Mycorrhizal fungi-Bradyrhizobium-soybean tripartite symbiosis in Iowa soils

Soybean [Glycine max (L.) Merr.] makes use of two important symbiotic microbial systems: the rhizobial system, in which Bradyrhizobium japonicum fix atmospheric N2 in root nodules, and the vesicular-arbuscular mycorrhizal system, in which VAM fungi increase uptake of phosphate and/or other nutrients from the soil or improve plant drought tolerance. Research has confirmed the advantage of bradyrhizobial and mycorrhizal associations in N and P deficient soils; however, these associations may be inhibitory, or have little effect on plant growth in well-fertilized soils. In Iowa over the past 30-40 years, farmers have been adding large quantities of fertilizers to get maximum yields. The question is, has increased soil fertilization selected against optimal symbiotic microbial associations? If so, how can we improve the present microbial associations for possible use by legumes in low-input, sustainable agricultural systems. Two studies were conducted to investigate the levels of VAM fungal colonization and sporulation in Iowa soils, and the possible influence of P-fertilization on mycorrhizal fungal efficiency and subsequent interaction with bradyrhizobia. The first part, entitled VAM Fungal Colonization of Soybean and Spore Populations in Iowa Soils, was a field survey of the soybean rhizosphere that evaluated the percentage VAM fungal colonization in soybean roots and the populations of associated VAM fungal genera. This part contains an Introduction, Materials and Methods, Results and Discussion, Conclusions, and References Cited sections. Tables also are included in the text

Relative Efficiency of Decision Making Units Producing Both Desirable and Undesirable Outputs: A Case of Textile Processing Units in Pakistan.

This paper aims at measuring the relative efficiency of the most polluting industry in terms of water pollution in Pakistan. The textile processing is country‘s leading sub sector in textile manufacturing with regard to value added production, export, employment, and foreign exchange earnings. The data envelopment analysis technique is employed to estimate the relative efficiency of decision making units that uses several inputs to produce desirable and undesirable outputs. The efficiency scores of all manufacturing units exhibit the environmental consciousness of few producers is which may be due to state regulations to control pollution but overall the situation is far from satisfactory. Effective measures and instruments are still needed to check the rising pollution levels in water resources discharged by textile processing industry of the country. JEL classification: L67, Q53 Keywords: Data Envelopment Analysis (DEA), Decision Making Unit (DMU), Relative Efficiency, Undesirable Outpu

Mycorrhizae (VAM) of soybean in soil toposequences and mycorrhizal dependency of corn and soybean cultivars

A field survey investigated the effect of soil toposequences on vesicular-arbuscular mycorrhizal fungal (VAMF) spore counts in soil and VAMF colonization of soybean. VAMF spores were significantly different among locations, series, and series within a location. Colonization was negatively correlated with soil drainage;A second study determined whether soybean and corn cultivars varied in mycorrhizal dependency (MD) and, if so, whether this variability was explained by differences in plant morphological or physiological characteristics. Mycorrhizal dependency, nutrient uptake, phosphatase activities, and leaf areas of six corn and five soybean cultivars grown in low P soil were studied under greenhouse conditions. Soybean cultivars had higher MD than corn cultivars. Among soybean cultivars, unimproved cultivars had higher MD than improved cultivars. Shoot growth of Soja was 19 times greater and Mandarin four times greater with VAMF colonization than without colonization. Argentine pop, unimproved corn cultivar, was highly responsive to VAMF colonization whereas Reid yellow dent was unresponsive. Total uptake of P, N, K, Ca, Mg, and Zn was higher in mycorrhizal plants, but percentages of N, Mg, and Ca were lower. Acid phosphatase activity, shoot weights, leaf areas, and percentages of P were positively correlated with VAMF colonization;A further study evaluated three soybean cultivars, from high MD to low MD, for differences in root morphologies, P uptake, P use efficiencies, and root acid phosphatase activity at three P levels. This study showed significant cultivar-by-mycorrhizae and cultivar-by-P level interactions. Mycorrhizal dependency of Soja decreased from 70% in low P to 10% in high P soils. VAMF colonization of Swift at high P resulted in a 4.3% reduction in shoot weight. At low P, VAMF Soja plants had 564% greater total P than nonmycorrhizal plants. Comparable values for Mandarin and Swift were 242 and 165%, respectively. Soja roots had higher acid phosphatase activity than other cultivars and a higher relative increase in activity with VAMF colonization than without colonization. The root lengths of Soja were significantly shorter than those of Swift and Mandarin. The mean diameter of lateral roots of Soja was greater than that of Swift and Mandarin roots. Root lengths and surface areas were negatively correlated with MD. (Abstract shortened by UMI.

Is Trade Good for Environment? A Unit Root Cointegration Analysis

One of the most debatable issues surrounding globalisation is the concern that trade hurts the environment, both locally and globally. Economists argue that expanding trade from domestic market to international market not only increases market share of each country but also rising competition among the nations and improve efficiency of utilising scarce resources because each country produces those goods in which she has comparative advantages. But on the other hand, environmental economists have opposed global trade and argue that the costs of spreading trade to international markets are depleting natural resources and rising pollution emissions that ultimately deteriorates environmental quality. [Copeland and Taylor (2001), Antweiler, Copeland and Taylor (2001), Chaudhuri and Pfaff (2002), Schmalensee, Stoker and Judson (1996).

Research Notes: Impacts of Economic Globalization on Sustainable Development

The last decade of the last century coined two strategic terms, Globalization and Liberalization which stand more than any other term for the global economic development. The economic policies, adopted and enforced globally by the industrial powers are described by globalization and liberalization after collapse of the socialist block and became dominant in the entire Western world. These policies basically constitute the market oriented free trade economies. Previously there were two political systems competing and influencing in the world. Developing countries receiving international development assistance therefore had a certain leeway. Most of these countries have little or no infrastructure or skills and also a very weak private sector. Such countries were, and many of them are still not prepared for the free trade system of economic development. They found it necessary to pursue a planned economic growth under the guidance of the state. These planned economies have not, in all respects, been a success. Far from it, the fact is that many developing countries have not had the necessary governing experience to run a planned economic system, and in some cases, corruption and internal conflicts have led them to tyranny and anarchy, unfortunately. But the question is whether the free trade system of economic growth under the auspices of globalization and liberalization has been a success

Role of Tourism in Economic Growth: Empirical Evidence from Pakistan Economy

Tourism activities are considered to be one of the major sources of economic growth. It can be regarded as a mechanism of generating the employment as well as income in both formal and informal sectors. Tourism supplements the foreign exchange earnings derived from trade in commodities and some times finance the import of capital goods necessary for the growth of manufacturing sectors in the economy. On the other hand rapid economic growth in the developed economies attracts foreign travels (Business travels), which leads to an increase in the foreign reserve of the country. Over the past several decades, international tourism has been gaining importance in many economies of the world. According to the World Tourism Organisation (2002), expenditures by 693 million international tourists traveling in 2001 totaled US $462 billion, roughly US$ 1.3 billion per day worldwide. In addition, tourists spending have served as an alternative form of exports, contributing to an ameliorated balance of payments through foreign exchange earnings in many countries. The rapid growth of tourism led to a growth of household incomes and government revenues directly and indirectly by means of multiplier effects, improving balance of payments and provoking tourism-promoted government policies. As a result, the development of tourism has generally been considered a positive contribution to economic growth