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

Digltaria 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.

Uittreksel

Digitaria eriantha en Chloris gayana plante is vir drie maande onder gekonroleerde toestande gekweek. Die behandelings wat voedingstofoplossings wat in alle gevalle 150 mM NaCl bevat het, maar verskillende konsentrasies en vorme van stikstof naamlik: 25 òf 200 mg/l NH4⁺ — N óf NO₃ ⁻ — N òf geen stikstof nie. Die toediening van N het droëmassa en blaaroppverlakte in albei grasse gestimuleer. Ammonium‐N was die voordeligste vir beidegrasse terwyl die hoë peil van NO₄ ⁻—Nook ‘n voordelige reaksie by C. gayana tot gevolg gehad het. Prolien is in beide grasse opgeberg maar het verskillende metaboliese weë gevolg. Oplosbare suikers is in D. eriantha opgeberg terwyl dit in C. gayana na die wortels getranslokeer is en was dus òf vir osmotiese regulering òf groei beskikbaar.

Additional index words:

• Nitrate nitrogen
• ammonium nitrogen
• sodium chloride
• pro‐line
• soluble sugars

Notes

Present Address: Grassland Research Centre, Private Bag X05, Lynn East, 0039