Resposta do inhame ao parcelamento da adubação nitrogenada

Abstract

The objective of this research is to evaluate the productive characteristics of yam, the percentage of tubers with symptoms of nematode attack on tubers and foliar N as a function of subdivision nitrogen. The experimental delineation that we used was randomized blocks with fifteen treatments with four repetitions. The treatments were represented by the following portions of nitrogen (100% on the plantation; 100% at 60 days after the plantation (DAP); 100% at 90 (DAP); 100% at 120 DAP; 50% on the plantation; and 50% at 60 DAP; 50% on the plantation and 50% at 90 DAP; 50% on the plantation and 50% at 120 DAP; 33% on the plantation and 33% at 60 and 33% at 90 DAP; 33% on the plantation, 33% at 90 and 33% at 120 DAP; 33% at 60, 33% at 90 and 33% at 120 DAP; 50% at 60 and 50% at 90 DAP; 50% at 90 and 50% at 120 DAP; 33% at 60, 33% at 90 and 33% at 120 DAP; 50% at 60 and 50% at 120 DAP; and 33% on the plantation, 33% at 60 and 33% at 120 DAP). Each subdivision there were 40 plants, and they were 1.2 x 0.6 m away, one from each other, and all of them were considered useful. The supplying of nitrogen of 100% at 90 DAP showed the greatest length of tubers that measured 25.33 cm, following the subdivisions of 50% on the plantation and 50% at 120 DAP (25.10 cm). The average mass of commercial tubers was superior only on the subdivision of nitrogen of 33% on the plantation, 33% at 60 DAP and 33% at 90 DAP reaching the maximum value of 2.23 kg. The subdivision of nitrogen of 50% at 60 DAP and 50% at 90 DAP provided the highest total productivity and commercial of tubers, 21.7 and 18.9 t ha-1, respectively. The maximum percentage of tubers with attack symptoms of nematodes (dried bark and thick bark) they were 53% and 94%, respectively, obtained when the nitrogen was applied 100% at 60 DAP and 100% on the plantation. When the nitrogen was divided in 33% at 60 DAP, 33% at 90 DAP and 33% at 120 DAP; and 50% on the plantation and 50% at 90 DAP, we did not observed any tubers with the attack symptoms of nematodes. For the content of N in the leaves, we did not see any difference among the treatments.