Bamboo resources of Sikkim Himalaya: diversity,distribution and utilization

We recorded 8 genera and over 30 species of bamboo in Sikkim of the reported 23 genera and 125 species in India. Thirty percent of bamboo species were recorded in tropical forests(0–900 m), 40% of species in sub-tropical forests(900–1,800 m), 17% of species in temperate forests(1,800–2,700 m), 9% of species in sub-alpine forests(2,700–3,500 m) and 4% of species in alpine vegetation(3,500–4,500 m). Bamboo is used for various purposes and its versatility qualifies it to be a multiple-use alternative to timber, food for villagers and for tribal in particular. Bamboo is also equally important to Red Panda(Ailurus fulgens), the state animal of Sikkim. We develop a list of bamboos occurring in Sikkim with their vernacular names, distributions and uses in the Himalayan state. However, more extensive study is required to fully describe the bamboo diversity of the Himalayan state.     

Characterization of natural orchardgrass (Dactylis glomerata L.) populations of the Thrace Region of Turkey based on ploidy and DNA polymorphisms

Determining the ploidy and geneticdiversity of a germplasm is necessarybefore initiating breeding or geneticstudies. This study was conducted tocharacterize the ploidy level of 57 naturalpopulations of orchardgrass (Dactylisglomerata L.) collected from the ranges ofThrace region of Turkey and the diversityamong populations based on RAPD (RandomAmplified Polymorphic DNA) markers. Flowcytometry was used to determine nuclear DNAcontent (pg 2C^-1 = DNA content of adiploid somatic nucleus) of 6 plants foreach population. Nuclear DNA contents werecorrelated to ploidy level with root tipchromosome counts on selected plants. Onthe basis of this study, mean nuclear DNAcontent of orchardgrass was determined as9.57 ± 0.33 (with 95% confidenceinterval) while all the plants used inchromosome counting were determined to betetraploid, with 2n = 28 mitoticchromosomes, suggesting that diploidorchardgrass plants are likely very rare orabsent in ranges of Thrace region ofTurkey. In the RAPD assay, over 40polymorphic fragments were generated whichallowed some populations to bedistinguished from the rest by uniquemarkers. A cluster analysis was performedusing Nei's (1972) genetic distance indexwith an unweighted pair group method witharitmetic mean (UPGMA). The clusteranalysis indicated that there is a highlevel of gene flow among naturalorchardgrass populations and thereforegenes distributed quite homogeneouslythrough out the region. The results of thisstudy can be useful in the development ofDactylis germ plasm collectionstrategies in Thrace region for breedingpurpose.     

Carbon stock assessment and soil carbon management in agricultural land‐uses in Thailand

The organic carbon pool in agricultural land‐uses is capable of enhancing agricultural sustainability and serving as a potential sink of atmospheric carbon dioxide. A study was carried out to estimate and map carbon stock of different agricultural land‐uses in a sub‐watershed of Thailand and to assess the land‐use sustainability with respect to carbon management. A quadrat sampling methodology was adopted to estimate the biomass and its carbon content of 11 different land‐uses in the study area. Existing soil data were used to calculate the soil carbon. GIS was used for integrating biomass carbon, soil carbon and carbon stock mapping. Roth carbon model was used to project the soil carbon of present land‐uses in the coming 10 years and based on which the sustainability of land‐uses was predicted. The total carbon stock of agricultural land‐uses was estimated to be 20·5 Tg, of which 41·49 per cent was biomass carbon and 58·51 per cent was soil carbon. Among the land‐uses, para rubber had the highest average biomass C (136·34 Mg C ha⁻¹) while paddy had the lowest (7·08 Mg C ha⁻¹). About four‐fifths of agricultural land‐uses in the watershed are sustainable in maintaining the desired level of soil carbon in coming 10 years while one‐fifths are unstable. Such information on carbon stock could be valuable to develop viable land‐use options for agricultural sustainability and carbon sequestration. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of Legume Management on Forage Production and Residual Effects on Upland Rice

An experiment was conducted over the period 1995–96 in a warm-temperate environment in Nepal to investigate the effect of cutting frequency on forage yields of three temperate legume species, grown during the winter season, and the residual treatment effects on a subsequent upland rice crop. The three species, Persian clover ( Trifolium resupinatum ), white clover ( Trifolium repens ) and vetch ( Vicia benghalensis ), proved to be well adapted to the winter growing conditions and produced cumulative forage yields between 6.8 t DM ha⁻¹ (vetch) and 9.2 t DM ha⁻¹ (Persian clover). Vetch grew vigorously throughout the winter months and provided reasonable forage yields between December and February, whereas the clovers provided green fodder up to July. These species may therefore make a substantial contribution to alleviating the severe shortage of quality feed during the winter months. Grain yields of the subsequent rice crop ranged from 3.6 to 7.3 t ha⁻¹. Rice yields were greatly affected by the previous legume species and forage management practices. In general, the removal of legume forage greatly reduced the residual effect, and farmers will have to seek a compromise between maximizing green fodder production and the immediate beneficial residual effect of the legume crop on rice yield.     

Diagnosis of zinc and boron availability in emerging vegetable‐based crop rotations in Nepal

Background : Nepal's traditional rice–wheat rotation systems are subject to continuing changes. Changing consumer demand currently drives a replacement of wheat by high‐value vegetables during the dry season, while emerging water shortages lead to a substitution of rice by maize in the wet season. Hence, associated changes in soil aeration status and shifting conditions of soil nutrient supply to match crop nutrient demand are expected to increase the requirements for the principle limiting micro‐nutrients such as boron (B) and zinc (Zn). Aim: Our aim was to investigate the changes in B and Zn availability as well as crop yields and nutrient uptake after system shifts from rice to maize and from wheat to vegetables. Method : We analyzed the B and Zn availability in rice‐ and maize‐based systems as well as crop yields and the nutrient uptake by wheat, cauliflower, and tomato during the dry season in Nepal. Plants were grown at two field sites (midhills vs. lowland) and under greenhouse conditions using soils from the field sites. Results : A change from irrigated rice to maize reduced soil C and N contents with resulting decreases in dry season crop yields. Low soil Zn after rice cultivation led to shortage in Zn uptake by vegetables in both greenhouse and field experiments. The shift from wheat to vegetables increased the demand for B and to a lesser extent for Zn, and consequently vegetables showed visual symptoms of B deficiency. Boron concentrations in dry biomass were below the critical limits with < 10 mg B kg^?1 in wheat, < 21 mg B kg^?1 in cauliflower, and < 23 mg B kg^?1 in tomato. Conclusions: Soils in larger parts of Nepal are low in available B and that the ongoing system shifts increase in the demand for B and Zn in the currently emerging and more diversified production systems.