ABSTRACT Basidiomycete fungi that decompose wood produce substances with promising biological activity for the alternative control of plant diseases. The production of these substances can change according to the climatic conditions and the substrate used for fungal cultivation. The objective of this study was to develop a substrate with sawdust from Eucalyptus sp. and to verify its influence on biomass and cinnabarin production by Pycnoporus sanguineus. Sawdust was used in two particle sizes: less than 500 microns (G1) and between 500–841 microns (G2). Four isolates of P. sanguineus were plated on Petri dishes containing potato broth and agar media added with 0%, 1%, 5%, 10%, and 15% sawdust for each particle size. The largest final diameter of the colony and speed of mycelial growth were observed in the substrate with G1 particle size, with the Ps14 isolate showing the highest averages. For these variables, the sawdust concentration did not influence G1 granulometry and provided the highest values in G2 granulometry. Fresh mycelium mass and cinnabarin production showed the highest values in G2, with the isolated Ps13 and Ps08 showing the highest averages, whereas in G1, Ps14 had the best performance for the analyzed variables. These results indicate that sawdust from Eucalyptus sp., at concentrations of 10% and 15%, is an alternative for the in vitro cultivation of P. sanguineus, and that particle size influences the growth speed, fresh mass production, and cinnabarin content.

ABSTRACT Information of the variation for important morphological and physiological traits of okra is still limited. Molecular analysis is an important additional tool in germplasm characterization studies. The study aimed to evaluate the performance of the growth and yield of 20 pre-commercial okra accessions to identify molecular markers’ association with morphological traits. Nineteen morphological traits were measured with five qualitative and 14 quantitative descriptors. For analysis of genetic patterns Random Amplified Polymorphic DNA (RAPD) markers were used with nine primers and 24 usable bands. The genetic dissimilarity was evaluated based in morphological and genetic matrices. Also, graphical representation of genetic distances was obtained by UPGMA and Tocher’s optimization method. The morphological characterization of the accessions detected polymorphism for all evaluated traits. RAPD markers were efficient in detecting genetic variability among okra accessions. For the primers used in the experiment, only OPE10 did not amplify the DNA strand. The other eight primers produced a total of 35 bands, in which 25 were polymorphic and ten were monomorphic. The morphological traits and molecular markers identified wide genetic variability among the 20 okra accessions, indicating successful crosses in breeding programs and isolating some interesting materials. Morphological and molecular cluster analyses were complementary and helped in the genotype selection. Molecular analysis indicated some divergent accessions that were not found in morphological analysis, which could highlight some materials that have a desirable trait, that is difficult and highly costly to access in field experiments.

ABSTRACT In recent decades, soybean has been one of the most widely grown crops in Brazil. The soybean looper, Chrysodeixis includens (Walker, [1858]; Lepidoptera: Noctuidae), is one of the main defoliating pests of soybean that cause damage and affect the cost of production. The overall objective of the present study was to characterize the resistance of C. includens to diamide insecticides. To this end, the baseline susceptibility of C. includens to flubendiamide, chlorantraniliprole, and cyantraniliprole was characterized to estimate their concentrations for diagnostic monitoring of resistance in populations collected in commercial soybean crops in southern Brazil during the 2018/19 season. Under field conditions, evaluations were made of the residual activity of three diamide insecticides: chlorantraniliprole + lambda-cyhalothrin, teflubenzuron, methoxyfenozide, and bifenthrin for discrimination between flubendiamide-susceptible and resistant C. includens. Chrysodeixis includens was more tolerant to cyantraniliprole than to flubendiamide and chlorantraniliprole. The field populations had a higher survival rate than the susceptible population. The resistant population showed a resistance ratio to flubendiamide of 70.1-fold. Under field conditions, the residue of the study insecticides, except for bifenthrin, enabled discrimination between flubendiamide-susceptible and resistant C. includens. The data indicate the need to study the cross-resistance relationships between insecticides to improve the rotation recommendation. They also reinforce the importance of using other good management practices, e.g., the use of insecticides based on pest sampling and the choice of other control methods to prevent C. includens from becoming resistant to diamide insecticides.

ABSTRACT The possibility of early soybean fertilization carried out on the predecessor crop has several benefits, mainly operational ones, making the production system more conservationist and balanced. An experiment was carried out at the Anhumas Experimental Station, Luiz de Queiroz College of Agriculture (USP/ESALQ), located in Piracicaba, SP, Brazil, during 2001/2002, 2002/2003, and 2003/2004 agricultural years on a typic Hapludox aiming to evaluate the effects of the early fertilization on soybean yield. The fertilization consisted of applying 90 kg ha−1 of P2O5, 50 kg ha−1 of K2O, and micronutrients (Co, Cu, Fe, Mn, Mo, and Zn). The experiment was conducted in a randomized complete block design with three replications and 12 treatments consisting of different levels of early soybean fertilization carried out on the finger millet crop: T1, no fertilization; T2, conventional soybean fertilization; T3, early 50% K fertilization; T4, early 100% K fertilization; T5, early 50% P fertilization; T6, early 50% P and K fertilization; T7, early 50% P and 100% K fertilization; T8, early 100% P fertilization; T9, early 100% P and 50% K fertilization; T10, early 100% P and K fertilization; T11, early 100% P and K fertilization + micronutrients; and T12, early leaf fertilization with micronutrients. The results showed that the early soybean sowing fertilization with phosphorus and potassium carried out during finger millet sowing does not interfere with the thousand-seed weight and soybean yield.

ABSTRACT Plant breeding programs have been investing in the development of high commercial standard onions; thus, they depend on the genetic resources available for obtaining commercial hybrids. The objective of this study was to evaluate genetic parameters and diversity, and phenotypic and genotypic correlations of characters related to onion production. The experiment was conducted in Uberlândia, Minas Gerais, Brazil. Fifty-three onion strains were evaluated, and a randomized block design was used. The number of plant and bulb characteristics evaluated was 13. The statistical analyses were performed using Genes and R software. A genetic variability among the genotypes was found for most of the characters at 1% level of significance in the F test. The heritability of most characters presented moderate to high values (≥ 70%) and high CVg/CVe ratio (≥ 1). The UPGMA method separated the genotypes into 20 groups, while the Tocher method separated them into 19 groups. The groups that stood out were V, XIV, XV, XV, XVI, XVII, XVIII, XIX, and XX. The results of t-test showed six significant phenotypic correlations with low to moderate degree of association, and the genotypic correlations, in most cases, were higher than the phenotypic ones and showed the same sign. From the genetic parameters studied, the possibility of gains in the selection is high. The separation of groups of divergent genitors was possible due to the wide genetic variability for the studied characters. Moreover, the phenotypic and genotypic correlations showed that indirect selection is not feasible.

ABSTRACT The invasive pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), is a pest that threatens the production of fruits, vegetable, and ornamental plants in Brazil. It is a phytophagous insect with a wide range of hosts; thus, there is an increasing demand for sustainable environmental-friendly control methods, such as biological control. This study aimed to investigate biological parameters of Ceraeochrysa everes (Neuroptera: Chrysopidae) fed on 2nd instar nymphs of M. hirsutus and eggs of Ephestia (Anagasta) kuehniella (Zeller) (Lepidoptera: Pyralidae). The duration of the immature stages of C. everes was longer when the predator was fed on 2nd instar nymphs of M. hirsutus, compared to the control (E. kuehniella). The survival rate of immature C. everes was 82.5% and 100% when fed on 2nd instar nymphs of M. hirsutus and eggs of E. kuehniella, respectively. The type of food resource offered at the larval stage affected the pre-oviposition, oviposition, and post-oviposition periods and the longevity of C. everes females. Adult females C. everes from immature individuals fed an exclusive diet of E. kuehniella eggs had longer oviposition, fecundity (daily and total), fertility, and post-oviposition periods and longevity. Ceraeochrysa everes has the capacity for predation, development, and reproduction while having 2nd instar nymphs of M. hirsutus as food resource. Therefore, C. everes has a promising potential for controlling M. hirsutus.

ABSTRACT Globally, the demand for food and consumer products has accompanied population growth, forcing the agriculture and livestock sector to optimize the production systems. In the specific case of agriculture, using improved edible and energetic plant cultivars associated with abiotic stress-reducing substances is a strategy adopted to solve this problem. This investigation aimed to evaluate whether silicon (Si) promotes physiological adjustments, an increase in production, higher yield, and improved quality of naturally colored cotton fibers. Five doses of silicon (0 (control), 5, 10, 15, and 20 kg ha−1) were tested in a completely randomized design. The variables assessed were physiological adjustments, production, yield and quality of fibers produced by BRS Rubi cultivar. Data were submitted to principal component analysis, multivariate and univariate analyses of variance, and multiple linear regression analysis. Silicon promotes physiological adjustments, enhanced production, yield, and quality of naturally colored cotton fibers of BRS Rubi cultivar grown in the Brazilian semiarid region. Fiber quality in plants that have been treated with Si is within the expected values for this cultivar and by the international standard D-4605 of the American Society for Testing and Materials. 10 kg ha−1 of Si is recommended to increase fiber quality of naturally colored cotton cv. BRS Rubi.

ABSTRACT In the Brazilian semi-arid region, water deficit is one of the main factors that compromise the growth and productive yield of crops, including yellow passion fruit, due to the limitation of carbon assimilation by the photosynthetic activity of plants. Therefore, it is necessary to manage the soil with technologies that can reduce the loss of water in the soil and mitigate the effects of water deficit on yellow passion fruit plants cultivated under semi-arid conditions. The objective of this study was to evaluate the application of hydrogel doses and mulching to the soil on the physiological aspects of irrigated yellow passion fruit cultivation. The experiment was carried out in a randomized block design, in a 5 × 2 factorial scheme, referring to five doses of hydrogel (0.0, 0.5, 1.0, 1.5 and 2.0 g dm−3 of soil) in soil without and with mulching from signal grass (Brachiaria decumbens L.). The variables analyzed were chlorophyll indices, fluorescence (initial, maximum and variable) and gas exchange. The total chlorophyll index was increased with the application of 1.5 g dm−3 of hydrogel and the use of mulching; when applying hydrogel doses of 2.0 g dm−3 the photosynthetic rate of yellow passion fruit plants increased, whereas their transpiration rate increased with the use of mulching and doses of hydrogel; as a consequence, there was a reduction in water use efficiency.

ABSTRACT Erythrina velutina Willd. (Fabaceae) is drought tolerant and has the potential for reforestation in the semi-arid region. The response of its seeds to the environmental conditions of each production area influences their size, weight, physiological potential, and health. Thus, this study aimed to assess how the environmental conditions of the different regions of Paraíba influence the biometric characteristics of E. velutina seeds. Seeds from 19 mother plants collected in Juru, Sumé, Araçagi, Guarabira, São João do Cariri, Esperança, Queimadas, Cuité, Boa Vista, and Areia, in the state of Paraíba, Brazil, were used in this study. Water content, thousand-seed weight, and biometric characteristics (length, width, and thickness) were determined in the seeds from each location. The water content ranged from 3.11 to 6.84%, while the thousand-seed weight was higher in mother plants grown in Sumé and Cuité. Seed length ranged from 9.00 to 16.84 mm, being higher in mother plants grown in Juru. Seed thickness and width ranged from 5 to 12.99 mm and were larger in mother plants from Cuité. Temperature, humidity, solar radiation, wind, and precipitation caused variations in the length, width, and thickness of E. velutina seeds, with higher means observed in mother plants grown in Cuité.

ABSTRACT Intensification of the eutrophication process in surface water leads to an increase in the intensity and frequency of cyanobacterial blooms, compromising the availability of drinking water. Therefore, the aim of this study was to investigate the spatio-temporal dynamics of cyanobacteria and identify the most important nutrients for such dynamics in a semiarid artificial lake, the Orós reservoir, in north-eastern Brazil. Seventy-seven water samples were collected in 11 campaigns (six during the dry season and five during the rainy season) from seven points. The attributes under investigation were the Secchi transparency, turbidity, pH, apparent colour, electrical conductivity, total solids, total phosphorus, soluble orthophosphate content, total Kjeldahl nitrogen, ammonia content, nitrate content, and cyanobacteria dynamics, resulting in a total of 924 samples (number of campaigns × number of points × number of attributes). Principal component analysis and cluster analysis were used to investigate the significance and determinant attributes of the spatio-temporal dynamics of cyanobacteria. Of the 17 species of cyanobacteria identified, 10 accounted for 72.47% of the total accumulated variance. During the rainy season, four homogeneous groups of cyanobacteria formed, whereas during the dry season, only three groups formed. The greatest concentrations occurred during the dry season, notably for Aphanocapsa spp., Cylindrospermopsis sp., and Geitlerinema sp., which are potentially toxic and show a greater affinity to the physical attributes of water. Climate seasonality was decisive in the spatio-temporal dynamics of cyanobacteria, and high transparency values limited excessive proliferation of the dominant species.