Effect of nitrogen application time (15N) in Thompson Seedless grapevines

Inés Pino N.1, Pedro Baherle V.2, Felipe Zapata3, Adriana Nario M.1 y Maria Paz Albornoz G.1

A field experiment was carried out in a coarse loamy sandy; skeletal mixed termic, typic xerochrepts, at the Metropolitan Region of Chile, to evaluate nitrogen application at two different times in cv. Thompson Seedless grapevines using isotopic techniques. Ammonium sulfate labeled with 10% 15N atoms in excess, was used at rates of SO and 100 kg ha-1 of N, at the end of budbreak and in early berry development. An initial and final destructive sampling were done (Ieaves, petiols, annual shoots, one year old wood, trunk and roots). Foliar sampling was also taken through the period of growth (Ieaves, petiols, leaf + petiol, tendril) and cluster samples (berries and rachis). The greatest amount of dry matter was represented by clusters, however, they do'not show the greatest amount of nitrogen derived from the fertilizer (expressed in grams). Treatments T1a (first application) and T1b (second application) presented the best %FUE (fertilizer use efficiency).

Keywords: grapevines, nitrogen, timing, 15N fertilizer.
1 Comisión Chilena de Energia Nuclear (CCHEN), Casilla 188·0, SantiagQ, Chile.
2 Centro Regional de Investigación La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.
3 Organismo Internacional de Energia Atómica, A-2444 Seibersdorf, Viena, Austria.