Odilon Peixoto de Morais Júnior

Genetic progress after cycles of upland rice recurrent selection

Periodic assessment of the genetic progress made in recurrent selection programs is essential for assessing the evolution of the programs and identifying the main factors that have contributed to this progress. This study aimed to estimate genetic progress in grain yield, plant height and days-to-flowering achieved in the CNA6 population of upland rice (Oryza sativa L.), after four cycles of recurrent selection; and evaluate the genetic potential of this population to generate superior inbred lines after each selection cycle. The experimental data were obtained from progeny yield trials of each recurrent selection cycle. These trials were carried out in two or three locations per cycle, and consisted of S0:2 progenies and at least three checks. Federer’s augmented block design, with one replication on location (the environment), was adopted. Results revealed genetic progress for grain yield and plant height, with total genetic gains of 375.87 kg ha−1 and -3.90 cm, respectively, during the four selection cycles. The annual relative gain observed for grain yield was 1.54 %. The genetic potential of the population was analysed by the expected proportion of superior inbred lines. The standard adopted as the limit for obtaining superior inbred lines was the average of the checks for each trait. The genetic potential for grain yield and plant height increased during the study period. For days-to-flowering, no genetic gain occurred; however, the genetic potential of the population to generate superior inbred lines for this trait was maintained after the selection cycles.

Emergência de plântulas de pequizeiro em função da planta matriz e uso de ácido giberélico

RESUMO of GA 3 , in subplots. Every seven days, emergence final percentage, average time and speed index were evaluated. The second field trial used a completely randomized design, with different numbers of replications, according with the number of seedlings from the first experiment. For emergence percentage, speed index and average time, treatments presented a significant effect, with a significant interaction between genotype and treatment, for emergence percentage and speed index, to overcome dormancy. It was observed that the use of 500 mg L -1 of gibberellic acid may minimize dormancy in Caryocar brasiliense seeds and that the field growth of mother plants was linear and continuous over time.

Agro-morphological characterization and genetic divergence assessment in bush snap bean genotypes1

1. Manuscript received in Oct./2016 and accepted for publication in May/2017 (http://dx.doi.org/10.1590/1983-40632016v4743525). 2. Universidade do Estado de Mato Grosso, Departamento de Agronomia, Nova Mutum, MT, Brazil. E-mail: daniela_gds2@hotmail.com. 3. Universidade Federal de Goiás, Escola de Agronomia, Departamento de Melhoramento de Plantas, Goiânia, GO, Brazil. E-mail: odilonpmorais@gmail.com. 4. Universidade Estadual de Goiás, Departamento de Agronomia, Ipameri, GO, Brazil. E-mail: nei.peixoto48@gmail.com. The characterization and identification of genetically divergent parents for crosses are important tasks in snap bean breeding programs, for a greater availability of cultivars to growers. This study aimed at characterizing bush snap bean genotypes originating from different countries; assessing the genetic divergence between the genotypes and the genetic variability extent, concerning 12 agro-morphological traits; and determining the relative importance of these traits for the genetic divergence. The experiment was conducted in a randomized complete block design, with 29 genotypes and four replications. The UPGMA and Tocher optimization methods, both based on the generalized distance of Mahalanobis, and the canonical variables method were used to analyze the genetic divergence. The genotypes exhibited a wide range of genetic variability for the agro-morphological traits evaluated, mainly for 100-seed weight, aspect and yield of commercial pods, plant height at harvest and pod weight. A high genetic divergence was detected between the genotypes, in which the 100-seed weight and aspect of commercial pods were the most important traits for clustering. Some genotypes own desirable characteristics for these and other traits, given the favorable genetic associations between traits. The snap bean genotypes originated from different countries tended to cluster together, indicating that similar germplasm is shared among different countries, thus suggesting a strong trans-national seed exchange.

Variabilidade genética durante quatro ciclos de seleção recorrente em arroz

The objective of this work was to estimate genetic and phenotypic parameters among progenies of the CNA6 population of upland rice (Oryza sativa) for grain yield and plant height in four cycles of recurrent selection, in order to evaluate the genetic variability and the genotype × location interaction. The experimental data were obtained from yield trials of S0:2 progenies, which were carried out in the experimental design of Federer’s augmented blocks, without replications for progenies within each location. The effect of S0:2 progenies was significant in all cycles for grain yield and in the first three cycles for plant height, indicating the maintenance of the population’s genetic potential to generate transgressive progenies. The participation of the component of the progeny × location interaction in phenotypic variance was of high magnitude. The genetic variability of the CNA6 population of upland rice is maintained for grain yield and plant height during the four cycles of recurrent selection.

MÉTODOS PARA SUPERAÇÃO DE DORMÊNCIA EM SEMENTES DE MURICI

Inumeros metodos tem sido empregados para superacao de dormencia em sementes, podendo apresentar vantagens e desvantagens, de modo que cada um deles deve ser estudado, levando-se em conta, o custo efetivo e sua facilidade de execucao. Objetivou-se com este trabalho avaliar tratamentos pre-germinativos em laboratorio que possibilitem superar a dormencia de sementes de murici ( Byrsonima crassifolia L. Rich.). O experimento foi conduzido na Universidade Estadual de Goias – Unidade de Ipameri – GO. O delineamento experimental utilizado foi inteiramente casualizado, com quatro repeticoes, sendo cada parcela representada por 30 pirenios. Os tratamentos pre-germinativos testados foram: A- testemunha (sem tratamento); B- esmerilhacao superficial da parede dos pirenios; C- escarificacao com acido sulfurico (H 2 SO 4 ); D- fragmentacao dos pirenios em morsa; E- fragmentacao dos pirenios seguido de imersao em solucao de acido giberelico (GA 3 ); e F- imersao exclusiva dos pirenios em solucao de acido giberelico (GA 3 ). Foram avaliadas a porcentagem de germinacao, tempo medio de germinacao e indice de velocidade de germinacao. Os metodos baseados em ruptura fisica do tegumento dos pirenios nao foram eficientes na superacao de dormencia. As sementes de murici apresentaram comportamento caracteristico de dormencia fisiologica, embora a ruptura do tegumento tenha aumentado a velocidade de germinacao. A fragmentacao dos pirenios seguida por imersao durante 24 horas em solucao de acido giberelico na concentracao de 500 mg L -1 foi o metodo mais eficiente para promover a germinacao em sementes de murici dessa especie.

INFLUÊNCIA DA CALAGEM E DO FÓSFORO NA EFICIÊNCIA DA ADUBAÇÃO FOLIAR COM ZINCO EM ARROZ DE TERRAS ALTAS

Elevar a produtividade do arroz de terras altas por meio do adequado balanco nutricional e uma excelente estrategia para busca da sustentabilidade do sistema produtivo, principalmente em solos com condicoes limitantes ao cultivo. O presente trabalho objetivou avaliar o efeito da adubacao com zinco via foliar na cultura do arroz de terras altas em solo calcareado para elevacao da saturacao por base para 60% e com diferentes niveis de fosforo, na produtividade de graos, nos componentes de rendimento e na intensidade de dano da broca do colmo ( Diatraea saccharalis ). O experimento foi instalado em Latossolo Vermelho distrofico, na Universidade Estadual de Goias, em Ipameri, GO. O delineamento experimental empregado foi o de blocos completos casualizados, em esquema fatorial 2 (90 e 150 kg ha -1 de fosforo no solo) x 5 (0, 1, 2, 3 e 4 numero de aplicacoes de zinco via foliar), com duas testemunhas adicionais (5,0 kg ha -1 de ZnSO 4 no solo com 90 e 150 kg ha -1 de fosforo) e quatro repeticoes. Os dados foram submetidos a analise de variância e ao teste de Tukey, sendo que, para o efeito de doses, foram ainda submetidos a analise de regressao, todos a 5% de probabilidade. As frequencias de aplicacoes foliares de zinco nao influenciaram as variaveis avaliadas. Nao houve efeito depressivo do fosforo sobre a eficiencia da adubacao com zinco, tanto foliar como via solo. A adubacao com zinco no solo, de forma exclusiva, proporcionou produtividades medias de graos equivalentes a adubacao foliar em solo com menor nivel de fosforo, e superiores a adubacao foliar em solo com maior nivel de fosforo.