Physiological and sanitary quality of ryegrass seeds submitted to different defoliation frequencies / Qualidade fisiológica e sanitária de sementes de azevém-anual submetidas a diferentes frequências de desfolha

This study determined the effect of different defoliation frequencies in a long-cycle ryegrass cultivar on yield components and the physiological and sanitary quality of seeds. Four defoliation frequencies were applied (without, one, two, and three defoliations). The time between defoliations was 350 degree-days. At the first, second, and third defoliation time, the plants were 15 cm, 20 cm, and 35 cm, respectively, and were lowered to half their height. The yield components and plant structure were evaluated through the tillers, along with the physiological quality of the seeds, which was verified by germination tests, first germination count, accelerated aging, tetrazolium test, field emergence, and weight of a thousand seeds. For the sanitary quality analysis, the percentage (%) of fungi incidence in the seeds was verified. The second defoliation determined the seeds' high physiological and sanitary quality due to the higher amount of primary and secondary tillers produced concerning the other treatments. However, there was no significant difference for the third defoliation since the aerial tillers issued the same quality of seeds originated from primary and secondary tillers. The average incidence of fungi such as Colletotrichum sp., Fusarium sp., Phoma sp., and Dreshslera spp. was lower in ryegrass plants subjected to three defoliations.

O presente estudo teve como objetivo determinar o efeito de diferentes frequências de desfolha em uma cultivar de azevém de ciclo longo, sobre os componentes de rendimento e a qualidade fisiológica e sanitária das sementes. Foram aplicadas quatro frequências de desfolhas (sem, uma, duas e três). O tempo entre desfolhas foi de 350 graus-dia. No momento da primeira, segunda e terceira desfolha as plantas estavam com 15 cm, 20 cm e 35 cm, respectivamente e foram rebaixadas para metade de suas alturas. Avaliaram-se os componentes de rendimento e a estrutura das plantas por meio dos perfilhos, juntamente com a qualidade fisiológica das sementes, a qual foi verificada por testes de germinação, primeira contagem de germinação, envelhecimento acelerado, teste de tetrazólio, emergência a campo e peso de mil sementes. Para a análise da qualidade sanitária verificou-se a porcentagem (%) de incidência de fungos nas sementes. A segunda desfolha determinou alta qualidade fisiológica e sanitária das sementes devido a maior quantidade de perfilhos primários e secundários produzidos em relação aos demais tratamentos. No entanto não houve diferença significativa para a terceira desfolha, visto que nos perfilhos aéreos emitidos observou-se a mesma qualidade das sementes originadas de perfilhos primários e secundários. A incidência média de fungos como Colletotrichum sp., Fusarium sp., Phoma sp. e Dreshsleras pp. foi menor em plantas de azevém submetidas a três desfolhas.

Seed germination and antioxidant enzyme activity in seedlings of diploid and tetraploid bahiagrass under water restriction / Germinação de sementes e atividade de enzimas antioxidantes em plântulas de grama forquilha diplóide e tetraploide sob restrição hídrica

The objective of the following research was to investigate the physiological responses of two bahiagrass genotypes (Paspalum notatum Flügge) submitted to water restriction, induced by polyethylene glycol (PEG6000), during seed germination. Seeds of cv. Pensacola (diploid) and Bagual ecotype (tetraploid) were placed on paper moistened with osmotic solutions at potentials of 0.0; -0.1; -0.2 and -0.3 MPa. Composed of two subsamples of 100 seeds and four experimental units per treatment, the germination test was conducted in a germination chamber under alternating temperatures of 30 °C (8 hours) and 20 °C (16 hours), with presence of light during the higher temperature. Final germination percentage and germination speed index of the seeds, as well as early growth, activity and expression of antioxidant enzymes of seedlings were evaluated. The water restriction induced by PEG6000 reduced the percentage of germination in Pensacola (from 74% to 59%) and Bagual (34% to 10%). For the latter, the evaluation of seedlings showed higher dry mass in relation to cv. Pensacola (1.7 times higher in root and 1.6 times in shoot). In response to moderate water restriction, the genotypes showed increases in root growth (1.7 times higher in -0.1 compared to 0.0 MPa), both in expression and enzymatic activity (superoxide dismutase and catalase).(AU)

O presente estudo objetivou avaliar as respostas fisiológicas de dois genótipos de grama forquilha (Paspalum notatum Flügge) sob restrição hídrica induzida por polietileno glicol (PEG6000) durante a germinação de sementes. Sementes da cv. Pensacola (diplóide) e do ecótipo Bagual (tetraplóide) foram colocadas em papel umedecido com soluções osmóticas nos potenciais de 0,0; -0,1; -0,2 e -0,3 MPa. Composto de duas subamostras de 100 sementes e quatro unidades experimentais por tratamento, o teste de germinação foi conduzido em câmara de germinação sob temperatura alternada de 30-20 ºC, com presença de luz durante a maior temperatura. Foram avaliados a porcentagem final e o índice de velocidade de germinação das sementes, assim como o crescimento inicial, a atividade e a expressão de enzimas antioxidantes das plântulas. A restrição hídrica induzida por PEG6000 reduziu o percentual de germinação em Pensacola (de 74 para 59%) e Bagual (34 para 10%). Este último, na avaliação de plântulas, apresentou massa seca superior em relação à cv. Pensacola (1.7 vezes superior em raiz e 1.6 vezes superior em parte aérea). Em resposta à restrição hídrica moderada, os genótipos apresentaram aumentos tanto do crescimento radicular (1.7 vezes superior em -0.1 em comparação com 0.0 MPa), quanto da expressão e da atividade enzimática (superóxido dismutase e catalase).(AU)

Nitrogen fertilization of self-seeding Italian ryegrass: effects on plant structure, forage and seed yield / Adubação nitrogenada em azevém anual, proveniente de ressemeadura natural: efeitos sobre a estrutura de plantas, produção de forragem e de sementes

This study aimed to evaluate the effect of different levels of self-seeding Italian ryegrass (Lolium multiflorum Lam.) and nitrogen rates - applied additionally after two defoliations - on plant structure, in forage and seed yield. Levels of self-seeding were classified as very high (777 kg ha-1), high (736 kg ha-1), intermediate (624 kg ha-1), and low (234 kg ha-1). Populations were fertilized with zero, 20.25, 40.50, and 60.75 kg ha-1 of supplemental nitrogen applied after two defoliations; respectively, in very high, high, intermediate, and low levels. Higher levels of self-seeding promoted greater forage yield and uniformity of vegetation structure. Number of fertile tillers and number of seeds per plant have benefited by the combination of high self-seeding and supplemental nitrogen fertilization. Despite influencing the uniformity and amount of forage obtained in two defoliations, the very high and low self-seeding levels did not differ in Italian ryegrass seed production. However, linear addition for this same variable was obtained with the inclusion of supplemental nitrogen fertilization. In pastures from low and intermediate self-seeding levels, total dry mass increases linearly with the levels of nitrogen fertilization assessed in this research.(AU)

O objetivo deste estudo foi avaliar o efeito de diferentes níveis de ressemeadura natural de azevém anual (Lolium multiflorum Lam.), bem como, doses suplementares de nitrogênio sobre a estrutura de plantas, produção de forragem e de sementes. Os níveis de ressemeadura foram classificados como: muito elevada (777 kg ha-1); elevada (736 kg ha-1); intermediária (624 kg ha-1) e baixa (234 kg ha-1). Populações oriundas destes níveis foram fertilizadas com zero, 20.25, 40.50, and 60.75 kg ha-1 de nitrogênio, aplicado de forma suplementar após duas desfolhas. Maiores níveis de ressemeadura propiciaram maior colheita de forragem e maior uniformização da estrutura da vegetação. A quantidade de perfilhos férteis e o número de sementes por planta foram beneficiados pela combinação de elevada ressemeadura e aplicação de nitrogênio. Apesar de influenciar a uniformização e a quantidade de forragem obtida em duas desfolhas, os níveis de ressemeadura natural, muito elevada e baixa não diferiram entre si na produção de sementes no ano subsequente. Todavia, acréscimo linear para esta mesma variável foi verificado com avanço suplementar da adubação nitrogenada. Em pastagem de azevém anual proveniente dos níveis baixo e intermediário, a produção de massa seca total é acrescida linearmente com os níveis de fertilização avaliados no presente trabalho.(AU)

Expression of seed vigor and initial growth of red clover under fungicide influence / Expressão do vigor de sementes e crescimento inicial de trevo vermelho sob influência de fungicida

The objective of this study was to evaluate the expression of seeds vigor and physiological performance of initial growth of red clover plants under the influence of fungicide doses of carboxin + thiram. Three lots of seeds were used (high; medium and low vigor) treated with 0; 150; 250 fungicide doses and 350 mL i.a./100 kg of seeds. Germination, first count, emergence, speed index of seedling emergence, length and dry matter of shoot and root, leaf area and shoot/root ratio were evaluated. The experimental design was completely randomized in a factorial 3 x 4 (three lots - high, medium and low vigor x four fungicide doses of carboxin + thiram). Data were submitted to analysis of variance and if significant at 5% probability, adjusted for orthogonal polynomials. It was possible to observe that there were significant differences for the means of the variables germination, first germination count, emergency, emergency speed index, shoot length, root length, aerial part dry mass, root dry mass, leaf area, leaf area ratio and shoot and root ratio. The fungicide doses of 150 to 350 mL i.a./100 kg of seeds result in greater seedling emergence, higher leaf area ratio and increased shoot/root ratio in plants from lots of medium vigor seeds.The fungicide consisted of carboxin + thiram enhances the expression of seed vigor and physiological performance of seedlings growth derived from lots of medium vigor seeds.

O objetivo deste trabalho foi avaliar a expressão do vigor de sementes e o desempenho fisiológico de crescimento inicial de plantas de trevo vermelho submetidas à influência de doses de fungicida à base de carboxin + thiram. Foram utilizados três lotes de sementes (alto; médio e baixo vigor) tratadas com as doses de fungicida 0; 150; 250 e 350 mL i.a./100 kg de sementes. Foram avaliados a germinação, primeira contagem, emergência, índice de velocidade de emergência de plântulas, comprimento e matéria seca de parte aérea e de raiz, área foliar, razão de parte aérea e raiz. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 3 x 4 (três lotes - alto, médio e baixo vigor x quatro doses fungicidas de carboxin + tiram). Os dados foram submetidos à análise de variância e se significativos a 5% de probabilidade, foram ajustados para polinômios ortogonais. De acordo com os resultados foi possível observar que houve diferença significativa para as médias das variáveis germinação, primeira contagem de germinação, emergência, índice de velocidade de emergência, comprimento de parte aérea, comprimento de raiz, massa seca de parte aérea, massa seca de raiz, área foliar, razão de área foliar e razão de parte aérea e raiz. As doses de fungicida 150 a 350 mL i.a./100 kg de sementes resultam na maior emergência de plântulas, superior razão de área foliar e incremento na razão parte aérea e raiz em plântulas originadas de sementes de lotes com médio vigor. O fungicida a base de carboxin + thiram realça a expressão do vigor de sementes e o desempenho fisiológico de crescimento de plântulas originadas de lotes de sementes de médio vigor.

Expression of seed vigor and initial growth of red clover under fungicide influence / Expressão do vigor de sementes e crescimento inicial de trevo vermelho sob influência de fungicida

The objective of this study was to evaluate the expression of seeds vigor and physiological performance of initial growth of red clover plants under the influence of fungicide doses of carboxin + thiram. Three lots of seeds were used (high; medium and low vigor) treated with 0; 150; 250 fungicide doses and 350 mL i.a./100 kg of seeds. Germination, first count, emergence, speed index of seedling emergence, length and dry matter of shoot and root, leaf area and shoot/root ratio were evaluated. The experimental design was completely randomized in a factorial 3 x 4 (three lots - high, medium and low vigor x four fungicide doses of carboxin + thiram). Data were submitted to analysis of variance and if significant at 5% probability, adjusted for orthogonal polynomials. It was possible to observe that there were significant differences for the means of the variables germination, first germination count, emergency, emergency speed index, shoot length, root length, aerial part dry mass, root dry mass, leaf area, leaf area ratio and shoot and root ratio. The fungicide doses of 150 to 350 mL i.a./100 kg of seeds result in greater seedling emergence, higher leaf area ratio and increased shoot/root ratio in plants from lots of medium vigor seeds.The fungicide consisted of carboxin + thiram enhances the expression of seed vigor and physiological performance of seedlings growth derived from lots of medium vigor seeds.(AU)

O objetivo deste trabalho foi avaliar a expressão do vigor de sementes e o desempenho fisiológico de crescimento inicial de plantas de trevo vermelho submetidas à influência de doses de fungicida à base de carboxin + thiram. Foram utilizados três lotes de sementes (alto; médio e baixo vigor) tratadas com as doses de fungicida 0; 150; 250 e 350 mL i.a./100 kg de sementes. Foram avaliados a germinação, primeira contagem, emergência, índice de velocidade de emergência de plântulas, comprimento e matéria seca de parte aérea e de raiz, área foliar, razão de parte aérea e raiz. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 3 x 4 (três lotes - alto, médio e baixo vigor x quatro doses fungicidas de carboxin + tiram). Os dados foram submetidos à análise de variância e se significativos a 5% de probabilidade, foram ajustados para polinômios ortogonais. De acordo com os resultados foi possível observar que houve diferença significativa para as médias das variáveis germinação, primeira contagem de germinação, emergência, índice de velocidade de emergência, comprimento de parte aérea, comprimento de raiz, massa seca de parte aérea, massa seca de raiz, área foliar, razão de área foliar e razão de parte aérea e raiz. As doses de fungicida 150 a 350 mL i.a./100 kg de sementes resultam na maior emergência de plântulas, superior razão de área foliar e incremento na razão parte aérea e raiz em plântulas originadas de sementes de lotes com médio vigor. O fungicida a base de carboxin + thiram realça a expressão do vigor de sementes e o desempenho fisiológico de crescimento de plântulas originadas de lotes de sementes de médio vigor.(AU)

Relationship between the morphogenesis of Italian ryegrass cv. "BRS Ponteio" with forage and seed production / 10.1590/0103-8478cr20150296 / Relação entre as características morfogênicas do azevém anual cv. "BRS Ponteio" com a produção de forragem e de sementes

This study aims to verify, accurate and precisely, the responses of Italian ryegrass "BRS Ponteio" cultivar to different frequencies of defoliation for forage production and especially for seed production. For this purpose, a randomized block design experiment with four replications was conducted. Four frequencies of defoliation were applied (zero, one, two, and three) based on the thermal sum, evaluating the rate of leaf appearance (LAR), phyllochron (P), leaf expansion rate (LER), leaf senescence rate (LSR), stems expansion rate (SER), tillering rate (TR), leaf life span (LL), forage production, proportion of leaf blades, stems plus sheaths, senescent material, and inflorescences, as well as seed production. Second defoliation noticeably altered the morphogenic plant responses, reduced expansion rates and leaf appearance, increased rates of tillering and stems expansion. This phenotypic maintained a high seed production and provided a harvest of forage mass 100% higher than the collected mass in the first cutting. Third defoliation led to an increase of 100% of the harvested forage mass; however, it caused drastic and negative changes in the morphogenic characteristics and seed yielding.(AU)

O presente estudo teve o objetivo de verificar, de forma precisa e detalhada, as respostas da cultivar de azevém anual "BRS Ponteio", às diferentes frequências de desfolha para a produção de forragem e de sementes. Realizou-se, para tanto, um experimento com delineamento de blocos casualizados com quatro repetições. Foram aplicadas quatro frequências de desfolhas (sem, uma, duas e três) baseando-se no acúmulo térmico, onde se avaliou a taxa de aparecimento de folhas (TApF), o filocrono (F), a taxa de expansão de folhas (TEF), taxa de senescência de folhas (TScF), taxa de expansão dos colmos (TEC), taxa de perfilhamento (TP), duração de vida da folha (DVF), produção de forragem, proporção de lâminas foliares, colmos mais bainhas, material senescente e inflorescências em cada tratamento, bem como a produção de sementes. A segunda desfolha alterou marcadamente as respostas morfogênicas da planta, reduziu as taxas de expansão e aparecimento de folhas e aumentou as taxas de perfilhamento e de expansão do colmo. Esta plasticidade fenotípica manteve a alta produção de sementes da planta e propiciou a colheita de massa de forragem 100% superior à massa colhida no primeiro corte. A terceira desfolha propiciou o aumento de 100% da massa de forragem colhida, todavia, promoveu alterações drásticas e negativas nas características morfogênicas e no rendimento de sementes.(AU)

Monensin controlled-release capsules do not change performance and metabolic profile in unchallenged beef cattle

Background: Some additives are able to improve animal performance in growing and finishing periods. Monensin was firstused to control coccidiosis in poultry and was extended to other animals, like ruminants, to act also as a growth promoterand improve cattle performance. In this species, monensin improves the synthesis of propionic acid in the rumen anddecreases methane synthesis and protein degradation, resulting in better performance in protein and energy metabolism.The objective of this study was to evaluate the use of monensin controlled-release capsules on animals grazing Loliummultiflorum intercropped with Trifolium repens on metabolic profile and performance.Materials, Methods & Results: Thirty Hereford cows were randomly distributed into two groups: control (CG) and monensingroup (MG). Monensin was individually administered by controlled-release capsules placed in the rumen through oroesophageal pathway. All animals were identified through earring and kept under the same management condition, grazingon upland pasture mixture of Trifolium repens and Lolium multiflorum. Data from biochemical profile and performancewere collected during 45 days. Blood samples started on the day of monensin controlled-release capsule placement (day0) and continued in periods of 15, 30 and 45 days, after initial placement. Serum levels of albumin, glucose, urea, lactatedehydrogenase (LDH) and aspartate aminotransferase (AST) were evaluated using colorimetric diagnostic kits. In the rumen fluid, pH was measured and protozoa count was performed. All statistical analyses were made using software SAS.Albumin, AST, glucose, LDH and urea were analyzed through MIXED procedure and Tukey-Kramer test was applied forcomparison of means. For average daily gain, the orthogonal polynomials test was applied. Treatments did not differ inBSC, body weight and average daily gain (ADG). None of these performance parameters were significantly affected...(AU)

Monensin controlled-release capsules do not change performance and metabolic profile in unchallenged beef cattle

Background: Some additives are able to improve animal performance in growing and finishing periods. Monensin was firstused to control coccidiosis in poultry and was extended to other animals, like ruminants, to act also as a growth promoterand improve cattle performance. In this species, monensin improves the synthesis of propionic acid in the rumen anddecreases methane synthesis and protein degradation, resulting in better performance in protein and energy metabolism.The objective of this study was to evaluate the use of monensin controlled-release capsules on animals grazing Loliummultiflorum intercropped with Trifolium repens on metabolic profile and performance.Materials, Methods & Results: Thirty Hereford cows were randomly distributed into two groups: control (CG) and monensingroup (MG). Monensin was individually administered by controlled-release capsules placed in the rumen through oroesophageal pathway. All animals were identified through earring and kept under the same management condition, grazingon upland pasture mixture of Trifolium repens and Lolium multiflorum. Data from biochemical profile and performancewere collected during 45 days. Blood samples started on the day of monensin controlled-release capsule placement (day0) and continued in periods of 15, 30 and 45 days, after initial placement. Serum levels of albumin, glucose, urea, lactatedehydrogenase (LDH) and aspartate aminotransferase (AST) were evaluated using colorimetric diagnostic kits. In the rumen fluid, pH was measured and protozoa count was performed. All statistical analyses were made using software SAS.Albumin, AST, glucose, LDH and urea were analyzed through MIXED procedure and Tukey-Kramer test was applied forcomparison of means. For average daily gain, the orthogonal polynomials test was applied. Treatments did not differ inBSC, body weight and average daily gain (ADG). None of these performance parameters were significantly affected...