Produção de minitubérculos de batata-semente básica em vaso e hidroponia, em função de doses de nitrogênio / Producing minitubercules of the basic potato-seed in either pot and hydroponics as function of nitrogen doses

AUTOR(ES)

Carla de Bem dos Santos Souza

DATA DE PUBLICAÇÃO

2009

RESUMO

New propagation techniques have been proposed for production of the basic potato-seed (Solanum tuberosum L.), such as the propagation by sprout, hydroponics and planting in pots containing substratum. Those new techniques represent an important progress in the potato productive process. In the available literature, there are few studies relating the effect of the nitrogen doses in solution and in substratum upon the yield of the basic potato-seed by the using the sprout as propagation material. This dissertation was carried out to determine the optimum nitrogen dose for the yield of minitubercules of the basic potato-seed in two production systems, by using the sprout of the Asterix cv. as propagation material. The planting in vase with the commercial substratum Plantmax and fibrocement tile were those systems. Each system corresponded to one experiment. The treatments in pot were five nitrogen doses (0; 45; 90; 180 and 360 mg dm-3), whereas in the hydroponic system were four nitrogen doses (45; 90; 180 and 270 mg L-1). In the pot system, 10% from each nitrogen dose were applied daily at pre-planting and the remainder via irrigation water for 30 days. In the hydroponic system, the nitrogen doses were supplied since the transplanting of the seedlings, and the nitrogen sources were the ammonium nitrate (10%) and calcium nitrate. Both experiments were set up in greenhouse. In both experiments, the N doses positively affected both physiological and nitrogenous indexes in either fourth leaf and the old one (length, width, leaf area, leaflet number, both fresh and dry, content and concentration of Norg and N-NO-3 respectively in the dry matter, and the SPAD index). The nitrogen doses also positively affected both number and matter of the tubercles. In the pot system, the highest number (5.44 tubercules/plant) and the maximum matter of tubercules (243.5 g/plant) were obtained, when using the N doses 360 and 332.9 mg dm-3, respectively. Yet in pot, the critical index SPAD found for the fourth leaf was 38.8, as QF being more sensible to the effect of the N dose than the oldest leaf. In the hydroponic system, the productivity values by plant were 14.1 tubercules and 68.4g at the N doses 188.9 and 270 mg L-1, respectively. The SPAD index found for the fourth leaf was 38.4. In both systems, the number and matter of the tubercules by plant were not optimized by the same nitrogen dose.

ASSUNTO(S)

hidroponia nitrogen nitrogênio potato-seed fitotecnia hydroponics batata-semente vaso pot

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