Genetic diversity analysis among pigeonpea genotypes adapted to South American regions based on microsatellite markers

The pigeonpea [Cajanus cajan (L) Millspaugh] is one of the most important perennial legume crops utilized in the food, fodder, soil conservation, crop-livestock integrated systems, reclaiming of degraded pastures and symbiotic nitrogen fixation. Microsatellite markers were used to estimate the genetic diversity of 77 pigeonpea genotypes selected from the germplasm collections at Embrapa Cattle-Southeast and, to evaluate their transferability to Phaseolus vulgaris and Vigna unguiculata species. The number of alleles per locus ranged from 2 to12, with an average of 5.1 alleles. The PIC values ranged from 0.11 to 0.80 (average 0.49) and the D values from 0.23 to 0.91 (average 0.58). The averages of observed and expected heterozygosity were 0.25 and 0.47, respectively, showing a deficit in heterozygosity. A model-based Bayesian approach implemented in the software STRUCTURE was used to assign genotypes into clusters. A dendrogram was constructed based on the modified Roger's genetic distances using a neighbor-joining method (NJ). A total of four clusters were assembled by STRUCTURE and a strong tendency of correspondence between the Bayesian clusters in the NJ tree was observed. The genetic distance ranged from 0.09 to 0.62 (average 0.37), showing a low genetic diversity in the pigeonpea genotypes. Transferability of pigeonpea-specific microsatellites revealed a cross-amplification and the presence of polymorphic alleles in P. vulgaris and V. unguiculata.

Genetic diversity analysis among pigeonpea genotypes adapted to South American regions based on microsatellite markers

The pigeonpea [Cajanus cajan (L) Millspaugh] is one of the most important perennial legume crops utilized in the food, fodder, soil conservation, crop-livestock integrated systems, reclaiming of degraded pastures and symbiotic nitrogen fixation. Microsatellite markers were used to estimate the genetic diversity of 77 pigeonpea genotypes selected from the germplasm collections at Embrapa Cattle-Southeast and, to evaluate their transferability to Phaseolus vulgaris and Vigna unguiculata species. The number of alleles per locus ranged from 2 to12, with an average of 5.1 alleles. The PIC values ranged from 0.11 to 0.80 (average 0.49) and the D values from 0.23 to 0.91 (average 0.58). The averages of observed and expected heterozygosity were 0.25 and 0.47, respectively, showing a deficit in heterozygosity. A model-based Bayesian approach implemented in the software STRUCTURE was used to assign genotypes into clusters. A dendrogram was constructed based on the modified Roger's genetic distances using a neighbor-joining method (NJ). A total of four clusters were assembled by STRUCTURE and a strong tendency of correspondence between the Bayesian clusters in the NJ tree was observed. The genetic distance ranged from 0.09 to 0.62 (average 0.37), showing a low genetic diversity in the pigeonpea genotypes. Transferability of pigeonpea-specific microsatellites revealed a cross-amplification and the presence of polymorphic alleles in P. vulgaris and V. unguiculata.

Extração de nutrientes e eficiência nutricional de cultivares de aveia, em relação ao nitrogênio e à intensidades de corte

The objective of this experiment was to study the effect of nitrogen levels (0, 40, 80, 160, 320 kg ha-1 N) and forage cutting intensities (none, one and two cuts) on nutrient uptake and nutritional efficiency of oats (Avena byzantina / Avena sativa). The potential mineral uptake by forage and grains and their cycling through their straw, were also evaluated. This experiment was conducted on a Hapludox soil, in a split-plot design with complete randomized blocks and four replications, using the São Carlos and UPF 3 oat cultivars. Increasing levels of N affected both, the extraction of S and N in the first forage cut of São Carlos, influenced the K assimilation of both cultivars in the second cut, and S uptake, in both cultivars and cuts. In addition P uptake by straw of both cultivars, and Zn, Cu and Mn by São Carlos, were altered. The K concentration and extraction decreased from the first to the second cut. Potassium uptake was higher when oats were used as forage, at a level of 145 kg ha-1. Straw assimiliation of K was about 60 kg ha-1, which returned to the soil, while grain uptake was about 6 kg ha-1. Potassium, N, Fe and Mn were the nutrients of highest demand by both cultivars, which had similar nutritional efficiency and produced the same amount of forage dry matter. For grain production and use of nutrients, UPF 3 was more efficient than São Carlos.

Com o objetivo de verificar o efeito de doses de nitrogênio e regimes de corte na extração de nutrientes, na eficiência de seu aproveitamento, bem como avaliar o potencial de exportação de minerais pela forragem e grãos, e a ciclagem de minerais pela palhada, foi conduzido um experimento, em Latossolo Vermelho-Escuro, irrigado, em blocos ao acaso, com quatro repetições e parcelas sub-subdivididas, com os cultivares de aveia São Carlos e UPF 3. Doses crescentes de N alteraram a curva de extração de S e N na forragem do cv. São Carlos, no primeiro corte, de K na forragem de ambos cultivares, no segundo corte, e de S na forragem acumulada de ambos cortes e cultivares, além da extração do P pela palha de ambos cultivares e de Zn, Cu e Mn do cv. São Carlos. Ocorreu redução na extração de K pela forragem do segundo corte. A extração de potássio foi maior pela aveia utilizada como forrageira e menor para a produção de grãos: foram extraídos em média 145 kg ha-1 de potássio pela forragem, 60 kg ha-1 pela palha que retornam ao solo e 6 kg ha-1 pelos grãos. Dentre os macronutrientes, o potássio, o nitrogênio, e dentre os micronutrientes, o ferro e o manganês foram os mais exigidos pelos dois cultivares, que apresentaram valores de eficiência nutricional semelhantes para todos os elementos, quando utilizados como forragem. Quando utilizados para a produção de grãos, entretanto, o cultivar UPF 3 foi mais eficiente em utilizar os nutrientes absorvidos.

Indicadores de determinação de cortes de cultivares de aveia forrageira

Dry matter (DM) yield increases as plants age, but at the same time there is a decrease in forage quality. Management studies on oat cultivars were performed to determine which indicators for the first cutting time and regrowth intervals would lead to the highest dry matter yield with the highest nutritive value. In 1994, a randomized complete block experimental design, with three replications was used, in a 3 x 4 factorial arrangement (the three first cut indicators were: sixty days after emergence, beginning of panicle differentiation (PD), and 10% of plants with culm elongation and apical meristem elevation (SE), while the four regrowth cutting intervals were: 28 days, 56 days, PD and 10% SE. Two oat forage cultivars were used, São Carlos and UPF 3. In 1995 and 1996, a 4 x 3 factorial arrangement (four regrowth intervals: 28, 35, 42 and 56 days and three cultivars, São Carlos, UPF 3 and IAPAR 61) also in a randomized block design with three replications. Forage DM yield, crude protein, Ca, P, Mg content, 'in vitro' DM digestibility and neutral detergent fiber were determined. There were statistical differences for DM yield and nutritive characteristics among cultivars, first cutting time and regrowth cutting interval. The first cut should be performed with 10% SE and regrowth cuttings should be performed using an interval of 28 to 35 days.

A produção de matéria seca total (MS) aumenta em função da idade da planta, mas simultaneamente ocorre decréscimo progressivo do seu valor nutritivo. O presente trabalho teve a finalidade de determinar a combinação de épocas de primeiro corte com a de intervalos de cortes da rebrota que proporcionasse a maior produção de matéria seca de aveia com as melhores características nutritivas. O delineamento experimental foi em blocos casualizados, com três repetições. Em 1994, os tratamentos foram organizados em fatorial 3 x 4 [três indicadores de primeiro corte: 60 dias depois da emergência, início de emborrachamento (IE) e 10% plantas encanadas (PE = alongamento do colmo, com elevação do meristema apical); quatro indicadores de intervalos de cortes da rebrota: 28 dias, 56 dias, IE, 10% PE]. Foram testados dois cultivares: São Carlos e UPF 3. Em 1995 e 1996, os tratamentos foram organizados em esquema fatorial 4 x 3 (4 intervalos de corte da rebrota: 28, 35, 42 e 56 dias; três cultivares: São Carlos, UPF 3 e IAPAR 61). Foram avaliados: produção de MS, teores de N, Ca, P, Mg, digestibilidade "in vitro" e fibra em detergente neutro. Houve diferenças na produção de matéria seca e nas características nutritivas entre cultivares, épocas de primeiro corte e intervalos de cortes da rebrota. O primeiro corte deve ser feito com 10% PE, e os cortes da rebrota devem ser efetuados em intervalos de 28 a 35 dias.

Indicadores de determinação de cortes de cultivares de aveia forrageira

Dry matter (DM) yield increases as plants age, but at the same time there is a decrease in forage quality. Management studies on oat cultivars were performed to determine which indicators for the first cutting time and regrowth intervals would lead to the highest dry matter yield with the highest nutritive value. In 1994, a randomized complete block experimental design, with three replications was used, in a 3 x 4 factorial arrangement (the three first cut indicators were: sixty days after emergence, beginning of panicle differentiation (PD), and 10% of plants with culm elongation and apical meristem elevation (SE), while the four regrowth cutting intervals were: 28 days, 56 days, PD and 10% SE. Two oat forage cultivars were used, São Carlos and UPF 3. In 1995 and 1996, a 4 x 3 factorial arrangement (four regrowth intervals: 28, 35, 42 and 56 days and three cultivars, São Carlos, UPF 3 and IAPAR 61) also in a randomized block design with three replications. Forage DM yield, crude protein, Ca, P, Mg content, 'in vitro' DM digestibility and neutral detergent fiber were determined. There were statistical differences for DM yield and nutritive characteristics among cultivars, first cutting time and regrowth cutting interval. The first cut should be performed with 10% SE and regrowth cuttings should be performed using an interval of 28 to 35 days.

A produção de matéria seca total (MS) aumenta em função da idade da planta, mas simultaneamente ocorre decréscimo progressivo do seu valor nutritivo. O presente trabalho teve a finalidade de determinar a combinação de épocas de primeiro corte com a de intervalos de cortes da rebrota que proporcionasse a maior produção de matéria seca de aveia com as melhores características nutritivas. O delineamento experimental foi em blocos casualizados, com três repetições. Em 1994, os tratamentos foram organizados em fatorial 3 x 4 [três indicadores de primeiro corte: 60 dias depois da emergência, início de emborrachamento (IE) e 10% plantas encanadas (PE = alongamento do colmo, com elevação do meristema apical); quatro indicadores de intervalos de cortes da rebrota: 28 dias, 56 dias, IE, 10% PE]. Foram testados dois cultivares: São Carlos e UPF 3. Em 1995 e 1996, os tratamentos foram organizados em esquema fatorial 4 x 3 (4 intervalos de corte da rebrota: 28, 35, 42 e 56 dias; três cultivares: São Carlos, UPF 3 e IAPAR 61). Foram avaliados: produção de MS, teores de N, Ca, P, Mg, digestibilidade "in vitro" e fibra em detergente neutro. Houve diferenças na produção de matéria seca e nas características nutritivas entre cultivares, épocas de primeiro corte e intervalos de cortes da rebrota. O primeiro corte deve ser feito com 10% PE, e os cortes da rebrota devem ser efetuados em intervalos de 28 a 35 dias.

Extração de nutrientes e eficiência nutricional de cultivares de aveia, em relação ao nitrogênio e à intensidades de corte

The objective of this experiment was to study the effect of nitrogen levels (0, 40, 80, 160, 320 kg ha-1 N) and forage cutting intensities (none, one and two cuts) on nutrient uptake and nutritional efficiency of oats (Avena byzantina / Avena sativa). The potential mineral uptake by forage and grains and their cycling through their straw, were also evaluated. This experiment was conducted on a Hapludox soil, in a split-plot design with complete randomized blocks and four replications, using the São Carlos and UPF 3 oat cultivars. Increasing levels of N affected both, the extraction of S and N in the first forage cut of São Carlos, influenced the K assimilation of both cultivars in the second cut, and S uptake, in both cultivars and cuts. In addition P uptake by straw of both cultivars, and Zn, Cu and Mn by São Carlos, were altered. The K concentration and extraction decreased from the first to the second cut. Potassium uptake was higher when oats were used as forage, at a level of 145 kg ha-1. Straw assimiliation of K was about 60 kg ha-1, which returned to the soil, while grain uptake was about 6 kg ha-1. Potassium, N, Fe and Mn were the nutrients of highest demand by both cultivars, which had similar nutritional efficiency and produced the same amount of forage dry matter. For grain production and use of nutrients, UPF 3 was more efficient than São Carlos.

Com o objetivo de verificar o efeito de doses de nitrogênio e regimes de corte na extração de nutrientes, na eficiência de seu aproveitamento, bem como avaliar o potencial de exportação de minerais pela forragem e grãos, e a ciclagem de minerais pela palhada, foi conduzido um experimento, em Latossolo Vermelho-Escuro, irrigado, em blocos ao acaso, com quatro repetições e parcelas sub-subdivididas, com os cultivares de aveia São Carlos e UPF 3. Doses crescentes de N alteraram a curva de extração de S e N na forragem do cv. São Carlos, no primeiro corte, de K na forragem de ambos cultivares, no segundo corte, e de S na forragem acumulada de ambos cortes e cultivares, além da extração do P pela palha de ambos cultivares e de Zn, Cu e Mn do cv. São Carlos. Ocorreu redução na extração de K pela forragem do segundo corte. A extração de potássio foi maior pela aveia utilizada como forrageira e menor para a produção de grãos: foram extraídos em média 145 kg ha-1 de potássio pela forragem, 60 kg ha-1 pela palha que retornam ao solo e 6 kg ha-1 pelos grãos. Dentre os macronutrientes, o potássio, o nitrogênio, e dentre os micronutrientes, o ferro e o manganês foram os mais exigidos pelos dois cultivares, que apresentaram valores de eficiência nutricional semelhantes para todos os elementos, quando utilizados como forragem. Quando utilizados para a produção de grãos, entretanto, o cultivar UPF 3 foi mais eficiente em utilizar os nutrientes absorvidos.