The objective of this study was to characterize the physiological acclimation responses of young plants of the dwarf coconut cultivar ̳Jiqui Green‘ associated with tolerance to conditions of multiple abiotic stresses (drought and soil salinity), acting either independently or in combination. The study was conducted under controlled conditions and evaluated the following parameters: leaf gas exchange, quantum yield of chlorophyll a fluorescence, and relative contents of total chlorophyll (SPAD index). The experiment was conducted under a randomized block experimental design, in a split plot arrangement. In the plots, plants were exposed to different levels of water stress, by imposing potential crop evapotranspiration replacement levels equivalent to 100%, 80%, 60%, 40%, and 20%, whereas in subplots, plants were exposed to different levels of soil salinity (1.72, 6.25, 25.80, and 40.70 dS m - 1 ). Physiological mechanisms were effectively limited when water deficit and salinity acted separately and/or together. Compared with soil salinity, water stress was more effective in reducing the measured physiological parameters. The magnitudes of the responses of plants to water supply and salinity depended on the intensity of stress and evaluation period. The physiological acclimation responses of plants were mainly related to stomatal regulation. The coconut tree has a number of physiological adjustment mechanisms that give the species partial tolerance to drought stress and/or salt, thereby enabling it to revegetate salinated areas, provided that its water requirements are at least partially met.

Our study was conducted in the experimental field of the Department of Technology and Social Sciences (DTCS) of the State University of Bahia - UNEB, Juazeiro - BA. The experimental design was comprised of randomized blocks, sub - subdivided in plots, with four replicates comprising the plots of three different shading methods, gray shading screen (GS), red shading screen (RS), and blue shading screen (BS), and the control treatment with no shading. The subplots comprised three mini - tomato cultivars (“Sweet Million”, “Red Sugar”, and “Shani”), and sub - subplots consisted of seven sampling times. The traits evaluated were: dry matter accumulation in leaves, stems, roots, and fruits, total dry matter, shoot length, root length, total number of fruits, and overall yield. The results of the growth analysis showed that dry matter accumulation in organs of mini tomatoes was similar in all treatments and that the highest total dry matter accumulation occurred under RS. In all treatments, fruit was the preferential drainage; however, the cultivar “Red Sugar” showed higher dry matter accumulation in other plant organs. “Red Sugar” also showed the highest number of fruits per plant; however, when we evaluated total productivity, “Sweet Million” and “Shani” showed similar, higher values than “Red Sugar”.

Research on the performance of cover crops in crop systems of annual crops in the Brazilian state of Piauí contributes to increases in yield, greater efficiency of fertilizers and mitigation of environmental impacts. The aim of this study was to evaluate the performance of cover crops in terms of biomass production and the accumulation and release of nutrients during the crop season (November to April) in an oxisol in the Brazilian Cerrado in the state of Piauí that was submitted to different crop production systems including soybeans, maize and upland rice. The experiment was established during the 2010/11 and 2011/12 crop years in the rural area near the municipality of Bom Jesus, Piauí. The experimental design was a randomized block in a split-plot array. Different soil management systems (conventional and no-till) were evaluated in the main plots. Different crop production systems consisting of cover crops sown in the off-season (April to November), and annual crops sown during the crop season (November to April) were implemented in the subplots. The crop production systems that included Urochloa ruziziensis and Pennisetum glaucum overseeded on soybeans and Urochloa ruziziensis simultaneously intercropped with maize stood out in terms of biomass production and the accumulation and release of nutrients. Yields of maize and upland rice declined when sown under newly implemented no-till soil management. Keywords: Brachiaria. Millet. Crotalaria. No-till. Research on the performance of cover crops in crop systems of annual crops in the Brazilian state of Piauí contributes to increases in yield, greater efficiency of fertilizers and mitigation of environmental impacts. The aim of this study was to evaluate the performance of cover crops in terms of biomass production and the accumulation and release of nutrients during the crop season (November to April) in an oxisol in the Brazilian Cerrado in the state of Piauí that was submitted to different crop production systems including soybeans, maize and upland rice. The experiment was established during the 2010/11 and 2011/12 crop years in the rural area near the municipality of Bom Jesus, Piauí. The experimental design was a randomized block in a split-plot array. Different soil management systems (conventional and no-till) were evaluated in the main plots. Different crop production systems consisting of cover crops sown in the off-season (April to November), and annual crops sown during the crop season (November to April) were implemented in the subplots. The crop production systems that included Urochloa ruziziensis and Pennisetum glaucum overseeded on soybeans and Urochloa ruziziensis simultaneously intercropped with maize stood out in terms of biomass production and the accumulation and release of nutrients. Yields of maize and upland rice declined when sown under newly implemented no-till soil management.

Among the factors negatively impacting guava ( Psidium guajava ) crop in Brazil, one of the most important is the root - knot nematode, Meloidogyne enterolobii , which may cause considerable yield losses and even the cessation of guava cultivation in some areas. In addition to affecting guava, the pathogen has been reported as a parasite in various other crops, among them both oleraceous and ornamental crops, as well as in spontaneous vegetation. The aim of this study was to verify the occurrence of M. enterolobii in plants collected in guava orchards in different counties of Ceará state, identified through electrophoresis with the isoenzyme esterase, and to observe its infecting behavior into Meloidogyne differentiating plants . Fifty root samples from guava, tasselflower ( Emilia fosbergii ), and jurubeba ( Solanum paniculatum ), were collected in 13 counties from eight micro - regions in the state of Ceará. In all analyzed samples, only esterase phenotype M2 (Rm: 0.6; 0.9), characteristic of M. enterolobii , was detected, showing that the nematode is widespread in orchards throughout the state, where is affecting these fruit tree, and that it is also able to parasitizing plants of the spontaneous vegetation. Based on the results, this nematode currently constitutes a serious threat to guava plantations in Ceará, and effective control mechanisms are crucial to prevent the spread of this pathogen to other, still unaffected, areas.

Sugarcane management practices (unburned cane - UC and burned cane – BC) interfere with dynamics of soil magnetic properties. This study focused on determining the potential of magnetic susceptibility as soil quality indicator in areas under sugarcane cultivation. The experiment area is on the limit between basalt from São Bento Group, Serra Geral Formation, and sandstone from Bauru Group – Adamantina Formation. Twenty soil samples were collected from two management areas (burned and unburned sugarcane prior to harvest) at a depth range of 0.0 - 0.2 m. Local soil was classified as eutroferric Red Latosol (Oxisol), with highly clayey texture. Chemical and physical properties, CO 2 emissions and magnetic susceptibility (MS) in air - dried fine earth (MS ADFE ), total sand fraction (MS TS ) and clay fraction (MS CF ). The magnetic signature from MS was effective in identifying changes of physical, chemical and mineralogical traits in Latosols under burned and unburned sugarcane crop. The information provided here can guide further studies on the genesis of minerals with magnetic expression in environments and exposed to fire burning

The objective of this work was to evaluate Fusarium guttiforme inoculation methods and genetic resistance of pineapple accessions. Thus, three experiments were conducted: pathogen inoculation of different leaf types ( B, D and F ) of pineapple (1), pathogen inoculation of pineapple cuttings and detached D leaves (2), and identification of resistance to fusariosis in 19 pineapple accessions (3) sampled in the State of Mato Grosso, Brazil. The cultivars Pérola (susceptible to fusariosis) and BRS - Vitória (resistant to fusariosis) were used as controls. The fusariosis severity was evaluated at 10, 15, 20, 25 and 30 days after inoculation with F. guttiforme . The lesion diameters (severity level) were used in order to calculate the area under the disease progress curve (AUDPC). The inoculation of detached D leaves was the most efficient, fast and inexpensive method, and the one that most satisfactorily reproduced the disease symptoms. The period of 10 to 20 days after inoculation of the D detached leaves with the pathogen is the most suitable to evaluate the resistance of pineapple accessions to fusariosis. The lowest lesion area and AUDPC was found in the accession 1, in all evaluations. Thus, the accession 1 can be used in pineapple breeding programs for resistance to fusariosis.

The insect Dysmicoccus brevipes (Hemiptera: Pseudococcidae) has been reported as an important pest for several crops, especially coffee. The citrus essential oils can be obtained as by-products of the citrus-processing industry and have been tested as an alternative to control different insect groups. Therefore, the objective of this work was to determine the chemical composition and evaluate the toxicity of commercial sweet orange (Citrus sinensis), bitter orange (Citrus aurantium) and Sicilian lemon (Citrus limon) essential oils and pure monoterpene D-limonene on D. brevipes. The essential oils were analyzed by gas chromatography. Two bioassays were conducted; the first assessing the insect mortality in all oils and the second assessing the lethal concentrations (LC50 and LC95) of the most effective oils. The main components of the oils were D-limonene (83.33%) and Linalool (8.91%) (sweet orange); D-limonene (78.53%) and γ-terpinene (12.65%) (bitter orange); D-limonene (59.78%), beta-pinene (14.71%) and γ-terpinene (10.19%) (Sicilian lemon) and the compound D-limonene had 97% of purity. The highest mortalities were found with the use of the Sicilian lemon (98.68%) and sweet orange (94.11%)oils. The sweet orange oil presented lethal concentrations at 2.21% (LC50) and 3.55% (LC95), and the Sicilian lemon oil at 0.72% (LC50) and 2.91% (LC95). The main component of the sweet orange and Sicilian lemon essential oils was the D-limonene, and the Sicilian lemon oil was most effective oil to control D. brevipes.

The soybean-corn succession in no-tillage system (DSS) is the most common cultivation practice in the state of Mato Grosso. Soils submitted to this type of system are prone to the formation of fertility gradients and surface compaction, restricting crop productivity. The objective of this work was to evaluate the physical-chemical attributes of an Oxisol after 11 years of continuous succession of soybean and corn in direct seeding, using geostatistical analysis techniques and main components. The experiment was conducted at the Chão Nativo farm located in the municipality of Sinop, Mato Grosso, Cerrado-Amazonian ecotone. For this, a rectangular mesh was installed with 103 sampling points distributed in an area of 7.02 ha, in which the grain yield of the soybean was determined as well as the physical and chemical attributes of the soil in the layers 0-10 and 0.10 - 0.20 m. Soybean showed a grain yield between 2.83 and 3.70 Mg ha-1, which was positively correlated with the spatial distribution of pH, phosphorus and potassium. The soil presented low physical quality due to high soil resistance to penetration and macroporosity less than 10%; however, no spatial correlation of physical attributes with soybean yield was observed.

The objective of this work was to evaluate the agronomic performance and estimate the genetic divergence of 18 cotton genotypes grown in the main season (sowed in December, 2012) and off season (sowed in January, 2013), considering their agronomic characteristics and resistance to Ramularia leaf spot. A randomized block experimental design was used, with five replications. The characteristics evaluated were plant height, first branch height, position of first fruiting branch, height of first fruiting branch, length between nodes, number of nodes, average number of bolls per plant, average boll weight, area under the disease progress curve (AUDPC) related to the Ramularia leaf spot severity, weight of 100 - seed from the plant middle third, fiber percentage, average production per plant, yield and cotton fiber quality. The results were subjected to individual and joint analysis of variance and the genetic divergence was estimated according to multivariate procedures (Mahalanobis' generalized distance and Tocher's optimization method). The dissimilarity matrices were summed to estimate the genetic divergence, considering both growing periods. Genetic variability was found among the genotypes evaluated, in both the main season and off season. The characteristic that most contributed to the genetic divergence in the main season was the production per plant and, in the off season, was the fiber percentage. According to the results of the present work, the crosses between the genotypes BRS - 335 and FMT - 707; FM - 910 and FMT - 707; and IMA - 08 - 12427 and FMT - 707 are recommended.

Soil salinity and sodicity are global problems since both promote the physical, chemical and biological degradation of soil, jeopardising the productive capacity of agricultural fields. Inorganic correctives or organic inputs are applied as an attempt to reduce the problem, alongside the use of salt-tolerant plants. This study aimed at evaluating the effects of organic inputs on the growth of neem (Azadirachta indica) strains in saline-sodic soil after cutting. Treatments were arranged in a randomised block design, with four replicates in a 3 × 5 factorial. Organic inputs — bovine manure, common bovine biofertilizer (equal parts of water and fresh bovine manure) and chemically enriched biofertilizer (common biofertilizer components combined with plaster, sugarcane molasses and cow’s milk) — were applied only once, after soil washing, two days prior to seeding, at the levels of 0, 3, 6, 9 and 12% of the substrate volume. Except effects on the stem diameter, the most efficient input was bovine manure, with strong effects on the height increase and biomass yield of neem plants after cutting, especially in treatments at a level greater than 6%. The organic inputs, despite increasing the soil salinity and sodicity in the interval between washing and cutting, stimulated biometric growth and biomass formation in saline-sodic soil.