusammenfassung Unterschiedliche Vektoreignungen können zwischen Rassen, Morphen und Altersstadien einer Blattlausart auftreten. Es wurden verschiedene Morphen vonMacrosiphum euphorbiae (Thomas) undAcyrthosiphon pisum (Harris) hinsichtlich ihrer Übertragungsfähigkeit für das persistente Enationenvirus der Erbse geprüft. Dabei erwiesen sich ovipare Weibchen und adulte Männchen vonM. euphorbiae als ungeeignete Überträger, während die gleichen Morphen von zweiA. pisum-Populationen die Virose übertrugen. Auch die Fundatrix desA. pisum-BastardsTrifolium pratense rot XSarothamnus scoparius grün übertrug zu einem relativ hohen Prozentsatz. Ovipare Weibchen und Männchen der inaktiven RasseLotus uliginosus gelb konnten keine Infektion bewirken; die persistente Virusübertragungsfähigkeit ist im Falle vonAcyrthosiphon pisum (Harris) offenbar ein genetisch fixiertes Merkmal.

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Summary Different vector abilities may exist between races, morphs and development instars of a given aphid species. Several morphs ofMacrosiphum euphorbiae (Thomas) and ofAcyrthosiphon pisum (Harris) were tested in their transmission ability for the persistent pea enation mosaic virus. Oviparous females and adult males ofM. euphorbiae proved insuitable for transmission, the corresponding morphs of twoA. pisum-populations, however, were successful in transmitting. The fundatrix of theA. pisum hybridTrifolium pratense red xSarothamnus scoparius green transmitted to a relatively high percentage. Oviparous females and males of the inactiv raceLotus uliginosus yellow failed completely in transmitting; in the present case ofA. pisum the transmission character of the persistent virus evidently is genetically fixed.

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Résumé Différentes aptitudes de vecteur peuvent se trouver entre les races, les morphes et les périodes d'âge d'une espèce de pucerons. Différentes morphes deMacrosiphum euphorbiae (Thomas) et deAcyrthosiphon pisum (Harris) ont été examinées en ce qui concerne leurs aptitudes de transmettre le virus persistant du pois(pea enation mosaic). En ce cas les femelles ovipares et les mâles adultes deM. euphorbiae se montraient impropres à la transmission, pendant que les mêmes morphes de deux populations deA. pisum transmettaient la virose. C'était la fondatrice du bâtard deA. pisum Trifolium pratense rouge avecSarothamnus scoparius vert qui transmettait à une pourcentage relativement haute. Les femelles ovipares et les mâles de la race «inactive» deLotus uliginosus jaune ne pouvaient pas effectuer d'infection; en cas deAcyrthosiphon pisum (Harris), l'aptitude persistante à transmettre le virus évidemment est un caractère fixé d'une façon génétique.

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, . Macrosiphum euphorbiae (Thomas) Acyrthosiphon pisum (Harris) peaenation mosaic virus). M. euphorbiae , {A. pisum} . A. pisum-Trifolium pratense Sarothamnus scoparius . «» Lotus uliginosus ; Acrythosiphon pisum (Harris) .

     

Versuche zur Bekämpfung der ObstbaumspinnmilbePanonychus ulmi Koch im Libanon

Summary During the application of several acaricides to manifest their effectivness againstPanonychus ulmi Koch living on the apple trees in Lebanon, it could be clearly noticed that a kind of resistance to the phosphoric acid organic preparations occurs, where these mentioned chemicals are regularly used against the mites. The control succes by means of some acaricides and ovicides combinations is here discussed. AsTetranychus urticae Koch in some apple plantations infests the different weeds growing together with the trees there and it wanders in summer to overrun the apple trees; the question of the mite control by means of respective sprays or by means of weed eradication is also discussed.

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Résumé L'étude de l'efficacité d'une série d'acaricides dePanonychus ulmi Koch sur pomme en Liban a démontré une certaine résistance de groupes des parathions, lá où ceux — ci sont appliqués régulièrement depuis des années. Les résultats de combat de quelques acaricides et combinaisons par des ovicides sont discutés. PuisqueTetranychus urticae Koch occupe les herbes, les plus différentes, et depuis — là en été change sur les pommiers la question d'un combat de cet acarien nuisible par des application ultérieures ou par l'extermination d'herbes est discuté e.

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, Pannonychus ulmi Phosphorsäureester. Akarizide Ovizide. Tetranychus urticae , .

     

Growth,nutrient, water relations,and gas exchange in a holm oak plantation in response to irrigation and fertilization

Eighty 6-years-old Quercus ilex L. subsp. ballota seedlings planted on a former agricultural land were subjected during two growing seasons to one of four treatments: fertilization and irrigation, irrigation, fertilization, and control. Seasonal and between-treatment variations on water relations, gas exchange parameters, growth and nutrient status were analyzed. Water potential () was related to climatic conditions. Thus, the frequent rain storms during the summer allow seedlings to maintain relatively high values, joined to moderate photosynthetic activity. Differences on , photosynthesis and stomatal conductance due to irrigation were shown at the onset and end of growth, related with lower water availability. Fertilization had a greater effect on growth than irrigation. Both fertilization and irrigation positively affected the relative increment on leaf nutrient concentration at the end of the second year. The results indicate that water availability was not a limited factor, thus irrigation is not justified; while fertilization improve growth.     

5α-Reductase inhibitory component from leaves ofArtocarpus altilis

The inhibitory effects of 17 samples prepared from Thailand plants on 5-reductase activity were examined. The acetone extract of leaves ofArtocarpus altilis showed potent 5-reductase inhibitory activity. Fractionation guided by 5-reductase inhibition led to the isolation of 2-geranyl-2,3,4,4-tetrahydroxydihydrochalcone from the acetone extract of leaves ofA. altilis. This compound showed more potent inhibitory effect (IC₅₀=38M) than-linolenic acid known as a naturally occurring potent inhibitor.