Genetic diversity in blast resistance of Bhutan rice landraces

With an objective to evaluate the Bhutan rice (Oryza sativa L.) landraces for genetic diversity in blast resistance, 402 accessions viz. 352 landraces, a differential set of 32 R gene lines and 18 modern cultivars were field-evaluated in three blast ‘hotspot’ sites followed by genetic analysis of the 352 landraces with 27 microsatellite markers. Across the sites, 19 landraces (5.4%) exhibited complete resistance with zero disease score and 203 (58%) and 163 (46%) landraces showed high partial resistance for early leaf and panicle blast, respectively, with disease score of four to six. Field evaluation for leaf and panicle blast at three experimental sites in Bhutan showed best cultivar discrimination in early leaf blast at the tillering stage (heritability, h² = 0.32) and in the panicle blast at maturity (h² = 0.44). Subdivision of the genetic variation into cultivar groups revealed the most variation for blast severity within the 352 landraces with h² of 0.31 and 0.46 for early leaf and panicle blast, respectively. Cluster analysis of the landraces revealed two distinct rice cultivar groups, which separated at dissimilarity of 0.84 according to origin of the cultivars from low, mid and high altitude zones in Bhutan. All microsatellites were polymorphic with two to 21 different alleles per marker and a high polymorphic information content value of 0.61. The identified blast resistant landraces were genetically diverse originating from different rice cultivation zones. Further investigation of the resistant and partial resistant material may reveal specific blast resistance genes, which could be useful to mitigate blast incidence in rice-producing countries.     

Linking physical, economic and institutional constraints of land use change and forest conservation in the hills of Nepal

This paper analyses the changes in spatial patterns of agricultural land use during the period 1976–2000 along the altitudinal gradients in a watershed in Nepal. Land change patterns during this period were examined using information on land use derived from satellite images from 1976, 1990 and 2000. During the 24-year period from 1976 to 2000 agricultural land use increased by 35% at a cost of loss of forestland. Agricultural expansion was most conspicuous at higher elevations (1150–2000-m). About 36%, 18% and 6% of forestland was converted into agricultural activities from higher, middle and lower elevations respectively in the period from 1990 to 2000. Spatial distribution of living standard parameters, including farm family income and, food availability obtained from family surveys, shows a decreasing trend as the elevation increases whereas percentage of food bought shows an increasing trend. In this way it was found that, lost forest areas were smaller when located around high-income areas with good quality agricultural land and near an administrative centre as compared to areas located around low-income areas with low quality agricultural land and far from an administrative centre. Additionally, a regression model is constructed, to link the socioeconomic variables with the conversion of forestland into agricultural activities, breaking the study area into smaller zones. The spatial trajectories of these zones are then contrasted, paying particular attention to the socioeconomic conditions and institutional arrangements governing access to land resources. The study finds that while overall land change patterns in the region are largely explained by elevation and the socioeconomic conditions of people living adjacent to the forestland, more specifically, in sub-regional areas, trajectories reflect the signatures of institutions governing access to land. As sustainability of the watershed is dependent on forests, continued depletion of forest resources will result in poor economic returns from agriculture for local people together with loss of ecosystem services.     

Metabolic Diversity of Xanthomonas axonopodis pv. vignicola, Causal Agent of Cowpea Bacterial Blight and Pustule

Fifty-five strains of Xanthomonas axonopodis pv. vignicola, isolated from blight and pustule symptoms of cowpea leaves, originating from 11 countries, were characterized for their carbon-source metabolization pattern using the Biolog GN microplate system. Great variation was found between strains according to origin. Dextrin, glycogen and succinamic acid were not used by strains from Benin, Uganda or Thailand, but by all the other strains (excluding two strains from Mozambique), whereas N-acetyl-D-glucosamine and malonic acid were used by the strains from Benin, Uganda and Thailand, but generally not by the other strains. The strains from Benin, Uganda and Thailand, as well as strains from Venezuela, Brazil and Mozambique, clustered separately from the others in multivariate analysis. Nineteen substrates were used by all the strains, 47 not by any strain and 29 only by some strains. No considerable differences were found between strains isolated from blight symptoms and from pustules. Virulence of strains was not related to the metabolic pattern. The Biolog database was not representative of the diversity of X. axonopodis pv. vignicola, since all strains were identified as Xanthomonas campestris, although belonging to eight pathovars, while only eight of nine strains from Benin and both strains from Thailand were identified as X. campestris pv. vignicola. The Biolog system appeared to be useful for characterizing the diversity of X. axonopodis pv. vignicola strains. A set of representative strains based on metabolic and molecular diversity, virulence and geographic origin is suggested for screening for resistant cowpea cultivars.     

Partnering with farmers to accelerate adoption of new technologies in South Asia to improve wheat productivity

There are many socioeconomic and technological constraints that affect the production of wheat and other staple cereals in South Asia. Wheat production is one of the economic mainstays in South Asia, but the yield gap between farmers’ fields and experimental yields is wide across the region. For the last 3 years, CIMMYT and the CAZS-NR have been collaborating with farmers, NARS, and other South Asian partners to promote improved wheat varieties and new resource conservation technologies (RCTs) in farmers’ fields. Participation fostered among farmers, scientists, extension specialists, NGOs and the private sector included variety selection (PVS), and evaluation of agronomic practices. Through PVS, several farmer-preferred technologies have been identified including wheat varieties for adverse conditions in eastern Uttar Pradesh (India) and for boron deficiency in parts of Nepal. There has been considerable improvement in the access of farmers to new varieties and technologies in the rural areas. Yield increases (15–70%) have been achieved by resource-poor farmers over the existing varieties through the adoption of new varieties and RCTs. The farmers have also made substantial cost savings and achieved higher yields through resource-conserving agronomic techniques such as zero till. Seed of the new farmer-selected cultivars has been multiplied by groups of collaborating farmers and widely distributed.     

Effect of collector temperature and conductivity on the chain conformation of nylon 6 electrospun nanofibers

Electrospinning is a versatile process used to prepare micro- and nano- sized fibers from various polymer solution. Here, we dealt with the variation in the morphology of nylon 6 electrospun nanofibers and their polymorphism depending on the type and physical state of the collectors. SEM study showed that the fiber diameter was increased from 80 to 103 nm while it was collected in water bath. Similarly the fiber diameter and bonding was increased 103 to 115 nm with the temperature whereas it was linearly decreased 103 to 90 nm with the conductivity of the water bath. Spectroscopic analysis (FT-Raman, FT-IR) showed that the polymorphism of nylon 6 depended on the types of collector (aluminum sheet and water bath). Nylon 6 electrospun nanofibers display theγ-phase while collected in aluminum sheet andα-phase while collection in water bath. The extent of transformation fromγ- toα-phase was linearly increased with temperature and conductivity of the water bath.     

Consumer Preferences for Live Seafood in the Northeastern Region of USA: Results from Asian Ethnic Fish Market Survey

Asian ethnic fish markets in the Northeastern region of the United States of America (USA) are popular for selling live fish and seafood. A consumer survey was conducted in selected supermarkets of New York, New Jersey, and Pennsylvania during the summer of 2009 to assess consumer preferences for live seafood species. A binary logit model was developed to study the factors influencing preferences for live and fresh fish products. Results indicated that consumer preferences for live fish species vary by ethnic group. Live fish customers visited supermarkets at least two to three times a week and spent $16 to $20 a week to purchase medium size fish (0 to .91 kg live fish, on average). Freshness and appearance (bright, free of bruises, healthy fish) were the most important attributes. Findings indicate that promotion of live fish sales should be targeted to those stores dominated by East Asian (Chinese, Korean, and Japanese) customers.