Environment factors in seed production of interspecific hybrids of brachiaria

Nos ??ltimos anos, para a maioria das esp??cies agr??colas, tem aumentado a utiliza????o de h??bridos gra??as a sua elevada produtividade al??m de outras qualidades que os colocam na frente das variedades. No g??nero Brachiaria a hibrida????o tem sido realizada atrav??s da utiliza????o do cruzamento de B. ruziziensis, que ?? sexual, e outras esp??cies apom??ticas do mesmo g??nero principalmente B. brizantha e B. decumbens. Entretanto, os h??bridos de braqui??ria obtidos at?? o momento s??o interespec??ficos e apresentam baixa produ????o de sementes, fator que limita a dissemina????o dos mesmos, visto a praticidade e menor custo de implanta????o/renova????o de pastagens utilizando-se sementes ao inv??s de mudas. Na busca pelo motivo dessa baixa produ????o de semente, este trabalho teve como objetivo verificar a exist??ncia de intera????o gen??tipo x ambiente na produ????o de sementes de gen??tipos h??bridos e o potencial produtivo de semente desses gen??tipos tendo como refer??ncia a cv. Marand??. Em um primeiro estudo, buscou-se verificar a interfer??ncia da temperatura sobre o gameta masculino de cinco h??bridos interespec??ficos de brachiaria (HBCG348, HBCG011, HBCG148, HBCG450 E HBCG148) e em um segundo estudo, foi avaliado a viabilidade pol??nica e a produ????o de semente desses mesmos h??bridos em diferentes condi????es ambientais. Concluiu-se que: a) o fator temperatura afeta a viabilidade pol??nica dos h??bridos; b) a viabilidade pol??nica dos h??bridos HBGC348 e HBGC148 ?? inversamente proporcional a eleva????o da temperatura; c) todos os h??bridos estudados tem anormalidade floral que afetam a dissemina????o pol??nica e consequente produ????o de sementes; d) houve intera????o genot??pica dos h??bridos estudados com o ambiente; e e) nenhum dos h??bridos estudados tem potencial de produ????o de sementes que os credenciem para entrar no mercado sementeiro.In recent years, for most agricultural species, has increased the use of hybrids by to its high yield and other qualities that put them in front of varieties. In the genus Brachiaria hybridization has been accomplished through the use of crossing B. ruziziensis, that is sexual, and other species of the genus mainly apomictic B. brizantha and B. decumbens. However, hybrids of Brachiaria obtained until now are interspecific and have low seed production, factor limiting the spread of the same, because the convenience and lower cost of implementation / renewal of pastures using seeds instead of seedlings. In the search for the reason that low seed production, this work was to verify the existence of genotype-environment interaction in seed production of hybrid genotypes and seed production potential of these genotypes with reference to cv. Marand??. In a first study, we sought to verify the influence of temperature on the male gamete of five interspecific hybrids of Brachiaria (HBCG348, HBCG011, HBCG148, HBCG450 and HBCG148) and a second study evaluated the viability of pollen and seed production of these same genotypes in different environmental conditions. It was concluded that: a) the temperature factor affect the pollen viability of hybrids; b) the pollen viability of hybrids HBGC348 and HBGC148 is inversely proportional to the temperature rise; c) all the hybrids studied have floral abnormalities that affect the spread of pollen and subsequent seed production; d) were studied the hybrid genotype interaction with the environment; and e) none of the hybrids studied has the potential to produce seeds that credentials to sign in seed-bed market