Cowpea is the main subsistence crop—protein source—for the Brazilian semi-arid region. The use of salt-stress-tolerant varieties can improve crop yields. We evaluated the effect of irrigation with brackish water on the growth, photosynthetic responses, production, and tolerance of fifteen traditional varieties of cowpea. The experiment was conducted in randomized blocks, in a 15 × 2 factorial scheme, composed of 15 traditional varieties of cowpea and two salinity levels of irrigation water (0.5 and 4.5 dS m⁻¹), with five replicates. Plants were grown in pots containing 10 dm³ of soil for 80 days. The reduction in the photosynthetic rate of cowpea varieties occurs mainly due to the decrease in stomatal conductance caused by salt stress. Salt stress increased the electron transport rate and photochemical quenching of cowpea varieties, but stress-tolerant varieties increased the CO₂ assimilation rate and instantaneous carboxylation efficiency. The Ceará, Costela de Vaca, Pingo de Ouro, Ovo de Peru, and Sempre Verde varieties are tolerant to salt stress. Salt stress decreases 26% of the production of tolerant varieties to salt stress and 54% of susceptible varieties. The present findings show the existence of variability for saline stress tolerance in traditional varieties of cowpea and that Ceará, Costela de Vaca, Pingo de Ouro, and Ovo de Peru varieties are more suitable for crops irrigated with saline water.

Cowpea is an important source of protein, being the main subsistence crop in the northeast region of Brazil, where water restriction and salinity are limiting factors. Identification of saline stress tolerant varieties can aid crop expansion and improve crop yields. The objective was to study the tolerance of traditional varieties of cowpea to the salinity of irrigation water in the emergency and initial growth phase. The experiment was carried out in a greenhouse using a completely randomized design (DIC), in a 23 x 2 factorial scheme, composed of 23 cowpea varieties (Canapu Vermelho, Boquinha, Pingo de Ouro, Sempre Verde, Ceará, Baeta, Manteiga, Roxão, Costela de Vaca, Feijão Branco, Coruja, Rabo de Peba Branco, Sopinha, Canapu Branco, Lisão, Canapu Miúdo, Sempre Verde Ligeiro, Vagem Roxa, Ovo de Peru, Rabo de Peba Miúdo, Feijão Azul, Canário, and Paulistinha) and two levels of salinity of irrigation water (S1 = 0.5 and S2 = 5.5 dS m-1), with four repetitions of 50 seeds. The seedlings were evaluated for emergence, vigor, salinity tolerance index, and dissimilarity. Increased salinity of irrigation water reduced emergence, vigor and dry matter accumulation of cowpea varieties. The cowpea varieties ‘Lisão’, ‘Costela de Vaca’, ‘Canário’, ‘Feijão Branco’, ‘Ceará’, and ‘Boquinha’ are the most tolerant to salinity, while the varieties ‘Sempre Verde’ and ‘Manteiga’ are the most sensitive to salinity in the emergency and initial growth phase.

DESEMPENHO DO CAPIM TANZÂNIA IRRIGADO COM ÁGUA SALOBRA APLICADA VIA ASPERSÃO E GOTEJAMENTO SAULO SAMUEL CARNEIRO PRAXEDES¹; MANOEL JANUÁRIO DA SILVA JÚNIOR²; JOSÉ FRANCISMAR DE MEDEIROS²; JOSÉ LEÔNCIO DE ALMEIDA SILVA³; FRANCISCO VALFISIO DA SILVA⁴ E ANA JAQUELINE DE OLIVEIRA TARGINO^{5   1}Doutorando do PPGMSA, Universidade Federal Rural do Semi-Árido, UFERSA, Av. Francisco Mota, 572 - Bairro Costa e Silva, CEP: 59.625-900, Mossoró/RN/Brasil, saulosamuel@rn.gov.br; ²Departemento de Ciências Agronômicas e Florestais, Universidade Federal Rural do Semi-Árido, UFERSA, Av. Francisco Mota, 572 - Bairro Costa e Silva, CEP: 59.625-900, Mossoró/RN/Brasil, mjanuario@ufersa.edu.br, jfmedeir@ufersa.edu.br; ³Doutorando do PPGEA, Universidade Federal de Viçosa, UFV/MG, Av. Peter Henry Rolfs, s/n - Campus Universitário, CEP: 36570-900, Viçosa - MG, jose.leoncio@ufv.br; ⁴Doutor em Engenharia Agrícola, Universidade Federal Rural do Semi-Árido, UFERSA, Av. Francisco Mota, 572 - Bairro Costa e Silva, CEP: 59.625-900, Mossoró/RN/Brasil, francisco@yahoo.com.br; ⁵Mestre em Manejo de Solo e Água, Universidade Federal Rural do Semi-Árido, UFERSA, Av. Francisco Mota, 572 - Bairro Costa e Silva, CEP: 59.625-900, Mossoró/RN/Brasil, ana_jacqueline2@hotmail.com.     1 RESUMO   O capim Tanzânia (Panicum maximum) é uma forrageira que vem se destacando nos últimos anos na alimentação de animais em todo o mundo, tanto pelo incremento de produtividade como fonte de nutrientes, sendo, portanto, a avaliação do seu crescimento e produção sob estresse salino, fator importante para potencializar o cultivo desta forrageira em regiões semiáridas. Com o objetivo de avaliar o desempenho desta gramínea sob estresse salino, estabeleceu-se um delineamento experimental inteiramente aleatorizado, analisado em esquema fatorial (5x2), com quatro repetições, totalizando 40 unidades experimentais. Os tratamentos consistiram na aplicação de águas com cincos níveis de salinidade (0,5; 1,5; 2,5; 3,5 e 4,5 dS m^-1) às plantas via aspersão e gotejamento. Avaliaram-se os componentes: altura (ALT), fitomassa fresca (FMF) e fitomassa seca (FMS) da parte aérea das plantas, as quais foram obtidas em 4 sucessivos cortes. Concluiu-se que a água de irrigação de elevada salinidade reduz a FMF e a FMS da gramínea, porém, é possível se obter resultados expressivos de produção com uma CEa máxima de 2,8 dS m^-1, com reduções máximas de 20% na produção fitomassa seca. Ao se utilizar água salobra, as plantas irrigadas via gotejamento apresentaram resultados de produção mais expressivos em relação às plantas irrigadas via aspersão. Palavras-chave: Panicum maximum, métodos de irrigação, condutividade elétrica.     PRAXEDES, S. S. C.; SILVA JÚNIOR, M. J.; MEDEIROS, J. F.; SILVA, J. L. A.; SILVA, F. V.; TARGINO, A. J. O. PERFORMANCE OF TANZANIA GRASS IRRIGATED WITH SALINE WATER APPLIED VIA SPRAY AND DRIPPING       2 ABSTRACT   Tanzania grass (Panicum maximum) is a forage that has stood out in the last years for feeding animals worldwide. Therefore, the evaluation of its growth and production under saline stress is an important factor to enhance the cultivation of this fodder in semi-arid regions. To evaluate the performance of this grass under salt stress, a completely randomized experimental design was established in a factorial scheme (5x2) with four replications, totaling 40 experimental units. Treatments consisted of application of water with five salinity levels (0.5, 1.5, 2.5, 3.5 and 4.5 dS m^-1) to the plants via sprinkling and dripping. The components: height (ALT), fresh phytomass (FMF) and dry matter (FMS) of the aerial parts of the plants were evaluated, which were obtained in four successive cuts. High salinity irrigation water reduces FMF and grass FMS, but it is possible to obtain significant results of production with a maximum ECa of 2.8 dS m^-1, and maximum reductions of 20% in dry biomass production. When brackish water is used, plants irrigated via drip irrigation presented more significant production results against plants irrigated by spraying. Keywords: Panicum maximum, irrigation methods, Electrical conductivity

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