Evaluation of isotopic dilution method for measuring N2 fixation in Azolla: Comparison with other methods 1

An isotopic dilution method that overcomes the drawbacks of commonly used methods for measuring N₂ fixation by aquatic N‐fixers such as Azolla pinnata‐Anabaena azollae association (Azolla) is presented. The method was compared with ¹⁵N₂ gas (while maintaining CO₂) and the difference methods of measuring N₂ fixation. The isotopic dilution method was used for two conditions: a. For ¹⁵N‐free growth medium, Azolla was pre‐enriched with ¹⁵N, and N₂ fixation was determined by measuring the dilution of ¹⁵N in the tissue. b. For the growth medium containing N, N₂ fixation was determined by providing ¹⁵N enriched ammonium sulfate in the growth medium and measuring ¹⁵N to ¹⁴N ratio in the tissue. An airtight chamber, necessary for ¹⁵N₂ gas and acetylene reduction methods, was not representative of the growing environment of Azolla. Temperature in the airtight chamber was far from uniform and CO₂ was rapidly depleted. The isotopic dilution method is simpler, relatively inexpensive, subject to fewer errors and applicable to more diverse conditions, and yet was as accurate as ¹⁵N₂‐gas method.     

Agro-morphological variation in “Jhinuwa” rice landraces (Oryza sativa L.) of Nepal

Jhinuwa is an aromatic rice (Oryza sativa L.) landrace from the Pokhara Valley of Nepal. A total of 210 accessions comprising seven types of Jhinuwa rice landraces were randomly collected from the rice fields to evaluate inter- and intra-population variability based on agro-morphological traits. The experiment was conducted in factorial randomized complete block design with three replicates in 2005. The first six principal components (PCs) accounted for 76.6 % variation for agro-morphological traits. Major traits that accounted for the variation by six PCs includes days to heading, days to maturity, total grain panicle^?1, fertile grain panicle^?1, culm length, panicle length, milling recovery, head rice recovery, aroma, 1,000 grain weight, sterile grain panicle^?1, grain sterility %, and leaf characteristics. Both principal coordinate analysis and cluster analyses revealed four phenotypic groups, two of which represent Bayarni, Jhinuwa, and Biramphul while the other two account for Tunde and Pakho Tunde. Tunde, Pakho Tunde, Kalo Bayarni, and Seto Bayarni showed higher intra- as well as inter-population variation compared to other populations. The phenotypic and genotypic coefficients of variation, broad sense heritability (h ²B) and genetic advance (GA) as a percent of the mean assessed for 210 accessions revealed high h ²B and GA estimates for leaf width, leaf length breadth ratio, ligule length, sterile grain panicle^?1, grain sterility % and 1,000 grain weight. The current study demonstrates that improvement in Jhinuwa rice landrace is possible by selecting superior accessions from existing natural populations while selection should be focussed to market traits with higher h ²B and GA estimates.     

Ultrastructural characteristics of the blood cells of chickens commonly reared under backyard poultry farming in Mizoram,India

The present study was undertaken to characterize the ultrastructural morphology of the blood cells of commonly reared chickens in the state of Mizoram, India under backyard poultry farming. For this study, 2 ml of whole blood was aseptically collected from the wings veins of 12 chickens of three different breeds namely the Zoar, Aseel and Rhode Island Red and processed for ultrastructural imaging under standard protocols. Under scanning electron microscopy (SEM) the matured erythrocytes of Zoar, Aseel and Rhode Island Red appeared elliptical in shape while the leukocytes and thrombocytes appeared round in shape with variable surface modifications. Under transmission electron microscopy (TEM) the granules of the heterophils of Zoar, Aseel and Rhode Island Red appeared predominantly fusiform in shape, the granules of the eosinophils appeared round in shape and that of the basophils appeared pleomorphic in shape. The cytoplasm of the monocytes, medium-to-large lymphocytes and thrombocytes of Zoar, Aseel and Rhode Island Red under TEM appeared to be vacuolated and granular while that of the small lymphocytes appeared to be granular but non-vacuolated. The study concluded that the ultrastructural characteristics of the blood cells of the three breeds of chicken studied were almost similar to the blood cells of other birds reported earlier.     

Bovine brucellosis – a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.     

低压低成本滴灌系统的设计、构造与评估(摘选)

使用当地产材料,包括KB管、KB压力脚踏泵、带有微型管的压力桶以及医用输液管开发了手动控制低压低成本( LPLC)滴灌系统.对该装置进行了田间试验,并且针对西红柿与椰菜,对该系统的各种独立参数,如营养生长、水力性能、农作物需水量、水分利用效率以及经济成本从不同方面进行了评估.该系统的投资回收期为1个季度,效益成本比为1...     

Effects of Different Management Practices on Stand Composition and Species Diversity in Subtropical Forests in Nepal: Implications of Community Participation in Biodiversity Conservation

In this article, we compared the structure, composition, and diversity of trees, shrubs and saplings, seedlings and herbaceous species of community- and government-managed forests in the lowlands of eastern Nepal. Results suggest that among the trees, the community forest was dominated by a single species, Shorea robusta. However, Shorea robusta and Terminalia myriocarpa were codominant in the government forest. Tree density and basal area were higher in the government forest, but shrub/sapling density and basal area were higher in the community forest, suggesting a positive effect of community management on tree regeneration. Overstory species assemblages showed an obvious compositional difference between the forests, but understory species assemblages were less obvious. Plot-level tree and shrub/sapling species richness was higher in the government forest than the community forest. However, seedling-herbaceous species richness was higher in the community forest. The dominance of Shorea robusta trees in the community forest suggests that people involved in managing forests may be more interested in a limited number of economically valuable species while removing less important trees. Such preferential management practices may increase resource heterogeneity within a forest and maintain species diversity in the understory. Thus, community participation in forest management should be encouraged, with guided management techniques and exercises, to achieve maximum forest recovery, provide sustainable ecosystem services, and maintain forest diversity.     

印度的加瓦尔喜马拉雅山丘中部南北坡的传统农林复合系统中生产力状况

2004-2006年间,调查印度的加瓦尔喜马拉雅山丘中部南北坡的传统农林复合系统（作物＋树）中生产力状况。为了分析农林复合系统的植物社会学特性,在南北坡共选育19个树种,其中在南坡有17个树种,在北坡有12个树种。最优树种为Grewia optiva,朴树（Celtis australis）和苦楝（Melia azedarach）。结果表明：南北坡上的树种的年生产量分别为3101kg·ha^-1．a^-1和3775kg·ha^-1．a^-1。在南北坡的所有树种中,Goptiva有最高的生产量,其他种依次为苦楝（M.azedarach）,橡树（Quercus leucotrichophora）和朴树（Caustralis）。优势农作物为龙爪稷（Eleusine coracana,夏季谷物）,菜豆（Phaseolus vulgaris,夏季油料作物）,小麦（Triticum aestivum,冬季作物）。北坡的平均农作物生产量比南坡的高16％。北坡的单一农作物系统中的农作物产量比南坡的高。在南北坡,树种和农作物年生产量都有明显差别。农林复合系统中,树种和农作物的生产量比单一农作物系统中的高24％（北坡）和21％（南坡）。图1表5参33。     

Comparative Anthelmintic Activity of Strategic Sustained Low-level Administration of Albendazole in Feed Pellets Compared to Single Doses of Closantel and Tetramisole against Natural Ovine Parasitic Gastroenteritis

The strategic use of single therapeutic doses of closantel, tetramisole or sustained low-level administration of albendazole in feed pellets in controlling naturally acquired parasitic gastroenteritis in sheep was investigated on a farm in semi-arid Rajasthan, India. A total of 303 5- to 6-month-old sheep were divided into three groups. Two groups were dosed with single therapeutic doses of closantel and tetramisole and the third group was given a low-level medication with albendazole through feed pellets for 30 days. Faecal egg counts revealed significantly lower counts (p<0.001) in the group treated with closantel compared to the other two groups. The faecal egg counts in the group receiving sustained low-level albendazole rose after withdrawal of the medication but remained significantly lower than those in the group treated with tetramisole up to 7 weeks after treatment (p<0.05). On the other hand, in the group treated with tetramisole, the mean faecal egg count rose from 3 weeks after treatment and remained continuously higher than those in any other group up to 12 weeks after treatment. The closantel-treated group gained more body weight but the first six-monthly greasy fleece yield was greater in the group treated with medicated pellets. During the first 3 months of the experiment, three animals in the group treated with tetramisole died of parasitic gastroenteritis. Following sustained low-level administration of albendazole in feed pellets, the plasma disposition curve of both the sulphoxide and sulphone metabolites reached its plateau level by day 5 and remained almost constant thereafter. The comparative cost-effectiveness of the three treatment regimes during the first 3 months of treatment was best for the group treated with closantel followed by the group treated with medicated feed pellets.     

Potential Yields and On-Farm Ethanol Production Cost of Corn, Sweet Sorghum, Fodderbeet, and Sugarbeet

Field experiments were conducted during 1980-82 at the Agronomy Farm of the University of California, Davis, to compare fermentable carbohydrate production and cost of potential ethanol from fodderbeet, sweet sorghum, sugarbeet, and corn in relation to the requirements of these crops for fertilizer nitrogen and irrigation. The response of hexose yields of these crops to fertilizer N varied in the two experiments. When all crops responded, sweet sorghum and sugarbeet required 36 % and fodderbeet 68 % of the fertilizer N needed for corn. Twelve weeks following a mid-season irrigation cut off, hexose yield of sugarbeet was decreased by 18 % as compared to an adequately watered crop. Water stressed sweet sorghum extracted higher amounts of soil moisture, increased in hexose concentration and produced 29 % higher hexose yield than when adequately watered. Stressed sugarbeet, however, had a higher hexose yield due to its higher sugar concentration.
When fertilized and irrigated adequately, fodderbeet produced 13.4, sugarbeet 11.9, sweet sorghum 10.0, and corn 8.15 Mg hexose ha⁻¹. Comparative on-farm ethanol production costs of these four crops were very close ($0.38 to 0.40 L⁻¹). Thus, growing established crops like corn and sugarbeet for which processing facilities and alternative markets already exist would be preferred.