Changes of soil chemistry,stand nutrition,and stand growth at two Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) sites in Central Europe during 40 years after fertilization,liming, and lupine introduction

Long-term (40 years) effects of two soil amelioration techniques [NPKMgCa fertilization + liming; combination of PKMgCa fertilization, liming, tillage, and introduction of lupine (Lupinus polyphyllus L.)] on chemical topsoil properties, stand nutrition, and stand growth at two sites in Germany (Pfaffenwinkel, Pustert) with mature Scots pine (Pinus sylvestris L.) forest were investigated. Both sites are characterized by base-poor parent material, historic N and P depletion by intense litter-raking, and recent high atmospheric N input. Such sites contribute significantly to the forested area in Central Europe. Amelioration resulted in a long-term increase of pH, base saturation, and exchangeable Ca and Mg stocks in the topsoil. Moreover, significant losses of the forest floor in organic carbon (OC) and nitrogen stocks, and a decrease of the C/N ratio in the topsoil were noticed. The concentrations and stocks of OC and N in the mineral topsoil increased; however, the increases compensated only the N, but not the OC losses of the forest floor. During the recent 40 years, the N nutrition of the stands at the control plots improved considerably, whereas the foliar P, K, and Ca concentrations decreased. The 100-fascicle weights and foliar concentrations of N, P, Mg, and Ca were increased after both amelioration procedures throughout the entire 40-year period of investigation. For both stands, considerable growth acceleration during the recent 40 years was noticed on the control plots; the amelioration resulted in an additional significant long-term growth enhancement, with the NPKMgCa fertilization liming + being more effective than the combination of PKMgCa fertilization, liming, tillage, and introduction of lupine. The comprehensive evaluation of soil, foliage, and growth data revealed a key relevance of the N and P nutrition of the stands for their growth, and a change from initial N limitation to a limitation of other growth factors (P, Mg, Ca, and water).     

Selective staining and visualization of hyphal sheath of a white-rot fungus <Emphasis Type="Italic">Phanerochaete crassa</Emphasis> WD1694 with phloxine B

The hyphal sheath is a morphological feature of many kinds of fungi. Although the fine structures of the sheath have been studied in detail by a number of electron microscopy techniques, the function and physiology of the hyphal sheath are not yet clarified. One reason for this is that the hyphal sheath is a colorless, mucilaginous, and delicate material so that it is not easily identified. We developed a simple method to visualize and identify the hyphal sheath of the white-rot fungus Phanerochaete crassa WD1694. The small mycelial pellets in shaken liquid cultures of P. crassa WD1694 were stained directly with phloxine B. Both the hyphae and the hyphal sheath that filled the gaps between each of the hyphae were visualized and observed by light microscopy. The stained hyphae were further studied by transmission electron microscopy, atomic force microscopy, and fl uorescence microscopy. Based on these observations, we confirmed that the staining of the hyphae was also due to the presence of the hyphal sheath that closely covered the fungal cell wall. These results clearly showed that the hyphal sheath was selectively stained with phloxine B and could be observed and identified by conventional light microscopy. Part of this report was presented at the 50th Lignin Symposium, Nagoya, October 2005     

Effect of adult nutrition and insect density on the performance of spotted stem borer, <Emphasis Type="Italic">Chilo partellus</Emphasis> in laboratory cultures

The spotted stem borer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is being successfully reared on artificial diets for screening programmes. Besides quality characteristics of the diet, rearing density and adult nutrition have significant implications on the successful mass multiplication of lepidopterans. The performance of C. partellus moths was assessed on different adult diets (water and sugar solution) and compared with unfed adults. Further, three pairing densities, viz. 2, 5 and 8 pairs/oviposition jar (1177.5 cm³) were compared for their effect on C. partellus longevity and fecundity. In another experiment, different larval densities (100, 150 and 200 neonate larvae/diet jar) were evaluated for their effect on the larval survival. Water-fed moths (both males and females) lived longer (7.32 and 7.26 days, respectively) and showed higher fecundity (307.17 eggs) than the sugar-fed or unfed moths. The latter, however, showed better egg hatchability (76.55%) than the water- or sugar-fed moths (60.45 and 50.59%, respectively). The longevity (5.67 days) and fecundity (258.46 eggs) were significantly greater at pairing density of 2 pairs/jar. The larval survival was higher (58.50%) at rearing density of 100 larvae/jar. The neonate larval release into diet jars was compared with conventional egg release and both modes were no different with respect to larval survival.     

Genetic difference in adventitious rhizogenesis in <Emphasis Type="Italic">Albizia procera</Emphasis> Benth. with IBA treatment

Variable adventitious rhizogenesis of juvenile shoot cuttings was observed in seven half-sib families (TP-1, BAN-1, AN-3, JR-3, SL-16, UM-3, and UM-5) of Albizia procera Benth. Treatment with IBA invariably promoted sprouting by 8%, adventitious rooting by 218%, root number by 869%, and root length by 36.4% compared with the control. Interaction between families and IBA treatment significantly enhanced sprouting and root length in BAN-1, JR-3, UM-3, and UM-5, and root number in all families, but had a significant suppressive effect on sprouting in AN-3. Treatment with IBA increased family heritability (h _f ²) 1.38-fold for sprouting, 2.86-fold for adventitious rooting, and 10.86-fold for root number, but reduced family heritability by a factor of 8.25 for root length. Thus, direct genetic effects seem to have strongly affected sprouting and adventitious rooting, with IBA playing an auxiliary role, but had little effect on root number and length, for which IBA had a dominant regulatory role.     

Application of mycorrhizal roots improves growth of tropical tree seedlings in the nursery: a step towards reforestation with native species in the Andes of Ecuador

Most tree species in tropical mountain rain forests are naturally associated with arbuscular mycorrhizal fungi. Previous studies in southern Ecuador of 115 tree species revealed that only three species were not associated with arbuscular mycorrhizal fungi. Seedlings of tropical tree species raised in the nursery may need to be associated with arbuscular mycorrhizal fungi to survive transplantation shock in higher numbers. Methods for establishing plantations with native tree species are not yet established for Ecuador. Thus, we investigated the feasibility of using mycorrhizal roots of seedlings of Inga acreana, Tabebuia chrysantha, Cedrela montana and Heliocarpus americanus that had trapped mycorrhizal fungi from forest humus in the nursery to inoculate C. montana and H. americanus with native arbuscular mycorrhizal fungi. Inoculation with either a mixture of mycorrhizal roots from the four species or only with mycorrhizal roots from the same tree species were compared with effects of moderate fertilization. Assessment of plant growth and mycorrhizal status of 6-months-old Cedrela montana and Heliocarpus americanus revealed an improvement in growth and diverse associated fungi through mycorrhizal root inoculation in comparison with moderate fertilization. Moderate fertilization did not suppress mycorrhization.     

Characterization and application of recombinant β-glucosidase (BglH) from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> KCTC 1918

β-Glucosidase (β-1,4-D-glucoside glucohydrolase: EC.3.2.1.21) catalyzes the hydrolysis of β-glucosidic bonds between saccharides and aryl or alkyl groups. A gene encoding β-glucosidase from Bacillus licheniformis KCTC 1918, an anaerobic spore-forming soil bacterium, was cloned and characterized. The structural gene for the β-glucosidase consists of 1410 bp encoding 469 amino acid residues, and has a molecular weight of 53.4 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis with 12% separating gel. The enzyme activity was determined against pNPG as a substrate. The enzyme was optimally active at pH 6.0 (citrate-phosphate buffer) and 47°C. β-Glucosidase retained 100% of its original activity for 24 h. The activity of the enzyme was stimulated by glycerol and urea and was decreased by Ca²⁺, Cu²⁺, Hg²⁺, Mg²⁺, and Mn²⁺. In particular, Cu²⁺ had the strongest negative effect on β-glucosidase activity. The purified β-glucosidase was active against pNPG and cellobiose. When the β-glucosidase was tested for cellulose hydrolysis, the supplement of β-glucosidase with cellulose increased the glucose yield from pine wood powder by 139.8%.     

Gas exchange responses of <Emphasis Type="Italic">Eucalyptus</Emphasis>, <Emphasis Type="Italic">C. africana</Emphasis> and <Emphasis Type="Italic">G. robusta</Emphasis> to varying soil moisture content in semi-arid (Thika) Kenya

A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g _s) and transpiration rate (E) at CO₂ concentrations of 360 μmol mol⁻¹ and ambient humidity and temperature. A, E and g _s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m⁻² s⁻¹) compared to eucalyptus hybrid GC 584 (21.0 μmol m⁻² s⁻¹), E. grandis (19.2 μmol m⁻² s⁻¹), C. africana (17.7 μmol m⁻² s⁻¹) and G. robusta (11.1 μmol m⁻² s⁻¹). C. africana exhibited high E values (7.0 mmol m⁻² s⁻¹) at optimal soil moisture contents than G. robusta (3.9 mmol m⁻² s⁻¹) and eucalyptus (5.3 mmol m⁻² s⁻¹) in field experiment and G. robusta (3.2 mmol m⁻² s⁻¹) and eucalyptus (4.2 mmol m⁻² s⁻¹) in pot-grown trees. At very low soil moisture content, extremely small g _s values were recorded in GC 15 and E. grandis (8 mmol m⁻² s⁻¹) and G. robusta (14 mmol m⁻² s⁻¹) compared to GC 584 (46.9 mmol m⁻² s⁻¹) and C. africana (90.0 mmol m⁻² s⁻¹) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol⁻¹ and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.     

Identifying important biophysical and social determinants of on-farm tree growing in subsistence-based traditional agroforestry systems

Many expert-designed agroforestry projects enunciated in 1970s around the world, particularly in the developing countries, had uneven success due to inadequate adoption or abandonment after adoption. There are many empirical studies on factors affecting on-farm tree cultivation mainly where expert-designed agroforestry programmes were introduced but lacking in case of traditional agroforestry. Moreover, the concern to identify key factors influencing on-farm tree growing is gaining importance. The present study identifies key factors in on-farm tree growing based on investigation of traditional agroforestry using logistic regression approach. The study is based on household survey of 401 households located in Indian Western Himalaya. The factors affecting on-farm tree growing were grouped into: biophysical (included land use and infrastructural aspects) and social. Models predicting on-farm tree growing for each category were developed and key factors affecting on-farm tree growing in the respective category were identified. A composite model was also developed by combining biophysical and social factors. In the present study, farm size, agroclimatic zone, soil fertility, mobility and importance of tree for future generations respectively were the key factors which influenced tree growing. In contrast to many previous studies which considered either biophysical or social factors, the composite model in the present study reveals that both biophysical and social factors are simultaneously important in motivating the farmers to grow trees on their farms in traditional agroforestry. Moreover, the present study open vistas for using farmers’ experience and knowledge of adoption of agroforestry to stimulate on-farm tree growing. The wider implication of the study is that biophysical as well as social variables should be considered together in designing suitable agroforestry systems in various parts of the world.     

Spice crops agroforestry systems in the East Usambara Mountains,Tanzania: growth analysis

A scarcity of cultivation land calls for more intensive and productive land use in the East Usambara Mountains in NE Tanzania. Spice crops could generate cash in higher parts of the mountains, but the present cultivation methods are depleting the valuable forest resources. The trial was established at the end of 2000 to find out how the two popular cash crops, cardamom (Elettaria cardamomum (L.) Maton.) and black pepper (Piper nigrum L.), normally grown under the natural forest, will produce in intensive agroforestry system with two multipurpose farm trees, Grevillea robusta A.Cunn. and nitrogen fixing Gliricidia sepium Jacq. Results from 6 years showed that cardamom produced better with grevillea than in natural forest; 5.5 times more in the fourth year than the average in the area. The Land Equivalent Ratios for black pepper and cardamom showed that pepper intercropped with grevillea produced 3.9 times more than in monoculture whereas cardamom intercropped with grevillea and pepper produced 2.3 times more than in monoculture. Gliricidia improved the nitrogen and organic matter content of the soil over the levels found in natural forest. Soil acidity was, however, preventing the plants from using the available mineral nutrients more effectively.