Waldênia de Melo Moura

Divergência genética em linhagens de pimentão em relação à eficiência nutricional de fósforo

Avaliaram-se 10 linhagens de pimentao (Capsicum annuum L.) quanto a eficiencia nutricional em relacao ao P, bem como a dose de P mais adequada para estudos geneticos, e o carater que mais contribuiu para a divergencia genetica. O experimento foi conduzido em casa de vegetacao, em solo, na Universidade Federal de Vicosa. Os tratamentos foram distribuidos em arranjo fatorial 10 x 5 x 4, constituidos de 10 linhagens, cinco doses de P (0, 250, 500, 750 e 1.000 mg de P/kg de solo) e quatro repeticoes, em delineamento de blocos casualizados. Em cada dose de P aplicada ao solo foi realizada uma analise multivariada. Constatou-se variabilidade genetica entre as linhagens estudadas em todas as doses de P adicionadas ao solo, sendo a dose 250 mg de P/kg de solo a que melhor discriminou as linhagens; portanto, a mais indicada para estudos geneticos. Com essa dosagem, constatou-se que a producao de materia seca da parte aerea foi o carater que mais contribuiu para a divergencia genetica entre as linhagens, podendo ser um parâmetro adequado para selecao em estudos geneticos.

Eficiência nutricional para fósforo em linhagens de pimentão

Ten sweet pepper lines were screened for phosphorus efficiency. An experiment was carried out in the greenhouse in pots filled with 5 dm3 of clayey latosol soil samples. The treatments followed a randomized complete block design, in a factorial layout (10 x 5 x 4), comprising ten lines, five doses of P (0; 250; 500; 750 and 1,000 mg of P/kg of soil) and four replications. Results showed genetic variability among lines for P-efficiency, characterized mainly by rooting efficiency, P-uptake and P-use efficiency. Low differences in the P- translocation efficiency were observed. Higher rooting efficiency was not translated into higher acquisition of P from the soil, which suggests that P-absorption was influenced by morphologic and physiologic characteristics of the root system. The L10 line showed high P-efficiency uptake and utilization, followed by the L8 line. The L1, L2 and L6 lines, were the least efficient in the P-utilization. The other lines showed variable performance in P-efficiency, according to the index used. The large variability observed might be explored in genetic improvement programs aiming to increase the nutritional efficiency for P.

GENETIC DIVERSITY IN ARABICA COFFEE GROWN IN POTASSIUM-CONSTRAINED ENVIRONMENT

Potassium is a source of non-renewable natural resource, and is used in large quantities in coffee fertilization through basically imported formulations in the form of potassium chloride. An alternative to make production systems more sustainable would be obtaining cultivars more efficient in the use of this nutrient. This study aimed to evaluate the genetic diversity among 20 cultivars of coffee, in conditions of low availability of potassium to identify the best combinations for composing future populations to be used in breeding programs. The experiment was arranged in a randomized block design with three replications of nutrient solution. Agronomic characteristics and efficiencies of rooting, absorption, translocation, biomass production and potassium utilization were evaluated. The clustering analysis was based on the unweighted pair group method with arithmetic mean clustering algorithm (UPGMA) and canonical variables. Variability was observed for most treatments. The multivariate procedures produced similar discrimination of genotypes, with the formation of five groups. Hybridizations between the cultivar Icatu Precoce IAC 3283 with cultivars Catuai Amarelo IAC 62, Araponga MG1, Caturra Vermelho IAC 477, Catuai Vermelho IAC 15, Rubi MG 1192 and Catucai 785/15, and between the cultivar Tupi IAC 1669-33 with cultivars Icatu Vermelho IAC 4045, Acaia Cerrado MG 1474 and Oeiras MG 6851 are the most promising for obtaining segregating populations or heterotic hybrids in breeding programs aiming more efficiency in potassium utilization.

Desempenho agronômico de genótipos de trigo em duas condições de cultivo: Sequeiro e irrigado - DOI:10.5039/agraria.v7i3a1785

Three experiments were conducted in the field, in the 2009/2009 season, under two conditions of cultivation, Dry farming and irrigated. Consisted of four cultivars suitable for Minas Gerais, two for upland conditions (MGS1 Alliance and MGS Bright) and two for cultivation with irrigation (BRS 264 and BRS 254), and twenty-six strains of EPAMIG in final evaluation . This study aimed to evaluate grain yield and hectolitre weight of different wheat genotypes ( T. aestivum L.) which grows under normal irrigation condition (no stress) and dry farming conditions (water stress), at two locations in the State of Minas Gerais. The statistical design was in randomized blocks, with thirty three replications. In the analysis of variance significant differences were observed among genotypes for all variables in all crop conditions, except for grain yield in Patos de Minas when grown under dry farming conditions. All variables showed significant differences, except for grain production, for the effect of genotype-environment interaction. The existence of high diversity among the three environments resulted differences between the response patterns of genotypes tested, the higher grain yield in irrigated environment and hectolitre weight in dry environments; Lines EP 063053, EP 063074, EP 063111, EP 063136, EP 064011 and EP 064035 had a lower risk, when considering two variables evaluated in the two crop conditions.