Physiology and morphology of rice plants with silicon supplementation and Dietholate seed treatment under water deficit

Silicon is an enzyme stimulator that promotes signaling for the production of antioxidant, osmoprotective compounds and attenuates interference in photosynthesis in rice plants subjected to water deficit. The aim of this study was to evaluate the possible effects of silicon as a stress reliever in rice plants grown from seeds treated with dietholate under of water deficit conditions. The experimental design was fully randomized with three replicates, 144 experimental units consisting of pots containing 4.4 pounds soil, and a 3x2x2x4 factorial arrangement: three soil water conditions (50% and 100% of soil water retention capacity and water blade of 5.0 cm); two cultivars (IRGA 424 RI and Guri INTA CL); two sources of Si (sodium and potassium metasilicate); and four Si rates (0; 4.0; 8.0 and 16 g L-1). Silicon boosted stomatal density; induced an increase in the maximum photochemical efficiency of photosystem II (PSII) under both water deficit and optimal conditions, boosting photosynthesis; and increased effective quantum yield of PSII and levels of total dry mass. Thus, silicon attenuated the effects of water deficit in plants grown from seeds treated with dietholate

Anatomical changes in Urochloa Plantaginea and Urochloa Platyphylla under different soil moisture conditions

Urochloa plantaginea and Urochloa platyphylla are common weeds in the highland area. However, in recent years, they have been found in wetlands and poorly drained soils, but the biology and behavior of the species in these conditions are not known. Thus, the objective was to assess anatomical changes in plants of Urochloa plantaginea and Urochloa platyphylla grown under different soil moisture conditions, as well as the adaptive structures generated as a result of each environment. A completely randomized experimental design in the form of a 2x2 factorial design was used, with factor A being two species of Urochloa (U. plantaginea and U. platyphylla), and species B being three soil moisture conditions (50 and 100% FC and 5 cm water depth), with four repetitions. The assessments were performed by means of anatomical cuts, observing the number and diameter (micrometers - μm) of aerenchymas in stems, roots and leaves; total diameter and the central root cylinder (μm); diameter of the fistula medulla and cortex (μm) in stems; mesophyll thickness and leaf midrib (μm). It was found that, for the two species of Urochloa, the water depth condition induced an increase in the number and diameter of aerenchymas in roots and leaves and provided a larger diameter of the fistulous pith in stems. The diameter of the central cylinder and the thickness of the leaf mesophyll midrib were more compact at 50% FC, also, for both species. Therefore, the adaptive structures generated vary as a result of the field capacity of the soil

CONTROL OF Cyperus difformis BY ALS HERBICIDES AND AUXIN MIMICS

A ocorrência de biótipos de Cyperus difformis L. com característica de resistência à aplicação de herbicidas no setor da orizicultura é uma preocupação mundial. Nesse sentido, objetivou-se avaliar a eficiência do controle de C. difformis por herbicidas inibidores da acetolactato sintase (ALS) e mimetizador de auxina. O delineamento experimental foi inteiramente casualizado, com quatro repetições, totalizando 252 unidades experimentais compostas por vasos com 12 quilogramas de solo e os tratamentos arranjados em esquema fatorial 3x7x2x2: três herbicidas (dois inibidores da ALS pirazossulfurom-etílico e bispiribaque-sódico e um mimetizador de auxina triclopir-butotílico); sete doses dos herbicidas (0.0x, 0.5x, 1x, 2x, 4x, 8x e 16x a dose de registro); dois biótipos de C. difformis (Santa Rosa do Sul e Meleiro, Santa Catarina (SC)); e duas umidades de solo (100% saturado e lâmina d’água de 5,0 cm). O biótipo C. difformis de Meleiro-SC é 8x (320 g. i.a. ha-1) mais resistente a dose de registro do bispiribaque-sódico, já o biótipo de Santa Rosa do Sul-SC é mais sucetivel, reduzindo 50% da massa seca da parte aérea com 0.5x da dose de registro (20 g i.a. ha-1). O pirazossulfurom-etílico demostrou-se ineficiente na redução da massa seca da parte aérea em ambos os biótipos. Os biótipo C. difformis de Santa Rosa do Sul-SC e Meleiro-SC, nas duas condições de umidade do solo são suscetíveis ao triclopir-butotílico, reduzindo 50% da massa seca da parte aérea com 0.5x (166 g. i.a. ha-1) a dose de registro.The occurrence of Cyperus difformis L. biotypes with characteristics of resistance to herbicide application in the rice sector is a worldwide concern. In this sense, the objective was to evaluate the efficiency of the control of C. difformis by acetolactate synthase (ALS) inhibitors and auxin mimic. The experimental design was completely randomized, with four replications, totaling 252 experimental units composed of pots with 12 kilograms of soil and the treatments arranged in a 3x7x2x2 factorial scheme: three herbicides (two ALS inhibitors pyrazosulfuromethyl and bispiribaque-sodium and a mimetic of triclopyr-butotyl auxin); seven doses of the herbicides (0.0x, 0.5x, 1x, 2x, 4x, 8x and 16x the registration dose); two biotypes of C. difformis (Santa Rosa do Sul and Meleiro, Santa Catarina (SC)); and two soil moisture (100% saturated and 5,0 cm water depth). The C. difformis biotype of Meleiro-SC is 8x (320 g. i.a. ha-1) more resistant to the registration dose of bispiribaque-sodium, whereas the biotype of Santa Rosa do Sul-SC is more susceptible, reducing 50% of the dry mass of the aerial part with 0.5x of the registration dose (20 g. i.a. ha-1). Pyrazosulfuromethyl proved to be inefficient in reducing the dry mass of the aerial part in both biotypes. The biotypes C. difformis of Santa Rosa do Sul-SC and Meleiro-SC, in both soil moisture conditions, are susceptible to triclopyr-butotyl, reducing 50% of the dry mass of the aerial part with 0.5x (166 g. i.a. ha-1) the registration dose

Desempenho fotossintético, peroxidação lipídica e aspectos morfológicos de papuã exposto a diferentes condições hídricas do solo

This paper aimed to elucidate the behavior of Urochloa plantaginea biotype with differential physiological characteristics, which allows a better growth and development in a flooded environment. A completely randomized experimental design was used 2x3, being the factors: populations of Urochloa plantaginea (lowlands and highlands) and soil water conditions (50% and 100% of soil water retention capacity (CRA); water depth 5 cm). Responses related to photosynthetic parameters and lipid peroxidation were verified 24h and 192h after the onset of water conditions. Morphology-relatedvariables were measured at the end of the plant cycle. The lowland biotype compared to the highland biotype showed superior morphophysiological characteristics under soil flooding. It can be emphasized, higher water use efficiency (about 30%), higher plant height, lower aerial part lipid peroxidation and higher aerial part dry matter increment. In addition, the lowland biotype was shown not to vary photosynthetic parameters A, Gs, Ci, E, USA and A / Ci when exposed to the water depth 5 cm, compared with the 100%CRA condition. Both populations survived and ended their cycle producing seeds. Thus, apossible adaptive process of the population to the flooded environment is evidenced.O presente trabalho buscou elucidar o comportamento do biótipo de Urochloa plantaginea com características fisiológicas diferenciais, que permite um melhor crescimento e desenvolvimento em ambiente alagado. Utilizou-se o delineamento experimental inteiramente casualizado 2x3, sendo os fatores: populações de Urochloa plantaginea (Várzea e Coxilha) e condições hídricas do solo (50% e 100% da capacidade de retenção de água no solo (CRA); lâmina d’água de 5 cm). Verificou-se as respostas relacionadas à parâmetros fotossintéticos e peroxidação lipídica 24h e 192h após o início das condições hídricas. Variáveis relacionadas à morfologia foram medidas no final do ciclo da planta. O biotipo de várzea frente ao biotipo de coxilha, demonstrou características morfofisiológicas superiores em condição de alagamento do solo. Pode-se ressaltar, maior eficiência no uso da água (cerca de 30%), maior altura de plantas, menor peroxidação de lipídeos de parte aérea e um maior incremento de massa seca de par te aérea. Adicionalmente, o biotipo várzea demonstrou não variar os parâmetros fotossintéticosA, Gs, Ci, E, EUA e A/Ci quando exposta à lâmina d’água, isto comparando-se com a condição de 100% da CRA. As duas populações sobreviveram e encerraram seu ciclo produzindo sementes. Logo, evidencia-se um possível processo adaptativo da população ao ambiente alagado

Silicon In the Growth of Rice Seedlings Pretreated with Dietholate and Subjected to Cold Stress

Silicon (Si) is an enzyme stimulator that can promote signaling for the production of antioxidant compounds, important in cellular detoxification of excess ROS accumulated during stress. The aim of the study was to evaluate the effects of Si on post-germination rice seeds in the mitigation of cold stress combined with stress induced by seed treatment with the dietholate protector. The experimental design was fully randomized with three replicates and a 3x2x2x4x2 factorial arrangement: three temperatures (5, 10 and 20 °C), two cultivars (IRGA 424 RI and Guri INTA CL), two seed pretreatments (with and without dietholate), four rates of Si (0; 4.0; 8.0 and 16 mg.L-1) and two sources of Si (sodium and potassium metasilicate). Seed pretreatment with dietholate reduced shoot and radicle length, especially at the lower temperatures of 5 and 10 °C. Sodium metasilicate as the source of Si was more efficient in boosting shoot and radicle length, both with and without pretreatment, regardless of temperature. Si was found to attenuate low-temperature stress and the impairment of shoot and radicle growth in rice seedlings grown from seeds pretreated with dietholate

Pre-emergent herbicides to the management of volunteer RR® corn in soybean crop

Alternativas para o manejo de milho voluntário RR® carecem de maior conhecimento no âmbito de produtos com efeito residual, principalmente para aplicação em pré-emergência da cultura da soja RR®. Neste trabalho foi avaliado o efeito de herbicidas com efeito residual para o controle de milho voluntário RR®, quando aplicados na cultura da soja pelo método “plante-aplique”. O experimento foi realizado no município de Santa Maria/RS, safra 2015/16, avaliando herbicidas, aplicados em pré-emergência da soja e do milho RR®. O delineamento experimental utilizado foi o de blocos ao acaso, com oito tratamentos e quatro repetições. Os herbicidas testados foram: flumioxazin, chlorimuron-ethyl, imazaquin e sulfentrazone; como associações desses herbicidas com o flumioxazin, relatando se houve efeitos sinérgicos. O melhor controle do milho voluntário RR® foi obtido com o herbicida imazaquin que restringiu em 90% a emergência das plantas de milho RR® e injuriou 97,5% das que emergiram. Entretanto o imazaquin causou sintomas de fitotoxicidade na cultura da soja. A associação em aplicações de imazaquin e flumioxazin, mostrou efeito aditivo de controle sobre o milho.Alternatives for volunteer corn RR® management need further knowledge in the product scope with residual effect, mainly for use in pre-emergence of the soybean RR®. This paper evaluated the performance of residual herbicides to control this species, when applied in soybean using the method "plant-apply". The experiment was carried in the municipality of Santa Maria/RS, crop season 2015/16; evaluating herbicides applied in pre-emergence of soybean crop and corn RR®. The experimental design was randomized blocks with eight treatments and four replications were evaluated inhibition of emergence of corn plants and injury on emerged plants. Sequential application responses were also addressed. Herbicides tested: flumioxazin, chlorimuron-ethyl, imazaquin, and sulfentrazone; as associations these herbicides with flumioxazin, in sequential applications, reporting if there were synergistic effects. The best control of RR® volunteer corn was obtained with the imazaquin herbicide, which reduced the emergence of RR® corn plants by 90% and injured 97.5% of those that emerged. However, imazaquin caused symptoms of phytotoxicity in the soybean crop, which did not measure yield losses in this work. The association in sequential applications of imazaquin and flumioxazin, showed additive control effect on maize

Comportamento de Hedypathes betulinus (Klug, 1825) em erva-mate em campo Behavior of Hedypathes betulinus (Klug, 1825) on the Paraguay tea plants

Foi avaliado o comportamento de cópula, postura, alimentação e deslocamento da broca da erva-mate, Hedypathes betulinus (Klug, 1825), na área experimental da Universidade Federal de Santa Maria. Essas características da broca foram avaliadas por um período de quatro dias através de observações visuais (de hora em hora), em duas gaiolas teladas colocadas sobre um ramo da planta, e contendo dois casais do inseto/gaiola. Observou-se que o macho, quando acompanhado de uma fêmea, tenta copular imediatamente, realizando cópulas durante todos os perí odos do dia, principalmente entre 14 e 18h, e em toda a extensão do ramo. A postura ocorreu nos ramos de 15-20mm de diâmetro. A maior intensidade de alimentação ocorreu no período compreendido entre 10 e 18h, sendo preferencialmente realizada em ramos de 30-40mm de diâmetro. O inseto apresentou comportamento sedentário e de fácil localizaç ;ão em função de sua limitada e lenta movimentação. Esses resultados são importantes para localização, amostragem, catação manual e manejo da praga.A trial was carried out in the experimental area of the Universidade Federal de Santa Maria to study the behaviour of mating, egg-laying, feeding and movement of Hedypathes betulinus (Klug, 1825) in the Paraguay tea (Ilex paraguariensis). These characteristics were monitored during four days (hourly) in two screen cages, each envolving a branch of a plant and containing two adult couples of H. betulinus. When approaching a female, the male tried to copulate immediately and usually mated several times during the day mainly between 2:00 and 6:00pm and on along the branch. Egg-laying was more frequent on branches between 15 and 20mm in diameter. Feeding ocorred more intensivel y fron 10:00am to 6:00p.m preferently on branches between 30 and 4mm in diameter The adults showed limited movement and sedentary behaviour