Uptake and Partitioning of Nitrogen by Maize Infected withStriga hermonthica

The uptake and partitioning of nitrogen (N) by maize infectedwith the parasitic angiosperm,Striga hermonthicawas investigatedin sand culture in a glasshouse. The purpose was to determinethe effect ofStrigaon N uptake and partitioning in maize. Maizewas grown at 22, 66 and 133 mg N per plant and sampled fivetimes. There was no significantStrigaxN interaction in any measuredresponse. Leaf dry matter ofStriga-infected maize, averagedover all N treatments, was 92% that of uninfected maize at thefour-leaf stage but by the 18-leaf stage it had decreased to58%. Similarly, stem dry matter of infected maize which was91% that of uninfected maize at the four-leaf stage was only42% at the 18-leaf stage. Root dry matter was similar for infectedand uninfected maize. N concentration in the leaf, stem androot declined asymptotically from the first to the last samplingdate for both infected and uninfected maize. The asymptoticvalue of N concentration inStriga-infected maize was 16% greaterin the leaf, 55% in the stem, and 21% in the root than in uninfectedmaize. The concentration of N inStrigawas higher than in maizeat the 16- and 18-leaf stages. Uptake of N was similar for infectedand uninfected plants at the four–eight leaf stage butat the eight–12 leaf stage, N uptake by infected maizewas 52% that of uninfected maize. However, the proportion oftotal plant nitrogen partitioned to the root was greater (P<0.001)forStriga-infected maize. These results showed that the extentto whichS. hermonthicareduced maize growth and N uptake, butincreased the proportion of N partitioned to the roots, didnot depend on the rate of N fertilizer applied.Copyright 1998Annals of Botany Company Maize; nitrogen; partitioning;Striga hermonthica; uptake.