Potential of twenty exotic germplasms to improve Brazilian maize architecture

Abstract

Temperate and temperate x tropical germplasms were introduced into the maize breeding of the Department of Genetics (ESALQ-USP). Twenty populations designated as P-1 to P-20 and a check population were evaluated in a randomized complete block design with two replications at Piracicaba, SP, Brazil. Plots were 2.0 m long, spaced 1.0 m apart, with 10 plants per plot after thinning. The following traits were evaluated: PH, plant height; EH, ear height; TB, tassel branch number; KW, 100 kernels weight; EL, ear length; ED, ear diameter; KR, kernels per row, and RN, number of rows of kernels. The means of the exotic populations showed a variation in performance for all traits. The population means were greater than check means for KW, EL, and KR. Populations P-9, P-10, P-12, and P-13 showed low relative ear placement values (EH/PH index), indicating that these materials could contribute to lower ear placement in local populations. P-1 and P-9 showed a high potential to reduce TB. The phenotypic correlation coefficients among populations were positive for most combinations, except for RN with PH, EH, TB, and KW. Predictions of 19 composite means were obtained for all traits.<br>Vinte populações de milho foram introduzidas dos Estados Unidos, representando germoplasmas originários de clima temperado e tropical x temperado. As populações e uma testemunha foram avaliadas na área experimental do Departamento de Genética (ESALQ/USP) em experimento em blocos casualizados com duas repetições. Os seguintes caracteres foram avaliados: altura da planta (PH), altura da espiga (EH), número de ramificações do pendão (TB), peso de 100 grãos (KW), comprimento da espiga (EL), diâmetro da espiga (ED), número de grãos por fileira (KR) e número de fileiras de grãos (RN). A variação observada nas médias das populações exóticas para todos os caracteres foi devida à adaptação diferenciada desses genótipos no ambiente estudado. As populações exóticas apresentaram médias superiores à testemunha para peso de 100 grãos, comprimento da espiga e número de grãos por fileira. As populações P-9, P-10, P-12 e P-13 mostraram baixos valores para posição relativa da espiga, sendo consideradas promissoras para reduzir esse índice nas populações locais. P-1 e P-9 são indicadas para diminuir o número de ramificações do pendão. Os coeficientes de correlação fenotípica entre populações foram positivos para todas as combinações, exceto para número de fileiras de grãos com altura da planta, altura da espiga, número de ramificações do pendão e peso de 100 grãos. Algumas populações exóticas apresentaram elevado potencial para contribuir no melhoramento da arquitetura das plantas em populações adaptadas. Foram obtidas predições de médias de 19 compostos, para os oito caracteres, envolvendo as populações exóticas estudadas

Genetic Enhancement of Semi-Exotic Maize Germplasm

“…The lower mean yield of set V shown in the present work is in accordance with the results discussed by Miranda Filho (1992). On the other hand, results reported by Regitano Neto et al (1997)…”

Partial diallel analysis among maize lines for characteristics related to the tassel and the productivity

“…According to Neto et al (1997), this character has taken attention of breeders in breeding programs, showing that the reduced size of the tassel is favorable for the increase of grain production, mainly to the adverse conditions of stress. The current hybrids have already suffered major reductions in the number of tassel branches, which is directly related to lower production of pollen per area.…”

“…have been gaining more attention from plant breeders in the prediction of crossings of inbred lines for tassel size reduction, due to the increased energy expenditure and the morphological changes associated with other phenotypic characteristics, as well as the gene actions that are involved in the expression of the characters (Neto et al, 1997;Sangoi et al, 2002;Westgate et al, 2003;Edwards, 2011). Allied with these reasons, this study aimed to estimate the combining ability of maize inbred lines belonging to two heterotic groups by partial diallel analysis, to predict the best combinations, in the characters related to the tassel and grain yield, and identification of predominant gene effects for the characters in five environments.…”

LETTER Partial diallel crosses for predicting yield of semiexotic maize populations

“…In Brazil, the great variability that characterize the maize germplasm has a significant contribution of exotic sources that largely contributed to increase the efficiency of breeding programs for the development of cultivars Santos and Miranda Filho, 1992;Regitano Neto et al, 1997). Old local varieties such as Cateto and Dente Paulista were the first sources for the development of the hybrid seeds.…”