Plants live in two very different, but of course connected, worlds, having their shoots in the airspace and their roots in the soil. In both parts of the environment, various factors act on the plants and thereby take influence on its physiology. Environmental factors have effects on gene expression, metabolism and phenotypic properties of the plants. The capability to adjust phenotypically to environmental factors enables plants to survive in their habitats. In crop plants, it is essential that plants deliver adequate harvest-determining phenotypes under a broad range of environmental situations that correspond to agricultural practice.
The experiment shown in the photograph demonstrates the influence of nutrients. Three crop plant species (tomato, barley, rapeseed) were exposed to low to high nutrient concentrations by providing liquid fertiliser into the pots. From no fertilisation (right) to fertilisation as recommended (second row from left), plant growth and leaf greeness was promoted with increasing fertiliser availability. Fertiliser excess (left row) caused dark green leaves but lodging stems.
Recording phenotypic properties, e.g. growth and leaf colour, together with environmental parameters is essential for many experiments. Beyond fertiliser availability, light, water, temperature, soil structure and other abiotic factors interact with the plants. Thereby, growth is a very sensitive phenotypic trait that quickly responds to any sub-optimal environment. However, many more physiological responses occur that turn out in phenotypes that can be measured with non-invasive technology. Such might comprise spectral reflectance signatures, morphological properties, or fluorescence signals that occur and change upon environmental stimulation.