Monitoring the dynamics of wheat stem elongation: genotypes differ at critical stages

Abstract

Stem elongation is a critical phase for yield formation in wheat (Triticum aestivum). This study proposes the use of terrestrial laser scanning (TLS) for phenotyping of growth dynamics during wheat stem elongation in high temporal resolution and high throughput in the field. TLS was implemented on a novel field phenotyping platform carrying a cable suspended sensor head moveable in 3D over a 1 ha field. Canopy height was recorded on 335 winter wheat genotypes across two consecutive years. Scans were done in 3-d intervals during the stem elongation phase. Per day, 714 plots (two replications plus checks) were scanned within 3.5 h. The results showed that canopy height increased linearly with thermal time. Based on this linearity, 15 and 95% of final height were used as proxy measures for the onset and termination of stem elongation, respectively. We observed high heritability between 0.76 and 0.91 for the onset, termination and duration of stem elongation. The onset of stem elongation showed a positive covariance with the termination of stem elongation and final height indicating some regulatory dependencies. Yet there was no apparent relationship between onset and duration of stem elongation. Due to its precision, the TLS method allows to measure the dynamics of stem elongation in large sets of genotypes. This in turn offers opportunities to investigate the genetic control of the transitions between early vegetative growth, stem elongation and flowering. Understanding the genetic control of these transitions is an important milestone towards knowledge-based crop improvement.

Temperature response of wheat affects final height and the timing of stem elongation under field conditions

“…This resulted in 328 genotypes present across all three experiments. Details about the experimental setup for the growing seasons 2015 and 2016 are described in Kronenberg et al (2017).…”

“…Height measurements were concluded when no further height increase was observed in any of the genotypes. Canopy height data was extracted from the LIDAR data as described in Kronenberg et al (2017).…”

“…The start, end, and duration of SE as well as final canopy height (FH) were extracted from the height data following Kronenberg et al (2017): FH was defined as the point, after which no increase in height was observed in several consecutive measurements. Normalized canopy height was calculated as percent of FH at each day of measurement for every plot and then linearly interpolated between measurement points.…”

“…In recent years, new high throughput phenotyping technologies have enabled monitoring plant height with high accuracy and frequency in the field (Bendig et al, 2013;Friedli et al, 2016;Holman et al, 2016;Aasen and Bareth, 2018;Hund et al, 2019). We have previously demonstrated that the ETH field phenotyping platform (FIP, Kirchgessner et al, 2016) can be used to accurately track the development of canopy height in a large set of wheat genotypes using terrestrial laser scanning (Kronenberg et al, 2017). Considerable genotypic variation was detected for the start and end of SE which correlated positively with final canopy height (Kronenberg et al, 2017).…”

“…We have previously demonstrated that the ETH field phenotyping platform (FIP, Kirchgessner et al, 2016) can be used to accurately track the development of canopy height in a large set of wheat genotypes using terrestrial laser scanning (Kronenberg et al, 2017). Considerable genotypic variation was detected for the start and end of SE which correlated positively with final canopy height (Kronenberg et al, 2017). While many temperature-independent factors affecting plant height are known, the influences of temperature-dependent elongation and timing of the elongation phase is less clear.…”