Percentage Of Caryopses Research Articles

ESTIMATIVA DO GANHO GENOTÍPICO POR MEIO DA SELEÇÃO EM GERAÇÃO SEGREGANTE DE AVEIA

A seleção de genótipos superiores busca explorar ao máximo a variância genética aditiva e, com isso, atribuir aos caracteres selecionados, no próximo ciclo de seleção, um maior potencial. Para isso, é interessante que o melhorista conheça a eficiência que pode ser alcançada quando da utilização de um método de seleção em populações segregantes. Assim, o presente trabalho foi proposto com o objetivo de determinar o ganho genotípico, considerando o diferencial de seleção e a herdabilidade no sentido amplo, estimado em caracteres agronômicos e de qualidade do grão da aveia por meio da seleção realizada na geração F3. O experimento foi conduzido no município de Pato Branco, Região Sudoeste do Estado do Paraná, durante o ano de 2001. Os estudos realizados envolveram os caracteres ciclo vegetativo, estatura de planta, peso de panícula, número de grãos/panícola, peso médio de grãos e percentual de cariopse em quatro cruzamentos de aveia branca, UPF 7 X OR 2, UPF 7 X CTC 5, OR 2 X CTC 5 e OR 2 X UPF 18. Os coeficientes de herdabilidade no sentido amplo apresentaram maiores valores para os caracteres ciclo vegetativo (0,60), peso médio de grãos (0,68) e percentual de cariopse (0,40). O diferencial de seleção foi mais expressivo para os caracteres diretamente relacionados a produção de grãos e, juntamente com os valores de herdabilidade no sentido amplo, resultaram em elevado ganho genotípico considerando que os mesmos representaram um único ciclo de seleção.

Relações entre a adubação nitrogenada e a qualidade de grãos e de sementes em aveia branca

Com o objetivo de avaliar o efeito da adubação nitrogenada sobre atributos qualitativos dos grãos e das sementes em aveia branca, foi conduzido experimento envolvendo os cultivares, CTC 5, UFRGS 15, UFRGS 19 e UPF 18, e 0, 24, 48 e 73kg ha-1 de N como doses de adubação, em Argissolo Amarelo eutrófico típico, com 26,7g dm-3 de matéria orgânica. A qualidade industrial dos grãos foi avaliada através do peso do hectolitro de grãos (PH), do teor de proteína e do rendimento industrial; a qualidade das sementes foi estimada pelos testes de germinação e de envelhecimento acelerado. Independentemente do cultivar considerado, o incremento, nas doses de adubação nitrogenada reduz o peso do hectolitro, eleva a concentração de proteína nas cariopses e a produção de proteína e não afeta o rendimento industrial e a qualidade fisiológica das sementes.

Atributos de desempenho industrial e qualidade de sementes em aveia branca em função da disponibilzação da adubação nitrogenada

O presente trabalho teve como objetivo avaliar os efeitos da adubação nitrogenada sobre atributos de desempenho industrial e na qualidade fisiológica de sementes em aveia branca (Avena sativa L.). O ensaio constou da combinação fatorial de cultivares (CTC 5, UFRGS 15, UFRGS 19 e UPF 18) e disponibilizações de N (ausência de aplicação de N; aplicação de 48kg ha-1 na semeadura; aplicação de 16kg ha-1 na semeadura e 32kg ha-1 no perfilhamento; aplicação de 16kg ha-1 na semeadura, 16kg ha-1 no perfilhamento e 16kg ha-1 na emergência da panícula). As disponibilizações de N não afetaram o peso do hectolitro, o rendimento industrial e a qualidade fisiológica das sementes. A aplicação de N na emissão da panícula elevou a concentração de proteína nas cariopses.

THE USE OF SODIUM HYPOCHLORITE IN TESTING THE SEED VIABILITY OF WILD OATS

When seeds of wild oats (Avena fatua L.) were imbibed in water for 24 h, followed by 24-h immersion in 6% sodium hypochlorite (NaOCl), the hulls were completely degraded. The embryos were clearly defined before the hull was completely degraded. Several hours were required for the maximum number of sharply defined embryos to develop after NaOCl treatment to dry seeds, and hull degradation was less rapid in these seeds relative to seeds that had been previously imbibed in water for 24 h. The maximum percentage of caryopses with sharply defined embryos was found to be closely correlated to percentage of viable seeds estimated by germination plus tetrazolium tests; thus the NaOCl treatment can be used to estimate the viability of wild oat seeds.

Selection for Caryopsis Percentage in Oats1

Three populations of oats (Avena saliva L.) were developed to study caryopsis percentage, the proportion of whole kernel that is caryopsis. Information was obtained on the heritability of the character, the relative importance of component changes in effecting changes in caryopsis percentage, and the relationship of the character to other important agronomic characteristics. F2‐derived F4 families were grown in the field in 1970 and bi‐directional selection was practiced for caryopsis percentage. A group of random lines also was used to provide an estimate of the unselected population mean. Selected and random lines were evaluated at two locations in 1971. Effectiveness of selection was measured by comparing selected with random line means. Realized heritability estimates were calculated for caryopsis percentage, and correlated responses were calculated for several important agronomic traits. Selection for caryopsis percentage was effective in all three populations. Differences in the magnitude of response among populations agreed well with theoretical expectations. Small but significant genotype × location interactions were detected. Realized heritability estimates for caryopsis percentage ranged from 0.34 to 0.72, all statistically significant. Genetic variability for caryopsis percentage was considerably reduced by a single cycle of selection. Progress in selection for caryopsis percentage could be attributed to changes in either caryopsis weight or hull weight or to changes in both. Correlated responses of agronomic characters were not consistent across populations and were not of sufficient magnitude to be a serious consideration when selecting for high caryopsis percentage.

Heritability of Oat Caryopsis Percentage and Other Grain Quality Components1

Three oat (Avena sativa L.) crosses involving parents with a wide range of caryopsis percentage and other grain quality components were studied in F2, F3, and F4. A single backcross was studied in BCF1 and BCF2. Primary caryopsis percentage of parents averaged 80.3% for ‘Q.O.30.28,’ 77.1% for ‘RL 2123.38,’ 73.1% for ‘Beedee,’ and 71.5% for ‘Coker 61‐13.’Progeny caryopsis percentages were generally within observed parental values with mean values approximating those of the midparents. The mean of the backcross progenies approached the high caryopsis percentage of the recurrent parent.Heritability estimates for primary caryopsis percentage by variance components were high with the exception of Q.O.30.28/RL 2123.38 where both parents were high in caryopsis percentage. Heritability estimates ranged from 0.36 for Q.O.30.28/RL 2123.38 to 0.93 for Q.O.30.28/Coker 61‐13. Estimates of genetic advance ranged from 0.51 to 3.95%, suggesting that increases above midparent and near high parent values could be attained by selecting for high caryopsis percentage. The data suggest difficulty in isolating segregates with more than 80% caryopsis.

Seed Yield, Seed Quality, and Total Establishment Capability of Indiangrass1

Relationships between criteria of seed quality and seed yield were studied in indiangrass, Sorghastrum nutans (L.) Nash. Quality and yield criteria also were evaluated as criteria of total establishment capability (TEC), the number of offspring established from seed produced per unit area under given conditions. Quality criteria were: caryopsis weight, seed set, caryopsis percentage, spikelet germination, and percentage of field establishment. Yield criteria were: spikelet yield, caryopsis yield, and number of spikelets per plot of the seed‐productionn ursery. Of the three yield criteria, caryopsis yield correlated most, and numbeorf spikelets, least with quality criteria. All quality and yield criteria were positively associated with TEC. Caryopsis yield was more, highly correlated with TEC than any other criterion not used directly to calculate TEC. Implications of component relationships are discussed in connection with various correlations. In covariance analyses significant seed‐source differences in TEC were generally more attributable to variation in caryopsis yield than to differences in other yield or quality criteria. Caryopsis yield was considered satisfactory as a single criterion of TEC so long as intensive selection for TEC is not anticipated. Where improvement in TEC was a primary breeding objective, however, it seemed hazardous to ignore such quality criteria as spikelet germination and caryopsis weight.

Caryopsis Percentage and Related Characters in Early Generations of Avena Sativa L.1

Heritability estimates in the broad sense, based on F2 variances for three oat, Avena saliva L., crosses, ranged from .52 to .76 for primary caryopsis percentage. Heritability estimates for primary caryopsis percentage, primary kernel weight, and primary caryopsis weight were similar in two crosses. Heritability for caryopsis percentage was higher than heritability for kernel weight and caryopsis weight in one cross. The F1 and F2 data suggest that multiple factors influence oat caryopsis percentage and that the effects are primarily additive.