Cowpea is an herbaceous legume susceptible to several insects and diseases; and the beetle Callosobruchus maculatus is the main pest causing direct losses in the production of this crop. The objective of this work was to assess the physical and bromatological characteristics of beans of cowpea varieties (Bico-de-Ouro, BRS-Novaera, BRS-Guariba and BRS-Tumucumaque) preferred by C. maculatus. Adults of C. maculatus were obtained from a storage unit of cowpea beans. The physical and bromatological characteristics and attractiveness of cowpea beans to insects were evaluated in laboratory. The preferences for oviposition with no choice and attraction to cowpea beans by C. maculatus are not related to the high protein content or physical characteristics of the bean seed coat (thickness and fiber content), since the insects were more attracted to beans of the variety Bico-de-Ouro, which had low crude protein content, the thickest seed coat and high NDF content.

Spatial arrangement and population density of component cultures, when well structured, may contribute to increased crop yields relative to monocultures. Thus, the objective of this work was to evaluate the productive performance of carrot and cowpea in an intercropping system under different spatial arrangements and population densities. This research was conducted on the “Rafael Fernandes” experimental farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, RN, Brazil. The experimental design was a randomized complete block with four replicates, where the treatments were arranged in a 3 × 4 factorial scheme, in which the first factor was three spatial arrangements (2:2, 3:3, and 4:4) and the second factor was four different population densities of cowpea (100%, 80%, 60%, and 40% of the recommended population in the single crop RPSC). Rooster tree Calotropis procera (Ait.) R.Br., a spontaneous species of the „Caatinga‟ biome, was used as fertilizer. The characteristics evaluated in carrot were as follows: total and commercial productivity of roots and classified root production. The following characteristics were evaluated for cowpea: number of pods per square meter, length and yield of green pods, number of grains per pod, 100grain weight, and yield of green grains. The modified monetary advantage was used to evaluate the feasibility of the intercropped systems. Spatial arrangements between the component cultures did not influence the agroeconomic performance of the carrot-cowpea intercropping system. The highest agro-economic performance of the carrot-cowpea intercropping was obtained in the population of cowpea, which was 42% of the RPSC.

The objective of this study was to evaluate genetic divergence among cowpea genotypes and to select parents for crosses aimed at the fresh pod and grain market. Two experiments were carried out during 2014, corresponding to two sowing times, in the municipality of Mossoró, State of Rio Grande do Norte. Twenty-three cowpea genotypes were evaluated in a randomized complete block design with four replicates. Fifteen descriptors were used to quantify divergence, using the Mahalanobis distance as a measure of dissimilarity, obtained from the genotypic mean predicted by the Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP) method. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) hierarchical method was used to group genotypes and the Singh criterion to quantify the contribution of traits to genetic divergence. The genotype × environment interaction (G × E) influenced divergence, both in the contribution of traits and in the grouping of genotypes. In the experiment 1, the genotypes were distributed among four groups. In the experiment 2, less discrimination occurred and the genotypes were represented by only two groups. When joint analysis of two evaluations was carried out based on two sowing times, genotypes were represented by six groups. The G × E interaction influences the contribution of traits and the grouping of cowpea genotypes in the study of divergence. The genetic divergence of the set of cowpea genotypes evaluated is mainly due to green grain and pod yield. BRS Aracê and BRS Xiquexique cultivars are the most divergent among the genotypes studied, representing 75% of the recommended crosses.

Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM).

New hybrid onions that are more productive are currently being cultivated. Information on growth and nutrient accumulation must thus be updated to assist in the refinement of existing recommendations, enabling the better exploitation of the productive potential of these new genotypes. We determined the growth of plants and the accumulation and export of nutrients of the short-day onion ‘Soberana’ established by direct seeding. The experimental design was a randomized block with four replicates and the treatments were evaluation times. Leaf number, tissue dry weight, nutrient accumulation, and the maximum daily rate of accumulation were evaluated throughout the growing cycle. The order of nutrient accumulation was (g plant-1) K (0.72) > Ca (0.38) > N (0.32) > S (0.14) > P (0.08) > Mg (0.06) and (mg plant-1) Fe (2.26) > Mn (1.43) > Cu (0.93) > Zn (0.91) > B (0.85). Macronutrient demand was highest between 61 and 148 days after sowing (DAS), and micronutrient demand was highest between 70 and 148 DAS.

Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization.

The objective of this work was to evaluate the interaction of microorganisms and phosphorus dosages in the development of gliricidia. The experimental design was completely randomized with six treatments (control, native microbial inoculant, and four arbuscular mycorrhizal fungi isolates: UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum, and UFLA401 - Acaulospora morrowiae), with four replicates. The parameters evaluated were: height plant, the number of branches, shoot and root dry mass matter, root length and volume, leaf phosphorus, mycorrhizal colonization, the number of spores of the arbuscular mycorrhizal fungi, the number of nodules of nitrogen fixing bacteria, and the presence of endophytic dark septate fungi, after 95 days of inoculation. The high mycorrhizal colonization of gliricidia does not guarantee an increase in biomass, which depends on the interaction of the arbuscular mycorrhizal fungi, the endophytic dark septate fungi, the nitrogen fixing bacteria, and the endophytic bacteria. Gliricidia was responsive to the inoculation of the native microbiota, UFLA372 and UFLA401. Mycorrhizal colonization by UFLA401 was influenced by the presence of nitrogen fixing bacteria. Gliricidia was not responsive to the inoculation of UFLA05 and UFLA351. The presence of the endophytic dark septate fungi did not inhibit mycorrhization and the formation of nodules of nitrogen fixing bacteria in gliricidia.

Sugarcane is one of the most affected crops by water scarcity. The efficient use of the irrigation water is an alternative to minimize this problem. The objective of this work was to evaluate biometric parameters, yield, and technological quality of sugarcane plants subjected to different controlled water deficit regimes in the sub-middle São Francisco Valley, Brazil. The experiment was conducted in a randomized block design, in two crop cycles, with three replications, with ten treatments consisted of three controlled water deficits (15%, 30%, and 45% of the crop evapotranspiration - ETc), applied at three development stages of the plant - sprouting and tillering (Stage I), grand growth (Stage II), and maturation (Stage III) - and a control with 100% of the ETc throughout the entire crop cycle. The controlled water deficit did not affect the technological quality of the sugarcane in any development stage. The sugarcane yield was higher when using a controlled water deficit of 30% of ETc in the sprouting and tillering stages of the plants. The water deficit of 15% of ETc is recommended for the grand growth, or maturation stages of the sugarcane plants for a greater water use efficiency of the production system.

Drip irrigation with diluted sanitary landfill leachate favors the development of grasses on the landfill surface, however, the clogging of emitters of the irrigation systems is the major obstacle for this practice. The objective of this study was to select empirical models of the Christiansen's uniformity coefficient, distribution uniformity coefficient, and statistical uniformity coefficient of drip irrigation sets applying sanitary landfill leachate diluted in water as a function of time of operation, and quality of the effluent. An experiment was conducted in a completely randomized experimental design with three replicates, using a split-split plot arrangement, with operating pressures (70, 140, 210, and 280 kPa) in the plots, types of drippers (G1, 1.65 L h-1; G2, 2.0 L h-1; and G3, 4.0 L h-1) in the subplots, and operating time of the drip irrigation sets (0, 20, 40, 60, 80, 100, 120, 140, and 160 hours) in the sub-subplots. Data regarding hydraulic performance and effluent quality were acquired every 20 hours during 160 hours of operation and subjected to simple and multiple regression analyses. The G3 dripper operating at pressures of 70 and 140 kPa were the combinations that best attenuated biofilm clogging. The linear regression and square root were the models that best represented the reduction in the uniformity of the effluent application as a function of the operating time of the drip irrigation sets. The linear correlations denoted that calcium contents and total coliform population rates were the characteristics of the sanitary landfill leachate that most affected the drip clogging process.

The objective of this work was to evaluate the biomass production and antioxidant enzymatic system activity of irrigated forage sorghum with saline aquaculture effluent under different leaching fractions. The experiment was conducted in the Caatinga Experimental Field of the Embrapa Semiarido, in Petrolina, State of Pernambuco, Brazil. The experimental design was a complete randomized block in a split-plot arrangement with four replications, consisting of three forage sorghum varieties (Volumax, F305 and Sudan) and four leaching fractions (0, 5, 10 and 15%). The vegetal materials were collected when the plants were at the soft-dough stage. The biomass production and activity of the enzymes superoxide dismutase, catalase and ascorbate peroxidase were evaluated. Irrigation with saline aquaculture effluent with leaching fraction of 15% results in low salinity level in the root zone and higher biomass production of forage sorghum Sudan and F305, in semiarid conditions. The antioxidant system was activated in the three sorghum varieties to prevent accumulation of reactive oxygen species, with the synchrony between the enzymes superoxide dismutase and catalase resulting in a better productive response of the varieties Sudan and F305.