Although much appreciated in Brazil, commercial popcorn is currently cropped on a fairly small scale. A number of problems need to be solved to increase production, notably the obtaintion of seeds with good agronomic traits and good culinary characteristics. With the objective of developing superior genotypes in popcorn, a second cycle of intrapopulation recurrent selection based on inbred S 1 families was carried out. From the first cycle of selection over the UNB-2U population, 222 S 1 families were obtained, which were then divided into six sets and evaluated in a randomized complete block design with two replications within the sets. Experiments were carried out in two Brazilian localities. The analysis of variance revealed environmental effects for all evaluated traits, except popping and stand, showing that, for most traits, these environments affected genotype behavior in different ways. In addition, the set as source of variation was significant for most of the evaluated traits, indicating that dividing the families into sets was an efficient strategy. Genotype-by-environment interaction was detected for most traits, except popping expansion and stand. Differences among genotypes were also detected (1% F-test), making viable the proposition of using the genetic variability in the popcorn population as a basis for future recurrent selection cycles. Superior families were selected using the Smith and Hazel classic index, with predicted genetic gains of 17.8% for popping expansion and 26.95% for yield.
-Reciprocal recurrent selection among full-sib families is one of the outstanding methodologies of maize improvement, since gains are possible in the per se and/or in cross populations. Here the selection index proposed by Smith and Hazel was used in the cited methodology; besides, an additional phase involving RAPD markers was introduced to preserve the genetic variability of the selected genotypes and identify contaminants before their recombination. Multivariate techniques of grouping and discriminant analyses were used for this purpose, to assure the continuance of the improvement program and amplify the genetic distance between the populations Cimmyt and Piranão, which were used for an intervarietal hybrid. The molecular technique proved useful to identify contaminants and helpful in the choice of the genotypes to be recombined to maximize heterosis among populations. The technique can be included in recurrent selection programs, mainly those that target the development of hybrids.
Com o objetivo de investigar a capacidade combinatória, bem como o efeito recíproco em dialelo envolvendo genótipos de milho doce e comum, avaliaram-se seis caracteres de interesse agronômico e industrial: altura de plantas, estande, porcentagem de espigas atacadas por pragas, teor de proteína no grão, peso médio de espiga sem palha e comprimento médio de espiga sem palha. Os valores dos quadrados médios referentes à capacidade geral de combinação (<IMG SRC="/img/revistas/hb/v23n1/a26img01.gif">) e capacidade específica de combinação (Sij) foram significativos para as características altura de planta, peso médio de espiga sem palha, comprimento médio de espiga sem palha e teor de proteína no grão, indicando a presença de efeitos gênicos aditivos e não aditivos no controle dos caracteres. Para peso médio de espiga sem palha e comprimento médio de espiga sem palha, as médias dos quadrados dos efeitos não diferiram, sugerindo a utilização de métodos intrapopulacionais ou interpopulacionais de melhoramento. Os genótipos Doce 13 e Sol da Manhã são os mais indicados para programas de melhoramento pelo comportamento dos valores de <IMG SRC="/img/revistas/hb/v23n1/a26img01.gif">. Com base nos efeitos de Sij, o melhor híbrido foi Doce 13 X Sol da Manhã.
Strawberry (Fragaria x ananassa) stands out among small fruits as the most planted in Brazil, generating considerable income and employment. However, producers are dependent on cultivars originating from international breeding programs and imported seedlings. This entails high costs and plants poorly adapted to the edaphoclimatic conditions of Brazil. In addition, the consumer market demands superior organoleptic and nutritional qualities. We assessed the potential of 194 hybrids for production and physicochemical characteristics from a population of seedlings obtained from intraspecific crosses of the short-day cultivars Dover, Camarosa, Sweet Charlie, Oso Grande, Milsei Tudla, and Festival Florida and the day-neutral cultivar Aromas. The experimental design was an augmented block design that had as control treatments the cultivars Camarosa and Camino Real. Five production and nine physicochemical characteristics were assessed. The mean comparison was performed by the Dunnett test. Among the 14 characteristics analyzed, eight presented significance. The significant production characteristics were the number of commercial fruits, mass of commercial fruits, mass of non-commercial fruits, and the total mass ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (2): gmr18156 E. Barth et al. 2 of fruits, with values of 45.03 fruits/plant, 13.17 g, 72.22 g/plant, and 720.77 g/plant, respectively. The physicochemical characteristics that varied significantly were soluble solids to titratable acidity ratio, pectin, ascorbic acid, and anthocyanin, which presented values of 10.23, 2.06 g total pectin/100 g pulp, 71.12 mg ascorbic acid/100 g pulp, and 39.51 mg cyanidin 3-glycoside/100 g pulp, respectively. The crosses that involved Camarosa and Aromas gave a greater number of hybrids with superior positive effects when compared to the controls in terms of production and physicochemical characteristics, respectively. Among the 194 hybrids, 30 were superior to the controls and were selected to advance in the breeding program.
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