Greenseeker to Capture Biomass Accumulation and Grain Filling Dynamics in Wheat Germplasm.

Trait characterization during the growing season in a wheat breeding program is challenging due to large numbers of lines tested across multi-location trials. However, it is imperative to capture dynamic changes in the plant phenome throughout the season to tailor varieties for specific environments. We hypothesized that genotype * environment interactions in wheat germplasm could be characterized by quantifying green leaf area through the growing season, as it theoretically follows a typical bell-shaped curve. A commercial GreenSeeker^® estimating normalized difference vegetation index (NDVI) was used in phenotyping winter wheat germplasm. Uniform wheat variety trial comprising 40 winter wheat lines from public and private breeding programs were tested at three diverse environmental conditions in High Plains and Rolling Plains of Texas across multiple years (2014 and 2015). NDVI was captured multiple times during the season in addition to data on biomass, plant height, grain yield and yield components. Results suggest that NDVI is extremely valuable in estimating stand establishment, early vigor, ground cover, and dynamic temporal patterns in biomass accumulation and senescence associated with grain filling. GreenSeeker based NDVI data was also useful in assessing damage and recovery after freeze and score for common cereal diseases. Our results reinforce the importance of recurrent trait characterization efforts in a plant breeding program and present rapid and reliable methods that could be used in efficient field phenotyping. In future, manned or unmanned aerial platforms with multi-sensor capabilities with various indices may offer better phenotyping solutions to characterize complex traits.