Evaluation of 10 Generations of Mass Selection for Corn Earworm Resistance¹

Abstract

Mass selection for resistance to corn earworm (Heliothis zea (Boddie)) was made in two corn, Zea mays L., populations (Synthetics C and S) grown in isolation for 10 generations during the period 1956 to 1965. Plantings were made on or about 15 June to enhance the chances for a high infestation of earworm. From each planting at least 1,000 ears were classified into three categories: (1) penetration of the earworm to the kernel resulting in damage, (2) earworm entry into the silk channel but no kernel damage, and (3) no evidence of earworm entry into the silk channel. Ears from class 2 were used for planting the subsequent cycleIn 1965, remnant seed of five cycles (spanning the 10 generations) for each synthetic was increased by sibpollinating approximately 200 plants. Evaluation tests were grown at two locations in 1966.Mass selection in both synthetics was effective. for Synthetic C the percentage of ears with kernel damage was reduced from 80.8% (1957) to 58.7% (1965), a reduction of 2.76% per generation. The percentage of ears with earworm damage for Synthetic S was reduced from 64.5% (1956) to 39.2% (1965). The average reduction per generation was 2.81%

Efeito da seleção para produção e qualidade protéica no grau de dano da lagarta-da-espiga, Heliothis zea em populações de milho opaco

“…ZUBER et alii (14), após dez ciclos de seleção massal para resistência a H. zea, em duas populações de milho (sintéticos C e S), evidenciaram que a seleção foi efetiva. Para o sintético C, a porcentagem de espigas com grãos danificados foi reduzida de 80,8 para 58,7, com uma redução de 2,76% por ciclo, enquanto no sintético S houve uma redução de 64,5% para 39,2%, isto é, 2,81% por ciclo.…”

“…Os resultados, todavia, diferiram daqueles obtidos por ZU-BER et alii (14), pois nenhum progresso foi conseguido para resistência à lagarta-da-espiga, após cinco ciclos de seleção.…”

Evaluation of mass selection for grain yield and estimation of genetic variability in three selected maize (Zea mays L.) populations

“…He described a breeding scheme similar to that described by Jenkins (1940); the only modification was the use of a narrow genetic base tester (a homozygous line) as the tester. Hull (1945) e.g., prolificacy (Kincer and Josephson, 1976;Lonnquist, 1967), ear length (Hallauer, 1968;Cortez-Mendoza and Hallauer, 1979), ear height (Acosta and Crane, 1972), early silking (Hallauer and Sears, 1972;Troyer and Brown, 1972), insect resistance (Zuber et al, 1971) Gardner (1969Gardner ( , 1973 reported a gain of 3% per cycle after 15 generations. After the l5th cycle, a yield reduction was observed, and it was hypothesized that genotype-environment interaction had caused a lack of response in later cycles of selection (Gardner, 1977(Gardner, , 1978Mareck and Gardner, 1979).…”

Mass-selection strategies for pearl millet improvement

“…It can be either the sole breeding procedure or it can be one component of a progeny evaluation program (Lonnquist, 1964). Response from mass selection depends upon the magnitude of the selection differential, the parental control, and the heritability of the trait under selection Mass selection has been used to modify a wide array of traits such as oil content of seeds (Sprague et al, 1952), prolificacy (Lonnquist, 1967), ear height (Vera and Crane, 1970), ear length (Cortez-Mendoza and Hallauer, 1979), time of flowering (Troyer and Brown, 1976), and reduced earworm (Hellothis zea Boddie) damage (Zuber et al, 1971) of maize (Zea mays). It has been used to increase grain yield of maize and oats (Avena sativa L.) when the selection nursery was gridded (Gardner, 1961;Chandhanamutta and Frey, 1973).…”