No-till system and high plant density are common practices in soybean crops of the Brazilian southern region, which has increased the incidence of stem and pod diseases. The objective of this study was to evaluate the effect of plant populations on stem blight incidence. The experiments were conducted in Muitos Capões Municipality, Rio Grande do Sul State, during the seasons 2006/07 and 2007/08, using cultivars BRS 255 RR and CD 213 RR. The evaluated populations had 12, 18, 24, 30 and 36 plants m-2, spaced 0.45 m between rows. The experimental plot units consisted of 5m width and 10m length, arranged in randomized blocks with four replicates. Stem blight incidence was quantified at phenological stages R5.1, R5.5, R6 and R7 and the collected data underwent regression analysis. Higher soybean plant densities caused a positive and significant increase on stem blight incidence in all four phenological stages for both cultivars and seasons. There was no significant difference for soybean grain yield according to the increase in plant population. Results indicated that soybean management preventing high plant densities can contribute to reduce stem blight incidence.
Macrophomina phaseolina is a soilborne pathogen with a wide range of hosts and its control through agricultural practices is difficult. The aim of this study was to quantify the severity of root rot (SRR) caused by M. phaseolina in common bean cultivars and its impact on yield components. The experiments were carried out under greenhouse conditions with the common bean cultivars ‘ANFC-9 Agro Norte’, ‘BRS Esteio’, ‘BRS Estilo’, ‘BRS Pérola’, ‘FTS Soberano’, ‘IPR Campos Gerais’, ‘IPR Tangará’, ‘IPR Tuiuiú’, ‘IPR Uirapurú’ and ‘TAA Dama’. Three isolates of M. phaseolina obtained from infected plants of common bean, soybeans and maize were inoculated in the common bean cultivars. In the phenological stage R9 of grain harvest maturity, the SRR and the yield components of root dry mass (RDM), number of pods per plant (NPP), number of grains per plant (NGP) and grain mass per plant (GMP) were assessed. All common bean cultivars were susceptible to M. phaseolina, showing a reduction in NPP, NGP and GMP. SPR was greater than 75%, regardless of the origin of isolates. Considering the average of cultivars, there was a significant decrease of 54.3% in RDM, compared to control treatments. The cultivars ‘IPR Tangará’, ‘ANFC-9 Agro Norte’, ‘BRS Esteio’, ‘BRS Pérola’ and ‘FTS Soberano’ had a decrease in at least one yield component, while a reduction occurred in all components for cultivar ‘IPR Tangará’. There was an average decrease in NPP, NGP and GMP of 7.9%, 7.6% and 7.2%; 13.4%, 12.8% and 6.7%; and 14.2%, 12.9% and 10.1%, considering the isolates obtained from beans, soybeans and maize, respectively.
Occurrence of rice seeds infected by Fusarium graminearum has shown the importance of identifying the most favorable phenological stage of panicles to grain infection. The experiments were conducted in two crop seasons under greenhouse conditions, using the rice hybrid INOV CL. The phenological stages during inoculation were complete booting, full heading and flowering. All plots were inoculated using two isolates of Fusarium graminearium species complex 15A (F. graminearium - 15-ADON) and FmNiv (F. meridionale - Nivalenol). Disease severity was estimated at weekly intervals and was used to calculate the area under the disease progress curve (AUDPC), while panicles were collected to determine the percentage of spotted grains and Fusarium incidence. Percentage of spotted grains and incidence of F. graminearum and F. meridionale were greater when inoculation was made during flowering stage, significantly differing from heading and booting stages. Rice flowering stage is more susceptible to infection by F. graminearum and F. meridionale, inducing higher disease severity and incidence of spotted grains, as well as presence of fungi in the grains. Flowering was the most susceptible stage in the two crop seasons for both isolates, and the complete booting stage presented the lowest values of AUDPC.
The state of Santa Catarina is the second-largest producer of rice seeds in Brazil. Research on phytopathogenicbacterias in this crop is scarce and the high frequency of panicle diseases leads to the hypothesis that seeds may be infected by bacteria. This research quantified the incidence of bacteria in the seeds, verified the bacteria viability during the storage period and characterized the associated bacteria. Seeds from the 2018/19 and 2019/20 seasons were analyzed. To check the incidence, the seeds were disinfected, plated on a nutrient agar + fungicide culture medium, and incubated for seven days at 27 °C. To assess viability, every 45 days, three cultivars stored in a processing unit were subjected to the same detection methodology. To characterize, prevalent colonies were isolated on semi-selective culture medium Pantoea genus-specific agar (PGSA), where the ones that showed growth were subjected to deoxyribonucleic acid (DNA) extraction and Polymerase Chain Reaction (PCR), DNA sequencing, and sequence comparison on GenBank. The hypersensitivity reaction (HR) in tobacco was performed using a bacterial suspension of each isolate. All seed samples had an average incidence of 83%. During storage, the seeds maintained stable bacterial viability, with an average incidence of 95% at the beginning of storage and 99% at the end of it. All isolates that grew in PGSA culture medium were identified by molecular characterization with 100% identity with two specimens of Pantoeaananatis and one of them induced RH in tobacco.
The aims of this study were to quantify the viability of Microdochium albescens in irrigated rice seeds stored during the time between harvests and to quantify its incidence in the seed structures. Samples of irrigated rice seeds of the cultivars SCS122 Miura and SCS121 CL were monthly collected and stored during the time between harvests 2018/19. Pathology analysis and viability quantification were performed in the laboratory. The location of the fungus in the seeds was determined by separating lemma, palea, endosperm and embryo, with subsequent disinfestation and sowing in culture medium. The fungus M. albescens showed 77.8% seed storage viability for nine months, considering the average of lots and cultivars. Average incidence was 48% in the lemma, 43.7% in the palea, 24.7% in the endosperm and 20.7% in the embryo. The fungus M. albescens remains viable in rice seeds between harvests, while mycelium is detected at a higher incidence in the external tissues of caryopsis.
As podridões de colmo do milho são responsáveis por significativas reduções em rendimento de grãos. O objetivo deste estudo foi avaliar a relação existente entre a incidência de podridões de colmo e o ciclo de seis híbridos de milho. O experimento foi conduzido a campo, semeados no mês de outubro nas safras 2012/2013 e 2013/2014 utilizando-se 70.000 sementes ha-1 dos híbridos comerciais P32R22 YHR e AG9045 VT PRO (superprecoces) e P30F53 Hx, DKB250 VT PRO2, AS1656 VT PRO2 e AG8025 VT PRO (precoces). O delineamento utilizado foi de blocos casualizados com quatro repetições avaliando-se, em cada parcela cinco metros lineares. A incidência de podridões foi determinada pela presença de descoloração e menor resistência do colmo. Espigas provenientes de plantas sadias e doentes foram trilhadas separadamente para determinação do dano percentual. Danos ocasionados por podridões de colmo, em função da severidade da doença podem ser variáveis em função dos híbridos, mesmo com características semelhantes de ciclo. Os fungos detectados nos colmos foram Stenocarpella sp., Colletotrichum graminicola, Fusarium graminearum e F. verticillioides. Todos os híbridos avaliados expressaram sintomas de podridão de colmo demonstrando não haver resistência, mas sim, apenas diferentes graus de suscetibilidade entre os materiais testados. O híbrido AG8025 VT PRO demonstrou ser o menos suscetível a podridões de colmo. Os híbridos superprecoces P32R22 YHR e AG9045 VT PRO apresentaram maior incidência do que híbridos de ciclos precoces, indicando que a maior precocidade está associada à maior suscetibilidade a podridões de colmo.
O objetivo deste trabalho foi avaliar a sobrevivência, a viabilidade e o controle do fungo Alternaria sp. em sementes de feijão carioca das cultivares BRS Estilo (lotes 07, 12, 201, 202, 203) ABSTRACTThe aim of this study was to evaluate survival, viability and control of the fungus Alternaria sp. in common bean seeds of cultivars BRS Estilo (lots 07,12, 201, 202, 203), BRS Tangará (lots 01, 02, 37, 46) and in black bean seeds of cultivars IPR Tuiuiu (lots 10 and 11), IPR Uirapuru (lots 07, 08, 12), totaling 14 samples. At every 45 days from May 2014 to the end of storage (November 2014), two hundred seeds per sample were disinfected and subjected to seed health test on potato-dextrose-agar culture medium + antibiotics. Bean seeds of cultivars BRS Estilo and IPR Tuiuiu, harvested in the 2015 crop season at Muitos Capões Municipality, were subjected to the test with fungicides for Alternaria Soldatelli, P.; Casa, R.T.; Lima, A.; Ribeiro, Y.C.K.; Martins, F.C. Survival, viability and control of Alternaria sp. in common bean seeds. Summa Phytopathologica, v.43, n.3, p.193-198, 2017. sp. control. The test was carried out by treating the seeds with fungicides and sowing them on potato-dextrose-agar culture medium + antibiotics, with 200 seeds per treatment. Data of Alternaria sp. incidence as a function of storage time were subjected to regression analysis. The fungus was detected in all cultivars, lots and samplings. There was a mean reduction in the incidence of Alternaria sp. cultivars as a function of time from 48.4% to 16.7%. At the end of the storage period, the fungus kept 34.5% mean viability for the average of cultivars. Fungicides with the active principle fluazinam, carboxin and fludioxonil provided greater control of Alternaria sp.
Grain quality is essential in the food industry, and it shows variations depending on crop management conditions in the field. The objective of this study was to quantify the effect of hybrids, sowing seasons, and topdressing nitrogen rates on the incidence of damaged grains and their correlation with pathogenic fungi. The experiment was conducted under field conditions in Atalanta, Santa Catarina, Brazil, in a split split-plot randomized block design consisting of the AG9025 PRO3 (super-early) and 30F53 VYH (early) hybrids, preferential (September 20) and late (December 5) sowing season, and nitrogen rates (0, 150, 300, and 450 kg ha -1 ). The percentage of normal, fermented, and burned grains, as well as the incidence
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