ABSTRACT. Ergot is a fungal disease and causes reductions in seed productivity and quality. We aimed to identify promising genotypes of brachiaria evaluating: (1) seed production potential (number of tillers, racemes per inflorescence, spikelets per raceme, raceme length, weight and number of seeds, and germination) and (2) resistance of seeds to Ergot (infected tillers, infected seeds). Five genotypes of Brachiaria grasses, four non-natural hybrids named BH1619, BH1810, BH1516 and Mavuno Palisadegrass (Urochloa brizantha x Urochloa ruziziensis), and Marandu Palisadegrass (U. brizantha Hoechst cv. Marandu) were evaluated. The BH1619 hybrid, despite the high weight of seeds, produced less viable, pure seeds. The hybrid BH1516 had a lower percentage of flowered tillers (42%) and seeds infected with ergot (8%). Marandu Palisadegrass had a higher percentage of infected tillers (95%) and infected seeds (38%). The hybrid BH1516 was the most resistant to ergot, followed by Mavuno Palisadegras sand BH1619. Among all materials, Mavuno Palisadegrass and BH1516 have a higher potential for seed production due to the higher percentage of flowered tillers and production of pure seeds with high germination capacity. The BH1516 hybrid was resistant to ergot, making it a better choice for use in infected areas used for seed or forage production.

Foram avaliadas características do sistema radicular (pré e pós-pastejo) dos capins aruana e tanzânia submetidos a doses de nitrogênio (150 e 300 kg ha-1 de N) e pastejados por ovinos em lotação rotacionada com três a sete dias de pastejo e período de descanso variável. O delineamento experimental foi o de blocos completos casualizados (dois) com duas repetições, em esquema de parcelas subdivididas (parcelas =capins e subparcelas=doses de N) e medidas repetidas no tempo. No pré-pastejo, o capim-tanzânia, na média entre doses de N e períodos de pastejo, apresentou maior quantidade de massa seca da matéria orgânica (MSMO) (1,7 mg cm-3 de solo) que o capim-aruana (1,2 mg cm-3 de solo), além de maior comprimento de raízes (119,1 cm cm-3 de solo e 68,7 cm cm-3 de solo, respectivamente). A dose de 300 kg ha-1 de N contribuiu para maior comprimento do sistema radicular (107,1 cm cm-3 de solo) que a dose de 150 kg ha-1 de N (80,7 cm cm-3 de solo). O crescimento radicular pós-pastejo demonstrou similaridade de comportamento entre as variáveis mensuradas, de modo que o crescimento de raízes se tornou mais evidente após a segunda semana de rebrotação. Na média de capins, doses de N e idades de crescimento, no período equivalente ao outono/inverno, o crescimento de raízes (em MSMO foi de 3,9 mg 100 cm-3) aumentou para 12,9 mg 100 cm-3 no inverno, caiu para 4,7 mg 100 cm-3 na primavera e elevou novamente para 17 mg 100 cm-3 no verão. Comportamento semelhante foi observado para comprimento e superfície de raízes, coincidindo os períodos de maior crescimento com os de maior pluviosidade. A dose de 150 kg ha-1 de N promoveu maior crescimento em comprimento e superfície de raízes que a dose de 300 kg ha-1 de N nos períodos de maior pluviosidade.

The root system (pre and post grazing) characteristics of aruanagrass and tanzaniagrass under two nitrogen rates (150 and 300 kg ha-1 N year) grazed by sheep in variable rotational stocking (three to seven grazing days) and variable rest period were evaluated in this study. The treatments were assigned to a complete randomized block (two) design with two replicates (plots = grasses and split-plots = nitrogen rates)within repeated measures. In the pre-grazing tanzaniagrass, averages within nitrogen rates and grazing period showed higher amount of dry matter of organic matter (DMOM) (1.7 mg cm-3 of soil) than aruanagrass (1.2 mg cm-3 of soil) and greater root length (119.1 cm cm-3 of soil x 68.7 cm cm-3 of soil). The 300 kg ha-1 N rate contributed to a higher root system length (107.1 cm cm-3 of soil) than the 150 kg ha-1 N rate (80.7 cm cm-3 of soil). Post-grazing root growth showed similar behavior among the variables measured and was more evident after the second regrowth week. Considering averages within grasses, nitrogen rates and growth age, in the period equivalent to Autumn/Winter, the DMOM growth root was of 3.9 mg 100 cm-3, increased by 12.9 mg 100 cm-3 in Winter, decreased by 4.7 mg 100 cm-3 from Winter to Spring, and increased by 17 mg 100 cm-3 on Summer. Similar behavior for both root length and surface was observed, when the periods with higher growth coincided with the ones with higher rainfall. The 150 kg ha-1 N rate promoted higher length and surface than the 300 kg ha-1 N in the periods with higher rainfall.

O cultivar Crioula de alfafa (Medicago sativa cv. Crioula) é utilizado no Sul do Brasil e existem poucos estudos referentes a sua exigência em boro. Foi conduzido um experimento com alfafa cultivada no inverno, com o objetivo de avaliar a quantidade de boro absorvido pelas plantas, o efeito de doses de boro na produção de massa seca, a distribuição do boro nas plantas e obter informações relacionadas à diagnose de boro nessa forrageira. As doses de 0; 0,0625; 0,125; 0,25; 0,50; 1,00 e 2,00 mg L-1 foram aplicadas no substrato, colocando-se 1 L de solução nutritiva em cada recipiente. As plantas foram cortadas aos 46 dias após o transplante. A massa seca da forrageira foi influenciada pelas doses de boro e foi insignificante quando a solução nutritiva apresentava a mais baixa concentração de boro. A concentração de boro nas folhas foi mais elevada que nas hastes e nas raízes. A utilização de boro da solução atingiu 90% na dose de 0,0625 mg L-1 e decresceu acentuadamente com o incremento das doses de boro. A concentração e o conteúdo de boro nas folhas e na parte aérea da planta foram mais elevados quando o boro se encontrava na solução nutritiva entre 1,5 e 1,6 mg L-1. O nível crítico de boro foi de 61 mg kg-1 nas folhas e 39 mg kg-1 na planta para este cultivar de alfafa.

Alfalfa cultivar Crioula (Medicago sativa cv. Crioula) is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.