Increasing profits and reducing risks in crop production using participatory systems simulation approaches

The development of cropping systems simulation capabilities world-wide combined with easy access to powerful computing has resulted in a plethora of agricultural models and consequently, model applications. Nonetheless, the scientific credibility of such applications and their relevance to farming practice is still being questioned. Our objective in this paper is to highlight some of the model applications from which benefits for farmers were or could be obtained via changed agricultural practice or policy. Changed on-farm practice due to the direct contribution of modelling, while keenly sought after, may in some cases be less achievable than a contribution via agricultural policies. This paper is intended to give some guidance for future model applications. It is not a comprehensive review of model applications, nor is it intended to discuss modelling in the context of social science or extension policy. Rather, we take snapshots around the globe to 'take stock' and to demonstrate that well-defined financial and environmental benefits can be obtained on-farm from the use of models. We highlight the importance of 'relevance' and hence the importance of true partnerships between all stakeholders (farmer, scientists, advisers) for the successful development and adoption of simulation approaches. Specifically, we address some key points that are essential for successful model applications such as: (1) issues to be addressed must be neither trivial nor obvious; (2) a modelling approach must reduce complexity rather than proliferate choices in order to aid the decision-making process (3) the cropping systems must be sufficiently flexible to allow management interventions based on insights gained from models. The pro and cons of normative approaches (e.g. decision support software that can reach a wide audience quickly but are often poorly contextualized for any individual client) versus model applications within the context of an individual client's situation will also be discussed. We suggest that a tandem approach is necessary whereby the latter is used in the early stages of model application for confidence building amongst client groups. This paper focuses on five specific regions that differ fundamentally in terms of environment and socio-economic structure and hence in their requirements for successful model applications. Specifically, we will give examples from Australia and South America (high climatic variability, large areas, low input, technologically advanced); Africa (high climatic variability, small areas, low input, subsistence agriculture); India (high climatic variability, small areas, medium level inputs, technologically progressing; and Europe (relatively low climatic variability, small areas, high input, technologically advanced). The contrast between Australia and Europe will further demonstrate how successful model applications are strongly influenced by the policy framework within which producers operate. We suggest that this might eventually lead to better adoption of fully integrated systems approaches and result in the development of resilient farming systems that are in tune with current climatic conditions and are adaptable to biophysical and socioeconomic variability and change. (C) 2001 Elsevier Science Ltd. All rights reserved.

Ethephon promotion of crop abscission for unshaken and mechanically shaken macadamia

Promotion of fruit abscission in macadamia, Macadamia integrifolia (Proteaceae), has potential to reduce costs associated with prolonged harvesting of late-abscising cultivars. Effects of ethephon [(2-chloroethyl) phosphonic acid] on fruit removal force and crop abscission were monitored at 3 stages of the harvest season on both unshaken and mechanically shaken trees of the late-abscising macadamia cultivar A16. Ethephon application, tree shaking, or a combination of the 2 methods, accelerated crop removal from the tree at all stages during harvest. Early harvest before natural abscission resulted in little or no difference in nut-in-shell and kernel weight, kernel recovery and kernel oil content. Delaying ethephon application or tree shaking until commencement of natural abscission resulted in greater crop removal. Fruit removal force declined naturally towards 1 kgf at this stage, and was further reduced by ethephon application. The most effective approach for harvest acceleration was to reduce fruit removal force, before tree shaking, by spraying trees with ethephon.

Establishment of Nilaparvata Iugens Stl in rice crop nurseries: a possible source of outbreaks

We tested the hypothesis that early-planted seedbeds of rioe are mere heavily infested with brown planthopper (BPH) than later seedbeds, and that transplanted plants with lBPH are a source of subsequent population increase and possible outbreaks. The experiments were conducted at CARDI and Takeo province in wet season 2000 and early wet 2 season 200 I. BPH at O. 25. 50, 100, 200 1m were infested onto plants with low and high fertilizer treatments. Rice seeds of varieties moderately and highly susceptible to BPH were sown 3 weeks early, 2 weeks early, at the normal time, and later than normal (5 weeks) and treated with low and high fertilizer rates. At Takeo, the 3< weeks early seedbeds were infested by BPH migration, and both varieties with high fertilizer caught more immigrant insects and subsequently had damaging outbreaks of BPH in the third generation. At CARDl, no seedbeds were infested with immigrant BPH. Seedbeds in areas with continuous cropping of rice have a high risk of BPH attack, Seedlings infested with 200, 100, and 50 BPI[/m2 resulted in death of the plant. Plants with 100 and 200 BPH/m'! were kj[Jed sooner. With 25 BPIVm2 plants were not kllled, but subsequent population increase caused yi eld reduction. Yield loss was high ill higlh fertilizer treated plants. Key words , ,

Pea mania: deranged behaviour in cattle grazing a pea crop (Pisum sativum var arvense)

Hypersensitivity to external stimuli, progressing in some animals to manic behaviour, occurred in a cattle herd that grazed a crop of field peas (Pisum sativum var arvense) in the pre-flowering stage. Haematological and biochemical analyses eliminated hypomagnesaemia and ketosis as diagnoses. Other than two steers euthanased due to injuries sustained during manic episodes, all affected animals survived, recovering over 3 days when moved to alternative pasture. No necropsies were conducted. No microbial pathogens or endophytes were found on or in the plants. A previously reported incident in Victoria in 1987 in cattle grazing peas appeared to be of a similar nature. Environmental factors leading to these incidents were not clearly identified.

Infusing the use of seasonal climate forecasting into crop management practice in North East Australia using discussion support software

Seasonal climate forecasting offers potential for improving management of crop production risks in the cropping systems of NE Australia. But how is this capability best connected to management practice? Over the past decade, we have pursued participative systems approaches involving simulation-aided discussion with advisers and decision-makers. This has led to the development of discussion support software as a key vehicle for facilitating infusion of forecasting capability into practice. In this paper, we set out the basis of our approach, its implementation and preliminary evaluation. We outline the development of the discussion support software Whopper Cropper, which was designed for, and in close consultation with, public and private advisers. Whopper Cropper consists of a database of simulation output and a graphical user interface to generate analyses of risks associated with crop management options. The charts produced provide conversation pieces for advisers to use with their farmer clients in relation to the significant decisions they face. An example application, detail of the software development process and an initial survey of user needs are presented. We suggest that discussion support software is about moving beyond traditional notions of supply-driven decision support systems. Discussion support software is largely demand-driven and can compliment participatory action research programs by providing cost-effective general delivery of simulation-aided discussions about relevant management actions. The critical role of farm management advisers and dialogue among key players is highlighted. We argue that the discussion support concept, as exemplified by the software tool Whopper Cropper and the group processes surrounding it, provides an effective means to infuse innovations, like seasonal climate forecasting, into farming practice. Crown Copyright (C) 2002 Published by Elsevier Science Ltd. All rights reserved.

Development of a generic crop model template in the cropping system model APSIM

The Agricultural Production Systems slMulator, APSIM, is a cropping system modelling environment that simulates the dynamics of soil-plant-management interactions within a single crop or a cropping system. Adaptation of previously developed crop models has resulted in multiple crop modules in APSIM, which have low scientific transparency and code efficiency. A generic crop model template (GCROP) has been developed to capture unifying physiological principles across crops (plant types) and to provide modular and efficient code for crop modelling. It comprises a standard crop interface to the APSIM engine, a generic crop model structure, a crop process library, and well-structured crop parameter files. The process library contains the major science underpinning the crop models and incorporates generic routines based on physiological principles for growth and development processes that are common across crops. It allows APSIM to simulate different crops using the same set of computer code. The generic model structure and parameter files provide an easy way to test, modify, exchange and compare modelling approaches at process level without necessitating changes in the code. The standard interface generalises the model inputs and outputs, and utilises a standard protocol to communicate with other APSIM modules through the APSIM engine. The crop template serves as a convenient means to test new insights and compare approaches to component modelling, while maintaining a focus on predictive capability. This paper describes and discusses the scientific basis, the design, implementation and future development of the crop template in APSIM. On this basis, we argue that the combination of good software engineering with sound crop science can enhance the rate of advance in crop modelling. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.

Future contributions of crop modelling - from heuristics and supporting decision making to understanding genetic regulation and aiding crop improvement

Crop modelling has evolved over the last 30 or so years in concert with advances in crop physiology, crop ecology and computing technology. Having reached a respectable degree of acceptance, it is appropriate to review briefly the course of developments in crop modelling and to project what might be major contributions of crop modelling in the future. Two major opportunities are envisioned for increased modelling activity in the future. One opportunity is in a continuing central, heuristic role to support scientific investigation, to facilitate decision making by crop managers, and to aid in education. Heuristic activities will also extend to the broader system-level issues of environmental and ecological aspects of crop production. The second opportunity is projected as a prime contributor in understanding and advancing the genetic regulation of plant performance and plant improvement. Physiological dissection and modelling of traits provides an avenue by which crop modelling could contribute to enhancing integration of molecular genetic technologies in crop improvement. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.

The Three-dimensional Solution Structure of NaD1, a New Floral Defensin from Nicotiana alata and its Application to a Homology Model of the Crop Defense Protein alfAFP

NMR spectroscopy and simulated annealing calculations have been used to determine the three-dimensional structure of NaD1, a novel antifungal and insecticidal protein isolated from the flowers of Nicotiana alata. NaD1 is a basic, cysteine-rich protein of 47 residues and is the first example of a plant defensin from flowers to be characterized structurally. Its three-dimensional structure consists of an a-helix and a triple-stranded anti-parallel beta-sheet that are stabilized by four intramolecular disulfide bonds. NaD1 features all the characteristics of the cysteine-stabilized up motif that has been described for a variety of proteins of differing functions ranging from antibacterial insect defensins and ion channel-perturbing scorpion toxins to an elicitor of the sweet taste response. The protein is biologically active against insect pests, which makes it a potential candidate for use in crop protection. NaD1 shares 31% sequence identity with alfAFP, an antifungal protein from alfalfa that confers resistance to a fungal pathogen in transgenic potatoes. The structure of NaD1 was used to obtain a homology model of alfAFP, since NaD1 has the highest level of sequence identity with alfAFP of any structurally characterized antifungal defensin. The structures of NaD1 and alfAFP were used in conjunction with structure - activity data for the radish defensin Rs-AFP2 to provide an insight into structure-function relationships. In particular, a putative effector site was identified in the structure of NaD1 and in the corresponding homology model of alfAFP. (C) 2002 Elsevier Science Ltd. All rights reserved.

Towards the on-farm conservation of the assassin bug Pristhesancus plagipennis (Walker) (Hemiptera : Reduviidae) during winter using crop plants as refuges

Habitat instability associated with seasonal crop succession in broad-acre farming systems presents a problem for the conservation and utilisation of beneficial insects in annual field crops. The present paper describes two experiments used to measure the potential of seven plant species to be utilised as winter refuges to support and conserve the predatory bug Pristhesancus plagipennis (Walker). In the first experiment, replicated plots of canola (Brassica napus ), red salvia (Salvia coccinea ), niger (Guizotia abyssinica ), linseed (Linum usitatissimum ), lupins (Lupinus angustifolius ), and lucerne (Medicago falcata ) were planted in a randomized experiment during Autumn 1998. Upon crop establishment, adults and nymphs of P. plagipennis were released into treatment plots and their numbers were assessed, along with those of their potential prey, throughout the ensuing winter months. Post-release sampling suggested that canola and niger retained a proportion of adult P. plagipennis , while niger, lucerne and canola retained some nymphs. The other plant species failed to support P. plagipennis nymphs and adults postrelease. In the second experiment, niger was compared with two lines of sunflower (Helianthus annus ). Both sunflower lines harboured significantly higher (P < 0.05) densities of P. plagipennis nymphs than did niger. The more successful refuge treatments (sunflower, niger and canola) had an abundance of yellow flowers that were attractive to pollinating insects, which served as supplementary prey on which P. plagipennis were observed to feed. Sunflower and niger also supported high densities of the prey insect Creontiades dilutus (Stal) and provided protective leafy canopies which supplied shelter during the winter months. The potential and limitations for using each plant species as a winter refuge to retain P. plagipennis during winter are discussed.

Centile reference for total energy expenditure in infants from 1 to 12 months

Background: A knowledge of energy expenditure in infancy is required for the estimation of recommended daily amounts of food energy, for designing artificial infant feeds, and as a reference standard for studies of energy metabolism in disease states. Objectives: The objectives of this study were to construct centile reference charts for total energy expenditure (TEE) in infants across the first year of life. Methods: Repeated measures of TEE using the doubly labeled water technique were made in 162 infants at 1.5, 3, 6, 9 and 12 months. In total, 322 TEE measurements were obtained. The LMS method with maximum penalized likelihood was used to construct the centile reference charts. Centiles were constructed for TEE expressed as MJ/day and also expressed relative to body weight (BW) and fat-free mass (FFM). Results: TEE increased with age and was 1.40,1.86, 2.64, 3.07 and 3.65 MJ/day at 1.5, 3, 6, 9 and 12 months, respectively. The standard deviations were 0.43, 0.47, 0.52, 0.66 and 0.88, respectively. TEE in MJ/kg increased from 0.29 to 0.36 and in MJ/day/kg FFM from 0.36 to 0.48. Conclusions: We have presented centile reference charts for TEE expressed as MJ/day and expressed relative to BW and FFM in infants across the first year of life. There was a wide variation or biological scatter in TEE values seen at all ages. We suggest that these centile charts may be used to assess and possibly quantify abnormal energy metabolism in disease states in infants.

Cobertura permanente de solo com leguminosas herbáceas perenes no cultivo de bananeiras no médio Vale do Jequitinhonha

A região da Caatinga é caracterizada pelas altas temperaturas durante o ano e má distribuição das chuvas. Em virtude desses fatores de clima regional, tem-se a necessidade de adoção por práticas que elevem à eficiência e sustentabilidade agrícola local. Assim, objetivou-se avaliar a aptidão de leguminosas herbáceas perenes como cobertura permanente de solo no cultivo de bananeira. Foram conduzidos três experimentos, para avaliação das leguminosas, utilizou-se um delineamento experimental em blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas no espaço e para algumas variáveis, sub-subdividida no tempo, sendo: Fator “A” os dois diferentes ambientes de plantio: municípios de Itaobim/MG e Virgem da Lapa/MG; Fator “B”, nas subparcelas, dois manejos de cobertura do solo e para algumas variáveis, três manejos, constituídos pelas leguminosas: cudzu tropical (Pueraria phaseoloides) calopogônio (Calopogonium mucunoides) e solo descoberto (solo capinado); Fator “C” épocas de coleta de dados. Para avaliação das bananeiras, foram dois experimentos em blocos casualizados, com quatro repetições, em esquema de parcelas sudivididas no espaço, sendo: nas parcelas, fator “A” constituído por três manejos de cobertura do solo, pelas leguminosas: cudzu tropical e o calopogônio, e solo descoberto (solo capinado); fator “B”, nas subparcelas, plantas de bananeiras em três idades morfofisiológicas (diferentes ciclos e tamanhos); Para algumas variáveis que foram submetidas a coletas periódicas, utilizou-se o esquema de parcelas subsubdivididas no tempo, acrescentando-se o fator “C”, datas das coletas nas sub-subparcelas, tendo como referência os dias após semeadura (DAS) das leguminosas. Foram avaliadas as seguintes variáveis: taxa de cobertura do solo; potencial de deposição de folhas e a ciclagem de nutrientes; capacidade de inibição da vegetação espontânea; conservação da temperatura e promoção da retenção de umidade do solo. Também foi avaliado o crescimento vegetativo e produtividade das bananeiras. Como resultados principais, notou-se que as leguminosas proporcionaram eficiente cobertura do solo, o calopogônio apresentou o maior acúmulo de N, P, K, e Ca, via deposição de material senescente, tal como maior inibição das plantas espontâneas nos pomares de bananeiras. Essa cobertura também promoveu uma eficiente redução da temperatura do solo, possibilitando menor variação térmica nas camadas de maior concentração radicular da bananeira, e consequentemente, obtendo maior acúmulo de umidade no solo. As bananeiras cultivadas sobre coberturas vivas de solo apresentaram aumento gradativo no crescimento e peso de cacho. Os resultados reforçam o potencial uso dessas espécies na fruticultura, principalmente em regiões de severas restrições hídricas, como forma de adubação e otimização de diversos processos biológicos em seu ambiente de cultivo.

Cenários de mudanças climáticas para a América do Sul : impacto no zoneamento agroclimático da cana-de-açúcar

O Painel Intergovernamental sobre Mudanças Climáticas (IPCC) através do seu Quarto Relatório de Avaliação das Mudanças Climáticas Globais (IPCC-AR4), publicado em 2007, atribui as emissões de gases de efeito estufa como a principal causa do aumento médio das temperaturas e alerta para uma elevação entre 1,8 ºC e 6,4 ºC até 2100, podendo modificar assim a aptidão climática para as culturas agrícolas em diversas regiões do planeta. Diante disso, existe a necessidade de substituição dos combustíveis fósseis por fontes renováveis e limpas de energia, como o etanol. A cana-de-açúcar apresenta-se, portanto, como uma cultura estratégica na produção do etanol. O presente trabalho teve como objetivos: 1) avaliar o desempenho dos Modelos Climáticos Globais (MCGs) do IPCC-AR4 na simulação de dados climáticos de temperatura do ar e precipitação pluviométrica para o período anual e mensal; 2) elaborar o zoneamento agroclimático da cana-de-açúcar para a América do Sul considerando o clima referência e o futuro para as décadas de 2020, 2050 e 2080 em função do cenário de emissão A1B considerado pessimista e que usa um equilíbrio entre todas as fontes de energia. Para a avaliação do desempenho dos MCGs, foram utilizados dados climáticos médios mensais observados de precipitação e temperatura do ar provenientes do Climatic Research Unit (CRU) e dados simulados oriundos dos 22 MCGs do IPCC (cenário 20c3m) compreendidos entre o período de 1961-1990, além do Multimodel (ensemble) – MM que é a média da combinação dos dados de todos os modelos. O desempenho dos MCGs foi avaliado pelos índices estatísticos: desvio padrão, correlação, raiz quadrada da média do quadrado das diferenças centralizadas e o “bias” dos dados simulados com os observados, que foram representados no diagrama de Taylor. Para a etapa da elaboração do zoneamento agroclimático procedeu-se o cálculo dos balanços hídricos (referência e futuros) da cultura, pelo método de Thornthwaite & Mather (1955). Para o cenário referência, utilizaram-se dados das médias mensais da precipitação e temperatura provenientes do CRU, enquanto que para as projeções futuras, dados provenientes das anomalias do Multimodel (ensemble) – MM para as décadas de 2020, 2050 e 2080, que foram ajustados, obtendo-se assim as projeções futuras para cada período analisado. Baseado nos mapas temáticos reclassificados de deficiência hídrica anual, temperatura média anual, excedente hídrico anual e no índice de satisfação das necessidades de água (ISNA), realizou-se uma sobreposição dessas informações obtendo assim, os mapas finais do zoneamento agroclimático da cana-de-açúcar. Posteriormente ao zoneamento, realizou-se a análise das transições (ganhos, perdas e persistências) entre as classes de aptidão climática da cultura. Os resultados mostram que o Multimodel (ensemble) – MM para o período mensal apresenta o melhor desempenho entre os modelos analisados. As áreas inaptas correspondem a maior parte da América do Sul e uma expressiva transição entre as classes de aptidão climática da cultura.