ALFACE AMERICANA FERTIRRIGADA COM DIFERENTES DOSES DE ÁCIDO FOSFÓRICO E HIDRÓXIDO DE POTÁSSIO

1 RESUMO A fertirrigacao com acido fosforico tem sido uma opcao para evitar o entupimento de gotejadores, porem a utilizacao do mesmo causa acidificacao do solo, e para tal problema uma alternativa e o uso de hidroxido de potassio. O trabalho teve por objetivo verificar o efeito de diferentes doses de acido fosforico e hidroxido de potassio via fertirrigacao comparando-o com a adubacao convencional na fertilidade do solo, nutricao e producao de alface. O experimento foi conduzido em casa de vegetacao, na Faculdade de Ciencias Agronomicas, campus de Botucatu/UNESP. O delineamento experimental foi em blocos ao acaso com 6 tratamentos e 4 repeticoes. Os tratamentos constituiram-se de combinacoes entre doses (25% e 50% da dose completa recomendada para a alface) e aplicacao de dose completa (100%) de fosforo (P) e de potassio (K) , aplicadas via fertirrigacao e uma testemunha com aplicacao de dose completa na forma convencional. A disponibilidade de P e K no solo e a concentracao destes nutrientes na planta foram influenciadas pelos tratamentos. A reducao das doses de P e K aplicadas via fertirrigacao mostrou-se ineficiente para o bom desenvolvimento da cultura de alface. Os tratamentos influenciaram significativamente as caracteristicas agronomicas e comerciais da alface, destacando-se o tratamento com aplicacao de dose completa de P e K via fertirrigacao. UNITERMOS: Latuca sativa L., fertilidade do solo, gotejamento, acidificacao, bulbo molhado. DEUS, A. C. F.; COSTA, C. D. O.; FORATTO, L. C.; FERNANDES, D. M.; CARRIBEIRO, L. S. CRISPHEAD LETTUCE FERTIRRIGATED WITH DIFFERENT PHOSPHORIC ACID AND POTASSIUM HYDROXIDE DOSES 2 ABSTRACT Fertirrigation with phosphoric acid has been considered as an option to avoid drips from clogging. In some cases, this acid cause soil acidification and it can be substituted by potassium hydroxide. This study had the objective of evaluating the effects of different phosphoric acid and potassium hydroxide doses, applied via fertirrigation, on soil fertility, plant nutrition and lettuce yield, compared to the conventional fertilization system. The experiment was carried out in greenhouse, in the College of Agricultural Sciences, FCA/UNESP, Botucatu-SP-Brazil. The experimental design was the completely randomized block, with 6 treatments and 4 replications. Treatments consisted of the combinations of doses (25% and 50% of the recommended complete dose for the lettuce) and application of complete dose (100%) of phosphorus (P) and potassium (K) applied via fertirrigation, and a control (conventional fertilization system). The results showed that P and K availability in soil and nutrient concentration in plants were affected by treatments. Low phosphorus and potassium doses, applied via fertirrigation, were not efficient for the appropriate development of lettuce plants. The results showed that agronomic characteristics and commercial lettuce were affected by doses and application systems, especially the treatment with application of P and K full dose fertirrigation. KEYWORDS: Latuca sativa L., soil fertility, dripping, acidity, wet bulb.