A precipitação é a principal variável climática para o Semiárido brasileiro, sendo um fator limitante para produção de vegetais, principalmente em regiões com histórico de ocorrência de baixas pluviosidades. Por outro lado, a pecuária é a principal atividade econômica dessa região e a produção de alimento para os animais, infelizmente, ainda se constitui no maior gargalo. A presente revisão tem como objetivo principal descrever o melhoramento genético das principais plantas forrageiras xerófilas cultivadas no Semiárido brasileiro e das espécies com potencial de cultivo para as áreas com registro histórico de baixas precipitações. As espécies discriminadas são: palma forrageira, capim buffel, algodão mocó, flor-de-seda, mandacarú, feijão-bravo e maniçoba. O programa de melhoramento genético dessas espécies se inicia com a formação de um banco ativo de germoplasma (BAG) e compreende a realização de diferentes estratégias, como a domesticação da espécie, que envolve o cultivo, avaliação, caracterização agronômica e bromatológica dos acessos, estudo de diversidade genética, seleção de plantas, hibridação, alteração cromossômica, uso de ferramentas de biotecnologia, entre outras estratégias. A execução de programas de melhoramento genético dessas culturas xerófilas torna-se uma ferramenta necessária para cultivo, domesticação de materiais silvestres e obtenção de novas variedades, com maior potencial de produção e com a função de elevar a renda das propriedades rurais do Semiárido brasileiro.

A B S T R A C TBrazilian semiarid region is marked by the constant incidence of droughts periods, which are climatic events responsible for great disorders for agricultural production, an activity traditionally based on subsistence agriculture. The study aimed at analyzing the evolution of bean production in the municipality of Itaporanga, Paraíba State, Brazil, between 2005, associating these results with local rainfall. It was performed the Principal Component Analysis. Six years of the 11-year series presented a value of annual precipitation lower than the historical mean of the municipality (838 mm). The crop area with beans in the municipality ranged from 5,560 hectares in 2006 to 150 hectares in 2013. There were large variations in the amount of bean production, with values ranging from 2 to 1,985 tons. The PCA recorded a value of 92.4% of explanation in the first two axes and demonstrated a strong correlation between the analyzed variables with the precipitation. Confirming that proper pluviometric indexes are determining factors on bean production in Itaporanga, Paraíba State, Brazil.

Agricultural production has become a challenge in arid and semi-arid regions due to the scarcity of water for irrigation, so brackish water is commonly used. The present study aimed to evaluate the physiological and production responses of cherry tomato cultivars under salinity levels of the nutrient solution in a hydroponic system. The experiment was conducted in a split plot and 5 × 3 factorial scheme with four repetitions. The factors corresponded to different values of electrical conductivity of the nutrient solution (ECns 2.5, 4.0, 5.5, 7.0 and 8.5 dS m-1) and cultivars (Samambaia, Tomate Vermelho and Caroline). The increase in nutrient solution salinity negatively affected the gas exchange, electrolyte leakage and photosynthetic pigments of the cherry tomato cultivars, mainly with the prolongation of stress. The photosynthetic system was efficient up to 4.0 dS m-1, but, above this electrical conductivity in the nutrient solution, there was photoinhibition or photodamage in the cherry tomato plants at 30 days after transplanting. The cherry tomato cultivars Samambaia and Caroline were the most adapted to brackish solutions, while Tomate Vermelho was the most susceptible.

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

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