Nitrate accumulation, nitrogen balance and cation-anion ratio during the regrowth of perennial ryegrass.

Abstract

The regrowth of ryegrass was harvested on various dates in a pot experiment. NO₃ accumulation occurred until a specific yield level was reached which was critical in respect to the N supply. Below this critical yield the N percentage in the yield gradually declined as a result of the decreasing capacity of the dry matter to assimilate N. After the critical yield was exceeded NO₃ disappeared from the leaves and no further N was taken up, so that the N percentage in the yield decreased more rapidly. At first there was a gradual increase in the cation-anion ratio as the grass aged. After the critical yield for N-depletion was exceeded there was a higher rate of increase. The relationship between cation-anion ratio and N status is connected with N metabolism.-From author's summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)