The effect of biochar application on soil properties and growth of the model plant Zea mays

The classic way of land cultivation means the use of inorganic fertilizers that are salts that dissolve rapidly in a short time and improve soil fertility. This process negatively affects soil salinity and the life of microorganisms. The use of biochar as a soil conditioner is a promising solution. The aim of the work is to enrich the properties of less fertile soils and to enhance the growth of the model plant Zea mays (corn) by biochar application. We used four different soil types commonly spread in the Czech Republic – regosol, chernozem, cambisol and fluvisol representing a broad range of organic matter content. Also, we applied two different EBC (The European Biochar Certificate) certified biochars for use in agriculture. Corn seeds were germinated and cultivated for 3 months in repeated plant life cycles. Soils and biochar samples were characterized before and after cultivation by TGA, EA, BET, SEM, extraction of organic matter. The effect of biochar application was observed continuously through the measurement of plant height, the number of leaves and cobs. After the finalization of cultivation experiments, the dry mass of individual plants was measured, and root image analysis of every plant was performed. Fluvisol and cambisol have much higher organic matter content than regosol and chernozem. The application of biochar had the most significant impact on regosol regardless of the application dose; these results are in good agreement with the root image analysis. Furthermore, plants in soils treated with biochar had more corn cobs. The analysis on biochar samples showed the continual leaching of both organic and inorganic molecules from biochar to surrounding soil, which is crucial for its possible use as a soil conditioner and confirms the long-timescale positive effect on soil properties.

Image Analysis of Root Induction in Sedum praealtum Cuttings

Production of adventive roots is a process induced and regulated by phytohormones where auxins play an important role in controlling the growth and development of them, with a direct influence on the regenerative ability of plants. The aim of this study was to compare the root induction and development on Sedum praealtum cuttings by the action of 3-indolylbutyric acid (IBA) and naphthylacetic acid (NAA) concentrations by root image analysis. Root length of plantlets showed that there was an interval between 0.1 and 1.0 mg/L concentrations of efficient root induction with a clearly decrease of it as IBA concentration increased, also as NAA treatment showed. In this work, the rooting response of Sedum praealtum cuttings evaluated by root image analysis showed the application of IBA as an efficient synthetic auxin for vegetative propagation.

Using a structural root system model to evaluate and improve the accuracy of root image analysis pipelines

Root system analysis is a complex task, often performed with fully automated image analysis pipelines. However, the outcome is rarely verified by ground-truth data, which might lead to underestimated biases.We have used a root model, ArchiSimple, to create a large and diverse library of ground-truth root system images (10,000). For each image, three levels of noise were created. This library was used to evaluate the accuracy and usefulness of several image descriptors classically used in root image analysis softwares.Our analysis highlighted that the accuracy of the different traits is strongly dependent on the quality of the images and the type, size and complexity of the root systems analysed. Our study also demonstrated that machine learning algorithms can be trained on a synthetic library to improve the estimation of several root system traits.Overall, our analysis is a call to caution when using automatic root image analysis tools. If a thorough calibration is not performed on the dataset of interest, unexpected errors might arise, especially for large and complex root images. To facilitate such calibration, both the image library and the different codes used in the study have been made available to the community.