Further studies on the propagation of cauliflower

Use of carefully lifted, decapitated cauliflower plants with 6 to 7 leaves per se, eliminated the need of the rooting of shoots and provided seeds in reduced time. Previously, shoots obtained from decapitated and de-leafed plants were rooted and allowed to produce seeds. This latter method did not assure that seed would be available in time for the following season's planting.     

Structural characteristics of cell walls of kenaf (<Emphasis Type="Italic">Hibiscus cannabinus </Emphasis>L.) and fixation of carbon dioxide

 Kenaf (Hibiscus cannabinus) plants are widely known for their contribution to the global and regional environment because of their ability to fix CO₂. On the other hand, some scientists have doubts about CO₂ fixation by kenaf and have misgivings about the effect of kenaf on the ecosystem. We have characterized the structural characteristics of cell walls of bast fibers, cores, roots, and leaves of kenaf during the maturation of plants and investigated the rate of photosynthesis. During maturation of the kenaf plant the cellulose (bast fiber 52–59%, core 44–46%) and lignin (bast fiber 9.3–13.2%, core 18.3–23.2%) contents increased significantly. The aromatic composition of the lignin of bast fiber was significantly different from that of the core lignin and of other plants. The lignin of bast fiber appears similar to pure syringyl lignin. Fixation of CO₂ by kenaf plants and their contribution to the global environment are discussed. A significatly high rate of photosynthesis of kenaf plants was observed compared to that of woody plants in Japan, but the amount of CO₂ fixation depends on the characteristics of the plantation. If the kenaf was planted in high density, about twice as much CO₂ was fixed as was fixed by trees in a tropical rain forest. Received: April 22, 2002 / Accepted: July 24, 2002 Acknowledgments This project was supported by the Science and Technology Agency (STA) fellowship of the Japan International Science and Technology Exchange Center (JISTEC), which has been successfully applied by Dr. Shuji Hosoya, Forestry and Forest Products Research Institute. We thank Dr. Toshio Sumizono and Mr. Masao Sakurai, Forestry and Forest Products Research Institute, for their kind help in determining the rate of photosynthesis and cultivating the kenaf plants, respectively. We also express our appreciation to Dr. Quang Hung Le, College of Agriculture and Forestry, Ho Chi Minh City, Vietnam for offering information about the cultivation of kenaf at Thu Duc District, Ho Chi Minh City.     

Studies on haemophilus infection in swine I. Application of the latex agglutination test to the diagnosis of Haemophilus pleuropneumoniae (H. Parahaemolyticus) infection

A latex agglutination test was evaluated as a method for the detection and titration of antibodies against swine Haemophilus infection and it was found that the test is applicable to the etiologic diagnosis of Haemophilus infection in swine. In swine infected experimentally with H. pleuropneumoniae (H. parahaemolyticus), the micromethod of agglutination using latex particles coated with antigens of H. pleuropneumoniae was found to be comparable agar-gel immunodiffusion and complement-fixation tests, which have previously been used for the etiologic diagnosis of the disease. Antibody titers determined by the latex agglutination test corrlated well with those determined by the other serological tests. The latex agglutination test tended to detect antibodies earlier than any of the other tests. By the latex agglutination test, weak cross-reactions were observed among different serotypes of H. pleuropneumoniae, whereas no cross-reaction was demonstrated between H, pleurophneumoniae and H. parasuis. The latex agglutination test was found to be simple and useful for the serological survey of swine Haemophilus infection, especially when dealing with a large number of samples.     

A greenhouse method for screening lettuce for resistance to Sclerotinia sclerotiorum

Agar blocks colonized by Sclerotinia sclerotiorum, causal agent of lettuce drop, were used as inoculum in screening for resistance to this pathogen in the greenhouse.Since the degree of resistance to the pathogen among cultivars varied with the time observed after inoculation, resistance was assessed by the number of days for 50% of the plants of each cultivar to die, as well as the number of plants that died. The cultivars ‘PI (Plant Introduction) 250427’, ‘Taiwan’, ‘PI 251790’, ‘PI 255568’, ‘MSU 73-44’ and ‘Bibb’ were found to have a higher level of resistance to S. sclerotiorum than the cultivar ‘Grand Rapids’ at 12 or 15 days following inoculation.     

Paper Electrophoresis Study of Sera of Dogs Immune to Wild Rabies Virus

Three hyperimmune dogs were injected intramuscularly with canine wild rabies virus. The dogs showed no clinical evidence of rabies. Intramuscular injection of the wild rabies virus in susceptible puppies induced fulminating disease and mortality in 14 to 16 days. Investigation of the serum proteins of the hyperimmune dogs by a paper electrophoresis technique revealed conspicuous changes in the beta and gamma protein bands.     

Productivity of Jatropha curcas under smallholder farm conditions in Kenya

With the global bioenergy boom, the planting of jatropha (Jatropha curcas) was widely promoted by the private sector and non-government organizations as one of the candidate tree species for bioenergy in Kenya. This was motivated by the belief that it grows easily with minimal management requirements. The present study attempts to determine whether management practices by smallholder farmers, which are heterogeneous, are optimal for jatropha yields in Kenya. A survey conducted in different agro-ecological zones showed that yields are very low under Kenyan farm conditions. Regardless of the age and management condition, 41 % of the farmers obtained no seed yield, while 79 % obtained up to 0.1 kg/tree. This is dismal in comparison with the figures (up to 2.0 kg/tree) reported from elsewhere for 1–5 year old trees grown under similar conditions. Examination of farmer management practices indicated that irrigation, manuring and weeding, in order to maximize yields, could be offset by misapplication of other components especially, selection of planting materials, timing of planting and choice of intercrops during the establishment phases. This indicates that the anticipated high yields have not been achieved partly because growers are still using unimproved germplasm, management practices are sub-optimal, and the biophysical boundaries of high jatropha yield are poorly defined. Thus at the current stage, jatropha should not be grown by smallholder farmers in Kenya because of low or dismal productivity. If jatropha is to play a role in the pro-poor bioenergy development, future projects need to identify management recommendations that optimize yields. This also needs to take into consideration the preferences and constraints of farm households on labor and land allocation to other farm and livelihood activities.     

Thermo characteristics of steam-exploded bamboo (Phyllostachys pubescens) lignin

Bamboo (Phyllostachys pubescens) internode was subjected to steam explosion treatment to produce an excellent fiber for binderless boards. Lignin was isolated from extract-free bamboo meal with Björkman’s procedure and steam-exploded pulp. The self binding-mechanism was discussed by scanning electron microscopy (SEM), thermo-gravimetry (TG), differential scanning calorimetry (DSC) and analytical ozonation. It is well-known that steam explosion treatment liberates lignin from the cell wall to the fiber surface, which is the most important component relevant to binderless board production. Results of TG and DSC analyses showed that steam-exploded bamboo pulp started mass loss at lower temperature compared to bamboo internode meal. The thermal softening temperature of lignin prepared from steam-exploded pulp was much lower than that of lignin prepared from extract-free bamboo meal. This suggests that intermonomer linkages of lignin, especially β-aryl-ether linkage which is the major intermonomer linkage of lignin, were cleaved during steam explosion treatment resulting in low molecular weight phenolic compounds. The cleavage of β-aryl-ether intermonomer linkage of lignin was also confirmed by ozonation analysis.     

Understanding patterns of tree adoption on farms in semi-arid and sub-humid Ethiopia

Trees on farms are a widespread feature of landscapes across a large part of Ethiopia with an important role in enhancing the resilience of smallholder livelihoods through the provision of ecosystem services. Despite their importance, little is known about what trees are planted or retained from natural regeneration by different types of farmers that results in the pattern of tree cover found in the region. We address this knowledge gap through analysis of household survey data from semi-arid and sub humid areas of Oromia regional state. A set of composite variables that represent distinctive patterns of tree cover on farms were derived from principal component analysis and Pearson correlation analysis. This revealed two major tree adoption strategies: farmer managed natural regeneration (FMNR) of trees to meet subsistence needs as well as contributing to other ecosystem services; and, high value agroforestry (HVAF) involving planted trees used largely to produce fruits, timber and fodder. Regression analysis further identified fine-scale variation in ecological and socio-economic factors that affect which of these two broad strategies are adopted by farmers. Favorable climatic conditions coupled with institutional arrangements to control free grazing were pre-conditions for HVAF, whereas poor biophysical potential and sloping land provided a positive incentive for farmers to adopt FMNR. Farmers with preferences for tree species with multiple utilities and locational flexibility favored FMNR while adoption of HVAF was more asset-driven. Our findings reveal that farmers integrate many native and exotic tree species on their farms to meet their variable farm conditions, needs and asset profiles in stark contrast to most tree promotion efforts that focus on a few, usually exotic, tree species. We recommend that future agroforestry promotion should embrace a diversity of tree species appropriate to matching the fine scale variation in ecological conditions and farmer circumstances encountered in the field.     

Tree establishment and management on farms in the drylands: evaluation of different systems adopted by small-scale farmers in Mutomo District,Kenya

Agroforestry systems in Sub-Saharan African drylands are complex and heterogeneous in nature even under similar biophysical conditions. This can be attributed to household needs and socioeconomic status which influence the species and utility of the adopted trees. This has an impact on the trees establishment and management system through planting or Farmer Managed Natural Regeneration (FMNR). This study evaluates how trees for different utilities are managed and which socioeconomic factors influence these decisions. The study used primary data collected in Mutomo District, Kenya through a household survey based on a structured questionnaire. A paired sample t-test was done to assess the preferred mode of adopting trees for different utilities while factor analysis was used to characterize the households as either planting trees or practicing FMNR. Multiple linear regression using household regression factor scores as independent variables and socioeconomic indicators as dependent variables was done to ascertain which socioeconomic factors affect tree adoption. The results show that trees planted were mostly exotic species valued for their nutrition and commercial value, while FMNR was used for subsistence products and environmental services. Household size, livestock levels and mobility had a positive correlation with tree planting, while income, access to markets and roads had an inverse correlation. Access to natural woodland, distance to the nearest motorable road and land size had a positive correlation with tree protection. It is hoped that this knowledge will act as a reference point when designing agroforestry projects in similar areas to ensure they are more aligned to specific site and household conditions.