RESUMO -A resistência induzida é um método alternativo de controle de doenças. Entretanto, há poucos estudos relacionando o uso destes produtos e outros métodos alternativos à produtividade das plantas e às características físicas e químicas dos frutos. Objetivou-se avaliar a severidade de doenças, as características físicas e químicas de frutos e a produtividade de plantas tratadas com produtos alternativos e fertilizantes foliares. Plantas de maracujazeiro BRS Gigante Amarelo clonadas, em campo, foram submetidas, por um ano, a pulverizações quinzenais com: água (testemunha), Cuprozeb ® (fungicida-padrão), acibenzolar-Smetil -ASM, Agro-mos ® , fosfito de potássio, fosetyl-Al, gesso agrícola e CPAC-GE (produto em teste). O delineamento foi o em blocos casualizados, com quatro repetições e 20 frutos por repetição. Para o estudo da produtividade, utilizaram-se quatro repetições e seis plantas úteis por parcela. As colheitas ocorreram de novembro/2008 a abril/2009. As severidades foram avaliadas com escala de notas. Houve redução da severidade da virose, verrugose e bacteriose em todos os tratamentos, com exceção do Cuprozeb ® para virose. Não foi observada redução da antracnose. Frutos com maior massa fresca foram obtidos com aplicações de gesso agrícola (236,83 g), CPAC-GE (234,10 g), fosetyl-Al (233,79 g), fosfito de potássio (230,64 g) e Agromos ® (221,15 g). Os mesmos resultados foram observados para diâmetro transversal e massa de polpa. Não houve diferenças significativas entre tratamentos para diâmetro longitudinal e espessura de casca. Quanto às características químicas dos frutos, com exceção do Cuprozeb ® , que não diferiu significativamente da testemunha, todos os produtos proporcionaram incremento no teor de sólidos solúveis. Maior acidez titulável foi obtida com Cuprozeb ® , gesso agrícola, Agro-mos ® , fosetyl-Al e ASM. Não foi constatada alteração no pH dos frutos. Em relação à produtividade, maiores quantidades de frutos por planta foram obtidas com fosfito de potássio (162,38 frutos), seguido pelo gesso agrícola (111,13 frutos) e CPAC-GE (102,50 frutos). Maiores produtividades (kg/ha), considerando 1.600 plantas/ha, foram alcançadas com fosfito de potássio (40,19 t/ha), seguido pelo gesso agrícola (30,48 t/ha) e CPAC-GE (29,04 t/ha). Termos para indexação: maracujazeiro-azedo, controle alternativo, resistência sistêmica adquirida, indução de resistência. AGRONOMIC PERFORMANCE OF PASSION FRUIT PLANTS TREATED WITH ALTERNATIVE PRODUCTS AND FOLIAR FERTILIZERSABSTRACT -Induced resistance is an alternative method to control of plants diseases. However, there are few studies relating the effect of these products and methods to the plants yield, and to the physical and chemical fruit characteristics. This study was carried out to evaluate diseases severity, fruits physical and chemical characteristics, and yield of passion fruits plants treated with alternative products and foliar fertilizers. Cloned plants of passion fruit cultivar 'BRS Gigante Amarelo' were sprayed at each fifteen days, during one year ...
Nitrogen fertilization is an important step for watermelon (Citrullus lanatus) production due to its influence over yield, fruit quality, and disease severity. Currently, the gummy stem blight (Didymella bryoniae) and the downy mildew (Pseudoperonospora cubensis) can be taken as the most important watermelon diseases, since they impose severe impairment to the crop. Furthermore, studies focusing on plant responses to nitrogen fertilization regarding fruit yield and quality, and disease resistance are rare. Hence, the present study aimed at evaluating the effect of nitrogen doses on fruit yield and quality, and on disease prevalence in watermelon. Two experiments were carried out at the Universidade Federal de Tocantins, employing sprinkler irrigation, in an area previously used to grow watermelon. The experimental design was blocks at random, with five treatments (N doses, applied twice as side-dressing, in kg ha-1, as follows: T1= control treatment without N, T2= 20, T3= 40, T4= 80, and T5= 120), and four replications. Urea (45% N) was used as the N source. In the first assay, the highest fruit yield and average weight were observed when 40 kg ha-1 of N were applied. The highest severity of the gummy stem blight was observed when the highest nitrogen doses were applied (80 and 120 kg ha-1). In the second assay, the highest severity levels of the gummy stem blight, as well as of mildew, were observed again when N doses were the highest (80 and 120 kg ha-1). The lowest severity levels for both diseases were observed in the control treatment.
; IGNÁCIO M. 2009. Reaction of melon genotypes to the gummy stem blight and the downy mildew. Horticultura Brasileira 27: 160-165.
ABSTRACT. The intensity of rice diseases in regions with poor levels of silicates (Si) in the soil, together with high control costs, can make the cultivation of rice unfeasible. Surprisingly, there are scarce research data available regarding the influence of Si on rice diseases in tropical lowland regions. Therefore, the aim of this study is to determine the effect of three silicon sources on rice yield and disease management. Three experiments were carried out from December 2005 to April 2006 at an experimental field area located in Formoso do Araguaia, Tocantins state, Brazil. Each experiment consisted of one silicon source (powder, granular or liquid) and the treatments consisted of six Si doses. All the treatments were performed in a completely randomized block design. The data presented in this study provide evidence that Si applications in Si-deficient soils of lowland regions, depending on the application source, dose and disease intensity, can decrease the severity of brown spot and the incidence of panicle blast. Calcium silicate effectively reduced the brown spot and the panicle blast, which resulted in an increased rice yield. In contrast, Ca and Mg silicate and potassium silicate did not show an efficient control of rice diseases nor an increase in productivity. RESUMO. Efeito de fontes de silício sobre as doenças e produtividade do arroz no Estado do Tocantins, Brasil. A intensidade de doenças do arroz em regiões com solos pobres em silício, aliada aos altos custos de controle, podem inviabilizar economicamente o cultivo do arroz. Por existir poucas pesquisas avaliando a influência do silício nas doenças do arroz em regiões tropicais de terras baixas, esse estudo objetivou avaliar o efeito de três fontes de silício na produção e manejo de doenças do arroz. Três experimentos foram realizados entre dezembro de 2005 e abril de 2006, em um campo experimental localizado em Formoso do Araguaia, Estado do Tocantins, Brasil. Cada experimento consistiu da avaliação de um fator (fonte de silício em pó, granular ou líquido), conduzido em delineamento experimental de blocos inteiramente casualizados com seis níveis (doses de silício). Os resultados obtidos mostram que a aplicação de silício em solos deficientes desse elemento, em regiões de terras baixas, promove redução da severidade da mancha parda e a incidência da brusone das panículas, dependendo da fonte de silício, dose e pressão da doença. Silicato de Ca reduziu efetivamente a mancha parda e a brusone, resultando em aumento da produtividade. Entretanto, silicato de Ca e Mg e o silicato de potássio não mostraram eficiência no controle das doenças ou aumento da produtividade. Palavras-chave:Oryza sativa, Bipolaris oryzae, Magnaporthe oryzae, silicato.
The objectives were to study the behavior of fifteen pre-commercial upland maize hybrids, analyze their agronomic performance regarding grain yield, and evaluate productivity components, as well as morpho-agronomic characteristics, in the Midwest Region of Brazil. Two experiments were conducted in the municipalities of Formosa-GO and Planaltina-DF, 2016/17 crop year. Both consisted of five pre-commercial maize hybrid platforms (HPA252, HPB262, HPB621, HPB646, and HPD354). Each platform consisted of three different versions: conventional, transgenic with a Bt gene that expresses the protein Cry1F, and transgenic with two Bt genes that express the proteins Cry1F and Cry1AB. The experiment was randomized blocks with four replications. The experimental plot was four lines five meters long considering the two central lines as useful. The lines were spaced 0.75 meters apart, and the final density was five plants per linear meter. To estimate grain yield, the plots were harvested, and the weight was extrapolated to kg.ha-1. The moisture was standardized at 14%. Data were submitted to analysis of variance, and the means were compared by Tukey test at 5% probability using the Sisvar software. Grain yield between treatments ranged from 8,381 to 12,908 kg.ha-1, and the average yield was 11,234 kg.ha-1. The parameters evaluated were divided into two groups. The first group contained parameters determining grain yield: grain depth, thousand grains weight, number of rows of grains, number of grains per row, and grain yield. The second group contained morpho-agronomic parameters that directly interfere with resistance to lodging and plant breaking: plant height, ear insertion height, and mean stem diameter. There was no direct effect of the transgenes on the evaluated hybrids since the classification of productivity was not divided into conventional and transgenic classes. It is suggested that the HPA252YH, HP621H and HP646H versions be discarded because grain yield performance was unsatisfactory compared to their respective conventional and transgenic counterparts. The parameters GD and W1000 are more effective for grain yield estimation than NR and NG. It was observed for HP621H that, in addition to a lower grain yield, there was a significant reduction in stem diameter, indicating a possible reduction in lodging tolerance and/or plant breaking when exposed to adverse climatic conditions such as windstorms. For the HPD354H version, the release of the transgenic counterpart HPD354YH is preferentially indicated since the H version had a significant reduction in stem diameter and a possible greater tolerance to lodging and/or plant breaking under the same conditions.
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