Irrigation with brackish water is common in the semiarid region of the Brazilian Northeast, potentiating the process of salinization of the soil in these areas. The hydroponic system stands out as an important strategy for crop management in semiarid regions, since crops show greater tolerance to the salt stress under hydroponic conditions, which minimize the effects of soil salinization. Thus, the objective of this work was to evaluate the effects of salt stress on the growth, fruit yield and mineral nutrition of sweet pepper in hydroponic system, using brackish water and coconut fiber substrate. The experiment was conducted in Recife, State of Pernambuco, Brazil (8°3'15''S, 34°52'53''W). A randomized block experimental design in a 5x2 factorial arrangement with five replications was used, consisting of five water salinity levels of the nutrient solution (2.0; 3.5; 4.5; 5.5 and 6.5 dS m-1) and two sweet pepper cultivars (Bruno and Rubia). The increasing salinity level of the nutrient solution decreased the fruit yield of the cultivars evaluated, reduced the potassium, phosphorus and sulfur, and increased the sodium and chlorine contents in the leaf tissues. The Ca contents of the cultivar Bruno decreased with increasing salinity, and increased in the cultivar Rubia. The cultivar Rubia stood out with the highest fruit yield and ionic selectivity, accumulating high amounts of potassium and calcium and maintaining low Na and Cl contents. The fruit yield of the cultivar Rubia (39.9 t ha-1) grown under solution with electrical conductivity of up to 3.5 dS m-1, denotes the potential viability of growing this cultivar under hydroponic conditions.

Recurrent selection can generate successive gains for characters of economic interest without causing genetic narrowing in the population. However, it has rarely been used in breeding programs in popcorn, especially when using full-sibling progenies to generate more expressive gains. The objective of this study was to estimate the genetic gain of the UENF-14 popcorn population through recurrent selection, and verify the evolution of the gains between the selection cycles four and eight. A total of 200 full-sibling progenies were evaluated in randomized blocks arranged in eight sets within three replicates in two environments; each set containing twenty-five progenies and six controls (selection cycles 4, 5, 6 and 7 of the UENF-14, BRS-Angela and IAC-125). The average height, prolificacy, 100-grain weight, ear weight, grain yield, and grain popping expansion of the plants were evaluated. In the selection of the thirty superior progenies for the eighth cycle, the Mulamba and Mock selection index was used, which generated estimated genetic gains of 4.60 for grain yield and 3.61% for popping expansion. The grain yield increased 111.99 kg ha-1 and the popping expansion increased 1.75 mL g-1 per cycle. The evolution of the cycles resulted in an accumulated genetic gain for the main characters of economic importance, allowing the prediction of success in the continuity of the recurrent selection.

Water deficit affects plant development and the overcoming of its effects depends on the genotype, duration of stress, severity of damage and development stage of the plant at water stress. Cowpea is considered tolerant to water deficit, however, studies have shown that its yield can be reduced under this condition. Thus, the objective of this work was to evaluate the effect of water deficit on F2 populations of cowpea and select tolerant genotypes. Thirty F2 populations of cowpea and their parents (BRS-Paraguaçu, Pingo-de-Ouro-1-2, BRS-Xiquexique, CNCx-698-128G, Santo-Inácio and MNC99-510F-16-1) were evaluated in two experiments, one under induced water deficit and other under full irrigation, in the experimental field of the Embrapa Mid-North, in Teresina, State of Piauí, Brazil. A triple lattice incomplete block experiment design was used, with three replications. The experimental plots consisted of six 2-m rows, with spacing of 1.0 m between rows and 0.50 m between plants. The grain production was evaluated and its decrease related to the relative production and tolerance to stress was calculated. The grain production of the genotypes had an average decrease of 29.83% under water deficit. The genotypes from the crosses BRS-Paraguaçu x CNCx-698-128G, BRS-Xiquexique x Pingo-de-Ouro-1-2, CNCx-698-128G x BRS-Xiquexique, CNCx-698-128G x MNC99-510F-16-1, Santo-Inácio x BRS-Xiquexique and MNC99-510F-16-1 x BRS-Paraguaçu had high production and high tolerance to water deficit.

The objective of the present work was to evaluate the use of extracts of leaves and fruits of neem (Azadirachta indica Juss) as coating for papaya Formosa fruits aiming to maintain their quality during post-harvest storage. A completely randomized experimental design in a 5x5 factorial arrangement was used, with 3 replications of 2 papaya fruits per plot. The treatments consisted of five coatings with extracts of neem leaves and fruits (leaf extracts at 5 and 10%, fruit extracts at 5 and 10% and a control treatment without coating) and five storage periods (0, 3, 6, 9 and 12 days) under mean temperature of 30.4 °C and relative humidity of 42%. The fruit weight loss, external appearance, pulp firmness, titratable acidity and soluble solids were evaluated, and the fungi species on the fruit surface of each storage were identified and quantified. The treatments with extract of neem leaves and fruits at 5% had papaya fruits with best external quality and provided best control of growth of phytopathogenic fungi. Regarding external appearance, papaya fruits coated with extracts of neem leaves and fruits at 5% had a shelf life of 12 days, while those coated with extracts at 10% had a shelf life of 9 days.

The tall coconut (Cocos nucifera L.) has great socioeconomic importance in Brazil and was first introduced on the coast of the north-eastern region, where it has been exploited in a semi-extractivist manner. The goal of this study was to quantify the genetic divergence between accessions introduced and preserved at the International Coconut Genebank for Latin America and the Caribbean, estimate the efficiency of descriptors used in the discrimination of the accessions, and indicate the essential descriptors for the activities of characterisation and evaluation. The accessions used were: Polynesia Tall; Tonga Tall; West African Tall; Rennel Tall; Rotuma Tall; Vanuatu Tall; Malayan Tall and Brazilian Tall Praia-do-Forte. Thirty-five quantitative descriptors recommended for the species were used. Genetic divergence was estimated by the Mahalanobis’s generalised distance and the cluster analysis was performed using the unweighted pair group method with arithmetic mean (UPGMA). The relative importance of the descriptors was measured according to Singh and Jolliffe’s methods, and the variables were selected taking into consideration the matching information in the two methods, eliminating those that were discarded in the two procedures. The agronomic characteristics indicated that the first canonical variable explained 90.25% of total variance. The most efficient descriptors for detecting the genetic divergence were: fruit equatorial circumference; nut polar and equatorial circumference; quantity of liquid endosperm; total fruit weight; nut weight; stem height; girth of stem at 1,5m height; number of leaflets; and number of bunches. The most dissimilar accessions according to the agronomic characteristics were Rotuma Tall and West African Tall, which can be primarily indicated as genitors for the formation of segregating populations in breeding programmes.

Reliable information on vegetation cover and its dynamics over time is essential for managing life, resources, and supporting policies. Although many related initiatives have been undertaken in Brazil since the 1980s, knowledge about its dry forests is still limited. In this study, we address the drivers of deforestation and their threat to the Brazilian dry forest called Caatinga. We evaluated the land cover dynamics and landscape metrics in the watershed of the Pontal River, as it has become one of the most socially and environmentally important areas in Brazil. The overall process consists of a systematic sampling grid of hydrological samples, where Landsat images (1975 to 2013) combined with the FRAGSTATS package were used to evaluate landscape metrics indices for the Caatinga. Data showed that the relative area (RA) decreased from 90.25% to 60.98% over the 38-year period, while fragmentation (PD) presented an increasing bias. In addition, the spatial distribution of both indices became more heterogeneous and clustered in the north. We suggest that appropriateness of land for farming was the leading cause of deforestation; rainfall is 112% more intense in the north of the watershed than in the south. Therefore, the northern fauna and flora have been significantly altered and reduced. The relationship between deforestation and time shows an increasing threat. Further studies evaluating these causes are needed to improve our understanding of the vegetation dynamics in this region.

The effects of soil compaction on crop growth and productivity have been well studied in recent years, however, studies on the physiological responses of crops to compaction are scarce. The objective of this study was to evaluate the effect of soil compaction on gas exchange, and photochemical efficiency of lima bean (Phaseolus lunatus L.) genotypes of different growth habits. The experimental design was a randomized block in a 3×4 factorial arrangement, with three lima bean genotypes (Branca-Pequena, Orelha-de-Vó and Roxinha) and four compaction levels (soil densities of 1.1, 1.3, 1.5 and 1.7 g cm-3), with four replications. The following variables were evaluated at 38 days after sowing: photosynthetic rate (A), leaf transpiration (E), stomatal conductance (gs), internal CO2 concentration (Ci), instantaneous water use efficiency (WUE), intrinsic water use efficiency (iWUE), instantaneous carboxylation efficiency (iCE) and photochemical efficiency (Fo, Fm, Fv and Fv/Fm). The data were subjected to analysis of variance at 5% probability by the F test. The genotypes showed a reduction in the photosynthetic rate with increasing soil compaction. The soil compaction affected the photochemical efficiency of the genotype Orelha-de-Vó, with the Fm and Fv fitting to the linear model, and the Fv/Fm fitting to the quadratic model. The genotype Orelha-de-Vó had the highest rate of E and gs at the soil densities of 1.24 and 1.29 g cm-3, respectively. Regarding the photosynthetic rate, the genotype Roxinha is more efficient than Branca-Pequena at the soil density of 1.7 g cm -3.