Weed Biology,Cropping Systems,and Weed Management

SUMMARY

Weeds pose a recurrent threat to agricultural productivity in both industrialized and developing countries. Weeds respond dynamically to all cropping practices, and therefore, the design and function of cropping systems plays a central role in the composition of weed communities. The unique and challenging nature of weed communities requires more integrated approaches to weed management than are currently being employed by most growers. Integrating weed management with cropping system design and application may be an effective approach to diversifying weed management systems. Each crop-weed system is a unique mix of genetics and biology and will respond dynamically to changes in management practices. Practices such as crop rotation, tillage, cover crops, and fertility management modify weed populations. The challenge is to integrate these and other practices with the best available control tactics to generate integrated management systems. Cropping system design provides an excellent framework for developing and applying integrated approaches to weed management because it allows for new and creative ways of meeting the challenge of managing weeds. Weed science must integrate the theories and application of weed management into cropping system design based on the unique characteristics of weed communities and the available weed management options.     

Education in Agroecology and Integrated Systems

Summary

Courses and curricula in agriculture are traditionally organized within disciplinary boundaries, while study of integrated systems has been confined to aggregation of components and often superficial analysis. Agroecology is emerging as an integrative field that expands our focus to embrace the broad complexities of agricultural production and the entire food system. Education in agroecology must provide the skills and knowledge needed to design and evaluate new systems, as well as the capacity to vision into the future and anticipate the impacts of systems as well as new challenges that will face humanity. Agricultural universities need to be organized to prepare students to meet these increasingly complex challenges in the food and natural resource arena. Agroecology courses can build awareness and competence in using ecological principles to inform the design of future systems that are productive, economically sound, environmentally sustainable, and socially viable for the indefinite future. A model program in the Nordic region is presented as an example of one innovative curriculum. Study of the ecology of food systems can put natural resource, human population, and agricultural production into a balanced perspective that can guide our research and development efforts toward a sustainable food system for the future.     

Integrating Agroecological Processes into Cropping Systems Research

Summary

Agroecology is defined as the application of ecological concepts and principles to the design and management of sustainable agroecosystems. By viewing cropping systems as agroecosystems, an understanding of the value of the emergent qualities of systems can become a guiding element in research design. A framework for applying this approach in cropping systems research in proposed. A protocol for researching the conversion to sustainable agriculture involves three levels of investigation. The first focuses on improving the efficiency of conventional farming inputs and practices in ways that reduce both their amounts and the environmental impacts of their use. The second focuses on substituting conventional inputs and practices with alternatives that meet broader environmental standards, such as certified organic. Since the problems addressed at these two levels continue to present themselves, a third level is proposed whereby the agroecosystem is redesigned so as to operate on the basis of a new set of ecological processes. At this third level, the emergent qualities of the system itself help prevent problems. Such an approach promotes the conversion to sustainability.     

Socioeconomic and Agricultural Factors Associated with Mixed Cropping Systems in Small Farms of Southwestern Guatemala

SUMMARY

Many small farming communities in Latin America have modified their traditional cropping systems to incorporate non-traditional export crops (NTEC). The shift from subsistence to commercial agriculture is perceived by development agencies as an opportunity to alleviate poverty in rural areas. However, most small-scale farmers are not familiar with the production problems of NTEC, such as Bemisia tabaci and various geminiviruses transmitted by this whitefly species. In the absence of adequate technical assistance, due to drastic budgetary reductions in national agricultural research programs, farmers have relied on agrochemicals to protect their NTEC. This situation has led to considerable pesticide abuse and rejection of contaminated produce in international markets. This study analyzes some of the factors determining the adoption of NTEC and displacement of traditional food crops in southwestern Guatemala, and suggests possible measures to allow small farming communities to benefit from broad-based cropping systems that include both traditional and non-traditional food and cash crops.     

Challenges and opportunities for improving N use efficiency for rice production in sub-Saharan Africa

ABSTRACT

In sub-Saharan Africa (SSA), rice production from smallholder farms is challenged because of a lack of fertilizer inputs and nutrient-poor soils. Therefore, improving nutrient efficiency is particularly important for increasing both fertilizer use and rice yield. This review discusses how to improve the return from fertilizer input in terms of agronomic N use efficiency (AE_N), that is, the increase in grain yield per kg of applied N, for rice production in SSA. The AE_N values we summarized here revealed large spatial variations even within small areas and a certain gap between researcher-led trials and smallholder-managed farms. Experimental results suggest AE_N can be improved by addressing spatial variations in soil-related factors such as P, S, Zn, and Si deficiencies and Fe toxicity in both irrigated and rainfed production systems. In rainfed production systems, differences in small-scale topography are also important which affects AE_N through dynamic changes in hydrology and variations in the contents of soil organic carbon and clay. Although empirical evidence is further needed regarding the relationship between soil properties and responses to fertilizer inputs, recent agricultural advances have generated opportunities for integrating these micro-topographical and soil-related variables into field-specific fertilizer management. These opportunities include UAV (unmanned aerial vehicle) technology to capture microtopography at low cost, database on soil nutrient characteristics at high resolution and more numbers of fertilizer blending facilities across SSA, and interactive decision support tools by use of smartphones on site. Small-dose nursery fertilization can be also alternative approach for improving AE_N in adverse field conditions in SSA.

ABBREVIATIONS: AE_N: agronomic nitrogen use efficiency; FISP: farm input subsidy program; VCR: value cost ratio; SOC: soil organic carbon; SSA: sub-Saharan Africa; UAV: unmanned aerial vehicle     

Problems and Perspectives of Yam-Based Cropping Systems in Africa

SUMMARY

Yams (Dioscorea spp.) constitute an important starchy staple in sub-Saharan Africa (SSA) where food security for a growing population is a critical issue. Mixed cropping in yam based systems is the norm in the region and productivity of yams in these systems is below potential. It is concluded that there is much scope for improvement of yam based cropping systems in SSA in order to meet the needs of the region. The strategy of crop breeding to select yam varieties suitable for various cropping systems must consider a truly multidisciplinary systems approach. Further manipulation must be made to tuber dormancy to expand flexibility in field propagation in different cropping systems and improve storage and marketing. The sustainability of yam based cropping systems in SSA could improve if agronomic research was focused on strategies for improving soil fertility, weed and pest management including design of cropping systems and suitable rotations.     

Cropping Systems and Integrated Pest Management: Examples from Selected Crops

SUMMARY

Cropping systems have been central to managing associated pests for centuries. This treatment focuses on the history, concepts, and the integration of available Integrated Pest Management (IPM) tools/strategies into cropping systems. Pest assessments/diagnoses, IPM-decision-making aids, and examples of pest management in selected crops/cropping systems (wheat, soybean, corn, cotton, potato, and strawberry) as well as emerging opportunities and challenges are discussed. The evolving philosophy of IPM and the recently renewed emphasis on ecologically based pest management address the fact that significant levels of predation and/or parasitism are desirable insofar as they promote diversity and sustainability of agroecosystems. Thus, cropping systems are beginning to focus on soil and crop health as well as specific IPM and production goals. Although extensive efforts have been directed toward modeling the many interactions between crops, associated pests and the environment, the general implementation of a systems approach to integrated crop and pest management remains to be accomplished.     

The analysis of the apparel supply chain systems with specific reference to the Korean apparel organisations of the overseas and domestic brand products

Case studies of apparel organisations, in two broadly distinguishable market groups in South Korea have been conducted for this research. One of the case study organisations,company A, sells high fashion knit wear products manufactured by a foreign supplier and the other,company B, deals fashionable ladies wear supplied by 8 to 10 domestic apparel manufacturers. The study identifies common issues and differences between these dissimilar apparel companies in their respective supply chain systems. The selected apparel systems were analysed and categorised into four sectors, i.e.: production management, product distribution management, customer buying behaviour analysis and the evaluation of business performance in terms of both quantity and quality. The analysis was conducted as a pre-cursor to simulation studies to investigate the effects of apparel supply chain control parameters on the relevant business performance. The predominant costs are the product cost and the outlet rent, both of which reflect the product volumes ordered. The forecast errors are high for both apparel companies. Therefore, improving the forecasting techniques should significantly reduce the costs and improve the profits. The data derived from the case studies can contribute new information on the globalised supply chain study area, especially the approach to compare the international to domestic apparel entrepreneurs’ activities/finances will be a useful guideline to compare relevant supply chain systems in other countries as well as in Korea.     

Forage Legumes for Sustainable Cropping Systems

SUMMARY

Perennial and annual forage legumes are important components of sustainable cropping systems. Forage legumes are a primary source of forage to supply protein and fiber for livestock rations. They can be grazed, or stored as hay or silage. They contribute biologically fixed N and sustain the soil by reducing erosion and increasing soil organic matter levels. Diversifying cropping systems by including legumes can also reduce weed, insect, and disease incidence. Potential new uses of legumes include phytoremediation of N contaminated sites and capturing N lost from cropping systems. Legumes also have potential use as a feedstock for renewable energy production. Legumes have traditionally been used in rotation with grain crops but more recently have been shown promise as winter cover crops, intercrops with grain crops, and as living mulches. In this review, we discuss traditional and new roles of forage legumes in sustainable cropping systems with examples primarily chosen from northern USA and Canada.     

The Importance of Biodiversity in Agroecosystems

SUMMARY

This article identifies the important functions and benefits of biodiversity in agriculture, for sustainable crop production and food security. After clarifying impacts from the decline of biodiversity in agriculture, the article summarizes principles, practices and policies for biodiversity conservation and enhancement in farming systems and in landscapes. Some of the strategies identified build upon valuable local experiences and knowledge in traditional farming practices, while others take advantage of recent scientific findings in agroecology and ecosystem health. The analysis suggests the value of adopting an agroeco-systems approach, beyond a focus on genetic resource conservation alone-to implement other biodiversity-enhancing methods in farms, such as integrated ecological pest and soil management. Attention is also given to the challenges by conflicting agricultural policies that contribute to the decline of biodiversity in farming systems, and potential of reforming such policies. The practices and approaches reviewed in this analysis show effective ways to link biodiversity conservation and sustainable agriculture.     

Redesigning Pest Management

SUMMARY

Social ecology provides a broad framework for critically examining the theory and practice of pest management, and the institutional and psychosocial contexts within which all theories and practices are developed and implemented. Such an analysis finds most current theories and practices seriously wanting, but also reveals extensive opportunities for innovation and improvement. The greatest need is for a shift in emphasis from a responsive, symptom-based, linear approach based on biocides and their substitutes to a proactive, holistic approach based on knowledge-intensive, ecosystem design and redesign, and whole systems management (based particularly on the further development of cultural controls). Although this will require broader parallel changes within individuals and throughout society, significant improvement can be made by focusing on small achievable initiatives and their public celebration to facilitate their spread. The developments in pest management being proposed here are regarded as one expression of the ongoing psychosocial evolution of our species.     

An Agroecological Basis for Designing Diversified Cropping Systems in the Tropics

Summary

Small scale diversified systems which rely mostly on local resources and complex crop arrangements, are reasonably productive and stable, exhibiting a high return per unit of labor and energy. In many ways complex polycultures and agroforestry systems used by small tropical farmers mimic the structure and function of natural communities therefore acquiring many features typical of such communities, such as tight nutrient cycling, resistance to pest invasion, vertical structure, and high levels of biodiversity.

An agroecological approach to improve tropical small farming systems must ensure that promoted systems and technologies are suited to the specific environmental and socio-economic conditions of small farmers, without increasing risk or dependence on external inputs. Rather, agroecological development projects should incorporate elements of traditional agricultural knowledge and modern agricultural science, featuring resource-conserving yet highly productive systems such as polycultures, agroforestry, and the integration of crops and livestock.

It is ecologically futile to promote mechanized monocultures in areas of overwhelming biotic intricacy where pests flourish year-round and nutrient leaching is a major constraint. Here, it pays to imitate natural cycles rather than struggle to impose simplistic ecosystems that are not inherently complex. For this reason, many researchers think that successional ecosystems can be particularly appropriate templates for the design of sustainable tropical agroecosystems.     

Changing Significance of Inland Fisheries for Livelihoods and Nutrition in Bangladesh

SUMMARY

Fish is an essential and irreplaceable food in the rural Bangladesh diet. Inland capture fisheries are still the main source of fish in the diet. Although wetlands and fish habitat have been lost to drainage and flood control, the contribution of aquaculture to total fish production has been increasing in the last two decades.

The contribution of different species to fish intake as well as micro-nutrient intakes has been investigated based on food consumption studies. The main distinction is between small indigenous fish species (SIS), which typically are caught in open waters and floodplains, and larger species including carps (which are now largely cultured in ponds) and other fishes. The contribution of nutrient-minerals and especially vitamin A–from SIS is particularly important. Some SIS have very high vitamin A contents, whereas other fish, including carps have low vitamin A content. SIS that are eaten whole are also an important source of calcium. In addition, fish as part of a meal can enhance the intake of minerals present in other foods. Lastly, SIS are well-liked by the rural poor and are considered tasty and nutritious.

Case studies of fisheries and aquaculture interventions in Bangladesh indicate that SIS still contribute more to fish consumption than do cultured species for both poor and rich households. Fish consumption levels and the proportion of SIS in the diet are seasonal, peaking in and immediately after the wet season. Examples of community initiatives to protect over-wintering fish in local sanctuaries and to restore fish habitat and migration routes appear to have increased fish catches and consumption. Where beel (lake) fisheries were enhanced by stocking carps, the user communities benefited from higher catches and incomes. However, it seemed that fish consumption for non-participants increase where fishing was not limited, but fell where they were excluded from fishing by participants.

Extension efforts have encouraged rapid growth in aquaculture production in the last two decades. A case study indicated that increases in production were sustained and that practices had spread from extension participants. Declining capture fisheries and increasing carp production mean that carps have become relatively cheaper, and it has been seen that the proportion of carps to other fish sold doubled in less than a decade in some local markets. However, poor rural consumers without ponds are now more dependent on purchased fish, and increased production of carp from ponds does not compensate for substantial declines in their SIS catches from open waters. Aquaculture in flooded rice fields would normally exclude the poor, but there have been attempts where NGOs have organized landless people to benefit from stocking carps.

SIS can be included in pond aquaculture systems, and on-farm experiments show this can complement carp production by increasing production and cash returns. A focus on incorporating vitamin A rich SIS in aquaculture combined with widespread and concerted efforts to restore and sustainably manage the floodplain fisheries (which are dominated by SIS) can result in an important food-based strategy to improve micro-nutrient deficiencies in poor people in Bangladesh and similar flood-plains.     

Cropping Systems in Eastern Europe: Past,Present, and Future

SUMMARY

The evolution of cropping systems in Eastern Europe has been a long and gradual process. The objective of this paper is to provide a comprehensive review of the cropping systems in Eastern Europe before World War II, the present cropping systems, and speculate on the future systems. Before World War II, the crop-long term fallow, the grass-crop, and the field rotation were the prominent cropping systems. Crop rotations were adopted in the 16th–17th century and various modifications of the ‘Norfolk’ and the ‘crop-grass’ rotation systems were used. Cash cropping, industrial cropping, and monoculture were extensively used after World War II. Major political, social, and economic changes took place in Eastern Europe after the dissolution of the Soviet Union. Nationalized land was returned to rightful owners. The new owners, however, lacked the skills and financial resources for intensive crop production and this has resulted in drastic reductions in crop yields. Integrated crop production seems to be the most viable option for the East European countries because organic or biological cropping is financially too demanding. Considerable efforts are being made to design new cropping systems which emphasize reductions in mineral fertilizers and pesticides, and conservation tillage. Eastern Europe may become important exporters of agricultural commodities by the year 2020.     

Improving Soil Quality

Abstract

Future advancements in crop production will rely on increased understanding of ecological principles that control interactions among cropping system components. Our interest in linking soil quality and weed management derives from the belief that greater understanding of key processes and properties that define soil-weed relationships will lead to the design of agroecosystems with greater capacity and opportunity to suppress weeds. We identified seed-bank persistence, seedling establishment, and interspecific interference as key processes that affect annual weed population dynamics. We then examined how soil processes and properties can affect each of these factors and how, in turn, soil-improving management practices and cropping system design may affect weed dynamics. We established weed-related soil management objectives as: (i) reducing the persistence of seeds in the soil; (ii) reducing the abundance of safe-sites for weed establishment and the filling of available sites; and (iii) reducing crop yield loss caused by a given density of weeds. Soil factors that can be managed to achieve these goals include: (i) chemical, physical, and biological conditions that affect resources required for weed seed germination, establishment and growth; (ii) habitat for herbivores and pathogens that attack weed seeds and seedlings; and (iii) phytotoxin production. We concluded that many as yet unexplored opportunities exist to manipulate the soil environment and to design cropping systems that create multiple weed suppressive conditions at critical junctures of weed seed-bank persistence, establishment, and interference.     

Crop Technology Introduction in Semiarid West Africa: Performance and Future Strategy

SUMMARY

The periodic food crises in agricultural production in semiarid sub-Saharan Africa have been the main public view of the subcontinent since the media perpetuates a Gloom and Doom perception. Actually the agricultural systems of sub-Saharan Africa have made some impressive achievements and there is potential to make more impact even in the more difficult regions where the poor are concentrated. In this paper the focus is on the successes, a strategy for introduction of new technologies in semiarid regions of West Africa, and supportive policy. More rapid technological change, with supportive policy, would have a substantial effect on rural poverty.     

Effects of Soil Moisture Depletion for One Month before Flowering on Dry Matter Production and Ecophysiological Characteristics of Wheat Plants in Wet Soil during Grain Filling

Abstract

The period from mid-March to April in the wheat-growing season in Japan corresponds to a wet period known as “Natanezuyu”. After this wet period, the weather remains rather dry until June. Fluctuations in soil moisture conditions during the growing season might be expected to affect the growth of wheat. Therefore, we compared the grain yield, dry matter production and ecophysiological characteristics of wheat grown with adequate moisture during the ripening stage after it had been grown under adequate (W-plot) or deficient (D-plot) soil moisture conditions for about one month before heading. The grain yield in the D-plot was higher by about 15 to 40% than that in the W-plot, with greater dry matter production. The larger dry weight in the D-plot resulted from a higher rate of crop growth before and after heading, which was due to a larger leaf area and higher net assimilation rate. During the ripening stage, leaf senescence of plants was delayed and the rate of photosynthesis fell more slowly in the D-plot than in the W-plot. Root systems developed better, resistance to water transport from root to leaves was lower, the exudation rate of roots was higher, and the cytokinin activity in xylem exudates from roots was higher in the D-plot. These characteristics of roots might have caused the significant difference in the growth and physiology of the aboveground parts of the plants. Our results indicate that encouragement of the development of the root systems, for example, by drainage during the wet period might be important for improving the grain yield of wheat in Japan.     

Population Growth,Food Production and Nutrient Requirements

Summary

World population has risen at a rate of 1.9% per year since 1960, but food production has grown at 2.8% per year due to the application of better crop production techniques. Most of the future population growth will occur in developing countries, those with limited ability to feed their growing populations or import food. Fertilizer use to increase production and maintain soil fertility has been essential to increasing food production, and will be essential in the future. World food grain reserves in 1996 were at their lowest levels since the early 1970s, and the rate of increase of food production has slowed. By the year 2020, the population is expected to be 8 billion people. To feed this population, the food grain production will have to increase from the current level of about 2 billion tonnes per year to over 3 billion tonnes. To achieve this level of crop output, intensification of the output on existing land must account for most of the growth, and the amount of fertilizer use will need to increase from 123 million tonnes of nutrients in 1994/95 to over 300 million tonnes in 2020. This requires substantial increase in fertilizer production capacity, which will only occur if relatively stable agricultural markets are established in the countries with expanding populations. The situation in Africa is particularly difficult, with poor input and output markets, declining yield levels due to the lack of nutrients, and continued population growth; there are few indications that fertilizer use will soon increase to reduce the rate of soil degradation and to produce the needed food.     

Towards effective soybean seed systems in Benin: Current situation and prospects for production and delivery of good quality seed

Facilitating farmers’ access to quality seed requires proper understanding of the functioning of seed systems. This study aimed at analyzing soybean (Glycine max [L.] Merr.) seed systems in Benin to pave the way for strengthening this sector. The research approach consisted of desk research, focus group discussions, individual interviews and validation workshop with stakeholders involved in soybean seed systems. Our findings revealed that despite the existence of an institutional and organizational framework, the formal soybean seed system is not at all functioning. Farmers mainly relied on informal seed system through self-saved seed and seed purchase in the markets. There is an emerging soybean seed system led by NGOs and farmers’ organizations. Current soybean seed systems are ineffective in timely supplying desired soybean varieties to farmers. Creation of enabling environment to attract private investment and develop local seed businesses is proposed along with new organizational arrangements among stakeholders. Farmers’ training in seed production, processing and managerial skills, as strategy to improve informal seed system, are proposed to strengthen local seed business. Farmers’ organizations have a critical role to play, as they serve as intermediary between their members and seed producers. Information and Communication Technology (ICT) could be exploited not only to promote improved seeds but also to ensure traceability in the system. Quality Declared Seed could be the most adapted quality insurance scheme in remote areas. The proposed arrangements among stakeholders in the seed systems in this study could be applied to legume crops other than soybean.     

Box-Wilson Design for Optimization of in vitro Levan Production and Levan Application as Antioxidant and Antibacterial Agents

Background:Levan or fructan, a polysaccharide of fructose, is widely used in various commercial industries. Levan could be produced by many organisms, including plants and bacteria. The cloning of the gene from Bacillus licheniformis, which expressed levansucrase in Escherichia coli host, was carried out successfully. In the present study, we performed the in vitro production of levan and analyzed its potential application as antibacterial and antioxidant agents. Methods: In vitro levan production catalyzed by heterologous-expressed levansucrase Lsbl-bk1 and Lsbl-bk2 was optimized with BW design. The antibacterial activity of the produced levan was carried out using agar well diffusion method, while its antioxidant activity was tested by free radical scavenging assays. Results:The optimum conditions for levan production were observed at 36 °C and pH 7 in 12% (w/v) sucrose for levansucrase Lsbl-bk1, while the optimum catalysis of levansucrase Lsbl-bk2 was obtained at 32 ^oC and pH 8 in the same sucrose concentration. The in vitro synthesized levan showed an antibacterial activity within a concentration range of 10-20% (w/v) against Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa. The same levan was also able to inhibit the DPPH radical scavenging activity with the antioxidant strength of 75% compared to ascorbic acid inhibition. Conclusion:Our study, therefore, shows that the optimized heterologous expression of levansucrases encoded by Lsbl-bk1 and Lsbl-bk2 could open the way for industrial levan production as an antibacterial and antioxidant agent. Key Words: Antioxidants, Fructans, In vitro technique, Levan