Influence of leguminous cover crops on microbial and selected enzyme activities in soils of a plantation     

R. Dinesh  M. A. Suryanarayana  G. Shyam Prasad  A. K. Bandyopadhyay  A. K. Nair  T. V. R. S. Sharma 《植物养料与土壤学杂志》1999,162(1):57-60

A study dealing with ecological sustainability of plantation based land use initiated in 1991 in a 19 yr old coconut plantation consists of growing certain leguminous crops like Atylosia, Pueraria, Centrosema and Calopogonium as soil cover in separate plots with lemon grass as live bounds. These cover crops are grown during the rainy season and incorporated into the soil towards the end of the monsoon every year. The effect of such cover crops on soil microbial counts (total counts, fungi, actinomycetes and bacteria), biomass C, organic C, total N and on the activity of enzymes like urease, amidase, L-glutaminase, aryl sulphatase and dehydrogenase was determined in soils (Ap horizon) collected from these plots after 5 years. Soils with cover crops registered significantly higher microbial biomass, biomass C, organic C and total N compared to control. Consequently, all the enzymes were activated to different degrees in soils with cover crops. Significant and positive relationships of enzyme activities with organic C, mineral N and total N suggested that growing cover crops, increased C turnover and N availability and therefore, provided a conducive environment for microbial proliferation, enzyme synthesis and accumulation in the soil matrix.  相似文献   

Empirical feed formulations for the marine ornamental fish,striped damsel,Dascyllus aruanus (Linné 1758) and their physical,chemical and nutritional evaluation     

Pananghat Vijayagopal  Gangadharan Nair Gopakumar  Koyadan Kizhakedath Vijayan 《Aquaculture Research》2008,39(15):1658-1665

Formulated feeds containing a common ingredient mixture (CIM) consisting of fishmeal (anchovies), shrimp meal (Acetes), squid meal (Loligo) and soybean meal incorporated in ascending levels to obtain protein levels ranging from 180 to 560 g kg^?1(18.34%, 25.35%, 36.27%, 46.61% and 56.28%) and an energy level of 19 MJ kg^?1 were fed to the marine ornamental fish, striped damsel, Dascyllus aruanus <200 mg and 200–300 mg in size for periods of 35 and 63 days. The <200 mg fish accepted particles <0.5 mm in size and showed maximum growth in terms of absolute growth rate (AGR), relative growth rate (RGR) and specific growth rate (SGR) with the feed containing 380 g kg^?1 CIM having a protein content of 362 g kg^?1. Second‐degree polynomial regression equations fitted confirmed these observations with a predicted requirement of 360 g kg^?1 protein. In fish weighing 200–300 mg, growth was not significantly different (P>0.05) in fish fed with feeds containing 380 and 580 g kg^?1 CIM with 360 and 470 g kg^?1 protein. With these data, the second‐degree polynomial regressions showed that a protein level of 464 g kg^?1 would result in an RGR of 107%. The feeds were well accepted by the damselfish, showing good colour retention and health.The cost of the feeds excluding processing costs ranges from US $ 1.35 to 3.36 kg^?1. This is the first report on the development of formulated feeds for damselfish that would help in rearing and aquarium keeping of damselfish worldwide.  相似文献   

Quantitative changes in soil microorganisms under rice-based multiple cropping in northern India     

P.K.R. Nair 《Soil biology & biochemistry》1973,5(3):387-389

  相似文献   

Agroforestry as a strategy for carbon sequestration   总被引：2，自引：0，他引：2  

P. K. Ramachandran Nair  B. Mohan Kumar  Vimala D. Nair 《植物养料与土壤学杂志》2009,172(1):10-23

During the past three decades, agroforestry has become recognized the world over as an integrated approach to sustainable land use because of its production and environmental benefits. Its recent recognition as a greenhouse gas–mitigation strategy under the Kyoto Protocol has earned it added attention as a strategy for biological carbon (C) sequestration. The perceived potential is based on the premise that the greater efficiency of integrated systems in resource (nutrients, light, and water) capture and utilization than single‐species systems will result in greater net C sequestration. Available estimates of C‐sequestration potential of agroforestry systems are derived by combining information on the aboveground, time‐averaged C stocks and the soil C values; but they are generally not rigorous. Methodological difficulties in estimating C stock of biomass and the extent of soil C storage under varying conditions are compounded by the lack of reliable estimates of area under agroforestry. We estimate that the area currently under agroforestry worldwide is 1,023 million ha. Additionally, substantial extent of areas of unproductive crop, grass, and forest lands as well as degraded lands could be brought under agroforestry. The extent of C sequestered in any agroforestry system will depend on a number of site‐specific biological, climatic, soil, and management factors. Furthermore, the profitability of C‐sequestration projects will depend on the price of C in the international market, additional income from the sale of products such as timber, and the cost related to C monitoring. Our knowledge on these issues is unfortunately rudimentary. Until such difficulties are surmounted, the low‐cost environmental benefit of agroforestry will continue to be underappreciated and underexploited.  相似文献   

Global scale of freshwater prawn farming     

Michael B. New  C. Mohanakumaran Nair 《Aquaculture Research》2012,43(7):960-969

In welcoming participants to Giant Prawn 2011, the authors briefly review the current scale of this component of global aquaculture. The expansion of freshwater prawn farming over the 30 years since the first global conference on this topic [Giant Prawn 1980 (GP1980)] is examined. At the time of GP1980, the output of farmed giant river prawns (Macrobrachium rosenbergii) was <3000 t. Almost three decades later (2009) the total annual aquaculture production of all species of freshwater prawns had risen to almost 444 000 t, with a value of US$2.2 billion. The farmed production of M. rosenbergii constituted 51.7% of the global total, while the oriental river prawn M. nipponense (reared totally in China) contributed 47.2%. The contribution of the monsoon river prawn M. malcolmsonii remains quite small so far, and does not show in the above percentages because no recent FAO data are available for this species. In 2007, however, the latter species contributed 1.0% of the total global production of freshwater prawns. The major freshwater prawn producing countries are in Asia (e.g. Bangladesh, China, India, Myanmar, Taiwan, Thailand and Vietnam) but Macrobrachium spp. are also farmed in other continents.  相似文献   

Protein at 69 kDa Expressed During the Initial Maturation Stage of Buckwheat (Fagopyrum esculentum) Seed Development     

Arun Nair  Taiji Adachi 《Cereal Chemistry》1999,76(2):321-322

  相似文献