RESUMO: Esse estudo avaliou a eficácia e as respostas espectrais de plantas de soja a quinze misturas de fungicidas utilizados no controle da ferrugem asiática da soja (FAS). A refletância do nível do dossel foi medida usando uma câmera multiespectral a bordo de um drone multirotor antes e duas horas após cada pulverização. A terceira aplicação de fungicidas melhorou o controle de FAS e aumentou a produtividade. Porém, três aplicações foliares consecutivas de fungicidas não afetaram a refletância de plantas de soja nos comprimentos de onda visível e infravermelho. Assim, drones podem ser uma estratégia viável para aquisição de dados independentemente da aplicação de fungicidas.

ABSTRACT: The study evaluated the efficacy and soybean spectral responses to fifteen foliar fungicide mixtures labeled to control Asian soybean rust. Canopy level reflectance was measured using a multispectral camera onboard a multirotor drone before and two hours after each spray. The third application of fungicides improved control of soybean rust and increased yield. Nevertheless, up to three consecutive foliar fungicides applications did not affect the reflectance of soybean plants at visible and infrared wavelengths. Thus, drones can be a viable strategy for data acquisition regardless of the application of the fungicides.

Resumo A fenologia é muito importante para o entendimento dos ciclos das plantas, a repetição de eventos biológicos e as causas desses ciclos em relação a fatores abióticos e bióticos. Diante disto, objetivou-se com este trabalho avaliar a época de ocorrência e intensidade das fases fenológicas vegetativas e reprodutivas e suas correlações com fatores externos e a influência da radiação fotossinteticamente ativa na biometria de frutos de Campomanesia adamantium (Cambess.) O. Berg. O estudo foi conduzido em fazenda localizada no município de Rio Verde-GO, Brasil. A caracterização da fenologia foi feita em dez indivíduos adultos. As observações fenologia das fases fenológicas vegetativas foram feitas mensalmente e os eventos fenológicos, reprodutivos, semanalmente. Foram utilizados dois métodos para o registro dos eventos fenológicos: o percentual de intensidade de Fournier e o índice de atividade. Foram feitas também avaliações do número total e diâmetros transversal e longitudinal dos frutos de dois ramos por planta com maior e menor incidência de radiação. Verificou-se atividade de folhas jovens e adultas em Campomanesia adamantium em quase todo o período de estudo, exceto nos meses de maio e agosto, para folhas jovens. A presença de brotos também foi bastante intensa durante o período. Observou-se um ciclo de fenofases de reprodução rápido e intenso entre os meses de outubro e janeiro para C. adamantium. A incidência da radiação interferiu na dimensão e produção dos frutos. Frutos desenvolvidos em ramos de sombra tiveram número reduzido e valores biométricos inferiores em relação àqueles que cresceram em ramos de sol.

Abstract Phenology is very important to the understanding of plant cycles, the repetition of biological events, and the causes of these cycles in relation abiotic and biotic factors. The aim of this to evaluate the time of occurrence and intensity of the vegetative and reproductive phenological phases, their correlations with external factors, and the influence of photosynthetically active radiation in the fruit Campomanesia adamantium (Cambess.) O. Berg. The study was conducted on a farm in the municipality of Rio Verde, Brazil. The phenological characterisation was performed using ten adult plants. Phenological observations of vegetative and reproductive phenological phases were made monthly and weekly, respectively. The total number and the transverse and longitudinal diameters of the fruit of two branches per plant, with higher and lower incidence of radiation, were also evaluated. The young and adult leaves in Campomanesia adamantium were active for almost the entire study period, except the young leaves were inactive in the months of May and August. The presence of sprouts was also very high during the study period. There was a phenophase cycle of rapid and intense play between October and January for C. adamantium. The incidence of radiation interfered with the size and production of the fruit. Fruits that developed in the shadow of branches were fewer and their biometric values lower than those who developed in sunlight.

ABSTRACT The objective of this study was to evaluate the responses of Raphanus sativus to the application of the herbicide tepraloxydim by analyzing photosynthetic and biometric characteristics of the plants. The experiment was conducted in a greenhouse and treatments were instituted when the plants had five expanded leaves. The herbicide tepraloxydim was applied at doses of 0, 75, 100, and 125 g of active ingredient per hectare (g a.i. ha-1). The herbicide dose of 125 g a.i. ha-1 led to a small decrease in the photosynthetic rate, water use efficiency, effective quantum yield of PSII, rate of electron transport, and the concentration of chloroplastidic pigments in the leaves of R. sativus. On the other hand, there was a small increase in CO2 concentration in the substomatal chamber. The number of branches, leaves, flowers, plant height and dry mass of the stem and flowers were reduced more prominently in response to herbicide doses than the photosynthetic characteristics. Therefore, treatment with tepraloxydim inhibits the growth and formation of the leaves, branches and flowers of R. sativus at the stage of development analyzed. However, doses of 75, and 100 g a.i. ha-1 neither compromise the photosynthetic apparatus nor the stability of cell membranes.

RESUMO A seca é o fator ambiental que mais prejudica a produtividade das culturas. Alguns produtos químicos têm sido utilizados na agricultura para mitigar os danos causados por esse estresse nas plantas. Portanto, examinamos se a pulverização dos compostos sulfato de zinco (ZS), fosfito de potássio (FP) e doador de sulfeto de hidrogênio (H2S) - hidrossulfeto de sódio (NaHS) - mitigam os efeitos deletérios do déficit hídrico em plantas de girassol, analisando características fisiológicas e biométricas. O experimento foi conduzido em casa de vegetação sob delineamento de blocos ao acaso com cinco repetições. Os tratamentos foram arranjados em esquema fatorial 4 x 2: [Fator A (aliviadores)] - pulverização de FP (0.5 L ha-1), ZS (3.2 kg ha-1), NaHS (1.2 g ha-1), e água; [Fator B (umidade do substrato, US)] - 100% (bem irrigado) e 30% (déficit hídrico, DH) da capacidade de campo. Nas condições de DH, os aliviadores levaram à manutenção de maiores valores de potencial hídrico (ΨW), menor teor de malonaldeído foliar (MDA) e aumento da atividade da enzima antioxidante peroxidase (POX), exceto para ZS. Entretanto, o potencial osmótico foliar, a concentração de prolina, as variáveis relacionadas às trocas gasosas, fluorescência da clorofila a e as características biométricas diferiram apenas em função do fator US. Os resultados de ΨW e MDA em plantas de girassol sob DH são indicativos da capacidade mitigadora do ZS, FP e H2S. Assim, a pulverização desses compostos em plantas de girassol mitiga os efeitos do DH, atuando especificamente em processos fisiológicos relacionados a respostas antioxidantes e na manutenção de água nos tecidos foliares.

ABSTRACT Drought is the most harmful environmental factor crop productivity. Some chemicals are used in agriculture to mitigate the damage from this stress on plants. Therefore, we examined whether the spraying of zinc sulfate (ZS), potassium phosphite (KPhi) and the hydrogen sulfide (H2S) donor sodium hydrosulfide (NaHS) would mitigate the deleterious effects of water deficit on sunflower plants by analyzing physiological and biometric characteristics. The experiment was carried out in a greenhouse using a randomized block design with five replications. The treatments were arranged in a 4 x 2 factorial scheme: [Factor A (Alleviators)] - spraying of KPhi (0.5 L ha-1), ZS (3.2 kg ha-1), NaHS (1.2 g ha-1), and water; [Factor B (substrate humidity, SH)] - 100% (well irrigated) and 30% (water deficit, WD) of field capacity. Under WD conditions, alleviators led to the maintenance of higher values of water potential (ΨW), a lower content of leaf malonaldehyde (MDA), and increased activity of the antioxidant enzyme peroxidase (POX), except for ZS. However, leaf osmotic potential, proline concentration, variables related to gas exchange and chlorophyll a fluorescence, and biometric characteristics differed only according to the SH factor. The results of ΨW and MDA for sunflower plants under WD are indicative of the mitigating capacity of ZS, KPhi, and H2S. Thus, the spraying of these compounds on sunflower plants mitigates the effects of WD, acting specifically in physiological processes related to antioxidant responses and in the maintenance of water in leaf tissues.

ABSTRACT The production of quality seedlings coupled with the correct choice of fertilizer doses/sources and the container type are essential in the planting of forest species. Thus, the objective of this study was to evaluate the relationship between morphological, physiological and anatomical characteristics and container volume with different fertilizations on Acrocarpus fraxinifolius seeds seedlings. The experiment was conducted in a 2 x 8 factorial scheme (2 volumes of containers and 8 fertilizations), tested in polypropylene tubes of 50 and 110 cm³ and according to different fertilizations: control without fertilization; 4 increasing doses of Osmocote® Plus: 3, 5, 7, 9 kg.per.m³ of substrate, respectively; and 3 split mineral fertilizers with coverings. It was possible to note that the tube with the greatest volume of 110 cm³ presented the best results regarding the morphological characteristics, however, when analyzing the physiological variables it was clear that the 50 cm³ tubes present similar results to those of larger volume when well fertilized. Split fertilization presented better results than slow-release fertilization, and 50 cm³ tubes were more sensitive to fertilization due to the lower volume. Thus, the use of 50 cm³ tubes with fertilization is recommended for producing A. fraxinifolius seedlings, due to presenting physiological quality and economy of inputs in nursery production, transportation and planting.

ABSTRACT The maturing of drift used in the culture of sugar cane can have harmful effects on other crops grown in the vicinity of sugar cane plantations. Among these, sunflower grown in the off-season can have its growth and productivity affected by drift. The objective of this research was to evaluate whether the drift of trinexapac-ethyl and glyphosate promotes changes in the photosynthetic metabolism of sunflower plants. Two trials were carried out to evaluate the effects of these products on gas exchange, chlorophyll fluorescence, chloroplastid pigments, membrane permeability, sugar content, as well as shikimic acid and malondialdehyde concentration in the treated plants. In the first experiment, we tested glyphosate in doses of 0 (control); 3.6; 7.2; 14.4; 28.8; and 86.4 g a.e.∙ha−1 and in the second, trinexapac-ethyl at doses of 0 (control) 3.12; 6.25; 12.50; 25, and 75 g a.i.∙ha−1. The growth regulator trinexapac-ethyl did not change the photosynthetic metabolism of plants. However, glyphosate caused damage to the photosynthetic apparatus and a reduction in the carbohydrate concentration and chloroplastid pigments, with casual damage to cell membranes; these effect were more intense at increased doses. The effects of glyphosate were evidenced by the increased concentration of shikimic acid, derived from its mechanism of action. Concludes that, the photosynthetic metabolism of sunflower plants is not affected by the growth regulator trinexapac-ethyl, unlike to the evident effects after application of glyphosate.