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Selection for deep rooting is critical for the development of genotypes that are able to explore deep soil water and nutrients, particularly as agricultural resources become more limited. However, current root phenotyping techniques demand significant investments of time, money, and effort, and measurements on very young plants or plants grown under soilless culture. This study introduced four novel and simple techniques for fast evaluation of root depth in tube rhizotrons, which enable root observation around the transparent tube walls, and allow roots growing to natural size in semi-field conditions. The first and second innovations involve the introduction of 15N tracer and herbicide to the roots, which estimated root activity by measuring the responses of the shoots aboveground. The third involves placement of a cone deep in the rhizotron, to increase chances to observe more deep roots along the tube walls. The fourth involves measurement of roots that emerge from the rhizotron bottom. The reliability of these techniques were assessed in a series of five experiments during 2014 and 2015. These tests compared two pairs of genotypes that previous studies had shown to have mutually distinctive root traits: the spring wheat pair of ‘April bearded’ vs. ‘Dacke’; and the winter wheat pair of ‘Tabasco’ vs. ‘Genius’, with the first of each pair being the genotype known for deep rooting. Results showed that the new techniques were as good as or better than existing alternatives at accurately measuring root traits. In eight of the nine comparisons, the measurements were consistent with the expectations of root characteristics for these known genotypes. Importantly, the indirect root activity measures (herbicide and 15N) showed the same trend as the direct root observation techniques in all experiments, but higher ability to distinguish the genotypes and more promise for future upscaling for plant breeding. [ABSTRACT FROM AUTHOR]

A letter is presented that proposes a rapid screening method for the parallel determination of various phytohormones such as abscisic acid (ABA) and indole-3-acetic acid (IAA), and phytoalexins like camalexin and scopoleptin in various plant species, notably "Arabidopsis thaliana" and "Nicotiana tabacum." It claims that this method can increase the process of physiological phenotyping in plants, thus helping researchers to develop effective strategies for the protection of agricultural crops.