Resistance to Helminthosporium leaf blight and agronomic performance of spring wheat genotypes of diverse origins

Helminthosporium leaf blight (HLB), caused by a complex of Cochliobolus sativus (Ito & Kurib.) Drechsler ex Dastur and Pyrenophora tritici-repentis Died, is a serious disease of wheat (Triticum aestivum L.) in the warm lowlands of South Asia. Wheat cultivars grown in the area are either susceptible to HLB or possess low levels of resistance to it. A replicated field study was conducted in 1999 and 2000 at two sites in Nepal to determine the level of HLB resistance and other desirable traits in 60 wheat genotypes of diverse origin. The test genotypes were planted in main strips divided into two strips one of which was sprayed four times with Tilt (a.i. propiconazole) @ 125 g of a.i. ha^–1. Four readings of HLB were recorded to calculate the area under the disease progress curve (AUDPC). Other traits under investigation included biomass yield (BY), grain yield (GY), 1000-kernel weight (TKW), harvest index (HI), days to heading (DH) and maturity (DM), plant height (PHT), and effective tiller number (ETN). Wheat genotypes differed significantly for all traits. Mean AUDPC values ranged from 45 to 1268. A few exotic genotypes were highly resistant to HLB. Losses in GY due to HLB ranged from 2 to 26%, and TKW was reduced by up to 33%. A few genotypes showed HLB tolerance, i.e., relatively smaller GY and TKW reductions despite high levels of HLB. In general, medium to late maturity and higher levels of HLB resistance and low to high GY and TKW characterized genotypes exotic to South Asia. Biplot analysis identified several genotypes that were HLB-resistant and agronomically superior. Results suggest it is possible to improve HLB resistance of local wheat cultivars based on selective breeding using this pool of germplasm.     

Diversity and detection of Korean Erwinia pyrifoliae strains as determined by plasmid profiling, phylogenetic analysis and PCR

Twenty-five strains of Erwinia pyrifoliae were investigated for their plasmid profiles and genetic relatedness. Four types of plasmid profile were observed for the first time, suggesting intraspecific plasmid profile diversity in E. pyrifoliae . Moreover, BOX-PCR and phylogenetic analysis based on the 16S-23S intergenic transcribed spacer (ITS) region showed genetic variations among E. pyrifoliae strains, although all strains were clustered in one group and separated from E. amylovora . On the other hand, ERIC-PCR and phylogenetic analysis based on partial groEL gene sequences revealed close genetic relatedness among the strains. Amplification with EpSPF and EpSPR primers of a fragment of approximately 0·65 kb from the genomic DNA of all E. pyrifoliae strains, but not from E. amylovora strains, suggested that this primer set is useful for identification of this pathogen.     

Development projects,success or failure? Personal perspectives on an FAO fertilizer project in Nepal

A development project introduces various changes into a community. Some of these changes are positive while others are negative or warrant better planning. Evaluation reports designed strictly for quantitative, targetoriented physical and fiscal achievements often overlook many of these changes. Our personal field observations and experiences with an agricultural development project showed us several examples of impacts brought about in the local farming system in some hill districts of Nepal. These impacts cannot be neglected and project evaluation and progress reports should accommodate such changes     

Conservation and climate change: Assessing the vulnerability of snow leopard habitat to treeline shift in the Himalaya

Climate change is likely to affect the persistence of large, space-requiring species through habitat shifts, loss, and fragmentation. Anthropogenic land and resource use changes related to climate change can also impact the survival of wildlife. Thus, climate change has to be integrated into biodiversity conservation plans. We developed a hybrid approach to climate-adaptive conservation landscape planning for snow leopards in the Himalayan Mountains. We first mapped current snow leopard habitat using a mechanistic approach that incorporated field-based data, and then combined it with a climate impact model using a correlative approach. For the latter, we used statistical methods to test hypotheses about climatic drivers of treeline in the Himalaya and its potential response to climate change under three IPCC greenhouse gas emissions scenarios. We then assessed how change in treeline might affect the distribution of snow leopard habitat. Results indicate that about 30% of snow leopard habitat in the Himalaya may be lost due to a shifting treeline and consequent shrinking of the alpine zone, mostly along the southern edge of the range and in river valleys. But, a considerable amount of snow leopard habitat and linkages are likely to remain resilient to climate change, and these should be secured. This is because, as the area of snow leopard habitat fragments and shrinks, threats such as livestock grazing, retaliatory killing, and medicinal plant collection can intensify. We propose this approach for landscape conservation planning for other species with extensive spatial requirements that can also be umbrella species for overall biodiversity.     

Diversity and Traditional Knowledge Concerning Wild Food Species in a Locally Managed Forest in Nepal

This study documents wild food species in a locally managed forest by the inhabitants of nine villages in the Dolakha district, Nepal. It presents data on their diversity, and traditional knowledge on plant use, propagation and local domestication collected through household and key informant interviews, forest transects inventories and herbaria verifications. Sixty-two wild food plants belonging to 36 families were recorded; most of them (80%) have multiple uses. Many of the food plants are herbaceous (24 species) and produce fruits for consumption (46%). Most of the food plants are consumed by the local communities as snacks, and are supplementary and nutritionally important especially prior to the harvest of staple foods. Elder women (>35 years) are the most knowledgeable group, being able to describe the use of 65% of all edibles as compared to only 23% described by young men (<35 years). Many villagers also possess knowledge on the modes of propagation for the food plants that may be used in the process of domestication. The local communities expressed a strong desire for the establishment of community enterprises based on the wild food resources for long-term income generation sources. To accomplish this, development of collective co-operative strategies based on assessments of the biology, size of harvestable population, sustainable harvesting techniques, and marketing value and demand of promising species would be required. Moreover domestication potential based on species identified in this paper and other species that local communities have knowledge on ought to be encouraged through incentive and policy interventions.     

Analysis of protease activity in <Emphasis Type="Italic">Aspergillus flavus</Emphasis> and <Emphasis Type="Italic">A. parasiticus</Emphasis> on peanut seed infection and aflatoxin contamination

Aspergillus flavus and A. parasiticus are aflatoxin-producing fungi that can infect peanut seeds in field crops. An association between A. parasiticus proteolytic enzyme activities and peanut fungal infection was examined. For this study, a model of inductive and non-inductive culture media to produce A. parasiticus extracellular protease before infection was used. These A. parasiticus cultures were used to infect peanut seeds of cultivars resistant and susceptible to aflatoxin contamination. Peanut seeds of both cultivars exposed to fungi grown on casein medium (inductive medium) showed higher internal and external infection and a higher fungal protease content than those observed on potato dextrose agar (PDA) and sucrose medium (non-inductive media). A further study showed higher fungal colonisation and aflatoxin contamination in seeds of the resistant cultivar pre-incubated with Aspergillus extracellular proteases than in those incubated without proteases. Moreover, protease activities affected the viability of non-infected resistant cultivar seeds, inhibiting germination and radicle elongation and enhancing seed tissue injury. The results strongly suggest that protease production by A. parasiticus is involved in peanut seed infection and aflatoxin contamination resulting in seed tissue damage, affecting seed viability and facilitating the access of fungi through the testa. The analysis of fungal extracellular proteases formed on peanut seed during infection showed that A. flavus and A. parasiticus produced metallo and serine proteases; however, there were differences in the molecular masses of the enzymes between both species. The greatest activity in both species was by serine protease, that could be classified as subtilase.     

Plant genetic resources of Nepal: A guide for plant breeders of agricultural, horticultural and forestry crops

Summary Nepal is rich in indigenous wild and landrace plant genetic resources for agronomic, horticultural, forestry, or medicinal uses, but much of this germplasm remains uncollected and awaits economic development. We list 485 entries (species, or genera for ornamental plants) in 14 categories, and compare these to existing germplasm collections in Nepal and the United States to highlight collection and conservation needs. To help plant plant collecting, we outline the key botanical and logistical data and legal framework for planning field work in Nepal.     

Determination of phosphorus saturation level in relation to clay content in formulated pond muds

An experiment was conducted to determine the amount of P needed to saturate simulated fish pond sediments, formulated to contain six levels of clay (0, 30, 41, 64, 73 and 81% by weight). A series of cylindrical cement tanks were filled to 20 cm depth with the six sediment types and triple superphosphate (TSP) solution was added to reach P saturation in sediment. Results showed that all sediment types reached constant inorganic-P concentration in the upper 5 cm after 12 weeks of TSP application, and P adsorption capacity of sediment increased with increasing clay content. Sediment P adsorption was slower and not significant (P > 0·05) below 5 cm depth except in the sediment type containing 0% clay. Regression analysis showed that the rate and adsorption capacity of P in sediment are primarily governed by clay content and its dominant minerals. While organic-P and loosely bound-P are commonly deposited in sediment, most inorganic-P is adsorbed by cations to form cation-P complexes. The linear relationship between cation-P saturation level and the percentage of clay in sediment is highly significant (r² = 0·84, P < 0·001) and, therefore, maximum adsorption capacity of cation-P in pond sediment can be approximated by Y = 0·019X (where Y represents the 100% saturation level in mg P g⁻¹ soil, and X is the percentage of clay in the sediment). In practice, the level of P saturation in sediment can be approximated by the initial cation-P and clay contents in the top 5 cm of pond mud using the equation: P saturation (%) = initial cation-P (mg g⁻¹ soil) × 100/P adsorption capacity (mg g⁻¹ soil).     

Flood vulnerability assessment in the light of rice cultivation characteristics in Mekong River flood plain in Cambodia

Demographic changes, such as aging and depopulation in rural areas, are major reasons for the recent abandonment of the terraced paddy fields in Japan. In addition, the low productivity of terraced paddy fields, due to their small area and the difficulty of using machinery on the plots, further abet this trend. Recent research has shown a growing interest in multifunctional conservation and maintenance of the ecosystem and traditional agro-culture of terraced paddy fields. This paper aims to elaborate on the conservation activities of endangered terraced paddy fields in Japan, by using the case of Shiroyone Senmaida to discuss conservation experience and lessons, and recommend future strategies for adaptive management of the rice terraces under the GIAHS framework, as well as the next necessary steps for research. As an outstanding cultural landscape and tourist attraction in Noto Peninsula, the conservation scheme combining financial support from governmental subsidy, the “owner system” of interaction with urban dwellers, and labor support by conservationist volunteers has contributed to the conservation of traditional farming on Senmaida’s terraced paddy fields. Still, as is the case in other parts of Japan, lack of financial support and an aging farming population threaten conservation of terraced paddy fields in Noto Peninsula.