Although stalk and ear rot is a major disease affecting corn plants, little is known regarding the genetic variability of Stenocarpella maydis, its main causal agent. In this study, we evaluated inter-simple sequence repeat (ISSR) primers for analysis of genetic variability of the pathogen. For DNA analysis, six isolates of S. maydis were amplified using 42 ISSR primers. Polymorphic information content (PIC), marker index (MI), and resolving power (RP) were calculated for all primers. Of the 42 primers, 50 % showed high-quality amplification products. The average polymorphism was 90.4 %, and the average similarity among the isolates was 33 %.
Management with synthetic fungicides in the control of phytopathogens in viticulture can cause environmental pollution and contamination with residues in grape cluster. The objective of this study was to verify the effect of aqueous cinnamon extract on the in vitro and in vivo control of Plasmopara viticola on catalase activity on ‘Isabel Precoce’ vines. The treatments used were: aqueous cinnamon extract (ACE) at concentrations of 0.12; 0.25 and 0.50% plus 0.25% vegetable oil (VO); being the standard treatments VO (0.25%), Bordeaux mixture 1:1:100 (lime: copper sulfate: water) and water only. The germination tests of P. viticola sporangia were carried out in incubation periods of 4 and 24 hours of the pathogen in contact with the treatments. In addition, the area under the disease progress curve (AUDPC) and the activity of the catalase enzyme were estimated in plants grown in the greenhouse. The results indicated that the treatments with 0.12%, 0.25% and 0.5% ACE with VO reduced the germination of P. viticola. In relation to the AUDPC, the 0.25% dose of VO associated ACE reduced 65% and 67% in leaf discs and vines in the greenhouse, respectively. This fact is related to the induction of CAT activity provided by this dose in the periods of 2HBA, 2HAI and 4HAI. Thus, it can be said that the ACE associated with VO can be used to control the downy mildew of the ‘Isabel Precoce’ vine.
ResumoO uso de altas doses de adubação nitrogenada, associado à aplicação de redutores de crescimento, pode ser uma alternativa para que plantas de trigo consigam expressar potencial produtivo elevado sem a ocorrência de acamamento. Por este motivo, o objetivo deste trabalho foi avaliar o efeito do redutor de crescimento trinexapac-etil associado à adubação nitrogenada elevada e parcelada no rendimento e seus componentes em plantas de trigo da cultivar BRS 220. O delineamento experimental foi de blocos ao acaso com dois tratamentos e quatro repetições, compostos da aplicação de 110 kg de N ha -1 associados ou não a 0,4 g L -1 de trinexapac-etil. Foram avaliados rendimento e seus componentes, diâmetro de colmo, comprimento de entrenó, altura de planta e comprimento do colmo. As médias foram submetidas ao teste-t de Student no programa Systat 13 ® . A aplicação do redutor de crescimento contribuiu com um aumento significativo no rendimento e no diâmetro do colmo das plantas, além da redução da altura, comprimento do colmo e do entrenó, quando comparado com o tratamento sem a aplicação do produto.Palavras chave:Nitrogênio, redutor de crescimento, Triticum aestivum.
Trinexapac-ethyl effect associated with high and split fertilization on wheat productivity cultivar BRS 220
AbstractThe use of high nitrogen doses, associated with the application of growth reducers, can be an alternative to wheat plants express high productive potential without the occurrence of lodging. For this reason, the aim of this study was to evaluate the effect of trinexapac-ethyl growth reducer associated with high and split nitrogen fertilization on yield and its components in wheat cultivar BRS 220. The experimental design was randomized blocks with two treatment and four replications, compose with the application of 110 kg N ha -1 with or without 0,4 g L -1 of trinexapac-ethyl. It was evaluated yield and its components, stem diameter, length of internode, plant height and stem length and the averages were submitted to Student t-test using Systat 13 ® . The application of the growth retardant contributed to a significant increase in yield and stem diameter of the plants, besides the reduction of height and length of stem and internode, when compared to the treatment without product application.
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