This is done by continuous scanning of the crop canopy (every 2 hours) with 3D imaging of the leaf area, that consists of projection of a laser line (940nm wavelength) which is fully reflected by the crop canopy and imaged at a high rate (50-80 pics s-1) by a camera with a 940nm filter. A 3D image is then reconstructed from the many 2D pictures and a3D laser triangulation of the crop canopy allows to extract a number of plant parameters, including the 3D leaf area, projected leaf area, plant height (See Vadez et al., 2015 doi:10.1093/jxb/erv251for a full description).
The platform uses a sensor-to-plant concept, contrary to most existing systems where the plants are conveyed to an imaging cabinet. Therefore, scanners are supported by an irrigation boom and are then moved above the plants (that are then undisturbed). The scanners use barcode references to set their x and y position in the platform. A typical experimental plot (called a sector) consists of a width of 65cm and a length of either 40 or 60 cm, giving a surface of either 0.26 m2 or 0.39m2. We have chosen to set up the platform in outdoors where environmental conditions are constantly monitored and data integrated every 30 min (relative humidity, temperature, solar radiation, wind and rain). In addition, plants are cultivated at densities reflecting the field conditions, so that a 0.26 m2 sector contains 8 chickpea plants or 4 pearl millet plants to reflect sowing densities of 30 or 15 plant m2 respectively. Plants are cultivated either in large pots (27 or 34 cm diameter containing 10 or 15 kg of soil – 2 pots/sector) or large trays (40x60x30cm widthxlengthxdepth and are filled with about 75 kg of Vertisol).
We are still at the beginning of the exploitation of these rich datasets. Simple analysis can be done of the different parameters measured at different time points using simple REmL analysis (all experiments follow an Alpha design). Analysis of rate of increase in parameters can be done. The first step is to convert the date measurements into thermal units, which allows to compare experiments across time. Then slope of increase of the different parameters can be measured for any chosen interval.
For us gems means GEMS, or G*E*M*S (genotype by environment by management by society) interactions, i.e. the fact that crop yields results from complex biophysical interactions while acceptance depends on farmer/consumer preferences. This complexity becomes an opportunity when it is cracked into components that can be analysed, understood, predicted, and then used to prioritise research investments to maximise return. This is what we do, and this is when GEMS become gems!
For us gems means GEMS, or G*E*M*S (genotype by environment by management by society) interactions, i.e. the fact that crop yields results from complex biophysical interactions while acceptance depends on farmer/consumer preferences. This complexity becomes an opportunity when it is cracked into components that can be analyzed, understood, predicted, and then used to prioritize research investments to maximise return. This is what we do, and this is when GEMS become gems!
A crop performs in different ways in different sites, years and agronomic managements. These are called genotype-by-environment-by management(G*E*M) interactions, and they are a main challenge for breeders and agronomists. There is one more layer of interaction, even more complex: the society (S). Farmers and consumers have different desires, needs, expectations, and a cultivar that fits one may not fit the other (G*E*M*S interactions). The puzzle is complex and challenging but if its components are understood, specific interventions can be undertaken.For instance, breeding for a particular genotype (G, with particular physiological characteristics), for a particular environment (E, with a particular kind of drought pattern that requires a specific adaptive trait), in a particular management practice (M, for instance a sowing density, or a N fertilizer treatment), and targeted to particular farmer/consumer (S, for instance a genotype that produces a lot of rich stover for cattle ranchers) is the need of the hour.