Yield of cowpea-beans as a result of levels of doses and ways of application of nitrogen

Avaliou-se o efeito de doses e formas de aplicação de nitrogênio sobre o rendimento de vagens e de grãos verdes e secos do feijão-caupi, cv. IPA 206. O experimento foi conduzido na área experimental da UFPB, em Areia, de abril a agosto/2001. O delineamento utilizado foi de blocos casualizados, com os tratamentos distribuídos em esquema fatorial 5 x 2, onde o primeiro fator correspondeu às doses de nitrogênio (0; 25; 50; 75 e 100 kg ha-1) e, o segundo fator, às formas de aplicação (solo e via foliar), em quatro repetições. Foram utilizadas parcelas de 20 plantas, espaçadas de 0,8 x 0,4 m. O rendimento máximo estimado de vagens (11 t ha-1), de grãos verdes (9,3 t ha-1) e de grãos secos (3,6 t ha-1) foi obtido com 62, 61 e 56 kg ha-1 de nitrogênio aplicados no solo, respectivamente. Quando o nitrogênio foi aplicado via foliar os rendimentos de vagens (10 t ha-1), de grãos verdes (8,4 t ha-1) e de grãos secos (3,4 t ha-1) alcançaram valores máximos nas doses de 64, 6 e 59 kg ha-1, respectivamente.The cowpea-bean, known as macassar-bean or rope-bean is one of the main crops in the Northeast region of Brazil. It is consumed either as fresh or dried beans. Cowpea is cultivated in almost all regions of the Paraíba State, representing 75% of the cultivated area with cowpea-beans. The low yield is attributed to the lack of a research program about mineral fertilization. The effect of levels and forms of nitrogen applications on yield of pods and green and dry grains of cowpea-bean, cv. IPA 206 was evaluates. The experiment was performed at the Universidade Federal da Paraíba, in Areia, Brazil, from April to August/2001, in a randomized blocks design. Treatments were distributed in a factorial scheme 5 x 2, where the first factor corresponded to nitrogen levels (0; 25; 50; 75 and 100 kg ha-1) and, the second factor, the application forms (soil and foliar application), in four repetitions. Each plot consisted of 20 plants, spaced 0.8 x 0.4 m apart. The estimated maximum pods yield (11 t ha-1), of green grains (9.3 t ha-1) and of dry grains (3.6 t ha-1) was obtained with 62, 61 and 56 kg ha-1 of nitrogen applied in the soil, respectively. With foliar applications the yield of pods (10 t ha-1), of green grains (8.4 t ha-1) and of dry grains (3.4 t ha-1) reached maximum values applying levels of 64, 63 and 59 kg ha-1 of nitrogen respectively