Indication of salt-tolerant cotton cultivars can make the agricultural exploitation with saline water irrigation feasible in the Brazilian semi-arid region. Thus, this study aimed to evaluate the gas exchanges and growth of cotton cultivars irrigated with saline water. The study was conducted in pots adapted as drainage lysimeters under greenhouse conditions, using a sandy loam Entisols as substrate. Treatments were distributed in completely randomized design, in 5 x 2 factorial arrangement, relative to five levels of irrigation water electrical conductivity - ECw (1.5, 3.0, 4.5, 6.0 and 7.5 dS m-1) and two cotton cultivars (BRS 368 RF and BRS Safira). Increase in irrigation water salinity inhibits the vegetative growth and gas exchanges of the cotton cultivars BRS Safira and BRS 368 RF. Leaf area and instantaneous carboxylation efficiency are the most affected variables. Physiological and growth performance of the cultivar BRS Safira in response to water salinity was higher than that of BRS 368 RF.

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The cultivation of cotton is a relevant socioeconomic activity in the Brazilian agricultural scenario. In the Brazilian Northeast, however, production is limited by low rainfall, requiring water supplementation, a problem for the cotton cultivation practiced in the semi-arid region, due to the presence of saline ions in several water sources, from where the water is used for irrigation. It is necessary to identify cultivars that better tolerate saline stress in order to provide subsidies for their cultivation under such conditions. In this sense, the objective was to evaluate the tolerance of cotton cultivars to salinity. The experiment was conducted in a greenhouse, belonging to the Natural Resource Technology Center of the

CRESCIMENTO DE CULTIVARES DE PALMA FORRAGEIRA IRRIGADA SOB DIFERENTES NÍVEIS DE SALINIDADE EM REGIÃO SEMIÁRIDA     MÁRCIA CRISTINA DE ARAÚJO PEREIRA1; CARLOS ALBERTO VIEIRA DE AZEVEDO 2; JOSÉ DANTAS NETO 3; MARIANA DE OLIVEIRA PEREIRA 4; JAILTON GARCIA RAMOS 5 E BEATRIZ DE ARAÚJO TOMAZ 6   1 Programa de Pós-Graduação em Engenharia Agrícola, Universidade Federal de Campina Grande, Rua Aprígio Veloso, 882, Bairro Universitário, 58428-830, Campina Grande, Paraíba, Brasil. E-mail: marciacristina794@gmail.com. 2 Programa de Pós-Graduação em Engenharia Agrícola, Universidade Federal de Campina Grande, Rua Aprígio Veloso, 882, Bairro Universitário,58428-830, Campina Grande, Paraíba, Brasil. E-mail: cvieiradeazevedo@gmail.com. 3 Programa de Pós-Graduação em Engenharia Agrícola, Universidade Federal de Campina Grande, Rua Aprígio Veloso, 882- Bairro Universitário,58428-830, Campina Grande, Paraíba, Brasil. E-mail: zedantas1955@gmail.com. 4 Pós-doutoranda em Engenharia Agrícola, Rua Aprígio Veloso, 882 -Universitário, Campina Grande -PB, Brasil. 58428-830, E-mail:  marianapereira.agri@gmail.com 5 Programa de Pós-Graduação em Engenharia Agrícola, Universidade Federal de Campina Grande, Rua Aprígio Veloso, 882, Bairro Universitário,58428-830, Campina Grande, Paraíba, Brasil. E-mail: jailtonbiossistemas@gmail.com. 6 Unidade Acadêmica de Engenharia Agrícola, Universidade Federal de Campina Grande, Rua Aprígio Veloso, 882, Bairro Universitário, 58428-830, Campina Grande, Paraíba, Brasil.  E-mail: beatrizatomaz2@gmail.com     1 RESUMO     A palma forrageira se destaca por ser uma cultura bem adaptada às condições edafoclimáticas do semiárido brasileiro, pois apresenta características anatômicas, morfofisiológicas e químicas que possibilitam seu desenvolvimento. Objetivou-se nesse trabalho avaliar o efeito de diferentes níveis de salinidade da água de irrigação, no crescimento de cultivares de palma forrageira na região do semiárido. O delineamento experimental foi em blocos casualizados em esquema fatorial 4 x 3, com quatro níveis salinos (0,2; 2,0; 3,8 e 5,6 dS m-1) e três cultivares (Miúda, Orelha de Elefante Mexicana e IPA-Sertânia), quatro repetições. Foram avaliadas as variáveis altura de planta, largura de planta, comprimento, largura, perímetro e espessura dos cladódios primários. As variáveis foram submetidas a análise de variância pelo teste F ao nível de 1 e 5% de probabilidade, quando significativo foram submetidos à análise de regressão linear e quadrática para variáveis quantitativas e teste de Tukey (p < 0,05) para a variável qualitativa. O desenvolvimento da palma forrageira irrigada com diferentes níveis salinos foi influenciado com o aumento da salinidade, sendo que a melhor condição para a cultivar Miúda foi a salinidade de 3,8 dS m-1, já para Baiana e Orelha de Elefante Mexicana foi a salinidade de 2,0 dS m-1.   Palavras-chave: Opuntias, Napolea, Águas Salinas, Semiárido.         PEREIRA, M. C. de A.; AZEVEDO, C. A. V. de; DANTAS NETO, J.; PEREIRA, M. de O.; RAMOS, J. G.; TOMAZ, B. de A. GROWTH OF IRRIGATED FORAGE PALM CULTIVARS UNDER DIFFERENT SALINITY LEVELS IN A SEMI-ARID REGION     2 ABSTRACT   The forage palm stands out for being a crop well adapted to the edaphoclimatic conditions of the Brazilian semiarid region, for it presents anatomical, morphophysiological, and chemical characteristics that enable its development. This work aimed to evaluate the effect of different levels of salinity of irrigation water on the growth of forage palm cultivars in the semiarid region. The experimental design was in randomized blocks in a 4 x 3 factorial scheme, with four salt levels (0.2; 2.0; 3.8 and 5.6 dS m-1) and three cultivars (Miúda, Mexican Orelha de Elefante, and IPA-Sertânia), four repetitions. The variables of plant height, plant width, length, width, perimeter and thickness of the primary cladodes were evaluated. The variables were subjected to analysis of variance by the F test at the level of 1 and 5% probability, when significant were subjected to linear and quadratic regression analysis for quantitative variables and Tukey test (p < 0.05) for the qualitative variable. The development of the forage palm irrigated with different saline levels was influenced with increasing salinity, and the best condition for the cultivar Miúda was a salinity of 3.8 dS m-1, and for Baiana and Mexican Elephant's Ear was salinity of 2.0 dS m-1.   Keywords: Opuntias, Napolea, Saline Water, Semi-arid.

Water scarcity and high levels of salinity in irrigation water limit irrigated cotton cultivation in the semiarid region of Northeast Brazil. So, it is necessary to adopt cultivation strategies that make the production system feasible. In this context, the present study aimed to evaluate the biomass and production of cotton cultivars subjected to different levels of saline water irrigation. The experiment was carried out under greenhouse conditions, with treatments distributed in a completely randomized design, in a 5 x 2 factorial arrangement, corresponding to five levels of irrigation water electrical conductivity - ECw (1.5, 3.0, 4.5, 6.0 and 7.5 dS m-1) and two cotton cultivars (BRS 368 RF and BRS Safira), with 4 replicates. Treatment effects were measured by the number of bolls per plant, lint weight, number of seeds per plant, total weight of seeds and dry and fresh biomass of stem, roots and leaves. Irrigation using water with electrical conductivity from 1.5 dS m-1 negatively affects the production of the cotton cultivars BRS SAFIRA and BRS 368 RF, causing reductions in all production variables analyzed. The cultivar BRS Safira has better production performance than BRS 368 RF when exposed to water salinity.