Influx and Efflux of Nitrate and Ammonium in Italian Ryegrass and White Clover Roots: Comparisons Between Effects of Darkness and Defoliation 

 -  Journal of Experimental Botany, 43(4), p.525-535, 1992 .
<br/><br/> Seedlings of Italian ryegrass (Lolium multiflorum Lam. cv. RVP)and clonal stolon cuttings of white clover (Trifolium repens L. cv. Blanca)were grown for 19 d in flowing solution culture, with N supplied as either 250 mmol m"3 NOJ or NH4 . Rates of net uptake, influx and translocation of NO^" and NH4 were then determined using 15N and 13N labelling techniques: between 3-5 h into the photoperiod following 8 h darkness for white clover (CL), and for ryegrass plants that were either entire (IL)or with shoots excised 90 min prior to 13N influx (IC); and 75 min into the photoperiod following 37-39 h darkness for ryegrass (ID). Rates of net uptake, influx and efflux of NH4 exceeded those of NO^ in IL and IC ryegrass plants: the opposite occurred in white clover (CL). The decrease in net uptake following defoliation of ryegrass was greater for NH4 (62 
<br/><br/><label>Subjects--Topical Terms: </label><br/>LOLIUM MULTIFLORUM<br/>TRIFOLIUM REPENS<br/>INFLUX<br/>EFFLUX<br/>NITRATE<br/>AMMONIUM<br/>13N