ABSTRACT The biological control, thinking about the integrated management, has been inserted with other management techniques to disease control, such as soybean anthracnose. The aims of this work were to verify the action of Trichoderma and Bacillus isolates in the induction of soybean resistance mechanisms to anthracnose as a function of seed treatment. The statistical design was entirely randomised, in a 5 x 2 (agent species x sampling times) factorial scheme with five replicates. Soybean seeds were treated with Bacillus amyloliquefaciens BV03, B. subtilis BV02, Trichoderma asperellum BV10, Carbendazim + Thiram and distilled water (control). Seven days after seedling emergence, 2 μL of 1 x 10−4 Colletotrichum truncatum spores were inoculated on the cotyledons. Catalase (CAT), peroxidase (POX), phenylalanine ammonia lyase (PAL) and glyceollin (GLY) activities before and after pathogen inoculation, as well as the diameter of the anthracnose lesion on the cotyledons, were evaluated. Data were submitted to analysis of variance and, when significant, the mean values were compared by Fisher’s test (p < 0.05). The treatments did not influence the first sampling time before inoculation. Trichoderma asperellum BV10 increased POX and PAL activities up to 173%, while B. amyloliquefaciens BV03 increased POX activity. Glyceollin was not influenced by the treatments. The T. asperellum BV10 reduces the diameter of the anthracnose lesion by up to 61%. Thus, T. asperellum BV10 has the potential to control soybean anthracnose, improved the response defense against C. truncatum, when performed on seed treatment.

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 The objective of this study was to evaluate the assimilated contents of mineral elements, yield characteristics and fruit quality of ‘Goldex’ yellow melon fertigated with different doses of nitrogen (N) and potassium (K) in two years of cultivation in the region of Apodi Plateau-CE. The design was randomized blocks in a 4x3 factorial scheme with four N doses (0%, 50%, 100%, 150% of the recommended dose) and three K doses (0%, 100%, 150% of the recommended dose). In the shoots of the melon plant, the highest levels of N (N Fert.) and K (K Fert.) fertilization promoted an increase in the assimilated N content up to 48 DAT and a reduction in the assimilated K content at the end of the cycle (62 DAT). The maximum shoot dry mass production was 3.23 t ha−1 with a fertilization of 150 and 100 kg ha−1 of N and K, respectively. The average marketable fruit yield obtained in the two years of cultivation was 34.68 t ha−1, reaching a maximum value of 40.28 t ha−1 under 150 kg ha−1 N and K fertilization. Total soluble solids increased as a function of the increase in N Fert. and K Fert., with a maximum value of 8.07 °Brix. The models indicated that the K Fert. factor was decisive in the increase of this variable. In future studies it is necessary to increase the concentrations of the two factors in order to optimize the maximum viability of yield and °Brix.

ABSTRACT Specific cultivars for production of green corn, more productive and adapted to the conditions of each region, combined with adequate population density, can increase the yield of the crop. This work aimed to identify, under different plant densities, the cultivars with agronomic characteristics for the production of green corn. The experiment was conducted from March to June 2018, in the experimental area of the Technical College of Teresina, at the Federal University of Piauí. The treatments were distributed in a randomized block design, in a factorial scheme, with three plant densities (40,000, 50,000 and 60,000 plants ha−1) and two corn cultivars (AG 1051 and BRS 3046). The variables evaluated were the diameter and length of the commercial green ear, the yield, the percentage of commercial green ear and the length of the period between the emergence (VE) and the flowering stage (VT) of the cultivars in relation to the accumulated number of degree-days (ADD). In terms of cycle (period between VE and VT), the hybrid AG 1051 was later, with 47 days after emergence (DAE) and 823.23 ADD, than the BRS 3046 (44 DAE and 773.32 ADD); however, there was an acceleration of the period of vegetative development in the hybrids, which ranged from 43 (773.32 ADD) to 47 (828.23 ADD) days, respectively, so that there was male flowering. With the increase in densities, there was decrease in the values of production. The highest yield of commercial ears (15.45 Mg ha-1) was obtained at a density of 50,000 plants ha−1.

ABSTRACT The aim of this paper was to study nectar in male and female flowers of pumpkin (Cucurbita moschata Duch) accessions, aiming at evaluating the species potential as a melliferous plant. Two experiments were conducted in an experimental area of the State University of Bahia, at the Department of Technology and Social Sciences, in Juazeiro-BA, in the period from January to December 2017. Nectar volume, soluble solids, and pH were evaluated in the two floral types using 32 accessions and Tetsukabuto hybrid, which was used as check. Using a sample of accessions, the types of sugar present in the nectar were studied. Male flowers did not have significant differences in nectar traits; however, there was significant variation in female flowers in the first experiment and in both floral types in the second experiment. In male flowers in both experiments, the maximum volume of nectar was 310 μL and in female flowers it was 803 μL. The sugar concentration was around 24 °Brix. Sucrose was similar in both floral types and was higher than glucose and fructose contents, showing mean values of 1,306.13, 357.14 and 351.88 g.mL−1, respectively. Obtaining progeny with contrasting characters in the accessions will be important for species improvement. These results indicate that pumpkin might be considered as a melliferous plant with great potential.

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 Light soils are more susceptible to degradation and need to be exploited in a conservational manner, thus avoiding rapid degradation. The objective of this study was to evaluate the physical-hydraulic properties of an Ultisol under no-tillage and crop-livestock integration in the Cerrado of eastern Maranhão state, Brazil. The evaluated managements were one area under no-tillage system for fourteen years (soybean/ millet) and three areas with different histories of adoption of the crop-livestock integration (CLI) system under no-tillage (soybean/millet), with the difference being: times of entry with CLI (2, 4 and 8 years), as well as a native Cerrado area, considered a control. Soil collection was carried out in June 2018 at depths of 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.50 m. Disturbed and undisturbed samples were collected to determine the following variables: bulk density, porosity, resistance to penetration, retention curve and available water capacity. Data were subjected to the calculation of means and confidence intervals (95%). The area with a recent history of crop-livestock integration showed better density, porosity, resistance to penetration, water storage capacity and available water. No-tillage for fourteen years leads to high resistance to penetration, less porosity and low water storage capacity. The integrated system (CLI) improves the quality of the physical- hydraulic properties and the values found are similar to those observed in an area under native vegetation.

ABSTRACT Mango (Mangifera indica L.) is a tropical fruit of great importance in the world. However, fruit postharvest losses are caused by anthracnose, a disease caused mainly by phytopathogenic fungi from the Colletotrichum genus. Thus, this work aimed to study morphology, genetic similarity, and pathogenicity of Colletotrichum spp. isolates from mango in Rio Grande do Norte state, Brazil. Morphological evaluation of 28 isolates, based on colony color, size of conidia and appressoria, and growth rate, showed that the isolates belong to the C. gloeosporioides species. It was later confirmed with species-specific oligonucleotides. Also, combined evaluation with RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter Simple Sequence Repeats) showed a genetic similarity of 0.23 between Isolates 12 and 21, and 0.71 between Isolates 2 and 4, an indication of high variability among isolates, with dissimilarity over 75%. Moreover, the dendrogram generated by the UPGMA method indicated that the isolates were arranged in eight groups, which did not correlate with the collection site. Based on pathogenicity, although most isolates showed low virulence for Tommy Atkins cultivar, some of them proved to be highly aggressive (Isolates 9, 15, 20, 21, 24, 26, and 27). Also, pathogenicity did not correlate with clusters. In conclusion, the results revealed high genetic and pathogenic variability in C. gloeosporioides isolated from mango cultivars in one of the main exporting regions in Brazil.