Agronomie

An extensive background overview on the use of agricultural residues (wastes) for production of paper, board, binderless board, energy, different types of fuels by pyrolysis (solid, liquid and gaseous fuel), many petrochemicals substitutes, charcoal (activated carbon), dissolving pulps and rayon. It includes both scientific and industrial data, case studies, current status, sustainability of paper and sugar industries, green nanotechnology, and future prospects.
Keywords: Agricultural Residues (Wastes); Paper and Board manufacture; Sustainability of Paper and Sugar Industries; Green Nanotechnology; Future Prospects

Stem rust disease caused by Puccinia graminis f. sp tritici is a major challenge to wheat (Triticum aestivum) production in Kenya and other wheat growing countries of Africa and Asia. The current study aimed at evaluating sixty four wheat genotypes for stem rust resistance at seedling stage in a greenhouse; as well assessing the genotypes for stability in adult plant resistance to stem rust and yield across three sites in Kenya in an alpha lattice design with three replications. Seedling disease Infection Type (IT) ranged from “0” (immune) to “4” (susceptible), while adult plant infection assessed by disease Coefficient of Infection (CI) and Area Under Disease
Progress Stairs (AUDPS) ranged from means of 0.2 to 1.7 and 30.2 to 1174.2, respectively. Mean grain yield ranged from 2.0 to 7.8 t ha-1. Genotype, location and genotype × location interaction for the AUDPS, CI, and yield were significant (P  0.01). There was a significant (P  0.01) linear and inverse relation of grain yield to AUDPS and CI. Considering the disease response, yield potential, and yield stability, genotypes KSL 42 and KSL 3 were consistently well ranked. These genotypes are suitable candidates for utilization in yield and stem rust resistance improvement programs in Kenya and potentially in other major wheat growing areas in Kenya and potentially in
other major wheat growing areas globally, where stem rust is significant.

An evaluation of a generic crop growth model, STICS, described in Brisson et al. [11], is presented, based on an agronomic database which combines various wheat crop and maize crop situations in France. Emphasis is placed on the need to use standard references for parameterising varieties, particularly concerning the development stages. The validation was carried out for the model's output variables, defined as being the final variables of agronomic interest (yield and components, above-ground biomass, flowering and maturity dates, nitrogen contents in the plant and grain, water and nitrogen contents in the soil) using several mathematical criteria (square errors, mean deviation, efficiency). Results indicated that the two crops behave quite similarly with square errors of 1.6 t . ha -1 for wheat yield and 2.4 t . ha -1 for maize yield. The two yield components, grain number and grain weight, were simulated less successfully, as was the case for the simulations concerning nitrogen both in the plant and soil, which were systematically biased. However, the water content in the soil was simulated accurately. An analysis of the dynamics of the main state variables in the system, such as leaf area index or nitrogen nutrition index, which in some cases were extracted from the database, made it possible to reveal the shortcomings in the model and propose ways of modifying it. The results we will retain include the introduction of a relationship between grain number and maximal grain weight, which makes the "grain number" variable dependent on the variety, the consideration of leaf senescence due to environmental stress, and the end of nitrogen absorption at the onset of grain filling. These modifications help to improve modelling results of yield components and soil and plant nitrogen contents. They have little effect on biomass and yield, for which errors remain at levels of approximately 15%; the impossibility of reducing the error concerning biomass, and consequently that concerning yield, illustrates the model's robustness. crop modelling / wheat / maize / water balance / nitrogen balance / validation Communicated by Jean-François Ledent (Louvain-La-Neuve, Belgium) Agronomie 22 (2002) 69-92 69 Résumé -STICS : un modèle générique pour simuler les cultures et leurs bilans hydrique et azoté. II. Validation du modèle pour le blé et le maïs. Une évaluation du modèle générique de culture STICS, décrit en détails dans Brisson et al. [11]

— La conservation des carottes au froid après récolte se développe depuis peu en France; l'objectif de cette étude est d'inventorier les agents pathogènes susceptibles de provoquer des dégâts dans cet environnement particulier et de définir les conditions optimales de stockage. L'analyse de la mycoflore réalisée sur racines de carottes stockées 50 ou 100 j au froid montre que dans les conditions de production et de conservation de la région de Normandie, les principaux problèmes parasitaires rencontrés sont dus à Mycocentrospora acerina et à Phytophthora megasperma; les dégâts occasionnés par Botrytis cinerea, Sclerotinia sclerotiorum et Stemphylium radicinum sont d'importance mineure. Par ailleurs, l'incidence des conditions de conservation est démontrée : les carottes stockées au froid humide (0,5 à 1 °C -98% d'humidité relative) présentent un pourcentage d'attaque plus faible que celles maintenues au froid conventionnel (2 °C -85-90% d'humidité relative). La caractérisation biologique des différents agents pathogènes isolés indique que seuls M acerina et B cinerea sont capables de provoquer des symptômes dès 0,5 °C. Le comportement de l'ensemble des parasites en relation avec la température et l'hygrométrie est discuté. L'intérêt d'un délai entre l'arrachage et la mise en conservation sur le développement des maladies et plus particulièrement sur M acerina est également mis en évidence; l'intensité d'attaque de ce parasite, dans les conditions optimales de conservation pour la carotte, reste toutefois considérable et justifie une étude sur la recherche d'une technique de lutte adaptée s'appuyant notamment sur la spécificité des relations hôte-parasite. Daucus carota = carotte / pathologie post-récolte / Mycocentrospora acerina / conservation au froid Summary — Post-harvest pathogens on cold stored carrots: Mycocentrospora acerina (Deighton), the major spoilage fungus. A survey was conducted to inventory pathogens likely to attack carrot roots stored under cold conditions. An analysis of the carrot root mycoflora under storage and production conditions in Normandy, France, showed that major fungal spoilage was due to Mycocentrospora acerina and Phytophthora megasperma; rot caused by Botrytis cinerea, Sclerotinia sclerotiorum and Stemphylium radicinum was only of secondary importance. The study also revealed that storage losses due to fungal spoilage were lower in ice-bank cooled stores at 0.5-1 °C, 98% relative humidity (RH) than in conventionally cooled stores at 2 °C, 85-90% RH. Only M acerina and B cinerea strains were pathogenic on carrot root slices at temperatures as low as 0.5 °C, but were not particularly adaptated for cold conditions. The behaviour of the pathogens related to temperature and relative humidity is discussed. This study showed the existence of a relationship between the healing of wounds in carrot roots and infection by M acerina by exposing them before cold storage. Nevertheless, spoilage wastage caused by this pathogen still remains important even under optimal storage conditions for carrot crops. Daucus carota / post-harvest diseases /Mycocentrospora acerina / cold storage * Correspondance et tirés à part 93, 69-71 Van Den Berg L, Lentz CP (1973) High humidity storage of carrots, parsnips, rutabagas and cabbage. J Am Soc Hortic Sci 98, 129-132

Vingt individus issus de populations ou cultivars tétraploïdes et diploïdes de Medicago sativa L. et de l'espèce Medicago falcata L. ont été évalués pour leur aptitude à la régénération à partir de cals. Les différences interet intra-populations ou cultivars sont très importantes. Les cals issus de 6 génotypes ont permis la régénération de plantes soit par organogenèse (2 génotypes) soit par embryogenèse somatique (4 génotypes). La qualité et le rendement des embryons somatiques ont été améliorés par l'utilisation d'une nouvelle séquence de milieux (UM-UMo). Deux génotypes de M. sativa tétraploïdes, l'un issu de la population chinoise « Mestnaya », l'autre du cultivar « Europe » ont un potentiel embryogène et de régénération très élevé, nettement supérieur à Regen S utilisé comme témoin.

Soil surface roughness affects surface depression storage, water infiltration, overland flow velocity as well as overland flow organisation. This paper attempts to give an overview of our knowledge of the effects of roughness on surface runoff and to indicate areas where further research is most needed. The relationship between soil surface roughness and depression storage is relatively well understood. On the other hand, few studies exist on the relationship between roughness and the infiltration characteristics of a tilled surface, although this may be more important. Insights, which have been developed over the past few years, may in the near future lead to a better prediction of the hydraulic resistance of interrill and concentrated overland flow. Recent studies have also provided important information on the effects of roughness on runoff patterns. soil roughness / depression storage / infiltration / hydraulic resistance / runoff pattern Résumé -Rugosité du sol et écoulement sur le terrain. La rugosité de la surface du sol affecte le stockage de l'eau dans les dépressions de la surface, son infiltration et la vitesse ainsi que l'organisation de l'écoulement sur le terrain. Cet article tente de donner une vue d'ensemble de nos connaissances actuelles sur les effets de la rugosité sur le ruissellement de surface et indique les domaines dans lesquels de nouvelles recherches sont les plus nécessaires. La relation entre la rugosité de la surface et le stockage de l'eau dans les dépressions est relativement bien connue. En revanche, il existe peu d'études sur la relation entre la rugosité d'une surface labourée et ses caractéristiques d'infiltration, bien que ce phénomène soit plus important. Les tentatives d'approche développées au cours des dernières années devraient conduire, dans un proche avenir, à une meilleure prédiction de la résistance hydraulique des zones de ruissellement diffus et concentré. Des études récentes ont fourni également des informations importantes sur les effets de la rugosité sur l'organisation spatiale de ruissellement.

A better understanding of the effect of environmental factors on growth and nitrate accumulation in plants is necessary to develop cultivation practices, and in particular for providing lettuces with a low nitrate content. This study was conducted to analyse the effect of nitrogen supply on the interception and conversion of the PAR in dry matter, and on the nitrate and water accumulations in fresh tissues of the lettuce, for various conditions of temperature and radiation. The growth, and water and nitrate concentrations of two soilless cultures of lettuce (summer and autumn) were measured for two levels of radiation and two levels of nitrogen supply. RUE ranged from 2.12 to 3.50 g·MJ -1 , being higher for a low radiation level and for a high nitrogen supply. There was a positive correlation between the lettuce nitrate and water contents. The slope of this relationship was not affected by environmental conditions, indicating a strong interdependance between nitrate and water accumulation in lettuce.

STICS (Simulateur mulTJdiscplinaire pour les Cultures Standard) is a crop model constructed as a simulation tool capable of working under agricultural conditions. Outputs comprise the production (amount and quality) and the environment. Inputs take into account the climate, the soi1 and the cropping system. STICS is presented as a model exhibiting the following qualities: robustness, an easy access to inputs and an uncomplicated f~~t u r e evolution thanks to a modular (easy adaptation to various types of plant) nature and generic. However, STICS is not an entirely new model since most parts use classic formalisms or stem from existing models. The main simulated processes are the growth, the development of the crop and the water and nitrogenous balance of the soil-crop system. The seven modules of STICSdevelopment, shoot growth, yield components, root growth, water balance, thermal environment and nitrogen balanceare presented in tum with a discussion about the theoretical choices in comparison to other models. These choices should render the model capable of exhibiting the announced qualities in classic environmental contexts. However, because some processes (e.g. ammoniac volatilization, clrought resistance, etc.) are not taken into account, the use of STICS is presently limited to several cropping systems. (O InraIElsevier, Paris.) crop modelling / wheat / corn / water balance / nitrogen balance Communicated by G6rard Guyot (Avignon, France) Résumé -STICS : un modhle générique pour simuler les cultures et leurs bilans hydrique et azoté. 1. Théorie et paramétrage appliqués au blé et au maïs.