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Late blight is a devastating disease in potato production world-wide. Breeding for resistance is complex because of the versatile and aggressive population of Phytophthora infestans, which overcomes any new genetic source of resistance very rapidly. There are reliable fungicides available to control the disease but chemical control is costly and harmful to the environment. There are no cultural practices reducing the infestation, which are reliable enough to cope with the disease in a non-chemical way. Given the close link between the physiological condition of the crop and its resistance to late blight, this paper addresses the question whether crop physiology can help to combat the disease. Although there are possibilities to (partly) escape to the late blight by advancing the crop cycle or the tuber bulking, it is concluded that crop physiology can do little to reliably reduce the susceptibility to late blight. Breeding for resistance remains the best option.

We investigated the effects of postharvest application of carbon disulphide (CS2) in various concentrations (0, 15, 25, 35, 45 and 55 ml m-3) and with different exposure duration (24, 48, 72 and 96 h) on breaking of dormancy and sprouting of potato (Solanum tuberosum L., cv. Marfona) minitubers of two ages (freshly harvested and one week after harvest) and two weight classes (1.5 and 12 g). In comparison with the control minitubers, CS2 treated minitubers showed significantly shorter dormancy and better sprouting. More rotting and weaker responses were observed in freshly harvested treated minitubers compared with minitubers treated one week after harvest. The number of sprouts per minituber and their length were significantly enhanced by treating minitubers with CS2 compared with the untreated control minitubers, but there were strong interactions with minituber weight. Results showed that duration of CS2 treatment was more important than concentration and longer duration of CS2 treatment exhibited a stronger action on breaking dormancy and sprouting of potato minitubers than shorter treatments. But, when longer duration was accompanied with higher concentration, treatment with CS2 led to formation of needle sprouts, which are undesirable as they do not produce vigorous stems

Drought stress is one of the major abiotic stresses in agriculture worldwide. This study was carried out to investigate the effect of drought stress on proline content, chlorophyll content, photosynthesis and transpiration, stomatal conductance and yield characteristics in three varieties of chickpea (drought tolerant Bivaniej and ILC482 and drought sensitive Pirouz). A field experiment with four irrigation regimes was carried out in a randomized complete block design with three replications. Treatments included control (no drought),drought stress imposed during the vegetative phase, drought stress imposed during anthesis and drought stress during the vegetative phase and during anthesis. All physiological parameters were affected by drought stress. Drought stress imposed during vegetative growth or anthesis significantly decreased chlorophyll a, chlorophyll b and total chlorophyll content. Proline accumulation was higher in ‘ILC482’ than in ‘Pirouz’ both under control and drought stress conditions. Photosynthesis, transpiration, stomatal conductance and yield were higher but sub-stomatal CO2 concentration was lower under drought stress conditions than under control conditions. The results showed that mesophyll resistance is the basic determinate of rate of phototosynthesis under drought stress conditions. Under drought conditions the drought tolerant variety ‘Bivaniej’ gave the highest yield whereas the drought sensitive variety ‘Pirouz’ gave the lowest yield. Drought stress at anthesis phase reduced seed yield more severe than that on vegetative stage

This study aimed to analyze the seed potato systems in Ethiopia, identify constraints and prioritize improvement options, combining desk research, rapid appraisal and formal surveys, expert elicitation, field observations and local knowledge. In Ethiopia, informal, alternative and formal seed systems co-exist. The informal system, with low quality seed, is dominant. The formal system is too small to contribute significantly to improve that situation. The informal seed system should prioritize improving seed quality by increasing awareness and skills of farmers, improving seed tuber quality of early generations and market access. The alternative and formal seed systems should prioritize improving the production capacity of quality seed by availing new varieties, designing quality control methods and improving farmer’s awareness. To improve overall seed potato supply in Ethiopia, experts postulated co-existence and linkage of the three seed systems and development of self-regulation and selfcertification in the informal, alternative and formal cooperative seed potato systems. Resumen Este estudio tuvo el propósito de analizar los sistemas de producción de papa en Etiopia, identificar limitantes, y priorizar opciones de mejorar, mediante la combinación de investigación de escritorio, apreciaciones rápidas y estudios formales, encuestas a expertos, observaciones de campo y conocimiento local. En Etiopia co-existen sistemas de semilla informal, alternativo y formal. Domina el sistema informal, con baja calidad de semilla. El sistema formal es muy pequeño como para contribuir significativamente al mejoramiento de esa situación. El sistema informal de semilla debería tener como prioridad el mejoramiento en la calidad de la semilla mediante el aumento en la atención y habilidades de los productores, mejorando la calidad de la semilla-tubérculo de las generaciones tempranas y el acceso al mercado. Los sistemas alternativo y formal de semilla deberían priorizar el mejoramient

Veldproeven met verschillende aardappelrassen, grondsoorten en bemestingen zijn uitgevoerd om het verschil in stikstofbenutting tussen aardappelrassen te bepalen.

Nearly three decades ago Farquhar, von Caemmerer and Berry published a biochemical model for C3 photosynthetic rates (the FvCB model). The model predicts net photosynthesis (A) as the minimum of the Rubisco-limited rate of CO2 assimilation (Ac) and the electron transport-limited rate of CO2 assimilation (Aj). Given its simplicity and the growing availability of the required enzyme kinetic constants, the FvCB model has been used for a wide range of studies, from analysing underlying C3 leaf biochemistry to predicting photosynthetic fluxes of ecosystems in response to global warming. However, surprisingly, this model has seen limited use in existing crop growth models. Here we highlight the elegance, simplicity, and robustness of this model. In the light of some uncertainties with photosynthetic electron transport pathways, a recently extended FvCB model to calculate Aj is summarized. Applying the FvCB-type model in crop growth models for predicting leaf photosynthesis requires a stomatal conductance (gs) model to be incorporated, so that intercellular CO2 concentration (Ci) can be estimated. In recent years great emphasis has been put on the significant drawdown of Rubisco carboxylation-site CO2 concentration (Cc) relative to Ci. To account for this drawdown, mesophyll conductance (gm) for CO2 transfer can be added. We present an analytical algorithm that incorporates a gs model and uses gm as a temperature-dependent parameter for calculating A under various environmental scenarios. Finally we discuss a C4-equivalent version of the FvCB model. In addition to the algorithms already elaborated for C3 photosynthesis, most important algorithms for C4 photosynthesis are those that capture the CO2 concentrating mechanism and the extra ATP requirement by the C4 cycle. Although the current estimation of the C4 enzyme kinetic constants is less certain, applying FvCB-type models to both C3 and C4 crops is recommended to accurately predict the response of crop photosynthesis to

One of the many gaps that needs to be solved by precision agriculture technologies is the availability of an economic, automated, on-the-go mapping system that can be used to obtain intensive and accurate ‘real-time’ data on the levels of nitrate nitrogen (NO3–N) in the soil. A soil nitrate mapping system (SNMS) has been developed to provide a way to collect such data. This study was done to provide extensive field-scale validation testing of the system’s nitrate extraction and measurement sub-unit (NEMS) in two crop (wheat and carrot) production systems. Field conditions included conventional tillage (CT) versus no tillage (NT), inorganic versus organic fertilizer application, four soil groups and three points in time throughout the season. Detailed data analysis showed that: (i) the level of agreement, as measured by root mean squared error (RMSE), mean absolute error (MAE) and coefficient of efficiency (CE), between NEMS soil NO3–N and standard laboratory soil NO3–N measurements was excellent; (ii) at the field-scale, there was little practical difference when using either integer or real number data processing; (iii) regression equations can be used to enable field measurements of soil NO3–N using the NEMS to be obtained with laboratory accuracy; (iv) future designs of the SNMS’s control system can continue to use cheaper integer chip technology for processing the nitrate ion-selective electrode (NO3 -–ISE) readings; and (v) future designs of the SNMS would not need a soil moisture sensor, ultimately saving on manufacturing costs of a more simple system

Asafoetida (Ferula assafoetida L.) is a medicinal plant with a problematic seed germination. Seeds of this plant have a long dormancy. The present research was carried out to investigate whether exogenous application of the hormones Gibberellic Acid (GA3), N6-furfurylaminopurine (kinetin) and 6-benzylaminopurine (BAP), alone or in combinations and chilling (for 0 or 28 days) could be used to alleviate the problem of dormancy. Germination was increased from 53.3% in a medium free of any hormones to 74.4% in a medium supplemented with 0.25 mg L-1 BAP. This was the only single hormone treatment giving a statistically significant increase in germination. Chilling increased germination from 37.5% (0 days of chilling) to 82.9% (28 days of chilling). Combining exogenous application of 0.25 mg L-1 BAP with 28 day chilling even gave more than 90% seed germination. Present findings suggest that seeds germination of Asafoetida can be greatly improved by combining chilling with BAP application

Until recently, arable production systems in the Netherlands were solely based on their production function, while ecological and societal functions were not or hardly taken into account. However, the Netherlands is a small and densely populated country that requires a well-planned management of the landscape if more functions are to be fulfilled. In an attempt to utilize the available space in a more efficient way, we designed Dutch arable production systems with a production, an ecological and a societal function, and tested systems differing in level of biodiversity in long-term field experiments. In this article special attention is paid to systems' societal function, which is attained when productive and biodiverse systems make the landscape more attractive than conventional ones. To explain differences in appreciation of arable production systems as elements of the Dutch landscape a study was carried out consisting of interviews combined with an appraisal of contrasting conventional and biodiverse systems and of field margins on the basis of colour photographs taken when the crops and the wild plants flowered. The pictures included fields with rye, barley, cereal-pea and cereal-pea-wild flower mixtures. In addition, pictures of other arable production systems in the Netherlands were used as a contrasting reference; these included forage maize, tulip fields and biodiverse field margins. The photographed systems were evaluated by a group of 30 interviewees, using the qualitative dialogue method. Each of the respondents was offered the possibility to express his feelings and to explain underlying thoughts when ranking and classifying the photographed systems. Most respondents appreciated the presence of wild flowers, but the farmers amongst them were hesitant as they feared yield loss. Barley was preferred to rye. Pea in mixtures was not liked much but was appreciated more in mixtures with rye than with barley. Also the reference systems provoked mixed feelings.

In West Africa two rice species (Oryza glaberrima Steud. and Oryza sativa L.) co-exist. Although originally it was thought that interspecific hybridization is impossible without biotechnological methods, progenies of hybridization appear to occur in farmer fields. AFLP analysis was used to assess genetic diversity in West Africa (including the countries The Gambia, Senegal, Guinea Bissau, Guinea Conakry, Sierra Leone, Ghana and Togo) using 315 rice samples morphologically classified prior to analysis. We show evidence for farmer interspecific hybrids of African and Asian rice, resulting in a group of novel genotypes, and identify possible mechanisms for in-field hybridization. Spontaneous back-crossing events play a crucial role, resulting in different groups of genetic diversity in different regions developed by natural and cultural selection, often under adverse conditions. These new groups of genotypes may have potential relevance for exploitation by plant breeders. Future advances in crop development could be achieved through co-operation between scientists and marginalized farmer groups in order to address challenges of rapid adaptation in a world of increasing socio-political and climatic uncertainty

Seed potato systems in East Africa are described and opportunities for improvement identified on the basis of interviews with potato producers in Kenya, Uganda and Ethiopia, and an assessment of Ralstonia solanacearum and virus disease levels in Kenya. 3% of seed potato sold in Kenyan markets was virus free. Ralstonia solanacearum was found in 74% of potato farms. Less than 5% of the farmers interviewed source seed potato from specialized seed growers. Over 50% rely entirely on farm-saved seed. Current seed potato prices justify this behavior. To improve the system the local and specialized chain need to be tackled simultaneously. To improve the local chain ware potato farmers require training on seed quality maintenance and managing bacterial wilt and viruses. Research into virus resistance and the effect of mixed virus infection on yield deserves attention. Private investment in seed potato production could increase volumes produced and reduce prices

Zinc is an important micronutrient for both crop growth and human nutrition. In rice production, yields are often reduced and Zn mass concentrations in the grains are often low when Zn is in short supply to the crop. This may result in malnutrition of people dependent on a rice-based diet. Plant breeding to enhance low-Zn tolerance might result in higher yields and nutritional quality but requires effective selection criteria embedded in physiological insight into the Zn husbandry of the crop and applicable in field evaluation of advanced breeding material or in screening of existing varieties. Using existing and newly developed low-Zn tolerance indices, this study presents the results of screening experiments carried out in high- and low-Zn soils. Sixteen accessions of aerobic rice were grown under greenhouse conditions to conceptualize the indices and 14 under field conditions to validate the indices. As the differences in soil-Zn levels in these experiments did not result in differences in grain yield, literature data were used from experiments where the soil-Zn level did have an effect on grain yield, to further check the validity of the indices. Several indices were applied to evaluate the genotypic low-Zn tolerance performance in attaining (relatively) high grain yield, high grain-Zn mass concentration, or both. The results indicate that the grain-Zn mass concentration efficiency index is different from the grain yield efficiency index and that the low-Zn tolerance indices identified superior genotypes best. Amongst the indices tested, the low-Zn tolerance index for grain yield and the low-Zn tolerance index for grain-Zn mass concentration were closely correlated with grain yield and grain-Zn mass concentration, respectively. Therefore, the low-Zn tolerance index for grain yield was effective in screening for high stability and high potential of grain yield, and the low-Zn tolerance index for grain-Zn mass concentration was effective for grain-Zn mass concentr

Main stream commercial onion breeders do not select varieties for organic farming, but solely for conventional farming. Seed companies consider the organic market too small to justify investments in breeding for this sector. In order to study if their varieties also suit organic farmers¿ needs we interviewed four Dutch commercial onion breeders on their breeding programme and selection criteria and compared the outcome with a variety profile composed of the priority traits of Dutch organic farmers. Breeders gave priority to the same storage and bulb quality traits that are demanded by organic farmers, because organic onions are exported to conventional supermarkets that apply the same quality standards to organic and conventional onions. However, organic farmers also need varieties that perform well in the field. Breeders give low priority to field selection. Furthermore, three of the four seed companies only breed hybrids. The cytoplasmic male sterility system used to produce these hybrids does not comply with organic principles. We conclude that at present breeders can provide varieties that meet organic farmers¿ demands for storability and quality traits, but they should give higher priority to field selection to also improve required field traits. The latter will only occur, if in future the organic seed market will grow. If the organic sector wants varieties developed according to its own principles, it should either set up its own onion breeding programme or seek alliances with breeding companies that are prepared to harmonize their breeding methodology with the organic principles

The high degradability of grass protein is an important factor in the low nitrogen (N) utilization of grazing bovines in intensive European grassland systems. We tested the hypothesis that protein degradability as measured by the Cornell Net Carbohydrate and Protein System (CNCPS) protein fractionation scheme, can be manipulated by herbage management tools, with the aim to reduce N loss to the environment. A field experiment comprising the factorial combinations of three fertilizer N application rates, three regrowth periods, two perennial ryegrass, Lolium perenne, cultivars and two cutting heights was conducted. The plots were sampled during four seasons and protein fractions were determined in both sheath and lamina material. The protein was highly soluble and on average 19% and 28% of total N was in the form of non-protein N, 16% and 19% in the form of buffer-soluble protein, 52% and 40% in the form of buffer-insoluble protein, and 12% and 13% in the form of potentially available cell wall N for lamina and sheath material, respectively. In both materials only 0.9% of total N was present as unavailable cell wall N. In general the herbage management tools investigated did not have much effect on protein fractionation. The effects of regrowth period, cultivar and cutting height were small and inconsistent. High N application rates significantly increased protein degradability, especially during late season. This is relevant, as it has been shown that enhanced protein degradation increases the potential N loss through urine excretion at a time when urine-N excreted onto pasture is prone to leaching. However, the effect was most evident for sheath material, which forms only a small proportion of the animals¿ intake. It was concluded that there appears to be little scope for manipulating the herbage-N fractionation through herbage management. The consequences for modelling herbage quality could be positive as there does not seem to be a need to model the individual N f

Home gardens are important for enhancing food and nutritional security for HIV/AIDS-afflicted rural households through dietary diversity. Female-headed households may depend on home gardens more than average households to supply and supplement the household's diet when tabour is constrained for Field cropping. This paper compares household characteristics, dietary diversity, tabour allocated to crop husbandry and home gat-den biodiversity amongst 22 HIV/AIDS-afflicted female-headed households, 15 non-HIV/AIDS-afflicted female-headed, To HIV/AIDS-afflicted dual-headed and 33 non-HIV/AIDS-afflicted dual-headed households in rural communities in the Eastern Region of Ghana. information on household characteristics and tabour allocation to home garden management was obtained through a cross-sectional survey and in-depth interviews. Dietary diversity score was estimated for each household based on a 24-hour qualitative dietary recall. Plant species in each home garden were recorded. HIV/AIDS affliction did not affect home garden diversity but afflicted households had more on-farm sources of income and a higher dietary diversity and allocated more adult tabour to home garden activities than non-afflicted households. Dual-headed households had more diversity in the home garden and allocated more adult male tabour to the home garden than female-headed households. Statistically significant interactions between HIV/AIDS affliction and headship were observed for Shannon-Wiener index, number of crop species, number of annual crop species and number of root and tuber crop species in the home gardens: there were no headship effects when households were afflicted whereas dual-headed households had higher values than female-headed households in non-afflicted households. HIV/AIDS-afflicted households had significantly more annual crop species and more root and tuber crop species than non-afflicted households for female-headed households, whereas there were no significant differences

This paper examines the gathering of wild orchids and its effect on orchid species diversity and abundance in rural communities with high prevalence of HIV/AIDS and high numbers of orphans. The study was conducted in three villages in the Makete District of Tanzania. The study used a triangulation of ethnobotanical, anthropological and sociological methodologies. on the three gathering sites, we found a total of 12 different orchid species (7 edible and 5 non-edible ones) confirmed by an expert botanist, although local gatherers identified many more species. The Shannon-Wiener diversity index significantly differed among the three gathering sites. Analyses of focus group discussions and household surveys revealed that HIV/AIDS orphans and non-orphan children were the main gatherers of wild orchids. HIV/AIDS orphans (n = 55) gathered significantly more frequently (4.1 +/- 1.8 times per week) than non-orphan children (n = 49; 1.9 +/- 1.3 times per week) (P <0.01). There was a statistically significant interaction between village and type of gatherer (P <0.05). Scattered observations of changes in orchid species abundance over time were (lone using gatherers' indigenous knowledge and opinions. Orchid abundance peaked during May 2006. The study showed increasing abundance of non-edible orchid species and decreasing abundance of edible ones. There were highly significant, linear negative relationships between gathering pressure on the one hand and total number of orchid plants, total number of orchid species, number of edible orchid plants and number of edible orchid species on the other. These relationships were not statistically significant for non-edible orchids. We surmise that gathering edible orchid tubers is likely to become unsustainable, because once its tuber is harvested the plant does not recover or survive

Characterization of genetic diversity among cultivated cowpea [Vigna unguiculata (L.) Walp.] varieties is important to optimize the use of available genetic resources by farmers, local communities, researchers and breeders. Random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic diversity in 70 cowpea accessions collected throughout Benin. Nine random primers were screened on 24 accessions to assess their ability to reveal polymorphisms in cowpea and four of them were selected for use in characterizing the total sample. A total of 32 amplified bands were generated by the four primers. The number of loci detected varied from 5 to 11. RAPD profiles were analysed and amplified polymorphic DNA fragments were used to construct a dendrogram, clustering the accessions into nine groups at a similarity index of 71% based on the Unweighted Pair-Group Method using Arithmetic Averages. The genetic diversity among the cowpea cultivars investigated was large and the RAPD proved to be a useful technique to characterise it. Based on the molecular variance, the fixation index suggests a large differentiation of cowpea cultivars in Benin.

NJAS wageningen journal of life sciences, Vol 56, No 1/2 (2008) Home About Log In Register Search Current Archives KLV Home > Vol 56, No 1/2 (2008) > Muasya Font Size: How weather during development of common bean (Phaseolus vulgaris L.) affects the crop¿s maximum attainable seed quality R.M. Muasya, W.J.M. Lommen, C.W. Muui, P.C. Struik Abstract Weather conditions affect the seed quality of major crops including common bean. This study aimed to evaluate whether seed quality is affected through weather effects on the quality achievable at the end of seed filling (PM) or through changes in quality during maturation drying in the period between PM and harvest maturity (HM). The research also aimed to establish relationships between seed yield and seed quality. Twenty-four common bean (Phaseolus vulgaris L.) crops from two cultivars were sown on different dates in Eldoret and Kitui, Kenya. Seed quality was quantified as the percentage of viable seeds determined with a tetrazolium test, and as vigour measured by electrical conductivity (EC). Over the range of weather conditions during our study, high temperatures were more detrimental to seed quality than little rainfall. The two cultivars differed in susceptibility to high temperatures. High temperatures and little rainfall seemed to reduce seed quality mainly through reducing maximum quality attainable during the course of crop development. The quality in general did not change significantly between PM and HM, but in some cases the proportion of viable seeds increased between PM and HM, especially when ambient temperatures were relatively low. For seed samples free from mechanical damage, EC appeared to be an unsuitable criterion to detect quality differences at HM, because in almost all seed lots quality was indiscriminately classified as `good¿, whereas viability varied between 69 and 100%. Production conditions leading to low seed yields or seeds of low weight resulted in a low percentage of viable seeds but condit

The internodes of forage maize (Zea mays L.) stems were studied at anthesis for variation in anatomy and chemical composition in relation to digestibility. The study was carried out with a short (Vitaro) and a tall (Volens) cultivar differing in whole-plant digestibility, both of which were grown in the field in the growing seasons of 1999 and 2000. Internode diameter increased from the top to the base of the stem and Vitaro had shorter and thicker internodes than Volens. The cell walls of the sclerenchyma tissue in the rind were thicker and the numbers of sclerenchyma layers around vascular bundles in the rind higher in lower than in upper internodes. The neutral detergent fibre content (NDF%) of the internodes increased from the top to the base of the stems of both cultivars, but was very high for the peduncle. NDF% was lower for Vitaro than for Volens in all internodes. The sugar content of the dry matter was highest for Internode 12, i.e., the internode near the position of the ear, and was very low for the peduncle. Vitaro always had a higher sugar content than Volens. When subjected to fermentation tests with rumen fluid in an automated gas production system, gas production values after 3, 20 or 72 h of incubation were higher for internodes from the top than for internodes from the base of the stem, and were lower for the peduncle than for Internode 14. The values were consistently higher for Vitaro than for Volens internodes; in general, this difference was most apparent for Internode 10. The differences in gas production amongst internodes and between cultivars were in line with differences expressed by in vitro digestibility measurements. Fermentation results of cross sections suggest that the cell walls in lower internodes disappeared faster and to a greater extent than the cell walls in upper internodes, except for Volens in 1999, and with the exception of the peduncle. The rate of cell wall disappearance was higher for Volens than for Vitaro, but ultimat

Article about the methods for tuber potato cultivation with a main focus on haulm killing, and why this is important for Potato Science and industry.

This paper is on coaching farmers in (re)designing a farm. It describes how farmers can become inspired to design a sustainable farm by the way medical doctors look at the human being and his health. Sustainability in farm management is usually strived for in such a way that damage to People, Planet or Profit is prevented. However, preventing such damage does not automatically mean that humans, animals, rural societies, landscape, and nature can develop and manifest themselves to the full extent. Only in examples where the emphasis is on positive characteristics of and actions in farming, and where the approach is based on coherence between the three layers described (agricultural production, agri-culture, and the meaning of life and existence), we observe that all stakeholders can fully express themselves. This approach is comparable with the positive way in which the World Health Organization describes human health, distinguishing three different layers of health: physical health, socio-cultural health, and mental health. Applying the metaphor of the healthy human enables us to ask relevant questions as to how to achieve farm health. The power of the metaphor of the living human lies in the possibility to introduce the concepts of life, the conscious direction, transformation and health in the process of (re)designing the farm organism. The living farm emerges under the direction of the farmer as a new entity in which the possibilities of the site, the societal and agro-ecological context and the people involved are all mutually fine-tuned. Only if all three interconnected layers of health (i.e., the physical, socio-cultural, and mental health) are equally addressed, true farm health, and, in our definition of farm health, also sustainability can be achieved. This paper does not address the issue of creating an absolutely healthy and sustainable farm but is about farm transformation and the art of development, step-by-step reshaping specific farm elements, thus al

The quality of grass in terms of form and relative amounts of energy and protein affects both animal production per unit of intake and nitrogen (N) utilization. Quality can be manipulated by herbage management and choice of cultivar. The effects of N application rate (0, 90 or 390 kg N ha¿1 year¿1), duration of regrowth period (2¿3, 4¿5, or 6¿7 weeks), and cutting height (8 or 12 cm) on the mass fractions of nitrogen (N), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and ash in lamina and sheath material of a high-sugar (Aberdart) and a low-sugar (Respect) perennial ryegrass (Lolium perenne) cultivar, were studied in a factorial field experiment during four seasons in 2002 and 2003. Expressing NDF and ADF mass fractions in g per kg WSC-free dry matter (DM) increased the consistency of treatment effects. The high-sugar cultivar had generally higher WSC mass fractions than the low-sugar cultivar, especially during the late season. Moreover, the relative difference in WSC mass fraction between the two cultivars tended to be higher for the lamina material than for the sheath material, which suggests that the high-sugar trait may be more important under grazing conditions, when lamina forms the bulk of the intake, than under mowing regimes. Longer regrowth periods and lower N application rates increased WSC mass fractions and decreased N mass fractions; interactions between regrowth period and N application rate were highly significant. The mass fractions of NDF and ADF were much less influenced. The NDF mass fraction in terms of g per kg WSC-free DM tended to be higher at lower N application rates and at longer regrowth periods. The effect of cutting height on herbage chemical composition was unclear. In conclusion, high-sugar cultivars, N application rate and length of the regrowth period are important tools for manipulating herbage quality.

This paper is on coaching farmers in (re)designing a farm. It describes how farmers can become inspired to design a sustainable farm by the way medical doctors look at the human being and his health. Sustainability in farm management is usually strived for in such a way that damage to People, Planet or Profit is prevented. However, preventing such damage does not automatically mean that humans, animals, rural societies, landscape, and nature can develop and manifest themselves to the full extent. Only in examples where the emphasis is on positive characteristics of and actions in farming, and where the approach is based on coherence between the three layers described (agricultural production, agri-culture, and the meaning of life and existence), we observe that all stakeholders can fully express themselves. This approach is comparable with the positive way in which the World Health Organization describes human health, distinguishing three different layers of health: physical health, socio-cultural health, and mental health. Applying the metaphor of the healthy human enables us to ask relevant questions as to how to achieve farm health. The power of the metaphor of the living human lies in the possibility to introduce the concepts of life, the conscious direction, transformation and health in the process of (re)designing the farm organism. The living farm emerges under the direction of the farmer as a new entity in which the possibilities of the site, the societal and agro-ecological context and the people involved are all mutually fine-tuned. Only if all three interconnected layers of health (i.e., the physical, socio-cultural, and mental health) are equally addressed, true farm health, and, in our definition of farm health, also sustainability can be achieved. This paper does not address the issue of creating an absolutely healthy and sustainable farm but is about farm transformation and the art of development, step-by-step reshaping specific farm elements, thus al

Millipedes can cause considerable damage in the production of sweet potato and some other crops in East Africa. Quantitative information on intake of crop diets by and body weight gain of millipedes was collected in short-term no-choice feeding activity laboratory experiments conducted in north-eastern Uganda using female millipedes of the species Omopyge sudanica. Diets consisted of sweet potato and cassava storage root material, groundnut seeds, or maize grains. Differences in intake and body weight gain between diets were not statistically different. The consumption index, i.e., the ratio between intake and body weight gain, was significantly higher for sweet potato than for most other diets. The efficiency of conversion of ingested food, i.e., 100 × the ratio between body weight gain and intake, was significantly lower for the root crops ? especially sweet potato ? than for the grain crops. The research showed how difficult it is to obtain reliable, quantitative data on the feeding habits of millipedes, but also illustrated that O. sudanica can cause harm to crops in north-eastern Uganda and elsewhere in East Africa

In north-eastern Uganda, the sweet potato crop of small subsistence farmers is severely affected by many pests, including (rough) sweet potato weevils, nematodes and millipedes. Field experiments with sweet potato (Ipomoea batatas (L.) Lam.) were conducted at Arapai Station in Soroti District, north-eastern Uganda in three consecutive seasons to study the differences between the indigenous practice of harvesting piecemeal in combination with storage `in-ground on plants¿ and one-time harvesting after crop senescence, with special reference to damage caused by sweet potato weevils (Cylas spp.), rough sweet potato weevils (Blosyrus spp.), millipedes (Diplopoda) and nematodes. The area has two rainy seasons per calendar year, the first one with long, reliable rains and the second one with short, unreliable rains. Severe sweet potato weevil damage in the vines was responsible for the mortality of 46% of the plants in Experiment 1, which was carried out during the first rainy season. Starting 3 months after planting (MAP), sizable storage roots could be harvested, although their number and weight declined after 4 MAP with piecemeal harvesting. The highest storage-root yield (17.8 Mg ha¿1) was found in Experiment 2 (second rainy season) at the final harvest. The yield of storage roots stored `in-ground on plants¿ during the prolonged dry season (Experiment 3) was very low compared with the yields of Experiment 1 (first rainy season) and Experiment 2 (second rainy season). Sweet potato weevil damage of the storage roots was significantly less with piecemeal harvesting than with one-time harvesting, and piecemeal harvesting also increased the quality of the storage roots for human consumption and commercial purposes. However, with piecemeal harvesting the rough sweet potato weevil (Blosyrus spp.) caused more storage root damage than with one-time harvesting. No statistically significant differences between the two types of harvesting were found for damage caused by nematode

In organic agriculture the use of genetically modified organisms (GMOs) is banned. Recently, two novel breeding techniques have been developed, i.e., cisgenesis and reverse breeding, both of which are based on gene technology but should raise less moral concerns from the public. Whether the products of these breeding processes are classified as GMOs depends on the interpretation of the relevant EU regulations. In cisgenic plants, the genes introduced through genetic modification are from a crossable donor plant so that the source of the genes is considered to be of the same nature. In reverse breeding, the recombinant genes, essential to the breeding process, are no longer present in the product resulting from the entire breeding process, and thus the product as such is not transgenic. Should varieties obtained through cisgenesis or reverse breeding be allowed in organic agriculture? The answer to this question depends on whether the product or the process of breeding is taken into account. Assessment based on the product implies a choice of an ethical approach that only considers the extrinsic consequences of human action by making a risk-benefit analysis. It neglects so-called intrinsic, ethical arguments related to the applied technology (the process) itself. The organic movement uses the intrinsic argument of ‘unnaturalness’ against genetic engineering. We therefore conclude that products of cisgenesis and reverse breeding should be subject to the current GMO-regulations in organic agriculture and should thus be banned from organic agriculture.In organic agriculture the use of genetically modified organisms (GMOs) is banned. Recently, two novel breeding techniques have been developed, i.e., cisgenesis and reverse breeding, both of which are based on gene technology but should raise less moral concerns from the public. Whether the products of these breeding processes are classified as GMOs depends on the interpretation of the relevant EU regulations. In cisgenic

In the future, more food needs to be produced with increasingly scarce natural resources. Genomics can play a key role in accelerating yield gains because it helps to improve our understanding ofgenetic traits and assists in breeding for better crop performance. The scientific muscle of genomicsattracted tremendous research investments, but the efficiency with which these investments are paying offis still low. How can we accelerate the application of molecular genetics to our understanding of crop physiology and subsequently to crop improvement? The missing link is a more detailed understanding of the effects of gene function on crop performance at field level under agronomically relevant conditions captured in robust, physiology-based mechanistic models. With such models the most sensitive processes and mechanisms at whole-crop level that contribute to improved crop performance can be identified. To achieve the detailed understanding necessary to build and feed these models, more research on wholeplant physiology and crop ecology is required, with a focus on the complexity of scaling up knowledge from the molecular level to the farmers¿ fields and production systems. Such studies assess how the plant is able to integrate the information at different levels of organization into the functioning of the whole plant and predicting the phenotype of transgenic plants engineered for improvement of a complex trait. More investment is needed in linking whole-plant physiology, crop ecology and crop simulation with molecular biology and genomics. Moreover, long-term progress can be enhanced by the formation of multidisciplinary teams that operate through networks of excellence in developing quantitative tools that integrate complex information and different levels of organization and by the exchange of young scientists between research groups working at different hierarchical levels. On the short term improvement of the characterization of experimental environments (preferabl

In organic agriculture the use of genetically modified organisms (GMOs) is banned. Recently, two novel breeding techniques have been developed, i.e., cisgenesis and reverse breeding, both of which are based on gene technology but should raise less moral concerns from the public. Whether the products of these breeding processes are classified as GMOs depends on the interpretation of the relevant EU regulations. In cisgenic plants, the genes introduced through genetic modification are from a crossable donor plant so that the source of the genes is considered to be of the same nature. In reverse breeding, the recombinant genes, essential to the breeding process, are no longer present in the product resulting from the entire breeding process, and thus the product as such is not transgenic. Should varieties obtained through cisgenesis or reverse breeding be allowed in organic agriculture? The answer to this question depends on whether the product or the process of breeding is taken into account. Assessment based on the product implies a choice of an ethical approach that only considers the extrinsic consequences of human action by making a risk-benefit analysis. It neglects so-called intrinsic, ethical arguments related to the applied technology (the process) itself. The organic movement uses the intrinsic argument of ‘unnaturalness’ against genetic engineering. We therefore conclude that products of cisgenesis and reverse breeding should be subject to the current GMO-regulations in organic agriculture and should thus be banned from organic agriculture.