Agronomic performance, nitrogen acquisition and water-use efficiency of the perennial grain crop Thinopyrum intermedium in a monoculture and intercropped with alfalfa in Scandinavia

Abstract

The perennial forage grass Thinopyrum intermedium (Host) Barkworth & Dewey, commonly known as intermediate wheatgrass (IWG) or by the commercial name Kernza™, is being developed as a perennial grain crop, i.e. being bred for its improved agronomic performance and food qualities. Intercropping legumes and grasses is a strategy for improving resource use and sustainability in cropping systems. Here, we show for the first time the agronomic performance of IWG as a perennial cereal grown as a monocrop and as an intercrop (alternate row, 0.5:0.5) with Medicago sativa L. (alfalfa/lucerne) in southern Sweden. The seeds of cycle 3 IWG were accessed from The Land Institute (TLI) of Salinas, Kansas, USA, and used to establish a local seed production plot (in 2014) for the establishment of the perennial systems (in 2016) utilised in this study. Both the monocrop and intercrop were sown with 25 cm row spacing with alternate rows of IWG and alfalfa in the intercrop (i.e. replacement design) with unknown sowing density. Intercropping provided sustained IWG grain production under the dry conditions of 2018, but also in the following year. This was evidently associated with a higher nitrogen accumulation in intercropped practice. Thus, intercropping seems to have stabilised the IWG grain production in the dry conditions of 2018, when the grain production in the intercrop was similar to that of the monocrop in the same year. This result was further supported by the lower discrimination against 13C (as an indicator of water use efficiency) in the intercrop components compared to the sole crop in 2018. The lower discrimination indicates high water use efficiency in the intercropped IWG in comparison to the IWG in monoculture, and we conclude that intercropping perennial cereal grain crops with legumes provides better growing conditions in terms of nitrogen acquisition, and water status, to cope with more extreme drought spells expected from climate change.

Intercropping legumes and intermediate wheatgrass increases forage yield, nutritive value, and profitability without reducing grain yields

“…Some experiences with perennial legumes have shown lower Kernza grain yields in intercropping with alfalfa (Medicago sativa sp.) or red clover (Trifolium pratense L.) than in the IWG monocultures (Tautges et al, 2018;Favre et al, 2019;Mårtensson et al, 2022). However, others showed similar Kernza grain yields in alfalfa, sweet clover, and white clover intercropping (Dick et al, 2018;Reilly et al, 2022).…”

“…However, changes in the available resources such The profitability of the IWG cropping systems depends on both grain and forage incomes (Hunter et al, 2020b). Therefore, the lower Kernza grain yields harvested in alfalfa and red clover intercrops (Tautges et al, 2018;Favre et al, 2019;Mårtensson et al, 2022) could be compensated by positive effects on the increased forage yield and nutritive value. Intercropping IWG with red clover has consistently increased the nutritive value of the summer and fall forage and tripled the amount of available forage in the fall (Favre et al, 2019), positively affecting the revenue perceived by the farmers.…”

Identification of promising alfalfa varieties in conditions of the southern forest-steppe zone (Republic of Bashkortostan): a study of economic and biological characteristics

“…In Turkey, farmers achieved high hay and seed yields even later, in early October (Kir 2022 ). The Swedish climate allows farmers to obtain high alfalfa yields through intercropping legumes and grasses (Mårtensson et al 2022 ).…”

Alfalfa (Medicago sativa L.)/Crops intercropping provides a feasible way to improve productivity under environmental constraints

“…Annual cereal and legume intercropping studies have shown that the intercropping improves both the nitrogen and protein concentrations of the cereal grains and could potentially improve their quality. The use of intercropping is a way to increase the concentration of nutrients in the biomass and thus improve their suitability for animal feed (Mårtensson et al, 2022).…”

“…Drought causes a restriction in crops growth, which is not only due to physiological limitations, but also to the plant's limited ability to utilize nutrients due to insufficient rainfall and low soil moisture levels. Nevertheless, M. sativa has maintained its growth despite drought conditions, most probably through its ability to biologically fix atmospheric N2 (Mårtensson et al, 2022). In drought conditions, alfalfa was more productive when grown in association with winter wheat (Triticumaestivum) (Skelton et al, 2005).…”