Quantitative variation in the tropical maize population, ESALQ-PB1

Abstract

Good yield and intermediate plant height, ear height, and tassel size characterize the maize population ESALQ-PB1 as an outstanding breeding population. Estimates of genetic parameters are reported for 13 traits: plant height (PH), ear height (EH), ear placement (EP), tassel length (TL), tassel weight (TW), tassel branch number (TB), ear weight (EW), total grain weight (GW), ear length (EL), ear diameter (ED), kernel row number (RN), kernel number per row (KR) and prolificacy (PR). Results refer to one location and one year. Genetic variation was detected for all traits, and the estimates of the additive genetic variance are presented. The coefficients of heritability (individual basis) varied from 0.14 to 0.72 and were considered high for PH, EH and TB; intermediate for EP, TL, TW, EL, EP, ED and RN, and low for EW, GW, KR and PR. The coefficient of heritability (progeny mean basis) showed approximately the same trend and varied from 0.40 to 0.75. The highest expected gain from selection was for TB (27% per cycle) under mass selection and for TW (16.4%) under progeny selection; the lowest expected gain was for ED either for mass selection (1.9%) or progeny selection (2.9%). Additive correlation coefficients (r A ) of 0.5<r A <0.6 were found for PH or EH and yield traits (EW and GW) and its components EL and KR, and 0.10<r A <0.44 for PH or EH and tassel traits. For the tassel traits the highest correlation was r A = 0.63 (TB.TW). EP was positively correlated with TB, TW, PH, EH and PR; and negatively correlated with ED and RN. The expected correlated responses in several traits after selection for GW, EH and TB are given. Key words: genetic parameters, genetic variability, heritability, recurrent selection VARIAÇÃO QUANTITATIVA NA POPULAÇÃO TROPICAL DE MILHO, ESALQ-PB1RESUMO: A boa produtividade e os valores intermediários para altura da planta e altura da espiga caracterizam a população de milho ESALQ-PB1 como agronomicamente promissora. São relatadas estimativas de parâmetros para 13 caracteres: altura da planta (PH), altura da espiga (EH), posição relativa da espiga (EP), comprimento do pendão (TL), peso do pendão (TW), número de ramificações do pendão (TB), peso de espigas (EW), peso de grãos (GW), comprimento da espiga (EL), diâmetro da espiga (ED), número de fileiras de grãos (RN), número de grãos por fileira (KR) e prolificidade (PR). Os resultados se referem a um único ambiente (um local e um ano). Foi detectada variação genética para todos os caracteres, e são apresentadas estimativas da variância genética aditiva. Os coeficientes de herdabilidade (indivíduos) variaram de 0,14 a 0,72 e foram considerados altos para PH, EH e TB; intermediários para EP, TL, TW, EL e ED, e baixos para EW, GW, KR e PR. O coeficiente de herdabilidade para médias de progênies mostrou aproximadamente a mesma tendência, variando de 0,40 a 0,75. O maior ganho esperado por seleção foi para TB (27% por ciclo) sob seleção massal e para TW (16,4%) por seleção entre progênies; o menor ganho esperado foi para ED, tanto por ...

Association of secondary traits with yield in maize F 1 's

“…In the analysis of the correlation pairs, the magnitude of genotypic relations is superior to the phenotypic correlations, indicating that genotypic components have greater magnitude in the total correlation (FALCONER & MACKAY 1996). The genetic correlation is important because it represents the heritable fraction of the parent characters to progeny, usually caused by effects of pleiotropic or linked genes, being one important attribute in breeding programs (COIMBRA et al, 2005;LOPES et al, 2007;ANDRADE & MIRANDA FILHO, 2008;HALLAUER et al, 2010;TOEBE & CARGNELUTTI FILHO, 2013).…”

“…With the decomposition of estimates via path analysis, direct magnitudes on grain yield are lower, with the linear relationshipbeing superior because of DLN that indirectly influence the NPB (Table 2). The number of branches has high heritability; therefore, the selection would become very efficient in reducing the number of branches (ANDRADE & MIRANDA FILHO, 2008). GERALDI et al (1985), noting the Table 2 -Results of the phenotypic and genotypic path analysis of nine independent characters on grain yield (dependent character).…”

“…Considering that the removal of the tassel is a practice that requires high labor and is costly, it has become unviable, thus the selection of lines with fewer secondary branches would be effective for obtaining increased corn kernels yield (ANDRADE & MIRANDA FILHO, 2008).…”

“…The literature presents some studies on the relationship between characters of agronomic importance to the corn crop, via path analysis (LOPES et al, 2007;ANDRADE & MIRANDA FILHO, 2008;BARROS et al, 2010;TOEBE & CARGNELUTTI FILHO, 2013). For secondary morphological characters, there are few studies linking them with the yield of corn grain.…”

Phenotypic, additive genetic and environment correlations of maize landraces populations in family farm systems

“…), v.67, n.6, p.685-691, November/December 2010 fore, the selection for another trait may result in indirect response in the low heritable trait, provided the following conditions are satisfied: the genetic correlation between them is substantial, and the heritability of the secondary trait is greater than that of the primary trait (Hallauer and Miranda Filho, 1995). Many authors have estimated genetic correlations among different maize traits in different maize types (Lemos et al, 1992;González et al, 1994;Pinto et al, 2000;Silva et al, 2001;Farias Neto and Miranda Filho, 2001;Saleh et al, 2002;Granate et al, 2002;Daros et al, 2004;Santos et al, 2005;Andrade and Miranda Filho, 2008). However, there is limited published research with genetic correlation estimates for maize landraces.…”