Agronomic assessment of two populations of intermediate wheatgrass—Kernza® (Thinopyrum intermedium) in temperate South America

Abstract

Background: Kernza ® intermediate wheatgrass is a perennial grain and forage crop that can provide several ecosystem services. Major research efforts focused on Kernza have taken place in high latitudes. The goal of this study was to evaluate, for the first time, the agronomic performance of Kernza in a low-latitude region with mild winters. Methods: A KS-cycle 4 Kernza population (A) was planted in spring in Wisconsin, USA, and selected in one cycle for lower vernalization requirements, obtaining a new population (B). These two populations, at three nitrogen (N) fertilization rates, were evaluated in a full factorial, completely randomized field experiment in Uruguay over 2 years. Results: The populations were similar in grain yields and flowering time in the 1st year, but population B had 63% lower grain yield in the 2nd year and 20% lower forage yield throughout the experiment. Increasing the N rate to 160 kg ha −1 led to a 63% increase in grain yield and 28% increase in forage yield across populations. Forage yields and nutritive values were similar to those reported in the northern hemisphere. However, grain yields for both the 1st (316 kg ha −1 ) and 2nd year (41 kg ha −1 ) were lower due to reduced flowering and weed competition. Conclusions: Expansion of Kernza to lower-latitude regions will require further breeding to improve reproductive performance.

Maintaining grain yield of Th. intermedium across stand age through constant spike fertility and spike density: Understanding its response to various agronomic managements

“…The lower spike density of this study may have limited competition between spikes and maintained relatively higher spike fertility. All in all, this sustains the hypothesis that yield and harvest index decline with stand age such as observed in other studies (Jungers et al, 2017;Pugliese, 2017;Frahm et al, 2018;Tautges et al, 2018;Bajgain et al, 2020;Locatelli et al, 2023) might partly be caused by the increasing competition in stands with excessive tiller density (Law et al, 2020;Cassman & Connor, 2022). While tillering is necessary for aboveground biomass production, selection for grain yield improvement should focus on the reduction of excessive tillering (incl.…”