Salinity reduces the forage quality of forage kochia: a halophytic chenopodiaceae shrub

Authors: Waldron, Blair; SAGERS, J - Utah State University; CREECH, J - Utah State University; Peel, Michael; Rigby, Craig; BUGBEE, B - Utah State University

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2019
Publication Date: 5/12/2020
Publication URL: https://handle.nal.usda.gov/10113/6797583
Citation: Waldron, B.L., Sagers, J.K., Creech, J.E., Peel, M., Rigby, C.W., Bugbee, B. 2020. Salinity reduces the forage quality of forage kochia: a halophytic chenopodiaceae shrub. Rangeland Ecology and Management. 73(3):384-393. https://doi.org/10.1016/j.rama.2019.12.005.
DOI: https://doi.org/10.1016/j.rama.2019.12.005

Interpretive Summary: Forage kochia is a perennial, salt-tolerant shrub adapted to saline, semiarid rangelands and steppes. It is noted for its ability to produce edible forage in saline environments; but the influence of salinity on its nutritive value had not been determined. Therefore, this study determined if increasingly saline environments affected forage kochia forage nutritive value. Plants were evaluated in hydroponics, eliminating the confounding effects of drought, for 28 days at 0, 150, 300, and 600 mM NaCl. Forage nutritive value and salt accumulation were determined using ground shoot samples. Digestibility and neutral detergent fiber (NDF) were corrected for salt by adjusting for organic matter. Salinity did not affect NDF, but salt accumulation, crude protein (CP), and digestibility were affected as salinity increased. Salt accumulation increased to 22% of forage kochia shoot mass (DM) at 600 mM NaCl, which may have potential consequences to voluntary intake by ruminants grazing forage kochia. Crude protein did not differ between two forage kochia cultivars, but average forage kochia CP decreased from 26 to 15% DM from the control to the 600 mM salinity level. Furthermore, digestibility decreased from 65 to 58% DM with the major change occurring between 300 and 600 mM NaCl. However, forage kochia digestibility and subsequent metabolizable energy (ME) were greater than Gardner’s saltbush, another salt-tolerant forage shrub, regardless of the salinity level. These results indicate that forage kochia nutritive value responds as typical with halophytic (salt-tolerant) shrubs to increasing salinity, and thus past estimates of digestibility and ME are probably inflated. Future forage kochia nutritive value estimates should account for soluble salt accumulation and correction factors are presented herein.

Technical Abstract: Forage kochia (Bassia prostrata) is a perennial, halophytic Chenopodiaceae shrub adapted to saline, semiarid rangelands and steppes. It is noted for its ability to produce edible forage in saline environments; but the influence of salinity on its nutritive value had not been determined. Therefore, this study determined if a dose-response existed between forage kochia forage nutritive value and increasingly saline environments. Plants were evaluated in hydroponics, eliminating the confounding effects of drought, for 28 days at 0, 150, 300, and 600 mM NaCl. Forage nutritive value and salt accumulation were determined using ground shoot samples. Digestibility (DOMD) and neutral detergent fiber (NDFomd) were corrected for salt by adjusting for organic matter (OM). Salinity did not affect NDFomd, but forage kochia exhibited a logistic dose-response for salt accumulation, crude protein (CP), and DOMD as salinity increased. Salt accumulation increased to 22% of forage kochia shoot mass (DM) at 600 mM NaCl, which may have potential consequences to voluntary intake by ruminants grazing forage kochia. Crude protein did not differ between two forage kochia cultivars, but average forage kochia CP decreased from 26 to 15% DM from the control to the 600 mM salinity level. Furthermore, DOMD decreased from 65 to 58% DM with the major change occurring between 300 and 600 mM NaCl. However, forage kochia digestibility and subsequent metabolizable energy (ME) were greater than Gardner’s saltbush (Atriplex gardneri), another chenopod forage shrub, regardless of the salinity level. These results indicate that forage kochia nutritive value responds as typical with halophytic Chenopodiaceae shrubs to increasing salinity, and thus past in-vitro estimates of digestibility and ME are probably inflated. Future forage kochia nutritive value estimates should account for soluble salt accumulation, and a correction factor based upon OM is presented herein.