No abstract

Nezara viridula (L.) (Hemiptera: Pentatomidae) is a cosmopolitan insect that causes economic damages to several cultures, in particular soybeans (Glycine max [L.] Merr.) Among the techniques that involve Integrated Pest Management, the resistance of plants is pointed as a tool of great value and can contribute to the reduction of populations of insects. The feeding preferences of adults of southern green stink bug (N. viridula), and the attractiveness of soybean genotypes were evaluated under laboratory conditions to detect the most resistant material against attack from this insect. A choice test, using mature grains and green pods of the genotypes was carried out, in which the number of individuals attracted in different periods was counted. Feeding preference was evaluated in the choice tests using green pods and the number of pricks and the average time spent feeding by pricks were evaluated. In addition, texture and trichome density in the green pods were evaluated. The mature grains of 'TMG 117RR' and 'TMG 121RR' were less attractive to the adults of N. viridula. Regarding the green pods, 'IAC 17' and PI 227687 were less attractive; 'IAC 17' and 'IAC PL1' were less consumed, indicating the feeding non-preference as a resistance mechanism. 'IAC 17', 'TMG-117RR' and PI 227687 presented high levels of trichome density, and in 'IAC 17' this morphological characteristic was considered to be the main resistance factor against N. viridula. These results may be useful for breeding programs that focus on the resistance of soybeans to insects.

This study aimed to evaluate the effects of nitrogen availability in fertigation and rainfed management, as well as their interactions with the incidence of and damage caused by D. saccharalis and red rot in sugarcane. The experiment consisted of four treatments (0 and 150 kg ha -1 of N-fertilizer with irrigation; 0 and 150 kg ha -1 of N-fertilizer in rainfed management) in a randomized complete block design with four replications. The evaluated parameters were the number of holes and internodes with red rot per meter of cultivation, stalk yield and sugar content. In the laboratory (T = 25 ± 2 °C; R.H. = 70 ± 10%: 12:12-L:D), we evaluated the attractiveness and consumption of fragments of stalks from the different treatments for fourth instar larvae through choice and no-choice tests in a randomized complete block design with ten replications. Nitrogen fertilization via irrigation has favorable effects on borer-rot complex and leads to higher gains in stalk and sugar yields when compared to rainfed management. The increments of stalk and sugar yields due to nitrogen fertilization compensates for the increase in borer-rot complex infestation. In laboratory tests, D. saccharalis larvae were similarly attracted to all treatments regardless of the doses of N-fertilizer or the water regimes evaluated. However, fragments of sugarcane stalks produced with nitrogen fertilization were consumed more by D. saccharalis in both water regimes.

Interactive keys are tools that aid research and technical work since identification of organisms has become increasingly present in the scientific and academic context. An interactive key was developed with the software Lucid v. 3.3 for the identification of eleven fungal species associated with onion, carrot, pepper and tomato seeds. It was based on a matrix composed of six features: crop, conidium, conidiophore, color of long conidiophore, color of mycelium and presence of setae, besides 21 character states. In addition, descriptions, illustrations and high-resolution photographs of the morphological characters and states were made available to aid in the correct identification of fungal species. Validation of the interactive key was performed by distinct groups of volunteers: (i) graduate students with prior knowledge and using the interactive key; (ii) undergraduate students with little prior knowledge and using the interactive key, and (iii) undergraduate students with little prior knowledge and using the conventional identification system such as the printed manuals used in seed pathology laboratories. We analyzed the time spent by each volunteer to evaluate 25 seeds infected with the fungal species in the key, as well as the percentage of success and the difficulty level for each participant. The high percentage of correct answers with the use of the interactive key and the ease of use by the volunteers confirmed its efficiency because there was an increase in the identification accuracy when compared to the conventional system. Furthermore, the rate of success and the difficulty level presented low variability within groups (i) and (ii). These results are a consequence of the interaction of the user with characteristics of the developed tool, such as high-resolution photographs, which faithfully reproduce the fungal characteristics observed in the seeds under a stereomicroscope. Thus, the interactive key presented here can aid in teaching, institutional and commercial research, inspection and certification of seeds, making diagnosis safer and more accurate. The key is available for free at https://keys.lucidcentral.org/keys/v3/seed_fungi/.

A dessecação química é uma das formas adotadas por alguns produtores para minimizar as perdas de qualidade das sementes no campo e antecipar a colheita. Nesse sentido, o estudo objetivou avaliar a qualidade de sementes de soja em estádio R7, provenientes de campos dessecados com glufosinato-sal de amônio e paraquat. Para tanto, três cultivares de soja, ‘NA 5909RG’, ‘NS 6823 RR’ e ‘NS 6229 RR’ foram dessecados com paraquat, glifosinato-sal de amônio e secas naturalmente a campo. As sementes oriundas destes campos foram avaliadas quanto à germinação, através de testes em rolo de papel, e vigor pelo teste de tetrazólio após 5 meses de armazenamento. Avaliou-se também o comprimento de plântulas e raízes. O experimento foi realizado sob delineamento de blocos ao acaso com cinco repetições por tratamento. As médias foram analisadas pelo teste de Tukey a 5% de probabilidade num esquema fatorial 3x3. A interação entre os tratamentos foi significativa para a germinação, revelando que paraquat aumentou a qualidade fisiológica das sementes, além de favorecer o desenvolvimento radicular da cultivar ‘NA 5909 RG’. Em relação ao comprimento de plântula, também houve diferença significativa entre ‘NA 5909 RG’ e ‘NS 6823 RR’ quando dessecados com paraquat.