The influence of nitrate and ammonium forms of nitrogen fertilizer on the growth and osmoregulation of Digitaria eriantha and Chloris gayana grown under saline conditions.

Abstract

Digitaria eriantha and Chloris gayana were grown under controlled conditions for three months and were treated with a nutrient solution containing 150 mMol NaCl and the following nitrogen sources: 25 or 200 mg/l NH4 +-N or NO3 +-N or no nitrogen. The application of nitrogen was found to stimulate growth, i.e. leaf area and dry mass in both grasses, with a greatest growth response to both NH4 +-N treatments in D. eriantha, and NH4 +-N and NO3 --N treatments in C. gayana. Proline accumulated in both grasses, but this accumulation followed different trends in the two grasses. Soluble sugars (non-structural) accumulated in the above ground component in D. eriantha, while in C. gayana soluble sugars accumulated predominantly in the roots, possibly as osmotica, or for storage and may thus have been available for regrowth.

Keywords: ammonia; ammonium; ammonium nitrogen; chloris gayana; digitaria eriantha; dry mass; fertilizer; grass; growth; growth response; leaf; leaf area; nitrate nitrogen; nitrogen fertilizer; nitrogen source; osmoregulation; proline; regrowth; sodium chloride; soluble sugars; treatments