Using indicators to assess the environmental impacts of wine growing activity: The INDIGO® method

Environmental assessment methods are needed by agronomists working on the enhancement of cropping systems to meet the demand for more sustainable farming practices. A growing number of operational methods based on a set of indicators have been designed, more for arable crops and livestock than for perennial crops like viticulture. Among them, the INDIGO^® method, originally developed for arable crops, offers a compromise between feasibility and predictive quality. Here we present a modified and expanded version of INDIGO^® for viticulture. The development of new indicators specific to viticulture and the adaptation of existing ones followed a five step approach: (i) preliminary definition of the objectives and identification of the end-users, (ii) construction of the indicator, (iii) selection of a reference value, (iv) sensitivity analysis and (v) validation. Stakeholders from professional institutions and winegrower organizations were closely associated with step (i) to define the framework and step (ii) to supply technical databases. We designed INDIGO^® indicators with all available scientific and expert knowledge which was aggregated into expert systems associating fuzzy subsets or, when possible, quantitative equations.Four indicators; pesticides, nitrogen, energy and soil organic matter, were directly adapted from the initial INDIGO^® method, whereas soil cover and frost protection management were new indicators. Potentialities of their use are highlighted by examples of implementation on different scales and for various purposes.     

A cropping system assessment framework—Evaluating effects of introducing legumes into crop rotations

Methods are needed for the design and evaluation of cropping systems, in order to test the effects of introducing or reintroducing crops into rotations. The interaction of legumes with other crops (rotational effects) requires an assessment at the cropping system scale. The objective of this work is to introduce a cropping system framework to assess the impacts of changes in cropping systems in a participatory approach with experts, i.e., the integration of legumes into crop rotations and to demonstrate its application in two case studies. The framework consists of a rule-based rotation generator and a set of algorithms to calculate impact indicators. It follows a three-step approach: (i) generate rotations, (ii) evaluate crop production activities using environmental, economic and phytosanitary indicators, and (iii) design cropping systems and assess their impacts. Experienced agronomists and environmental scientists were involved at several stages of the framework development and testing in order to ensure the practicability of designed cropping systems. The framework was tested in Västra Götaland (Sweden) and Brandenburg (Germany) by comparing cropping systems with and without legumes. In both case studies, cropping systems with legumes reduced nitrous oxide emissions with comparable or slightly lower nitrate-N leaching, and had positive phytosanitary effects. In arable systems with grain legumes, gross margins were lower than in cropping systems without legumes despite taking pre-crop effects into account. Forage cropping systems with legumes had higher or equivalent gross margins and at the same time higher environmental benefits than cropping systems without legumes. The framework supports agronomists to design sustainable legume-supported cropping systems and to assess their impacts.     

Formalizing agro-ecological engineering for future-oriented land use studies

Agriculture faces an array of interrelated problems that call for development of new and revision of existing cropping systems towards the multiple needs of the 21st century. Agro-ecological engineering approaches aimed at design and exploration of alternative land use systems at various scales may support the identification of appropriate land use options. Engineering approaches are based on mathematical representations of well-founded agro-ecological principles while taking into account available resources and prevailing land-related objectives. The goal of this paper is to contribute to the development of a formalized approach to engineer cropping systems at the land unit level that can be used as building blocks for systematic explorations of land use options at farm or regional scale. The approach for engineering cropping systems at the land unit level consists of three steps: (i) goal-driven design of cropping systems, (ii) quantification of biophysical production targets and (iii) definition of the optimal mix of inputs required to realize production targets. This paper describes the approach and illustrates it with examples from the Sudano-Sahelian zone of Mali. Explicit attention is paid to the required numerical tools and their application to analyze consequences of uncertainty in the performance of engineered cropping systems. Using numerical tools, uncertainty is made explicit with the aim to better manage or reduce it. Identification of uncertainty at the designer's desk allows taking uncertainty into account before applying engineered land use systems in regional model studies or testing such systems in practice. Problems related to the application of numerical tools are discussed, including the future role of agro-ecological engineering as independent discipline within agricultural science.     

Determination of chemical composition and nutritional attributes of silage corn hybrids by near-infrared spectroscopy on chopper: evaluation of traits, sample presentation systems and calibration transferability

Determination of dry matter and feeding value of silage corn ( Zea mays L.) limits the number of genotypes that can be evaluated in breeding programmes. Measuring plot material by near-infrared spectroscopy on chopper (NOC) allows to increase the number of genotypes to evaluate, and improves dramatically the efficiency of the data collection processes. The objectives of our study were to (i) compare the performance of two NOC sample presentation systems (conveyor belt vs. spout) for determination of dry matter and feeding value of silage corn hybrids (ii) identify limiting parameters in the performance of alternative NOC sample presentation designs and (iii) evaluate the calibration transferability between NOC systems equipped with different sample presentation designs. Two chopper machines were equipped with near-infrared diode array spectrometers. Sample presentation designs comprised the conveyor belt and spout systems. Drying-oven and laboratory near-infrared spectroscopy were used as reference methods to develop NOC calibrations. In association with its higher dynamic signal range the conveyor belt system yielded lower standard errors of prediction than the spout system for most traits. Calibration transferability between NOC systems with different sample presentation designs was feasible.     

Choosing the most representative technical management routes within diverse management practices: Application to vineyards in the Loire Valley for environmental and quality assessment

Diversity of agricultural systems can be described at different scales in terms of three main types of variables: technical management of cropping systems, farming systems and food supply chains. We focus on the diversity of technical management routes (TMRs), defined as logical successions of technical options (TOs) designed by the farmers. The study, comparison and assessment of this great diversity of complex routes are impossible with classical agronomic experiments or exhaustive assessments such as life cycle assessment (LCA). Hence, the selection of representative cases is necessary. Multidimensional data analysis methods permit the characterization of a diversity of TMRs and the construction of typologies but do not allow the consideration of the specific associations of TOs constituting the various TMRs.The aim of this paper is threefold: (i) to propose a new combined method, “Typ-iti”, to classify the field TMRs of farmers, to identify key TO associations and to select the most relevant cases for study; (ii) to test this method on vineyard management diversity using a panel of vineyard fields of Loire Valley producers; and (iii) to discuss the capability of the proposed Typ-iti method for use in the characterization and selection of cases of other agricultural systems at diverse scales.The example developed in this paper is the selection of vineyard management cases for grape LCA combined with grape quality evaluation. The cases were selected to represent the regional diversity of management practices. A detailed on-farm survey of management methods was performed on a diverse range of wine production estates in the Middle Loire Valley. The Typ-iti method was constructed and implemented on the survey database. It combines a multidimensional analysis of qualitative survey data and typology and partitioning (clustering) associated with data mining methods (frequent pattern mining search and association rules).The surveyed sample was partitioned into 5 types of management practices, 2 of which were organic and 3 conventional. The partitioning was driven primarily by choices involving pest management and floor management. Each type was characterized by specific TOs, specific associations of TOs and remarkable TMRs. The cases were chosen on the basis of these 3 parameters.The Typ-iti method can be applied to other crops and at different scales; the only limitation is the availability of precise information on the practices used by farmers in their fields.     

A Multivariate Analysis of Soybean Genotypes Grown Under Different Cropping Systems

Nature and magnitude of genetic diversity was assessed using Mahalanobis's D² statistics and canonical analysis in 50 genotypes of soybean grown in monoculture and in association with maize. All the genotypes were grouped in 10 clusters in case of monoculture, while 8 clusters were formed for intercropping. Monoculture was more suitable environment for expressing the genetic diversity than intercrop. Some genotypes had consistently the similar clustering pattern in both the cropping systems, while others were affected by the cropping system in expressing the genetic diversity. This was confirmed by the canonical analysis. Days to flowering and maturity, seed yield/plant, plant height and 100-seed weight were mainly responsible for genetic diversity in monoculture. Besides phenological traits, pod length and width, and seed yield/plant exerted marked influence on the genetic diversity of soybean genotypes grown in association with maize. Geographical distribution was not necessarily reflected by the genetic divergence, though some degree of relationship between geographic diversity and genetic diversity was evident under both the cropping systems. The performance of some genotypes varied from cropping system to another, while that of others remained unaffected. Breeding programmes to develop varieties suitable for sole crop, intercrop and both the cropping systems have been suggested.     

Physiological traits and cereal germplasm for sustainable agricultural systems

Plant breeding is not a discipline that readily comes to mind when agricultural sustainability is being considered. Sustainability is normally associated with farming practices such as stubble retention, direct-drilling, or amelioration practices such as contour farming or liming, or rotation practices for nutrient management and disease control. The contribution of plant breeding will be in providing germplasm for these changed practices and devising new methods of selection. This paper reviews opportunities where plant breeding can contribute to improvements in sustainable farming practices. The emphasis is on rainfed cropping systems and cereal improvement. The main contribution for breeding is to (i) increase crop water and nutrient use so that less escapes from the root profile; and (ii) preserve the soil resource with conservation farming systems by developing cultivars specifically adapted to changed farming systems and competitive cultivars that reduce herbicide use. To achieve these outcomes identification of desirable traits, suitable selection methods and development of appropriate germplasm are discussed.     

Methods for Comparing the Yield Stability of Cropping Systems

The stability of yield is an important characteristic to be considered when judging the value of a cropping system relative to others. In the context of agricultural research, the analysis of yield stability has been largely confined to multienvironment trials of crop cultivars. This review emphasizes that methods for comparing the stability of cultivars can also be used for comparing different agronomic treatments in general, of which cultivars are but a special case. Throughout the paper, different agronomic treatments are referred to as cropping systems. Some of the methods useful for stability analysis of cropping systems are discussed and a brief review of applications of these methods is given. The paper puts different stability measures into a unifying mixed model perspective.     

Current status and future scenarios of hemp breeding

Summary Hemp is a multi-use crop, able to provide fiber, cellulose, seeds and seed oil, cannabinoid, and biomass. Integrating many agroindustrial chains, Cannabis is considered a crop model in which insights into specific metabolic pathways and biosynthetic processes are valuable for improvement of the plant for all sets of industrial derivatives. In this review the hemp breeding status is elucidated and many aspects are focused: (i) recovering, maintenance and characterization of genetic resources; (ii) widening of germplasm and genetic variability; (iii) marker-assisted selection and development of breeding programs; (iv) sexual differentiation; (v) monitoring of THC content. Modern hemp varieties for fiber and other specific end uses have been developed and new varieties are entering production. The scenario for the breeding advances in hemp relies on basic and applied research which provides insights to identify a strategy for the design of modified plants with enhanced performance. This is accounted by the dissection of traits into components and the modification of single steps of the related metabolic pathways. These advances are provided by genomic techniques and are able: (i) to identify key genes encoding enzymes and regulatory factors participating in cannabinoid, fiber and oil biosynthesis; (ii) to identify the mode of regulation of these genes; (iii) to characterize the function of the selected genes through higher, lower or specific expression incited by specific promoters. The identification of molecular markers for specific traits, gathered in a saturated linkage map, will have a remarkable impact on hemp breeding. The advances in basic and applied research make it possible to design methods for the identification of superior parents and cross combinations and the development of selection schemes that rely on less labour-intensive and time-consuming methods.     

PRACT (Prototyping Rotation and Association with Cover crop and no Till) – a tool for designing conservation agriculture systems

Moving to more agroecological cropping systems implies deep changes in the organization of cropping systems. We propose a method for formalizing the process of innovating cropping system prototype design using a tool called PRACT (Prototyping Rotation and Association with Cover crop and no Till) applied to a Malagasy case study. The input information for PRACT is comprised of: (i) crop and cover crop adaptation to biophysical conditions, (ii) agroecological functions of the cover crops, (iii) crop production, (iv) association possibilities between crop and cover crop, and (v) agroecological functions of the cropping system. All the information was derived from expert knowledge developed over more than 12 years of agronomic experiments in Madagascar. The final output from PRACT is a list of cropping systems, i.e., crop and cover crop associations and their sequences over three years. These cropping systems are characterized by their potential agroecological functions and crop production. The PRACT model selects a list of cropping systems taking into account the above information by using elaborate rules governing the intercropping and sequences between crops and cover crops. Examples of the outcomes of model simulations are provided for four different kinds of field. Taking into account the range of potential crops and cover crops, the number of cropping systems that was theoretically possible for the different field types ranged from 19,683 to 2.98 ×  10¹³. In a first step, PRACT reduced this number by a factor of up to 28 times to propose possible cropping systems. To do so, cropping systems are selected in terms of the biophysical requirements of plants, plant compatibility and agronomic rules. Not all of these systems are suitable for every farmer. Thus using PRACT output, a second cropping system selection step can be taken based on these cropping system characteristics, i.e., crop production and agroecological functions. By doing so the number of cropping systems selected can reach a reasonable value that can be handled by technicians and farmers. Possible uses and further development of the tool are discussed.     

Innovative cropping systems to reduce N inputs and maintain wheat yields by inserting grain legumes and cover crops in southwestern France

The reduction in crop diversity and specialization of cereal-based cropping systems have led to high dependence on synthetic nitrogen (N) fertilizer in many areas of the globe. This has exacerbated environmental degradation due to the uncoupling of carbon (C) and N cycles in agroecosystems. In this experiment, we assessed impacts of introducing grain legumes and cover crops to innovative cropping systems to reduce N fertilizer application while maintaining wheat yields and grain quality. Six cropping systems resulting from the combination of three 3-year rotations with 0, 1 and 2 grain legumes (GL0, GL1 and GL2, respectively) with (CC) or without (BF, bare fallow) cover crops were compared during six cropping seasons. Durum wheat was included as a common high-value cash crop in all the cropping systems to evaluate the carryover effects of rotation. For each cropping system, the water use efficiency for producing C in aerial biomass and yield were quantified at the crop and rotation scales. Several diagnostic indicators were analyzed for durum wheat, such as (i) grain yield and 1000-grain weight; (ii) aboveground biomass, grain N content and grain protein concentration; (iii) water- and N-use efficiencies for yield; and (iv) N harvest index. Compared to the GL0-BF cropping system, which is most similar to that traditionally used in southwestern France, N fertilizer application decreased by 58%, 49%, 61% and 56% for the GL1-BF, GL1-CC, GL2-BF and GL2-CC cropping systems, respectively. However, the cropping systems without grain legumes (GL0-BF and GL0-CC) had the highest water use efficiency for producing C in aerial biomass and yield. The insertion of cover crops in the cropping systems did not change wheat grain yield, N uptake, or grain protein concentration compared to those of without cover crops, demonstrating a satisfactory adaptation of the entire cropping system to the use of cover crops. Winter pea as a preceding crop for durum wheat increased wheat grain production by 8% (383 kg ha⁻¹) compared to that with sunflower − the traditional preceding crop − with a mean reduction in fertilizer application of 40–49 kg N ha⁻¹ during the six-year experiment. No differences in protein concentration of wheat grain were observed among preceding crops. Our experiment demonstrates that under temperate submediterranean conditions, properly designed cropping systems that simultaneously insert grain legumes and cover crops reduce N requirements and show similar wheat yield and grain quality attributes as those that are cereal-based.     

Overview on Control Strategies of High Voltage Direct Current Transmission System

Recent research progresses are summarized about the High Voltage Direct Current(HVDC) transmission system in control methods and modulation of HVDC transmission system,coordinated control of multi-infeed HVDC transmission system and AC-DC system.Some outsanding problems in current research are pointed out on such sides as system modeling,studying object,aim of coordinated control and engineering application.Based on the requirements of real systems and some latest research achievements on control technology and measure methods,some new research thoughts about HVDC transmission system for some problems of assessment and optimal combination of current control strategies,application of intelligent control methods and enhancement of coordinated control are proposed.     

Using a multicriteria assessment model to evaluate the sustainability of conservation agriculture at the cropping system level in France

Several international research and development organizations are promoting conservation agriculture in a wide range of contexts. Conservation agriculture is based on a combination of three main principles: (i) minimal or no mechanical soil disturbance; (ii) diversified crop rotations and (iii) permanent soil cover (consisting of a growing crop or a dead mulch of crop residues). However, in the face of the diversity of practices that can be associated with conservation agriculture, of goals assigned to agricultural systems, and pedoclimatic contexts, there is still no empirical evidence about the overall performance of conservation agriculture in France. Global assessments of conservation agriculture, with the full or partial application of its principles and in different contexts, are required to provide a more comprehensive picture of the performance of such systems. We tackled these objectives simultaneously, by evaluating 31 cropping systems with the MASC^® model (for Multicriteria Assessment of the Sustainability of Cropping Systems). These systems were selected to represent a wide diversity of practices, from ploughed conventional systems to crop sequences based on the full application of conservation agriculture principles. Positive interactions were observed between the key elements of conservation agriculture, resulting in better sustainability performances (particularly in terms of environmental criteria). Nevertheless, the systems most closely respecting the principles of conservation agriculture displayed several weaknesses, principally of a social or technical nature, in this study. Careful attention should be paid to attenuating these weaknesses. A more detailed analysis of the results also suggested that decreasing soil tillage tends to decrease the overall performance of the system unless associated with a diversification of the crop rotation.     

Weed tolerance in soybean: a direct selection system

Weed competition can severely reduce soybean (Glycine max (L.) Merr.) yields, particularly in organic systems. An efficient screening and breeding approach is needed to increase breeding progress for weed tolerance. This study sought to (i) establish a system for direct selection of competitive genotypes, (ii) evaluate genotypic differences in weed tolerance among six early‐maturing genotypes and (iii) assess the contribution of selected morphological traits to weed tolerance. A direct selection system providing two different levels of weed competition through all development stages of a soybean crop was developed, using mixtures of selected crop species as sown competitors. Two resulting mixtures induced intermediate (<30%) and strong (>50%) yield reduction, respectively. This selection system can be applied in screening and breeding programmes to facilitate breeding for weed tolerance. No significant difference in weed tolerance was detected between six soybean genotypes of maturity groups 000 to 00. Morphological traits that might influence competitive ability, for example light absorption, leaf area and lateral shoots, were assessed, and their potential for indirect selection for weed tolerance is discussed.     

Interrelationships between cropping systems for pod and seed quality components and breeding implications in common bean

Breeding programmes in common bean (Phaseolus vulgaris L.) have mainly focused on performance under monoculture conditions. Interactions among cultivars and cropping systems do occur and genotypes bred for pure cropping may not be suitable for intercropping. This study was undertaken to obtain estimates of genetic parameters of quality traits for bush bean landraces grown in two cropping systems, and the interrelationships of these traits between pure cropping and intercropping with maize (Zea mays L.). Field experiments were conducted at two locations for two years. Expression of most traits was not strongly influenced by genotype × environment interactions. Heritability estimates were similar in both cropping systems for most pod and seed quality traits. Positive correlations were observed between pure cropping and intercropping for pod characters (weight, length, width and texture) and seed characters (dry and imbided weight, length, hardness, coat proportion, water absorption and crude protein). Use of a selection index is suggested for breeding for seed size, water absorption,coat proportion and crude protein for both cropping systems. However, larger gains would be expected in pure cropping for most traits. Bean accessions PHA-0267, PHA-0285, PHA-0286 and PHA-0299 should be used for developing acceptable culinary and high protein breeding lines for either cropping system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sustainability of European maize-based cropping systems: Economic,environmental and social assessment of current and proposed innovative IPM-based systems

There is strong social and political pressure to reduce pesticide use in European agriculture. Evaluating the sustainability of cropping systems is a complex task due to the conflicting objectives underlying its economic, social and environmental dimensions. Multi-criteria assessment of different Integrated Pest Management (IPM) scenarios and evaluation of the most sustainable options at regional, national and European level is essential. Within the EU Network of Excellence ENDURE, two expert-based surveys were conducted (i.e. interviews), where experts from four European regions (northern region, Denmark and The Netherlands; central-eastern, Tolna and Békés counties in Hungary; south-western, Ebro Valley in Spain; southern, Po Valley in Italy) determined which are the main current maize-based cropping systems (MBCSs) in their region and proposed innovative IPM-based systems. The DEXiPM^® (DEXi Pest Management) model for arable cropping systems was used to evaluate and compare the economic and environmental sustainability of these systems. The social sustainability was evaluated by adapting indicators of this model to the specificities of maize systems. The assessments showed that all innovative rotated MBCSs proposed in the four regions can have a higher environmental sustainability than and maintain the same economic sustainability as current rotated systems. These cropping systems are thus acceptable for testing under “real” field conditions. Only the innovative continuous maize system proposed in the central-eastern region was both economically and environmentally more sustainable than the current system. All innovative systems had a positive impact on work safety but according to local expert opinion producers and consumers are not ready to implement them or to accept their higher-priced products, with the exception of consumers in the northern region. These results suggest the need for European and regional policies to encourage the adoption of innovative rotated MBCSs that have positive agronomic and environmental impact through IPM implementation. The major constraints that inhibit this adoption were predominantly relating to (1) the lack of access that farmers have to the practical knowledge needed to effectively manage these systems and (2) the insufficient consumer awareness and acceptance of product improvements associated with IPM. To overcome these constraints supportive policy environments, well-functioning knowledge management systems (including good farmer support networks) and effective marketing is required.     

Methodology to design agroecological orchards: Learnings from on-station and on-farm experiences

Agricultural research has to tackle complex questions such as the design of sustainable cropping systems. System experiments are innovative approaches to address this challenge and a framework to iteratively design annual cropping systems has been proposed by Debaeke et al. (2009). However, specificities of some other cropping systems are not considered. Orchards are complex perennial agroecosystems formed of grass and tree layers aiming at the production of fresh fruit that require specific design and management over space and time. To identify orchard specificities and adapt the design framework to such perennial systems, we used two case studies of orchards aiming at decreasing pesticide use in temperate (apple, system experiment) and tropical (citrus, on-farm network) fruit productions. Specificities to take into account in the design framework are: (1) the spatial heterogeneity of the orchard with grass and tree layers, and tree rows and alleys; (2) the succession and interrelations among a young unproductive and then a productive stage; (3) the permanency of the fruit-tree crop constraining the management of soil fertility, (4) ground cover and (5) pest control, especially for pests that complete their lifecycle in the orchard and can build up important populations or inoculum across years. This is especially true in tropical areas where there is no dormant season. (6) Conversely, the permanency of the orchard habitats facilitates the sowing, planting or conservation of plant assemblages (e.g., ground covers, lining hedgerows) to enhance conservation biocontrol and/or compete weeds, provided non-disruptive practices are applied.Because of their longevity, orchards contribute to foster both plant-mediated (e.g., bottom-up) and natural enemy-mediated (e.g., top-down) processes in the foodweb to avoid direct measures against pests. Interactions among the orchard life stages, spatial and functional dimensions and practices need to be explicitly considered to optimize the efficiency of the system as a whole. Using the generic framework proposed by Debaeke et al. (2009) to design annual cropping systems, our framework includes adaptations to account for orchard specificities: (i) Agronomic objectives have to be fixed for each orchard stage; (ii) The cultivar choice and the composition and spatial arrangement of plants within the orchard are key elements to provide the expected services in the long term. This entails to include an additional step of perennial spatial design; (iii) Within-time and −space interactions have to be considered in the decisional system; (iv) Evaluation has to consider all the orchard stages in the global impact or performance, to account for carry-over effects and possible ‘paybacks’ of a given stage or period to the orchard whole lifetime. Last, to handle such complex interactions, design needs knowledge from many stakeholders in the food system (growers, advisors, scientists etc.) and requires more and renewed interactions among those stakeholders in a co-design process.     

Adaptation of crop management to water-limited environments

Farmers must combine various crop management strategies to cope with water deficit resulting from soil, weather or limited irrigation: drought escape, avoidance or tolerance, crop rationing, irrigation (supplemental, deficit). These strategies can be translated into six objectives: (i) increasing soil stored water at plant sowing, (ii) increasing soil water extraction, (iii) reducing the contribution of soil evaporation to total water-use, (iv) optimizing the seasonal water use pattern between pre- and post-anthesis, (v) tolerate water stress and recover after stress alleviation, and (vi) irrigate at the most-sensitive growth phases. To reach these objectives, tactical decisions concern soil tillage, type of crop and cultivar, sowing date and density, N fertilization, irrigation timing, amount and frequency. Flexible crop management systems based on decision rules should be preferred to the recommendation of fixed packages of techniques. Timing, intensity, and predictability of drought (intermittent, terminal) are important features for choosing the cropping alternatives. Simulation models may help the farmer to select best-bet management options on the basis of historical long-term weather records. Simple soil and plant indicators associated with real-time decision support systems should be developed to revise the initial management plan by integrating in-season weather information.     

Yield and grain protein concentration in bread wheat: how to use the negative relationship between the two characters to identify favourable genotypes?

A study of the relationship between grain yield (GY) and grain protein concentration (GPC) in bread wheat was carried out on a 11-year series of trials conducted by the Groupement d’Etude des Variétés Et Semences (GEVES) for the registration of new cultivars on the French National List. Values for GY and GPC came from 458 individual trials, grouped together in 21 series of bi-annual and multi-site data. The correlations between the two characters, calculated environment by environment, appeared highly variable due to high “genotype × environment” interactions for GY and GPC. The use of mean values, calculated on the 21 series of GEVES trials, enabled a better assessment of the relationship between the two characters, and an algorithm was proposed to avoid bias due to potential outliers. Using the well-assessed relationship obtained, grain protein deviations (GPDs) were defined as the standardized residuals of the regression of GPC on GY. These deviations appeared to have a partly genetic basis, as the lines with high deviations were about the same in the two independent datasets constituted by the two consecutive years of GEVES experiments. Some lines used as standards in GEVES trials obtained significant GPD for different series of bi-annual and multi-site trials, confirming the genetic origin of high-GPD. Simulations made to determine the minimum experimental design, showed that at least five sites per year for two consecutive years, were necessary to have a good assessment of the GY–GPC relationship, and hence reliable estimates of GPD.