Genetic variation and phylogenetic relationships among Indian Citrus taxa revealed by DAMD-PCR markers

Genetic variation and phylogenetic relationships among 50 wild and cultivated accessions of 19 Indian Citrus genotypes were examined through comparison of Directed Amplification of Minisatellite DNA (DAMD) markers and morphological characters. DAMD-PCR analysis with four primers resulted in amplification of a total of 45 bands, of which 35 (78 %) were polymorphic. Morphometric evaluation using 76 morphological characters showed high level of variability ranging from 0.18 to 1.00 (avg 0.39), whereas the Jaccard’s coefficient values of genetic similarity calculated from DAMD data ranged from 0.41 to 1.00 (avg 0.68), indicating moderate genetic divergence among the accessions studied. UPGMA dendrograms generated separately from morphometric and DAMD data segregated all the accessions of Citrus into four main clusters, each containing a true basic species and their probable hybrids. The grouping of individual accessions/genotypes under respective species or cultivars in DAMD dendrogram was based purely on their genetic relationships rather than geographical origin. There was no absolute congruence between the data and dendrograms generated from morphometric and DAMD analyses. The study demonstrates the resolving power of DAMD markers for discrimination of individual genotypes of Citrus under its respective species, hybrid or cultivar groups and inferring their genetic and phylogenetic relationships as well. This is the first report on application of DAMD markers in Citrus.     

Impact of Arbuscular-Mycorrhizal Fungi on Phosphorus Efficiency of Wheat,Rye, and Triticale

Genotypic variation and mycorrhiza play an important role in plant uptake of phosphorus (P). A pot experiment was conducted with three cereals, wheat (Triticum aestivum L. cv. PBW-34), rye (Secale cereale L. cv. R-308), and triticale (Triticale octoploide L. cv. DT-46), a hybrid of wheat and rye, to examine the genetic variation in the degree of arbuscular-mycorrhizal (AM) infection and its inheritability from parents (wheat and rye) to their progeny (triticale). The soil used for pot culture was low in available P (7.8 mg P kg^?1soil). Inoculation with AM fungi showed a significant increase in extent of root colonization for all three cereals (average 70%) compared with their performance without AM (average 19.1%). However, among the three cereals, this increase was significantly greater in rye than in the other two crops, while wheat and triticale did not differ significantly. Mycorrhizal infection resulted in 1.6, 1.7, and 1.8-fold increases in shoot, root, and total plant dry matter, respectively, compared with the un-inoculated treatment. Among the three cereals, rye recorded maximum shoot, root, and total plant dry mass and P content with AM inoculation. The P uptake by wheat, rye, and triticale was 10%, 64%, and 35%, respectively, higher with rather than without mycorrhizal infection. Rye was most responsive to AM inoculation, with mycorrhizal dependency of 193%; here again, triticale followed wheat, with similar mycorrhizal dependency. Rye showed an increase in P utilization efficiency (PUE) without AM inoculation while the PUE of triticale was intermediate between wheat and rye. High efficiency of AM symbiosis in terms of P uptake exists in rye and most of these traits in triticale seem to be inherited from wheat rather than rye.     

Hemagglutinins in vegetative tissues of Bengal gram

Hemagglutinating activity was identified in the roots and vegetative tissues of Bengal gram using rabbit erythrocytes. The activity in the roots appears to be similar to that of the seeds in respect to their sugar inhibition property. Seed and root extracts were found to have fetuin inhibitory agglutinating activity, whereas cotyledons showed different sugar specificity. However, 7-day cotyledons and roots from 3 and 7-day plants were also found to have galactose and N-acetyl-D-galactosamine inhibitory activity. Protein profile in different tissues during their developmental stages was analyzed by SDS-PAGE. A major band at 66 kDa was common to all tissues at different stages of their development except 3-day cotyledons where 2 major bands at 22 kDa and 74 kDa were observed. Two prominent bands at 74 kDa and 86 kDa were found along with 60 kDa protein in 3-day old roots whereas a major band at 33 kDa was found in 15-day old roots. Total protein content and specific activity of hemagglutinin were measured. Increase in specific activity with lower protein content was observed in cotyledons of 15-day old plant. Specific activity was eight times higher in the roots and four times more in leaf tissues of 7-day old plants in comparison to 15-day old plants. Stems also showed a significant increase of specific activity (p = 0.013) in 7-day old plants without any significant alteration in the protein content.     

Adoption potential of fruit-tree-based agroforestry on small farms in the subtropical highlands

Worldwide, fruit-tree-based agroforestry systems have been only modestly studied, although they are common on smallholder farms. Such systems based on apple (Malus spp.), peach (Prunus spp.), and pear (Pyrus spp.) are common in northwest Guatemala as low intensity homegardens and are known to increase total farm productivity in communities where farm size is a limiting factor. This study investigated the potential for adoption of fruit-tree-based agroforestry by resource-limited farmers using ethnographic investigation and linear programming simulations of farm activities at the household level. Two communities with differing demographics, infrastructure, and access to regional markets were selected based on the presence of extensive fruit-tree-based agroforestry. The influences of family size, land holdings, and tree and crop yields on the optimal adoption levels of fruit trees were evaluated through a comparative study of the varying social and physical infrastructure present in the two communities. Fruit-tree-based agroforestry was potentially more attractive to relatively prosperous families or those with larger land holdings. Improvements in fruit-tree productivity and interspecies competition were of greater importance where family land holdings were smaller. The inability of families to produce sufficient food to meet annual needs, poor fruit quality, and lack of market infrastructure were identified as constraints that limit adoption. The complementarity of production with the dominant maize (Zea mays) crop, home consumption of fruit, and the potential to generate additional cash on limited land holdings were identified as factors promoting adoption of fruit-tree-based agroforestry.     

A method for establishing a core collection of Saccharum officinarum L. germplasm based on quantitative-morphological data

A technique is proposed for establishing a representative core collection of S. officinarum accessions from the world collection of sugarcane germplasm maintained at the Sugarcane Breeding Institute-Research Centre, Cannanore, India. In the proposed method, the accessions were first sorted based on their relative contributions to the total variability by means of principal component scores based on a set of quantitative characters. Then, the cumulative proportion of their contributions to the total variance was computed. A logistic regression model was fitted to evaluate the functional relationship between the cumulative proportion of variance and the number of accessions. The size of the core set was decided as the inflection point on that fitted curve, i.e., the point beyond which the rate of increase in cumulative proportion of variability contributed by an accession began to decline. A method for eliminating entries with a high degree of similarity from the selected core set is also proposed.     

猪败血型链球菌病的诊疗报告

本文阐述了猪链球菌病的临床症状、实验室检验及防治方法，力求为科学防控猪链球菌病提供有益的探索和参考。     

Agroforestry potential in the southeastern United States: perceptions of landowners and extension professionals

The first steps in developing an agroforestry extension and training program involve compilation, synthesis, and analysis of current knowledge on existing practices. Equally important is to understand the perceptions of landowners and professionals of agroforestry as a land use option. No systematic effort has been made to assess these critical issues in the southeastern United States. Therefore, needs assessment surveys were developed following an analysis of major demographic issues that frame land use in the region and synthesis of information obtained from informal site visits and interviews with people engaged in resource and land use in the Atlantic and Gulf Coastal Plain. Surveys of extension professionals and landowners were then undertaken in the states of Alabama, Florida, and Georgia to represent the southeastern region. In addition to getting insights into the perceived benefits and concerns about agroforestry practices, the surveys indicated that the extent of alley cropping, forest farming and silvopasture practiced by landowners was less than anticipated, and that the prominence of windbreaks was overlooked by professionals. Managed riparian forest buffers or streamside management zones and windbreak technologies were the most widely used forms of agroforestry in the study area, although landowners did not recognize influence of agroforestry practices on quality or quantity of water among benefits of highest importance to them. Multistrata patio- or home gardens were also a prominent landowner-practice and acknowledged by professionals. These survey results can be useful for developing a relevant agroforestry extension and training program in the subtropical Southeast and may be of interest to agroforestry efforts in other similar settings. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pharmacokinetics and relative bioavailability of tiamulin in broiler chicken as influenced by different routes of administration

The bioavailability and pharmacokinetic disposition of tiamulin in broiler chicken were investigated after administration through the crop, drinking water, and feed at 40 mg/kg body weight. Residues of tiamulin in tissues of broiler chicken were also assessed. Plasma and tissue concentrations of tiamulin were analyzed by reverse‐phase high‐performance liquid chromatography (HPLC) method. Plasma concentration–time data were described by the non‐compartmental model for all three routes, and pharmacokinetic parameters were calculated. There were no significant differences (p > 0.05) in pharmacokinetic parameters and mean plasma concentrations of tiamulin between three routes tested (crop, water, and feed), indicating equal efficacy. Tiamulin residues in edible tissues (muscles, skin, and fat) were lower than the advocated maximum residue limit (MRL of 0.1 µg/g and that of liver was 1 µg/g) on the 3rd day. No traces were found on the 5th day after drug administration. This indicated that the withdrawal period (less than 5 days) is very short, which makes it safer. This study shows that tiamulin can be used with equal efficacy through all routes of administration in broiler chicken (crop, water, and feed).     

Coconut kernel protein modifies the effect of coconut oil on serum lipids.

Feeding coconut kernel along with coconut oil in human volunteers has been found to reduce serum total and LDL cholesterol when compared to feeding coconut oil alone. This effect of the kernel was also observed in rats. Since many plant proteins have been reported to exert a cholesterol lowering effect, a study was carried out on the effect of isolated kernel protein in rats. Feeding kernel protein resulted in lower levels of cholesterol, phospholipids and triglycerides in the serum and most tissues when compared to casein fed animals. Rats fed kernel protein had (1) increased hepatic degradation of cholesterol to bile acids, (2) increased hepatic cholesterol biosynthesis, and (3) decreased esterification of free cholesterol. In the intestine, however, cholesterogenesis was decreased. The kernel protein also caused decreased lipogenesis in the liver and intestine. This beneficial effect of the kernel protein is attributed to its very low lysine/arginine ratio 2.13% lysine and 24.5% arginine.     

Potential for adoption of Sesbania sesban improved fallows in Zimbabwe: A linear programming-based case study of small-scale farmers

Farmers' adoption of improved technologies is the ultimate measure of the success of any agricultural innovation. In a joint project of the International Centre for Research in Agroforestry (ICRAF) and the Department of Research and Specialist Services of Zimbabwe, the potential for adoption of the improved planted fallow technology using Sesbania sesban was assessed in the Mangwende Communal Area. The study was based on experimental data of maize (Zea mays) yields following 1-, 2- and 3-year improved fallows at Domboshawa Training Center, northern Zimbabwe where the improved fallows were promising. The data indicated that maize yields were higher after S. sesban fallows than after Cajanus cajan and Acacia angustissima fallows. A five-year linear programming model sensitive to the diversity within households was developed to simulate the livelihood system of households in the Mangwende Communal Area. Improved fallows of S. sesban were incorporated into the model to determine the potential for their adoption. Model results indicated that there is potential for the technology to be adopted by 80% of the farmers. According to the model, the new technology on average occupies 60% of the area under maize. Nevertheless, households continue to use fertilizers and cattle manure. One-year improved fallows are planted every other year; three-year improved fallows are also planted. Farmers who adopt the fallow technologies realize an increase in the cash available for discretionary spending. Factors such as composition of the household in terms of fulltime workers, size of the arable land owned by the farmer, and whether the household differentiates activities by gender, determine the adoption of the improved-fallow technology. This revised version was published online in June 2006 with corrections to the Cover Date.