ABSTRACT The Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a worldwide pest of Brassicaceae. Resistance has evolved against various insecticides including chlorfenapyr one of the most recently registered molecules to control this pest. The failure of chlorfenapyr to control this pest could be related to resistance in P. xylostella in the state of Pernambuco (Brazil), but there is currently no information on its heritability. Here, we estimated the heritability of resistance of P. xylostella to chlorfenapyr and the number of genes involved in the resistance in a field-derived population (PxClf-SEL). A field population was selected in the laboratory with increasing doses of chlorfenapyr (for five generations), and the LC50s were estimated for every generation using the leaf dip bioassay. The selection increased resistance to chlorfenapyr in the PxClf-SEL as the LC50 shifted from 27.6 (F1) to 256.5 (F5) mg chlorfenapyr/L. As a result, the resistance ratio (RR) increased from 33-fold (F1) to 310-fold (F5). The heritability of resistance of P. xylostella to chlorfenapyr was 0.90 (h2), and the number of generations needed for a 10-fold increase in the resistance to chlorfenapyr was 5.20 (G). Other methods have shown different numbers of genes (0.64 and 1.88) involved in resistance of P. xylostella to chlorfenapyr. There was sufficient variation regarding resistance in the field population to account for a high realized heritability influenced mainly by additive genetic factors. Therefore, there is a high risk of chlorfenapyr resistance in the field. | RESUMO A Plutella xylostella (L.) (Lepidoptera: Plutellidae) é uma praga mundial de Brassicaceae. A resistência tem evoluído para vários inseticidas incluindo clorfenapir, uma das moléculas registradas recentemente para o controle desta praga. As falhas de clorfenapir para controlar esta praga podem ser relacionadas com a resistência em P. xylostella no Estado de Pernambuco (Brasil), mas atualmente não há informações sobre sua herdabilidade. Aqui, foi estimada a herdabilidade da resistência de P. xylostella para clorfenapir e o número de genes envolvidos na resistência em uma população derivada do campo (PxClf-SEL). A população de campo foi selecionada no laboratório com doses crescentes de clorfenapir (por cinco gerações) e as CL50s foram estimadas para todas as gerações usando bioensaio de imersão de folha. A seleção aumentou a resistência para clorfenapir na PxClf-SEL, como também deslocou a CL50 de 27,60 (F1) para 256,50 (F5) mg de clorfenapir/L. Como resultado, a razão de resistência (RR) aumentou de 33 (F1) para 310 vezes (F5). A herdabilidade da resistência de P. xylostella para clorfenapir foi 0,90 (h2) e o número de gerações necessário para aumentar em 10 vezes a resistência foi 5,20 (G). Outros métodos tem mostrado diferente número de genes (0,64 e 1,88) envolvidos na resistência de P. xylostella para clorfenapir. Houve variação suficiente na população de campo em relação à resistência para justificar a alta herdabilidade, influenciada principalmente por fatores genéticos aditivos. Portanto, existe um alto risco de resistência no campo.

RESUMO O raleio consiste na retirada do excesso de frutos e tem como objetivo aumentar o tamanho de frutos comercializáveis, evitar a quebra de ramos, reduzir os custos da colheita e promover um equilíbrio entre a fase vegetativa e a reprodutiva da planta. Além disso, este procedimento pode promover a melhora de coloração, aumento do teor de sólidos solúveis e manter o vigor da planta. Este trabalho teve como objetivo avaliar os efeitos do raleio de frutos em cinco variedades de lichieira (Bengal, Americana, Mauritius, Sweft Cliff e WB4), para as condições do município de Jaboticabal - São Paulo. O delineamento experimental foi inteiramente casualizado (DIC), com 5 tratamentos e 7 repetições, sendo três plantas por repetição. Os tratamentos utilizados foram as intensidades de raleio caracterizadas pelo número de frutos deixados nas panículas do ramo terminal, sendo T1: 3 frutos/ramo; T2: 6 frutos/ramo; T3: 9 frutos/ramo; T4: 12 frutos/ramo; T5: sem raleio (controle). As avaliações foram por meio da colorimetria dos frutos maduros, análises físicas e químicas para cada uma das variedades estudadas. Os tratamentos influenciaram a resposta das variedades em relação às variáveis analisadas. A “Mauritius” apresenta características físicas e químicas interessantes, atendendo as exigências do mercado consumidor. | ABSTRACT 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.

The aim of this study was to report the occurrence of Xanthopastis timais (Cramer, 1780) (Lepidoptera: Noctuidae) in amaryllis ( Hippeastrum hybridum Hort ., Amaryllidaceae), as well as estimating lethal concentrations (LC 50 and LC 99 ) of soursop seed extract, Annona muricata L. (Annonaceae), against its larvae. The experiment was carried out at the Laboratory of Entomology of the Research Center for Agricultural Sciences, Federal University of Alagoas, in Rio Largo - AL, Brazil . First, we collected caterpillars from amaryllis plants that were reared until pupal and adult stages (parental generation). Next, part of the adults was used for species identification, and the rest were bred to produce next generation (F1), being after that applied in a laboratory bioassay. The lab trial was performed in a completely randomized design, with six treatments and five replications containing three second - instar caterpillars. These larvae were fed pieces of amaryllis leaf (4 x 4 cm), which were previously soaked in treatments for 30 seconds and, air - dried on absorbent papers for one hour. Each treatment consisted of one concentration of ethanol extract of soursop seeds (0.0, 1.0, 0.5, 0.25, 0.125 and 0.0625% w/ v) with distilled water and DMSO at 1% (v/ v), for solutions. We noted that the lethal concentrations LC 50 and LC 99 were 0.29% (w/ v) and 2.27% (w/ v), respectively. In view of our results, we can state that larval stage of X . timais were influenced by extract application in terms of survival, mortality, larvae weight and larval stage length. Besides of that, it was the first time this species was recorded in Alagoas state.

Mangabeira fruits are collected from native populations under anthropic pressure. It is therefore essential to obtain morphogenetic information to genetically improve populations, thereby preventing genetic erosion. This research was carried out in the state Amapá and aimed to verify the morphological dissimilarity between two populations, one composed of 36 native progenies and one of eight progenies from Paraiba, outlined in lattices with two replications and six plants per part. The evaluated characteristics were: agronomic value (VA), treetop circumference (CCP), plant height (ALP), estimated number of fruits per plant (NEF), fruit color (COF), average weight of 10 fruits (PMF), fruit diameter (DF), average pulp weight of ten fruits (PMP), average length of 10 fruits (CMF), average number of seeds of 10 fruits (NMS). Our results indicate that the phenotype was mainly determined by responses to environmental changes; in the correlations, inherent fruit characteristics (weight, size, and color) did not affect the VA, while biometric characters influenced VA values. Higher plants presented larger fruits and a larger diameter, bigger quantities, there is also apparent contrast, with a larger amount of smaller size; the populations are dissimilar, indicating the possibility of obtaining of diverging superior segregating.

The objective of this work was to evaluate the response of sugarcane genotypes to Meloidogyne javanica and Pratylenchus zeae . Sugarcane seedlings of the genotypes RB985944, RB987932, RB877935, RB855156, RB935744, RB996961, RB925345, RB935581 and RB966928 obtained from tissue cultures and maintained in pots with sterilized soil in a greenhouse were inoculated with 5,000 eggs + second - stage juveniles of M. javanica or 1,600 of P. zeae per plant, using six replicates per treatment. Tomato (Rutgers) and sorghum (BRS506) plants were used as control and proof of viability of the inoculum for the M. javanica and P. zeae , respectively. The number of root - knot in the plants inoculated with M. javanica , final nematode population and reproduction factor (RF) of both nematodes were evaluated at 120 days after inoculation. The averages of the different variables were compared by the Scott - Knott's clustering test at 5%. The nematodes M. javanica and P. zeae showed RF>1.00 in all sugarcane genotypes assessed, however, different levels of susceptibility were found. The lowest reproduction of the nematodes was found in the genotypes RB008347, RB877935, RB975944 and RB987932 ( M. javanica ) and RB987932 and RB966928 ( P. zeae ).

This study aimed to evaluate the quality of minimally - processed cassava treated with antioxidants and a starch - based edible coating. Cassava roots were washed, cooled, immersed in cold water, peeled and then cut. Root pieces were then immersed in a chloride solution, centrifuged, and subsequently immersed in either a starch suspension (3%), a solution containing antioxidants (3% citric acid and 3% ascorbic acid), or in both the coating and antioxidant solutions. Coated root pieces were dried at 18 ± 2°C for 1 hour, then packaged into polypropylene bags (150 g per pack) and kept at 5 ± 2°C for 15 days, and assessed every 3 days. A completely randomized design was used in a 4 × 6 factorial consisting of the treatment (control, coating, antioxidant, or coating and antioxidant) and the storage period (0, 3 6, 9, 12 or 15 days), with three replicates in each group. The pH, blackened area and peroxidase and polyphenol oxidase activities of the cassava was reduced in treatments containing antioxidants and the scores of visual analysis and phenolic content were higher. Therefore, treatment with antioxidants was effective for reducing browning in minimally - processed cassava, retaining the quality of cassava pieces stored for 15 days at 5 ± 2°C. The combination of antioxidants and the edible coating showed no improvement compared to treatment with antioxidants alone.

This study aimed to characterize and select silk blossom genotypes (Calotropis procera) with forage potential. Between April and July 2014, we cultivated 89 genotypes in plastic tubes arranged in a randomized block design with three replications; each experimental plot was composed of 8 plants. The following characteristics were evaluated: plant height (PH), stem diameter (SD), number of leaves (NL), total leaf area (TLA), leaf fresh mass (LFM), stem fresh mass (SFM), root fresh mass (RFM), leaf dry mass (LDM), stem dry mass (SDM), and root dry mass (RDM). Significant differences (p < 0.05) among genotypes were observed for all characteristics, except for NL at 45 and 60 days after sowing (DAS) and for RFM at 60 DAS. Broad-sense heritability estimates and genotype means had medium and high values for most characteristics. Genetic variability among C. procera genotypes was observed. High gain selection was found for the characteristics TLA, PH, SFM, LFM, SDM, and LDM as the genotypes 79, 65, 48, 12, 51, 35, 63, 25, 1, and 46 are suitable for future breeding works to improve forage production.

The development of technologies to increase stand establishment efficiency and seed vigor, as well as to maximize profits, is of fundamental importance for the sustainability of agriculture. Products based on humic substances, such as humic acids, have been recently used in Brazilian agriculture to produce seedlings with high vigor, which positively influences the establishment of the initial stand. Thus, this study aimed to evaluate the effect of treatment of corn seeds with a commercial humic acid-based product, Humykos® (18% of humic acid content), on germination and seedling vigor. The treatments consisted of six doses (0, 100, 200, 300, 400, and 500 mL 100 kg-1 seed) of Humykos®, and the treated seeds were analyzed for germination and vigor (first count, emergence, emergence speed index, length, and dry mass of shoots and roots). Our results show that humic acid promotes greater seedling growth and increased shoot dry mass in corn; in addition, it has a positive influence on the emergence speed index up to a dose 158 mL 100 kg-1 seeds.

The objective of this work was to evaluate seeds of cowpea, cultivar BRS Tumucumaque, subjected to different water stresses induced by polyethylene glycol (PEG-6000) and mannitol and different salt stresses induced by NaCl and CaCl2 solutions. The water and salt stresses was evaluated in laboratory using completely randomized experimental designs in 2x6 factorial arrangements, with six osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and two stress inducers for each experiment, with four replications of 50 seeds. The percentage of germination, germination speed index, root and shoot lengths and seedling fresh weight were evaluated at the tenth day (end of the evaluation period). The simulated water stress showed effects on the cowpea seed germination and seedling initial growth by decreasing the rates of the variables evaluated, which had greater effect in treatments with PEG-6000. The salt stress induced by NaCl showed greater effect on the variables evaluated than that induced by CaCl2, due to the sodium toxicity in the salt chemical composition.

The aim of the present study was to identify fungal pathogens associated with prickly pear rot and the main components of squamous rot on plantations in the semiarid region of the state of Paraíba, Brazil. Pathogens were identified morphologically. The determination of the main components of squamous rot intensity was based on the incidence and severity of the disease. Fifteen genera of fungi were associated with rot, including Scytalidium sp., which was found on all plantations. The analyses indicated that relative humidity and rainfall favored the intensity of rot more than temperature. At least three pathogens were found to be associated with a high incidence of rot in prickly pear species in the semiarid region of the state of Paraíba, Brazil, but Scytalidium sp. was the most widely distributed. Moreover, the disease caused by this fungus intensifies and progresses under conditions of high humidity at moderate temperatures.