The objective of this work was to technically and economically evaluate the productivity of tomato grown under different irrigation frequencies in the coast of Ceará, Brazil. The experiment was conducted in the experimental area of the Federal University of Ceará, Fortaleza, State of Ceará, Brazil, from August to December of 2011 and 2012. A randomized block experimental design was used in the two crop cycles, with six irrigation frequencies, consisted of 2 (F2), 3 (F3), 4 (F4), 5 (F5), 6 (F6) and 7 (F7) days of interval between irrigations, and four replications. The treatments were evaluated at twenty days after transplanting (DAT), when the plants were fully acclimated to the field. The harvesting began at seventy DAT and ended at ninety DAT. The variables analyzed were fruit length, diameter and weight, number of fruits per plant and fruit yield. The economic performance of the crop was also evaluated. Tomato producers of the coastal region of the State of Ceará, who aim to increase economic return, i.e., net income, must adopt a two- day irrigation frequency (F2).

Wheat is a major winter crop in southern Brazil. To maximize its productivity, there should be no biotic or abiotic restrictions that can affect the yield components. Thus, the objective was to evaluate the changes caused in the wheat crop yield components by silicon foliar application. The experiment was conducted in two growing seasons. In the first year, five wheat cultivars (Quartzo, Campo Real, Onix and Fundacep Lineage) were assessed and in the second year four were assessed (Mirante, Campo Real, Horizonte and Quartzo). In both years the crops were subjected to three doses of silicon (0, 3 and 6 L of silicon ha -1). The silicon was applied during the tillering, booting and anthesis stages. The yield components assessed were the number of plants, number of ears, number of fertile tillers, dry matter per plant, hectoliter weight, number of spikelets, number of grains per spike, weight of hundred grains, grain yield and harvest index. Most yield components did not respond to the silicon foliar application. The harvest index (first year) and the number of tillers (second year) however presented a quadratic relationship with the supply of silicon. The remaining differences were attributed to variations among the wheat cultivars.

The use of organic residues and compost is a common practice to improve soil quality and content of organic matter. In this study, the labile and stable fractions of soil organic matter were evaluated after application of layers of fresh (non-composted) or composted organic residues in a 6-year-old citrus orchard. The experiment was set up as a randomized block design, with 6 treatments: control without NPK, control with NPK, non-composted organic residue (NCOR, with and without NPK), and composted organic residue (humus, with and without NPK), with three replicates. The treatments were applied under the plant canopy. Soil samples were collected from the 0-0.05, 0.05-0.10, and 0.10-0.15 m layers. There were increases of 10.3, 22.4, 16.3, and 37.1 % in the organic carbon contents of the surface soil for the treatments using NCOR without NPK, NCOR with NPK, humus with NPK, and humus without NPK, respectively. The organic carbon contents of the labile fraction varied from 1.0 to 12.8 g kg-1, representing between 8 and 62 % of the total carbon. The carbon concentrations in the stable fraction varied from 3.1 to 9.7 g kg-1, representing between 38 and 92 % of the total carbon, and this was the dominant fraction for most of the treatments.

The replacement of natural vegetation by crop systems directly impacts the soil organic matter fractions. The objective of this study was to evaluate the total organic carbon (TOC) and nitrogen (TN) contents in different fractions of the soil organic matter (SOM) of an Oxisol of the Brazilian semiarid region under different irrigated crops and different soil management systems. Seven treatments were evaluated, which consisted of two soil management systems (no - till and conventional tillage) and three crops (maize, sunflower and sorghum), using as reference the soil under a native forest (NF). The summer crops preceded common bean crops in the autumn - winter. The total organic carbon content, total nitrogen, carbon content in humic substances and their constituents (fulvic acids, humic acids and humin) and labile, non - labile and water - soluble carbon contents were evaluated two years and three months after the experiment implementation to determine the carbon lability (L) lability index (LI), partitioning index (CPI) and management index (CMI). The greatest carbon, nitrogen and organic matter contents in the soil surface layer (0.00 - 0.05 m) were found in crops under no - till system (NTS), especially maize. The crops under NTS presented greater carbon content in humic substances than the conventional tillage system (CTS) ones in the layer 0.05 - 0.10 m. The crops under NTS presented greater sustainability in the Brazilian semiarid region compared with those under CTS, as shown by their higher CMI in the soil surface layer.

Characterizing genetic diversity based on evaluations involving germination and seed vigor, is a fundamental stage in starting the development of a cultivation system for Calotropis procera. Thus, this study aimed to estimate genetic diversity among 35 C. procera genotypes based on germination and vigor of seeds stored for 1 year. The genotypes, which originated from areas in Paraíba (Brazil), where they occur naturally, were collected and stored in March 2014. In order to evaluate the physiological potential of the seeds, two experiments were conducted between March and April 2015. The first involved a propagation test conducted in a germination chamber, while the second involved an emergence test in washed sand, performed in polyethylene trays in a screened environment under uncontrolled conditions. In both experiments, an entirely randomized design was used, with four repetitions of 25 seeds per genotype. The characteristics evaluated were germination, average daily germination, daily germination speed, the speed of germination index, the plantlet vigor index, emergence, the speed of emergence index, total length, and total dry mass. The results showed that genetic variability exists among the C. procera genotypes for variables involving germination and vigor of seeds stored for 1 year. Also, emergence, total dry plantlet mass, and germination characteristics contribute most to the genetic divergence among C. procera genotypes.

Fruit thinning is the removal of fruitlets in heavy fruit set situations and aims to increase salable fruit sizes, avoid branch breakdown, reduce harvesting costs, and promote a balance between the vegetative and reproductive growth of plants. Furthermore, this procedure may improve coloring, increase soluble solids, and maintain plant vigor. This study aimed to evaluate the effects of fruit thinning in five varieties of lychee (Bengal, American, Mauritius, Sweet Cliff, and WB4), in the conditions of Jaboticabal - São Paulo state (Brazil). The experimental design was a completely randomized design (CRD) with five treatments and seven replications of three plants each. Treatments consisted of fruit thinning intensities characterized by the number of fruit left on terminal branch panicles, being T1: 3 fruits/branch; T2: 6 fruits /branch; T3: 9 fruit/ branch; T4: 12 fruits/branch; T5: no thinning (control plot). Evaluations were made through a colorimetric assay on ripe fruits, besides a physical and chemical analysis for each variety. The treatments affected the response of varieties on each studied variable. The variety “Mauritius” showed interesting physical and chemical characteristics for the consumer market.

Early blight (caused by Alternaria tomatophila ) is a major disease of tomato with no resistant cultivars. Thus, it is necessary to identify sources of resistance and productive genotypes for the development of new cultivars. Therefore, this study aimed to evaluate the productive potential of cherry tomato genotypes grown in the summer / fall, the severity of early blight on leaves and the incidence of disease in fruits. The treatments consisted of Carolina tomato genotypes, Cereja Vermelho, CH 152 and CLN1561A. The experimental design consisted of randomized blocks with six replications, and the experimental plot had 16 plants. The following characteristics were evaluated: area under the disease progress curve (AUDPC), average number of microinjuries on the fruits (MF), average number of fruits per bunch (NFC), average number of bunches per plant (NCP), average number of fruits per plant (NFP), average yield, number of fruits with incidence of early blight per plant (NFI) and the severity of early blight in leaves (%). The cherry tomato genotype CH152 showed tolerance to early blight with a smaller area under the disease progress curve, lower severity and fruits with incidence of A. tomatophila were not observed in this genotype. The CH152 had the highest number of fruits per bunch, greater number of bunches per plant, higher number of fruits per plant and higher productivity. This line has great potential of being integrated into breeding programs.

The objective of this work was to evaluate the growth and yield of cowpea grains in different intercropping systems with millet, in wet and dry seasons. The experiments were performed in the experimental field of the Department of Plant Science of the Federal Rural University of Rio de Janeiro, Brazil, using a randomized block design with three replications and five treatments: T1- sole crop of millet; T2- sole crop of cowpea; T3- intercrop of millet (1 row) and cowpea (1 row) with 0.5 m between rows (1Mx1C-0.50); T4 - intercrop of millet (1 row) and cowpea (1 row) with 0.75 m between rows (1Mx1C-0.75); and T5 - intercrop of millet (1 row) and cowpea (2 rows) with 0.5 m between rows (1Mx2C-0.50). The cowpea shoot dry weight, root dry weight, number and dry weight of nodules, grain yield and 1000-grain weight, and the millet fresh weight, shoot dry weight, grain yield and 1000-grain weight were evaluated. The land-use efficiency index (LUE) showed significant differences in yield between the sole crop of cowpea and the intercropping system, with greater grain weight in the intercrop 1Mx2C-0.50. On the other hand, the intercrop 1Mx1C-0.75 was not recommended for the study conditions.

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.

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.