ABSTRACT The objective of this work was to evaluate the physiological variables of the cultivar Opuntia stricta (Haw.) Haw in the first cycle and in the regrowth, under different frequencies of drip irrigation, cultivated in the Agreste da Paraíba mesoregion. Therefore, a randomized block design was used, with 2 treatments (irrigation frequencies) and 4 replications (blocks), with each treatment repeated 3 times within the block (triplicate) totaling 24 experimental plots. For physiological variables, data were evaluated by analysis of variance (ANOVA) and means compared by t test at 5% probability using SAS ® (2002). The present study shows that the stress of environmental conditions had a greater impact on the frequency of irrigation every 28 days, since the forage cactus irrigated every 7 days had the highest internal concentration of CO2; CO2 absorption rate; instant efficiency in water use; intrinsic efficiency of water use; instantaneous carboxylation efficiency, both in the first cycle and in the regrowth period. Respiratory rate and stomatal conductance did not differ between irrigation frequencies for both cycles, showing the good adaptation of the cultivar to the semiarid region.

Abstract Physiological and yield evaluation of perennial forage plants grown in intercropping in the semiarid region is indispensable in the search for higher efficiency of the agricultural and livestock production systems. In this context, an experiment was carried out at the Experimental Station of the National Institute of the Semiarid Region - INSA, in the municipality of Campina Grande, Paraíba, Brazil, to evaluate the physiological efficiency and yield of prickly pear and gliricidia in intercropping. Treatments were distributed in randomized blocks, with six replicates, being represented by four spacings between gliricidia plants: S1 (1.0 m), S2 (1.5 m), S3 (2.0 m) and S4 (3.0 m) x 2.30 m between rows. Prickly pear was planted in double rows of 1.5 m x 0.8 m x 0.5 m. The analyzed variables were initial, maximum and variable fluorescence chlorophyll a, variable/initial fluorescence ratio, potential quantum yield and the fresh matter yield of both crops. Density planting of gliricidia up to 4,348 plants ha-1 increases its photochemical efficiency and yield, but reduces light energy capture by prickly pear in intercropping, whereas its yield is not influenced by cultivation density. Regardless of gliricidia density, prickly pear yield was not influenced.

RESUMEN El nopal forrajero Oreja de Elefante Mexicano está ampliamente incorporado a la cadena productiva animal de la región noreste de Brasil. Sin embargo, faltan estudios sobre la dinámica fisiológica de este cactus. Por lo anterior, se realizó este estudio en la Estação Experimental Prof. Ignácio Salcedo del Instituto Nacional do Semiárido (INSA), en Campina Grande, estado de Paraíba, Brasil. El objetivo del estudio fue evaluar la absorción de CO2 y los niveles de eficiencia en el uso del agua in Opuntia stricta (Haw.) durante diferentes estaciones e horas de evaluación. Los tratamientos se distribuyeron utilizando un arreglo factorial de 24×2, que correspondió a la evaluación de los procesos de intercambio de gases durante 24 horas en la época de lluvias (junio) y sequía (diciembre). Los parámetros evaluados fueron la conductancia estomática, la tasa de transpiración y absorción de CO2, la concentración interna de CO2, la eficiencia instantánea de uso del agua y la eficiencia intrínseca de uso del agua. Los resultados revelaron que el intercambio de gases en el nopal forrajero son más intensos durante la estación de lluvias, con buena estabilidad, que los bajos niveles de intercambio durante la estación época de sequía. Independientemente de la estación, la absorción de CO2 alcanzó su pico entre las 24:00 y las 2:00. Además, este intervalo de tiempo es el más adecuado para realizar análisis en condiciones de campo.

ABSTRACT The forage cactus Mexican Elephant Ear is widely incorporated into the animal productive chain of the northeast region of Brazil. However, there is a lack of studies on the physiological dynamics of this cactus. Therefore, this study was conducted at the Estação Experimental Prof. Ignácio Salcedo of the Instituto Nacional do Semiárido (INSA), in Campina Grande, State of Paraíba, Brazil. The aim of this study was to evaluate CO2 uptake and water-use efficiency levels in Opuntia stricta (Haw.) during different seasons and evaluation times. The treatments were distributed using a 24×2 factorial arrangement, which corresponded to the evaluation of gas exchange processes for 24 hours in the rainy (June) and dry (December) seasons. The evaluated parameters were stomatal conductance, transpiration and CO2 uptake rate, internal CO2 concentration,instantaneous water-use efficiency and intrinsic water-use efficiency. The results revealed that gas exchange in the forage cactus was more intense during the rainy season, with good stability, than the low exchange levels during the dry season. Regardless of the season, the CO2 uptake peaked between 24:00 and 02:00. In addition, this range of time is the most suitable to conduct analyses under field conditions.

ABSTRACT. The objective was to evaluate the morphometric, productive and chemical aspects of purple elephant grass as a function of nitrogen fertilization. The treatments consisted of applying 0, 20, 40, 60, and 80 kg ha-1 of N, using a randomized block design, with five treatments and four replications. The following were evaluated: plant height, number, length and leaf mass, stem diameter and mass, leaf/stem ratio, production of green and dry mass, support capacity for dairy cows, crude protein, neutral detergent fiber and mineral matter. The data were submitted to analysis of variance and Tukey's test at 5% probability. The increase in N doses did not affect (p < 0.05) the morphometry of the purple elephant grass, however it positively stimulated the productivity, the animal support capacity and the bromatological components of the harvested material. The lack of response to nitrogen fertilization may be related to the edaphocilimatic conditions during the experiment and efficiency in the use of N of the variety used. The results demonstrate the high demand of the cultivar for N, actively interfering in the forage yield.

Abstract Climatic variation throughout the day influences the ecophysiological performance of plants at different growth stages and phases. Therefore, this work aimed to evaluate the effect of climatic variation on ecophysiological aspects of T. roseoalba and H. heptaphyllus at different hours of the day and indicate the ideal time for measuring ecophysiological variables in these species. The research was carried out in a greenhouse at the forest nursery of the Federal University of Paraíba, Campus II, in the municipality of Areia, Paraíba state, Northeastern Brazil. The experimental design was completely randomized, consisting of 10 evaluation times throughout the day (from 8 am to 5 pm), with 1 h hour interval between each evaluation. Temperature and air relative humidity inside and outside the greenhouse were evaluated to understand the effect on gas exchange (net assimilation rate of CO2, stomatal conductance, transpiration rate, internal concentration of CO2, and vapor-pressure deficit) and chlorophyll a fluorescence (initial, maximum, and variable fluorescence, photochemical quenching, and electron transport rate). Data were submitted to canonical correlation analysis and principal component analysis to verify the relationship between climatic and ecophysiological variables. For both species, higher correlation was found between internal and external relative humidity with all the ecophysiological variables analyzed, except for initial fluorescence. Thus, climatic factors influenced the photosynthetic performance of T. roseoalba and H. heptaphyllus plants, and 8 am to 9 am is indicated for carrying out ecophysiological evaluations in both species.

ABSTRACT Public squares are important spaces in the cities and stand out for providing improvements in the quality of urban life. Thus, this study aimed to carry out the floristic survey of public squares in the city of Areia, Paraíba state, Brazil, and analyze the similarity between their flora. The species classification was performed by consulting experts and through comparative morphology. The floristic similarity was calculated using the Jaccard index. Twenty-nine species distributed in 26 genera and 20 families were recorded. Stenotaphrum secundatum (Walter) Kuntze had the highest relative frequency (8.52%). Sixty-three percent of the species are exotic and 28% contain toxic substances. There was a significant similarity (1) only between Tenente Juvenal Espíndola and Simeão Patrício squares. The data evidence the need for better planning of floristic composition of the squares in the city of Areia, as well as for a tree planting manual.

RESUMO Objetivou-se avaliar agronomicamente 14 genótipos de sorgo no semiárido brasileiro. Utilizou-se delineamento experimental em blocos casualizados com os tratamentos representados pelos genótipos de sorgo e três repetições. Foram avaliadas matéria seca (MS), altura da planta (AP), número de folhas vivas, produção de matéria verde (PMV), produção de matéria seca (PMS), lamina foliar (LF), colmo, panícula (PAN), material morto (MM), acúmulo de água (ACA), eficiência do uso da chuva (EUC) e capacidade de suporte (CS). Houve efeito entre todas as variáveis. O genótipo com maior percentual de MS foi BRS 655 (26,42%). Houve efeito para PMV, os genótipos com maior produção foram BRS 655, BRS 506, B1141340, 13F04(1141572) e PONTA NEGRA, com valores de 48.517, 48.500, 44.879, 44.788, 43.549 kg/ha. Os genótipos que apresentaram maior PMS foram BRS 655, B1141340, 13F04(1141572), BRS 506 e PONTA NEGRA, com valores de 12.426, 10.344, 9.778, 9.756 e 9.176 kg/ha, respectivamente e também apresentaram maiores valores para EUC, ACA e CS. Houve correlação positiva significativa entre variáveis produtivas (PMV com PMS, AP, EUC e ACA) e correlação negativa não significativa (PMV com LF e PAN) com variáveis morfométricas. Houve formação hierárquica de quatro grupos, sendo os grupos I e III compostos pelos genótipos mais produtivos. O genótipo BRS 655 pode ser recomendado para o cultivo, pois possui características agronômicas desejáveis.

SUMMARY This study agronomically evaluated 14 sorghum genotypes in the Brazilian semi-arid region. A randomized complete block design, with the treatments represented by sorghum genotypes and three replicates, was used. The dry matter (DM), plant height (PH), number of live leaves, fresh matter production (FMP), dry matter production (DMP), leaf blade (LB), stem, panicle (PAN), dead material, water accumulation (WA), efficiency of rainwater use (ERU) and carrying capacity (SC) were measured. There was an effect of genotype among all the variables. The genotype with the highest percentage of DM was BRS 655 (26.42%). The genotypes BRS 655, BRS 506, B1141340, 13F04 (1141572) and PONTA NEGRA produced the most FMP, with values of 48,517, 48,500, 44,879, 44,788 and 43,549 kg/ha, respectively. Not only did the genotypes BRS 655, B1141340, 13F04 (1141572), BRS 506 and PONTA NEGRA present the highest DMP, with values of 12,426, 10,344, 9,778, 9,756 and 9,176 kg/ha, respectively, but also the highest values for ERU, WA and SC. There was a significant positive correlation between productive variables (FMP with DMP, PH, ERU and WA) and a nonsignificant negative correlation between morphometric variables (FMP with LB and PAN). A hierarchical formation of four groups was observed, with groups I and III composed of the most productive genotypes. BRS 655 can be recommended for cultivation since this genotype has desirable agronomic characteristics.

Resumo Objetivou-se neste estudo identificar e analisar as secas e seus impactos na agropecuária no município de Campina Grande - PB. Foram utilizados dados de totais mensais precipitados para o período de 1994-2015 do município de Campina Grande para analisar duração, déficit hídrico e intensidade das secas nesse período. Para análise dos impactos foram utilizados dados de agricultura, pecuária e produtos agropecuários obtidos no Instituto Brasileiro de Geografia e Estatística. As secas mais graves no município, aquelas com as maiores durações, déficits hídricos e intensidades, ocorreram nos períodos de 1997-1999, 2012-2015 e 2001-2003. As culturas permanentes tiveram maior impacto na quantidade produzida e rendimento médio. Já as temporárias tiveram redução de área plantada, área colhida, quantidade produzida, rendimento médio e valor da produção. Os maiores impactos ocorreram para banana, coco, mamão, feijão e milho durante 2012 e 2013. Ocorreu redução do efetivo de animais durante a seca, principalmente em 2012 e 2013. A maior redução foi apresentada pelos rebanhos bovino, caprino e ovino. Com relação aos produtos agropecuários, só houve redução da quantidade e do valor da produção de leite durante 2012 e 2014.

Abstract This study aimed to identify and analyze the droughts and its impacts on agriculture in the municipality of Campina Grande - PB. Were used of monthly total data precipitates for the period 1994-2015 of Campina Grande municipality to analyze duration, water deficit and intensity of droughts in this period. To analyze the impacts were used data of agriculture, livestock and agricultural products obtained from the Brazilian Institute of Geography and Statistics. The most severe droughts in the municipality, those with longer durations, water deficits and intensities occurred in the periods of 1997-1999, 2012-2015 and 2001-2003. The permanent crops had greater impact on the quantity produced and average income. Already had temporary acreage reduction, harvested area, amount produced, average yield and production value. The greatest impacts occurred banana, coconut, papaya, bean and corn during 2012 and 2013. There was a reduction of the effective animals during drought, especially in 2012 and 2013. The largest reduction was presented by bovine cattle, goats and sheep. With regard to agricultural products, only decreased the quantity and value of milk production during 2012 and 2014.