The Imperata grasslands of tropical Asia: area, distribution, and typology     

D. P. Garrity  M. Soekardi  M. van Noordwijk  R. de la Cruz  P. S. Pathak  H. P. M. Gunasena  N. van So  G. Huijun  N. M. Majid 《Agroforestry Systems》1996,36(1-3):3-29

The rehabilitation or intensified use of Imperata grasslands will require a much better understanding of their area, distribution, and characteristics. We generated estimates of the area of Imperata grasslands in tropical Asia, and suggested a typology of Imperata grasslands that may be useful to define the pathways toward appropriate land use intensification. We conclude that the area of Imperata grasslands in Asia is about 35 million ha. This about 4% of the total land area. The countries with the largest area of Imperata grasslands are Indonesia (8.5 million ha) and India (8.0 million ha). Those with the largest proportion of their surface area covered with Imperata are Sri Lanka (23%), the Philippines (17%), and Vietnam (9%). Laos, Thailand, Myanmar, and Bangladesh evidently all have similar proportions of their land area infested with Imperata (about 3 to 4%). Malaysia (< 1%), Cambodia (1%), and the southern part of China (2%) have but a minor proportion of their total land area in Imperata. The species was found widely distributed on the full range of soil orders. It occupied both fertile (e.g. some of the Inceptisols and Andisols) and infertile soils (Ultisols and Oxisols) across a wide range of climates and elevations. Imperata lands fall into four mapping scale-related categories: Mega-grasslands, itmacro-grasslands, meso-grasslands, and micro-grasslands. The mega-grasslands are often referred to as sheet Imperata. They are the large contiguous areas of Imperata that would appear on small-scale maps of say 1:1,000,000. We propose that this basic typology be supplemented with a number of additional components that have a key influence on intensification pathways: land quality, market access, and the source of power for tillage. The typology was applied in a case study of Indonesian villages in the vicinity of Imperata grasslands. We propose an international initiative to map and derive a more complete and uniform picture of the area of the Imperata grasslands. This should include selected studies to understand conditions at the local level. These are critical to build the appreciation of change agents for the indigenous systems of resource exploitation, and how they relate to local needs, values and constraints.  相似文献   

The application of polyamines by pressure or immersion as a tool to maintain functional properties in stored pomegranate arils     

Mirdehghan SH  Rahemi M  Serrano M  Guillén F  Martínez-Romero D  Valero D 《Journal of agricultural and food chemistry》2007,55(3):755-760

Pomegranate fruits were treated with putrescine (Put) or spermidine (Spd) at 1 mM either by pressure infiltration or by immersion and then were stored at 2 degrees C for 60 days. Samples were taken biweekly and were further stored 3 days at 20 degrees C for shelf life study. The treatments were effective on maintaining the concentration of ascorbic acid, total phenolic compounds, and total anthocyanins in arils at higher levels than in control samples. In addition, the two ways of polyamine application increased the levels of total antioxidant activity (TAA) during storage, especially when polyamines were applied by pressure infiltration. Moreover, Spd showed the best results on increasing TAA through maintenance of total phenolic compounds.  相似文献   

Monitoring the efficacy and metabolism of phenylcarbamates in sugar beet and black nightshade by chlorophyll fluorescence parameters     

Abbaspoor M  Streibig JC 《Pest management science》2007,63(6):576-585

Desmedipham, phenmedipham and a 50% mixture of the two decreased the maximum quantum efficiency of photosystem II (F(v)/F(m)) and the relative changes at the J step (F(vj)) immediately after spraying in both sugar beet and black nightshade grown in the greenhouse. Sugar beet recovered more rapidly from phenmedipham and the mixture than from desmedipham. Desmedipham and the mixture irreversibly affected F(v)/F(m) and F(vj) in black nightshade at much lower doses than in sugar beet. Black nightshade recovered from phenmedipham injury at the highest dose in the first experiment (120 g AI ha(-1)) but not in the second experiment (500 g AI ha(-1)). The dry matter dose-response relationships and the energy pipeline presentation confirmed the same trend. There was a relatively good correlation between F(vj) taken 1 day after spraying and dry matter taken 2 or 3 weeks after spraying. The differential speed of herbicide metabolism between weed and crop plays an important role in herbicide selectivity and can be studied by using appropriate chlorophyll a fluorescence parameters.  相似文献   

Effect of site and elevation on wood density and shrinkage and their relationships in Carpinus betulus     

Majid KIAEI 《中国林学(英文版)》2012,14(3):229-234

This study examined the effect of site and elevation on the oven-dry density and volumetric shrinkage of hornbeam (Carpinus betulus) wood.For this purpose,45 normal hornbeam trees from three different sites (Mazandaran,Guilan and Golestan) at three elevations,300 m (low elevation),700 m (intermediate elevation) and 1100 m (high elevation) from natural forest in northern Iran were selected.Disks were cut at breast height from mature wood and test samples were prepared to determine physical properties,i.e.,wood density and volumetric shrinkage.The results show that there are significant differences between site and elevation on these physical properties of wood.The interaction effects between site × elevation on wood density and volumetric shrinkage were also statistically significant.At any fixed site,wood density and volumetric shrinkage increased with elevation.As well,their values at Guilan were higher than those at the other two sites.The relationship between wood density and volumetric shrinkage was determined by simple regression equations.Strong,positive relationships between wood density and volumetric shrinkage at each site were found.Again,these were stronger at the Guilan site than at the other two sites.Given a fixed site,the correlation at high elevation was stronger than at the other two elevations.  相似文献   

Selective genotyping to identify late blight resistance genes in an accession of the tomato wild species <Emphasis Type="Italic">Solanum pimpinellifolium</Emphasis>     

Heather L. Merk  Hamid Ashrafi  Majid R. Foolad 《Euphytica》2012,187(1):63-75

Late blight (LB), caused by the oomycete Phytophtohra infestans, is one of the most destructive diseases of tomato (Solanum lycopersicum) and other Solanaceae species. Current disease control and prevention strategies are not sufficient to control the disease in tomato. Recent germplasm screening experiments led to the identification of a new source of resistance (PI 270443) in the tomato wild species S. pimpinellifolium. This study was conducted to identify genomic regions associated with LB resistance in this accession. A large F₂ population (n = 986) derived from a cross between PI 270443 and a LB-susceptible tomato breeding line (NCEBR-2) was screened for LB resistance using a highly aggressive isolate of P. infestans. Twenty-five of the most resistant and 29 of the most susceptible, but surviving F₂ individuals were identified based on disease evaluations conducted in the F₂ and F₃ progeny populations. The selected individuals were genotyped with 153 DNA markers located across the 12 tomato chromosomes. A selective genotyping approach led to the identification of two genomic regions on tomato chromosomes 1 and 10 associated with LB resistance in PI 270443. Identification of two genomic regions associated with resistance was consistent with a previous estimate of the number of LB resistance genes in this accession. Research is currently underway to fine map the two resistance genes and incorporate them into new tomato breeding lines and hybrid cultivars.  相似文献   

Parent–offspring correlation estimate of heritability for late blight resistance conferred by an accession of the tomato wild species Solanum pimpinellifolium     

Heather L. Merk  Majid R. Foolad 《Plant Breeding》2012,131(1):203-210

  相似文献   

Metals in Main Rivers of Azerbaijan: Influence of Transboundary Pollution     

Bahruz Suleymanov  Majid Ahmedov  Kamala Safarova  Eiliv Steinnes 《Water, air, and soil pollution》2010,213(1-4):301-310

Silver, arsenic, cadmium, chromium, cobalt, copper, mercury, lead, and zinc were determined monthly during 2004–2008 at 11 sites in the Kura–Araks river system, Azerbaijan. Suspended fractions of the elements were studied at the five sites experiencing the highest load. Metal concentrations varied moderately at each site but differed substantially between sites. Sites near the borders with Armenia and Georgia were most polluted, both with respect to soluble concentrations and percentage transported in suspended form. Lower parts of the Kura river were shielded from metal contamination by an upstream reservoir acting as a metal trap. Corresponding removal was not evident in Araks, its main tributary, where particularly high concentrations of arsenic were observed. At the most contaminated sites, more than 60% of cadmium, cobalt, chromium, copper, manganese, nickel, lead, and zinc was transported in suspended form whereas arsenic and molybdenum occurred mainly in soluble form. Dynamics of metals in the Kura–Araks water/sediment system should be further studied to meet future problems.  相似文献   

Assessment of soil erodibility and aggregate stability for different parts of a forest road     

Aidin Parsakhoo  Majid Lotfalian  Ataollah Kavian  Seyed Ataollah Hosseini 《林业研究》2014,25(1):193-200

We measured erodibility and mean weight diameter （MWD） of soil aggregates in different parts of a forest road. Samples of topsoil were collected from cutslope, fillslope, road surface and forest ground to assess the texture, bulk density, moisture, CaCO3 and organic matter. Soil aggregate stability was determined by wet sieving. Soil erodibility on the road surface was 2.3 and 1.3 times higher than on the fillslope and cutslope, respectively. The forest soil had the lowest erodibility. Aggregate stability of cutslope and road surface were low and very low, respectively. There was a significant negative relationship between cutslope erodibility with CaCO3 and sand content. Cutslope erodibility increased with increasing silt, clay and moisture content. On fillslopes, MWD increased with in-creasing rock fragment cover, plant cover, litter cover, organic matter and sand. There was a strong negative correlation between fillslope erodibility and organic matter, sand and MWD. There was no significant difference between erodibility of bare soil and soils beneathRubus hyrcanusL. and Philonotis marchica （Hedw.） Brid.  相似文献   

Symbolic and social dimensions in the economic production of seaweed     

Fadzilah Majid Cooke 《Asia Pacific viewpoint》2004,45(3):387-400

Abstract: Based on the thesis of ‘deagrarianisation’ of farming economies, work on sustainable rural livelihoods (SRL) has successfully captured the agency of rural producers as they diversify their livelihoods to minimise risk. SRL captures a complex interplay of local and global factors, as well as the synergies emanating from natural (environmental), economic and social capital that underpin diversification. The framework has been found useful for analyses of change in coastal, marine‐based livelihoods. However, agency at the local level implies equal power to accept and reject development interventions. The way groups diversify or use the options open to them depends as much on access to resources (the means), as on how that access is interpreted (the meaning), and the latter dimension is a creative (unpredictable) one. New introduced forms of economic activities, in this case seaweed farming, can be assigned meaning by participants that were unanticipated by change agents. Livelihood diversification through seaweed cultivation on Banggi island off Kudat, northern Sabah (East Malaysia) is not attained by economic factors alone but also by the meaning attached to the activity.  相似文献   

Responses of Growth and Chemical Composition of Pistachio Seedling to Phosphorus Fertilization Under Saline Conditions     

Majid Fekri  Latifeh Gharanjig 《Journal of plant nutrition》2015,38(12):1836-1848

A greenhouse study was conducted to evaluate effects of phosphorus (P) levels (0, 50 and 100 mg kg^?1 soil) under saline (0, 1000 and 2000 mg sodium chloride (NaCl) kg^?1 soil) conditions on growth and chemical composition of pistachio seedlings (Pistacia vera L.) cv. ‘Badami-zarand’ in a completely randomized design (CRD) with four replications. Results showed that salinity application decreased leaf, stem, and root dry weights, number of leaf, length of stem and leaf area, while this effect diminished with P fertilization. By increasing salinity levels, all of the nutrients concentration in leaf, stem and root except sodium (Na) content were reduced. P application increased P and potassium (K) concentrations in the leaves, stem and root, while decreased Na and Zinc (Zn) leaf, stem and root concentrations. However, the results indicated that proline accumulation and reducing sugar content were increased by salinity, P and their interaction application. The results suggest that fertilization of phosphorus can diminish some adverse effects of high salinity on growth and chemical composition of pistachio seedlings.  相似文献