Reducción de la distancia entre hileras en maíz bajo siembra directa ante distintas ofertas de nitrógeno.

PABLO A. BARBIERI, HERNÁN. R. SAINZ ROZAS, FERNANDO H. ANDRADE, HERNÁN. E. ECHEVERRÍA.

Pergamino

Congreso; VI Congreso Nacional de Maíz. Pergamino; 1997

No-till (SD) corn crops at Balcarce do not intercept all of the incident radiation during the critical period of yiel definition (PC) (15 d before through 15 d after flowering) because of nitrogen (N) stress asociated with SD. The reduction of the distance between crop ros would allow a greter interception during PC; and consequently,a greter yield. The objetie of this works was the determinate corn dry matter (MS) accumulation and gran yield under SD as a function of different crop row distamnces (0.35 and 0.70 m) and N rates (0 and 120 kg ha-1,and 0 and 140 kg ha-1 for the growing seasons 1995/96 and 1996/97, respectivelly). The experiment was carried on in the EEA-INTA at Balcarce (37º 45´ S, 58º 18´ W). Intercepted radiation was measured durin g PC during 1995/96 and during entire crop cycle in 1996/97. Besides, during pre- and post-flowering periods in 1996/97 accumulation of MS and N, and leaf area index (IAF) were evaluated. Treatment combining reduced between roe distance and N addition significantly increased grain yield in both years. The most afecceted yield components was the number of grains, wich was associated wit the intercepted radiation during PC (slope= 18 grains (intercepted Mj-1)). Intercepted radiation during 1996/97 PC was positicely related to the IAF. This demostrates that increased interception under reduced between row-distance can be explined not only by a better plant distribution onthe fiel, but also by a greater IAF. The response of numger of grain to reduced row distance was greater under no N fertilizer Key words: Corn, No tillage, Between row distance, Nitrogen