A simple and versatile 2-dimensional platform to study plant germination and growth under controlled humidity

We describe a simple, inexpensive, but remarkably versatile and controlled growth environment for the observation of plant germination and seedling root growth on a flat, horizontal surface over periods of weeks. The setup provides to each plant a controlled humidity (between 56% and 91% RH), and contact with both nutrients and atmosphere. The flat and horizontal geometry of the surface supporting the roots eliminates the gravitropic bias on their development and facilitates the imaging of the entire root system. Experiments can be setup under sterile conditions and then transferred to a non-sterile environment. The system can be assembled in 1-2 minutes, costs approximately 8.78$per plant, is almost entirely reusable (0.43$ per experiment in disposables), and is easily scalable to a variety of plants. We demonstrate the performance of the system by germinating, growing, and imaging Wheat (Triticum aestivum), Corn (Zea mays), and Wisconsin Fast Plants (Brassica rapa). Germination rates were close to those expected for optimal conditions

Mind the (yield) gap(s)

This paper explores the origin of the notion of “yield gap” and its use as a framing device for agricultural policy in sub-Saharan Africa. The argument is that while the yield gap of policy discourse provides a simple and powerful framing device, it is most often used without the discipline or caveats associated with the best examples of its use in crop production ecology and microeconomics. This argument is developed by examining how yield gap is used in a selection of recent and influential agricultural policy documents. The message for policy makers and others is clear: “mind the (yield) gap(s)”, for they are seldom what they appear

Estimation de la concentration en chlorophylles de feuilles par mesure de leur réflectance ou par analyse numérique de photographies prises au laboratoire

Des simulations effectuées avec un modèle de réflectance de feuille permettent de proposer une méthode simple d'estimation de la concentration en chlorophylles, fondée sur la mesure de la réflectance dans le rouge ou le vert. Les résultats obtenus sont évalués sur des feuilles de betteraves à sucre, en utilisant 2 capteurs adaptés à la mesure de la réflectance sur des échantillons de dimensions importantes : - en mesurant directement la réflectance foliaire, avec un densitomètre photographique qui permet une mesure rapide mais ponctuelle (5 mm2); - en estimant la réflectance par numérisation de photographies de feuilles prises au laboratoire, qui fournissent une image de la distribution spatiale des pigments. Les résultats expérimentaux confirment l'existence d'une relation simple entre la réflectance et la concentration en chlorophylles; toutefois les paramètres ajustés expérimentalement pour cette relation diffèrent sensiblement de ceux calculés par le modèle. Cette différence semble provenir principalement de l'utilisation de capteurs à bande spectrale large. L'utilisation des capteurs proposés nécessite donc de disposer d'un échantillon d'apprentissage pour l'ajustement de 2 paramètres.Estimation of chlorophyll content of leaves using reflectance measurements or digitalized photographs of leaves taken in the laboratory. A simple method based on model simulations of leaf reflectance was proposed for the estimation of leaf chlorophyll content from reflectance measurements in the red or green parts of the spectrum. The results were evaluated with sugar beet leaves using 2 methods to acquire the data. The methods were chosen for their ability to provide measurements on large samples: first, direct measurements of leaf reflectance were made using a photographic densitometer capable of taking quick measurements on small areas (5 mm2). Second, indirect estimates of leaf reflectance were made from digital analysis of color photographs of leaves taken in laboratory; this gave an image of the spatial distribution of pigments. Experimental results confirmed that a simple relation exists between reflectance and chlorophyll content. However, the experimental parameters of the relation significantly differed from those computed from the model. It seems that the difference is mainly due to the use of broad band sensors. Thus for operational use, it is necessary to calibrate 2 parameters on a sample of leaves of known chlorophyll content

Future climate impact on the productivity of sugar beet (Beta vulgaris L.) in Europe

The impact of future climate change on sugar beet yields is assessed over western Europe using future (2021-2050) climate scenario data from a General Circulation Model (GCM) and the Broom's Barn simulation model of rain-fed crop growth and yield. GCM output for the 1961-1990 period is first compared with observed climate data and shown to be reliable for regions west of 24°E. Comparisons east of this meridian were less reliable with this GCM (HadCM2) and so were omitted from simulations of crop yield. Climate change is expected to bring yield increases of around 1 t/ha of sugar in northern Europe with decreases of a similar magnitude in northern France, Belgium and west/central Poland, for the period 2021-2050. Averaged for the study area (weighted by current regional production), yields show no overall change due to changed climate. However, this figure masks significant increases in yield potential (due to accelerated growth in warmer springs) and in losses due to drought stress. Drought losses are predicted to approximately double in areas with an existing problem and to become a serious new problem in NE France and Belgium. Overall west and central Europe simulated average drought losses rise from 7% (1961-1990) to 18% (2021-2050). The annual variability of yield (as measured by the coefficient of variation) will increase by half, from 10% to 15% compared to 1961-1990, again with potentially serious consequences for the sugar industry. The importance of crop breeding for drought tolerance is further emphasised. These changes are independent of the 9% yield increase which we estimate, on the basis of work by Demmers-Derks et al. (1998), is the likely direct effect of the increase in atmospheric CO2 concentration by 2021-2050

Actual and Potential Yield Levels of Potato in Different Production Systems of Japan

Japan annually produces 2.4 million tons of potato on 79,700 ha. There are four cropping seasons stretching from 24° to 45° N: a winter crop at Okinawa, spring and autumn crops at Kyushu and southern Honshu, and a single summer crop at Hokkaido. Using the crop growth model LINTUL-POTATO-DSS, actual yields were compared with potential yields. The spring and summer crop yields of all prefectures varied from 10 to 43 t ha−1 and were 16 t ha−1 on average (not weighted by area); the actual/potential yield ratio varied between 0.21 and 0.63 and was 0.40 on average (not weighted). Actual and potential yields of the autumn crops were half those of the spring crops. Actual yields of the Hokkaido summer crops in 21 years decreased from 35 to 32 t ha−1 because of a change of varieties whereas potential yield remained stable at 56 t ha−1. Increased temperature would reduce the potential yield to 53 t ha−1 but would move it up to 60 t ha−1 by lengthening the growing season and to 77 t ha−1 when the CO2 effect on growth is taken into account. The actual/potential yield ratio at Hokkaido was benchmarked against that of other growing regions in the world, showing that this area compares well with that of other efficient production systems in northern Europe and America.</p