High-throughput phenotyping (HTP) identifies seedling root traits linked to variation in seed yield and nutrient capture in field-grown oilseed rape (Brassica napusL.)

Abstract

Background and Aims Root traits can be selected for crop improvement. Techniques such as soil excavations can be used to screen root traits in the field, but are limited to genotypes that are well-adapted to field conditions. The aim of this study was to compare a low-cost, high-throughput root phenotyping (HTP) technique in a controlled environment with field performance, using oilseed rape (OSR; Brassica napus) varieties.Methods Primary root length (PRL), lateral root length and lateral root density (LRD) were measured on 14-d-old seedlings of elite OSR varieties (n = 32) using a ‘pouch and wick’ HTP system (∼40 replicates). Six field experiments were conducted using the same varieties at two UK sites each year for 3 years. Plants were excavated at the 6- to 8-leaf stage for general vigour assessments of roots and shoots in all six experiments, and final seed yield was determined. Leaves were sampled for mineral composition from one of the field experiments.Key Results Seedling PRL in the HTP system correlated with seed yield in four out of six (r = 0·50, 0·50, 0·33, 0·49; P < 0·05) and with emergence in three out of five (r = 0·59, 0·22, 0·49; P < 0·05) field experiments. Seedling LRD correlated positively with leaf concentrations of some minerals, e.g. calcium (r = 0·46; P < 0·01) and zinc (r = 0·58; P < 0·001), but did not correlate with emergence, general early vigour or yield in the field.Conclusions Associations between PRL and field performance are generally related to early vigour. These root traits might therefore be of limited additional selection value, given that vigour can be measured easily on shoots/canopies. In contrast, LRD cannot be assessed easily in the field and, if LRD can improve nutrient uptake, then it may be possible to use HTP systems to screen this trait in both elite and more genetically diverse, non-field-adapted OSR.

Imaging and functional characterization of crop root systems using spectroscopic electrical impedance measurements

“…Moreover, attempts should be made to increase the number of experimental repetitions to consolidate the results and their biophysical interpretation (see, e.g., Fig. 5 in Thomas et al 2016). While this has been achieved already for studies involving two-electrode capacitance measurements (e.g., Cseresnyés et al 2016) and four-electrode SIP/EIS measurements (e.g., Postic and Doussan 2016), it is challenging for tomographic, broadband four-electrode impedance measurements given the data acquisition and processing demands.…”

“…Neutron radiography has also been successfully used to image live root segments and their surrounding environment (e.g., Moradi et al 2009;Carminati et al 2010). However, these methods are still limited to small sample sizes and laboratory conditions (e.g., Thomas et al 2016), and are subject to high application costs.…”

Nitrogen use efficiency in rapeseed. A review

“…To accelerate breeding programs, efficient methods and platforms to screen large breeding populations for meaningful variation at early stages of development would be immensely valuable. Thomas et al (2016) compared a "pouch and wick" high-throughput phenotyping technique to evaluate root traits such as primary root length and lateral root density of 32 elite rapeseed cultivars, along with their root vigor and seed yield, in six field experiments. They concluded that primary root length was the best predictor of early vigor and final seed yield, and that measuring lateral root density could be an additional lever for the improvement of nutrient uptake in rapeseed.…”

Multivariate analyses of root phenotype and dynamic transcriptome underscore valuable root traits and water‐deficit responsive gene networks in maize

“…For instance, young seedling root vigor has been correlated with mature field‐grown root vigor (Wasson et al., ). Seedling root traits have been shown to be linked with mature plant traits such as height and yield in multiple crop species (Bai, Liang, & Hawkesford, ; Thomas et al., ). In this study, we show that two maize cultivars differing in seedling RSA traits exhibited contrasting water‐deficit performance, as evidenced by survival rate, physiological responses, and root system (Figure ; Figure ; Table ).…”