Maize Breeding Research Papers - Academia.edu (original) (raw)

Gray leaf spot (GLS) caused by Cercospora zeae-maydis or Cercospora zeina is one of the devastating maize foliar diseases worldwide. Identification of GLS-resistant quantitative trait loci (QTL)/genes plays an urgent role in improving GLS resistance in maize breeding practice. Two groups of recombinant inbred line (RIL) populations derived from CML373 × Ye107 and Chang7-2 × Ye107 were generated and subjected to genotyping-by-sequencing (GBS). A total of 1,929,222,287 reads in
CML373 × Ye107 (RIL-YCML) and 2,585,728,312 reads in Chang7-2 × Ye107 (RIL-YChang), with an average of 10,961,490 (RIL-YCML) and 13,609,096 (RIL-YChang) reads per individual, were got, which was roughly equal to 0.70-fold and 0.87-fold coverage of the maize B73 RefGen_V4 genome for each F 7 individual, respectively. 6418 and 5139 SNP markers were extracted to construct two high-density genetic maps. Comparative analysis using these physically mapped marker loci
demonstrated a satisfactory colinear relationship with the reference genome. 11 GLS-resistant QTL have been detected. The individual QTL accounted for 1.53–24.00% of the phenotypic variance explained (PVE). The new consensus QTL (qYCM-DS3-3/qYCM-LT3-1/qYCM-LT3-2) with the largest effect was located in chromosome bin 3.05, with an interval of 2.7 Mb, representing 13.08 to 24.00% of the PVE. Further gene annotation indicated that there were four candidate genes (GRMZM2G032384, GRMZM2G041415, GRMZM2G041544, and GRMZM2G035992) for qYCM-LT3-1, which may be related to GLS resistance. Combining RIL populations and GBS-based high-density genetic maps, a new larger effect QTL was delimited to a narrow genomic interval, which will provide a new resistance source for maize breeding programs.

- by
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- Genetics, Molecular Biology, Biology, Agriculture

Maize ear rots caused by Aspergillus flavus, Fusarium graminearum and Stenocarpella maydis reduce the quality of maize through production of mycotoxins and carcinogenic compounds that are harmful to both humans and animals when consumed. The objective of this study was to determine the relationship between yield and fungal ear rot infections caused by the three fungal pathogens. Tropical inbred lines with varying resistance to A. flavus and both F. graminearum and S .maydis were mated in a North Carolina II Design. The progeny consisting of single crosses, test crosses and their parental inbred lines were thereafter evaluated using single pathogen inoculation. Regression of the three ear rot mean infection scores on mean yield scores across three test locations for both the test and single cross hybrids revealed low yieldvariations in response to fungal ear rot infections. Further, it suggests that maize grain yield cannot be reliably predicted from any of the three ear rot pathogen infection scores. This also suggests that multiple resistance to the three pathogens is inherited independently of yield performance. Resistance to the three ear rots and yield performance should be directly evaluated and improved by separate and independent breeding strategies. Résumé Les pourritures du maïs causées par Aspergillus flavus, Fusarium graminearum et Stenocarpella maydis réduisent la qualité du maïs à travers la production de mycotoxines et de composés cancérigènes qui sont nocifs pour les humains et les animaux lorsqu'ils sont consommés dans les aliments. L'objectif de cette étude était de déterminer la relation entre le rendement et les infections des pourritures causées par les trois agents pathogènes fongiques. Des lignés pures de maïs tropical ayant une résistance variable à A. flavus et aux F. graminearum et S. maydis étaient croisées dans le modèle de croisement du North Carolina II. La progéniture composée de croisements simples, les croissements tests et leurs parents lignées pures a ensuite été évaluée en utilisant une inoculation simple de pathogène. La régression des moyennes des scores des trois types de pourritures avec les scores moyens de rendement sur les trois sites expérimentaux à la fois pour les hybrides simples et ceux issus des croisements tests, a révélé une faible variation du rendement en réponse aux infections fongiques. En outre, il est suggéré que le rendement en grain du maïs ne peut être prédit de façon fiable à partir de scores de l'une des trois des agents

- by Chemutai Job and +1
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- Rice Breeding, Maize Breeding, Coffee breeding, Maize ear rot resistance

Heterotic group classification has a crucial impact on maize (Zea mays L.) breeding efficiency in a hybrid-based breeding program. The objectives of this study were to: (i) investigate whether or not breeding efficiency could be improved using a three heterotic-group (TriHG) classification (Reid and non-Reid, and Suwan1 heterotic groups) system instead of a usual two heterotic-group (DiHG) classification (Reid and non-Reid heterotic groups) system; and (ii) estimate the impact of TriHG and DiHG systems on breeding efficiency, utilizing the same data in computing specific breeding efficiency (SBE) and general breeding efficiency (GBE) in a subtropical breeding program in southern China. Twenty-five adapted tropical and subtropical lines were crossed to six testers using a line × tester mating design. Data on grain yield were used to calculate SBE and GBE for comparing DiHG- and TriHG-based strategies. The TriHG classification system increased GBE by 77.8% over the DiHG system without a significant loss in SBE. We concluded that the TriHG system was better than the DiHG system for improving maize-breeding efficiency. Therefore, maize breeders may re-think their breeding strategy for improving breeding efficiency in long-term breeding programs by adopting the suggested TriHG system. Hybrid maize improvement programs, especially in the early stages of breeding for identifying hybrids with high yield potential, can be become more efficient by using three testers with one from each of Reid, nonReid, and Suwan1 heterotic groups. This would improve the chances of developing high-yielding hybrids in a breeding program with the available, diverse germplasm.

Utilizar algas y pastos marinos como sustrato para elaborar compostas, es otra forma de emplear un material sin uso aparente, dándole un manejo a estos residuos que abunda en las costas y que no tienen un manejo productivo actualmente. El objetivo de este trabajo fue evaluar el uso del pasto marino Thalassia testudinum como sustrato para la elaboración de compostas y su efecto como abono en la biomasa del maíz. El estudio se llevó a cabo dentro de las instalaciones del CCBA-UADY, en la comisaría de , Mérida, Yucatán. Para los 2 experimentos que conforman este trabajo se utilizó un diseño experimental de bloques completamente al azar. Para el primer experimento se elaboraron 12 unidades de compostaje (UC), divididas en 4 tratamientos con tres repeticiones. Los tratamientos se conformaron por: un testigo a base de cerdaza y viruta, y tres tratamientos a base de pasto marino con tres proporciones de cerdaza. Las variables evaluadas fueron temperatura, pH, C, N y relación C/N. Para el segundo experimento, se utilizaron 5 tratamientos, con 5 repeticiones cada uno, empleando una bolsa por planta de maízcomo repetición. Los 5 tratamientos estuvieron compuestos por los 4 tipos de composta más un tratamiento control empleando solo tierra. Las variables determinadas fueron biomasa, altura de la planta, ancho de las hojas, diámetro de tallo, amplitud y longitud de raíz. Se realizó un análisis de la varianza simple (ANOVA) para todas las variables estudiadas, con una prueba de Rango Múltiple para comparar entre si las medias de los tratamientos. Los resultados obtenidos en el presente estudio indican que las compostas elaboradas con T. testudinum tuvieron un buen desarrollo en el proceso del compostaje. Las compostas elaboradas con pasto marino también mostraron un mayor aporte de nutrientes en las plantas de maíz, reflejado en raíces más desarrolladas, mayor producción de biomasa, con hojas y tallos más anchos, así como una mayor altura respecto al tratamiento testigo con composta de viruta y el control sin composta (P<0.05). Es posible recomendar la utilización de compostas elaboradas con pastos marinos sin importar el porcentaje en combinación de sustratos, ya que eso no influye en un mayor o menor aporte de nutrientes.

ABSTRACT
The introduction and utilization of new maize
(Zea mays L.) germplasm from sources, such as
the International Maize and Wheat Improvement
Center (CIMMYT), can be valuable for broaden-
ing the genetic base of breeding populations
through the introgression of new alleles. Twenty-
five inbred lines, derived from CIMMYT breed-
ing populations, were selected on the basis of
grain color, resistance to turcicum leaf blight,
and per se line performance in Yunnan. To use
the lines effectively, information on their perfor-
mance in hybrid combinations and on general
combining ability (GCA) and specific combining
ability (SCA) needed to be obtained. The objec-
tives of this study were (i) to evaluate these lines
for grain yield (GY) in hybrid combinations and
determine GCA of parental lines and SCA of
crosses between the 25 introduced lines and six
testers using North Carolina Design II; and (ii) to
classify the lines into different maize heterotic
groups. The field testing at three locations iden-
tified crosses with lines from Cateto and Popu-
lation 147 (P147) as having significantly higher
GY than those from SA3 and other introduced
populations, and the high GY was largely attrib-
utable to their high positive GCA effects. Lines
from the same population were not necessar-
ily classified into same maize heterotic group.
Lines selected at S 4 or a later generation would
be expected to have more stable GCA effects
than lines selected in earlier generations.

- by Prof Manjit S Kang
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- Biology, Quantitative Genetics, Plant breeding and genetics, Maize

El objetivo de este trabajo ha sido determinar la calidad química del grano y del aceite extraído de diferentes híbridos experimentales. Entre 2011/12 a 2013/14 se ensayaron 23 híbridos de maíz VEC (waxy y alta lisina) en el campo experimental del Instituto de Genética E.A. Favret-INTA Castelar. Los granos fueron obtenidos mediante polinización controlada para evitar la influencia de polen extraño sobre los atributos químicos. Se tomó una muestra representativa de granos de cada híbrido y se la conservó a 4º C hasta la realización de los análisis. El contenido de aceite, proteína y almidón del grano entero fue determinado mediante transmisión en el infrarrojo cercano (NIT) utilizando un equipo Foss Infratec 1241. Se analizó el perfil de ácidos grasos (AG) de cinco híbridos mediante cromatografía de gaseosa (GC) utilizando detector FID y columna capilar EC-1000 Altech. El análisis NIT reveló que los híbridos analizados tienen un contenido proteico de 9,0 a 14,3%; 4,4 a 7,3 % de aceite y 67,1 a 73,0% de almidón. Se hallaron correlaciones altamente significativas y negativas entre el nivel de proteína y los niveles de aceite y almidón (r= -0,63 y -0,53, respectivamente; p≤ 0,01). En cambio se detectó una asociación significativa y directa entre el nivel de aceite y almidón (r= 0,35; p≤ 0,05). El contenido proteico medio de los híbridos HC superó en 20% al reportado por ILSI Argentina para maíces cultivados en el país. Dieciséis de los híbridos estudiados pueden ser considerados de alto contenido de aceite (6,0% a 7,3%) y por ende son una alternativa óptima en el campo de la alimentación por su aporte calórico y nutricional. Los estudios de GC permitieron detectar que los híbridos HC138 y HC52 tienen alto contenido de ácido oleico (45,2% y 50,3%, respectivamente). Este último híbrido es de alto contenido de aceite (6,5%). Se halló una correlación negativa (r= -0,37 n.s.) entre contenido de ácido oleico y la concentración total de aceite en el grano. En los aceites estudiados se encontró que la razón media entre ácidos poli-insaturados y saturados (Índice P/S) es de 2,8 (rango= 1,6 – 3,7). Los niveles de proteína y aceite hallados en varios de estos híbridos de uso especial (VEC), así como el contenido de ácido oleico y los valores del Índice P/S reflejan la calidad nutricional de los mismos. Los resultados alcanzados sugieren que sería ventajoso emplear estos nuevos materiales como materia prima para la industria alimentaria e incluso tendría ventajas comparativas respecto a otros maíces que ya se cultivan en el país.

- by Victor Corcuera and +1
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- Analytical Chemistry, Near Infrared, Near Infrared Spectroscopy, Maize Breeding

The objective of this work was to identify highly stable specialty corn experimental hybrids through different methods included in the parametric approach and also multivariate analysis. Twelve single-crosses termed HC1 to HC2 were sown in four locations during three running growing seasons (2004/05 to 2006/07). Stability of grain yield was estimated using: coefficient of variation CV%; Finlay & Wilkinson’s regression coefficient bi; Eberhart & Russell’s deviation parameter S2di; Wricke’s ecovalence W and Pinthu’s coefficient of determination r2. Genotype-environment interaction, response patterns, environments classification and genotype stability were also studied through principal components analysis using AMMI 1 and SREG-GEE models. The parametric approach recognized HC1, HC3, HC4, HC9 and HC11 as stable genotypes in relation to yield expression through several environments and considering types of stability. The principal component analysis identified the waxy hybrids HC1 and HC12 as well as the quality protein single-crosses HC6 and HC9 as the most stables and this result partially agrees with those from the parametric approach. The AMMI 1 biplot also revealed that locations Esperanza and Pergamino contributed the most to genotype- by- environment interaction.

- by Victor Corcuera
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- Maize Breeding

To access the genetic variability present on hybrid maize genotypes, a research was carried out at Farmers field of Rapti municipality-7 Chitwan, Nepal during the winter season of 2018. Ten hybrid maize genotypes were replicate thricely in a randomized complete block design. Analysis of variance showed that all the studied traits were significantly different except the number of kernel row per ear, ASI, ear aspect, days to physiological maturity and thousand kernel weight which showed the existence of enough genetic potential present for crop improvement Program. Plant height, ear height, number of kernel row, ear aspect, ear length, thousand kernel weight, and grain yield showed moderate to the high genotypic coefficient of variation, phenotypic coefficient of variation along with high heritability with moderate to high genetic advance as a percentage of the mean. Selection can be performed on those traits showing the high genotypic and phenotypic coefficient of variation, heritability with high genetic advance as a percentage of the mean for yield improvements program. Cluster analysis showed that the hybrid genotypes showed considerable genetic diversity among themselves by occupying three different clusters.

- by bishnu kandel
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- Maize, Maize Breeding, Hybrid maize

Broadening the maize (Zea mays L.) genetic base is essential for
improving grain yield. Suwan1, developed from a broad base of
tropical germplasm in Thailand, has recently been identified as
a heterotic group different from Reid and non-Reid heterotic
groups. The objectives of this study were (i) to evaluate the grain
yield (GY) of crosses to see if there is value to utilizing Suwan1
as a heterotic group in maize breeding, and (ii) to investigate
the general combining ability and specific combining ability to
determine if Suwan1 shows good combining ability with Reid
and non-Reid heterotic groups for GY. Three testers, one from
each of the three heterotic groups, were crossed with 20 elite
lines collected from across China. Eighteen lines improved
via introgression of exotic germplasm and two lines improved
via pedigree selection were crossed with TRL02 (non-Reid),
YML46 (Suwan1), and TRL211 (Reid). Grain yield, ear
length, ear diameter, kernel rows per ear, kernels per row, and
100-kernel weight of crosses and a check were evaluated at three
locations. The results suggested that the Suwan1 x temperate
crossing system was a very useful heterotic pattern. Suwan1
improved all five yield components in crosses and demonstrated
good combining ability for GY with Reid and non-Reid
heterotic groups. We have also determined that the appropriate
percentage of introgressed germplasm should be between 6.25
and 12.5%.

- by Prof Manjit S Kang
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- Genetics, Biology, Agriculture, Quantitative Genetics

A study of heritability and genetic advance was undertaken at the University of Agriculture, Peshawar and Cereal Crops Research Institute, (CCRI) Pirsabak, Nowshera, during 2013 in two crop seasons. In spring crop season (season 1), the testcrosses were developed from maize variety Azam at CCRI. In summer crop season (season 2), the resulting testcrosses were evaluated in a 12×12 partially balanced lattice square design with two replications at The University of Agriculture, Peshawar for different agronomical traits. Data were recorded on days to tasseling, silking, anthesis, anthesis silking interval (ASI), plant height (cm), ear height. Highly significant differences were observed among all the traits in both seasons, while non significant differences were observed for days to tasseling and ASI in season 1. Low to moderate estimation of heritability and genetic advance was observed in both seasons. Moderate level of heritability 0.45 was observed for days to tasseling and ear height in season 2, while low estimation of 0.09 was recorded for days to tasseling in seasons 1. High genetic advance (GA) 6.11 was observed for plant height in season 1, while low (GA) was recorded 0.15 for ASI in season 1. Estimation of heritability and genetic advance for all the parameters were low to moderate which displayed comparatively high environmental influence on the traits expression, hence further evaluation should be carried out in different environments. The TC-97, TC-183, TC-107 in season 1 and TC-187, in season 2, were having desirable ASI and can be utilized as progenitors in succeeding generations of maize breeding programs.

- by Habib Ullah and +1
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- Maize Breeding

This paper draws from research on small-scale maize production in Mexico’s Central Highland region to discuss the geopolitical implications of everyday agricultural practices. An overwhelming majority of maize farmers in this region, as well as in the country more broadly, continue to cultivate locally-adapted maize varieties they have bred themselves – criollo maize is the vernacular term – despite decades of concerted government attempts to effect the widespread adoption of commercially-bred and licensed hybrid varieties. This state effort to restructure agricultural systems and food security according to nationalist and capitalist priorities is one tactic in a long and violent struggle for control over peasant land and labor in Mexico. By integrating feminist scholarship in geopolitics and in political ecology, I am following the lead of geographers who regard the materialities of everyday life as a foundation for political tensions and conflicts that are constantly unfolding along intersecting lines of difference. Though geopolitics has rarely turned its attention directly to theories of intimate socio-ecological relations, I argue that the field has much analytical and political leverage to gain by engaging with political ecology, and that feminist geographic imaginaries provide a crucial space in which to do so. This approach allows for an analysis of how a dominant geopolitics of land and agriculture is being undermined through the routine production of criollo maize, revealing new potential for creating broad political alliances with social movements that are currently working toward alternative visions of agriculture and food security.

- by Emma Gaalaas Mullaney
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- Critical Theory, Agricultural Engineering, Sociology, Feminist Sociology

Hybrids involving diverse parental genotypes generally produce high specific combining ability effects and hybrid vigor. Therefore, the choice of the suitable breeding program depends on the inheritance of the quantitative traits. This research aims at detecting the extent of the genetic diversity (GD) among 8 wheat parental genotypes, and its implication on F1 crosses for biological and grain yield plant-1. Thus the 8 parents were screened using ten RAPD primers. These primers produced 89 fragments, 58 of them were polymorphic. A GD value as high as 0.474 was found just one cross (P1xP4). Half diallel mating, design involving 8 parents, was made to initiate a set of 28 F1 crosses. Parents and their crosses were tested under normal and drought stress conditions for biological and grain yield per plant. Genotypes, general (GCA) and specific (SCA) combining ability were significant for the two traits. The non-additive gene action is substantial in controlling these traits. Five crosses showed all showed relatively high mean performance and SCA effects for both traits in both and across normal and drought environment. For biological and per plant grain yield, Pearson's correlation coefficients with GD were 0.34 and 0.69. Hence, RAPD marker can be used as a tool for determining the extent of genetic diversity among wheat genotypes and to precisely predict the yield performance value for F1 hybrids.

- by Ahmed El Hosary
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- Molecular Marker, Maize Breeding

Eight inbred lines of white maize were crossed in half diallel scheme in 2016 season to assess mean performance, general (GCA) and specific (SCA) combining ability and their interaction with locations. Two experiments were conducted at two locations, viz. Moshthor, (L 1) and Sohag (L 2) using RCBD with 3 replications in season 2017. Each block consisted of 28 F 1 hybrids along with the single cross SC 10. Location mean squares for all traits under study were significant with values in L 1 higher than those in L 2 for grain yield plant-1. Significant hybrid mean squares were observed for all traits in both and across the studied locations, except for shelling% at L2. Significant hybrid x location mean squares occurred for all traits, except for No. of kernels row-1. The crosses P 2 xP 3 , P 1 xP 7 , P 6 xP 8 , P 2 xP 4 , P 1 xP 8, P 4 xP 8, and P 3 xP 5 exhibited significant and positive superiority over SC 10 mean value for grain yield across the two locations and surpassed the check hybrid by 18.19, 18.13, 15.33, 14.97, 14.23, 11.88 and11.72%, respectively. GCA and SCA mean squares were significant for all studied traits, except for GCA concerning No. of rows ear-1 at L 1 and ear diameter at L 1 and combined across locations, SCA at L 2 for No. of rows ear-1 and shelling%. A large part of total variability for ear height, 100-kernel weight and ear weight plant-1 was non-additive gene action. On the contrary, additive and additive x additive gene action was associated with grain yield plant-1. GCA×L and SCA×L interaction mean squares were significant for most studied traits. P3 and P8 expressed positive and significant ĝ i effects for ear and grain yields. The most desirable inter and intra-allelic interactions (ŝ ij effects) were obtained by the combinations; P 1 xP 7 , P 3 xP 5 and P 4 xP 8 for grain yield and ear weight plant-1 .

- by Ahmed El Hosary
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- Maize Breeding

Abstract:
To estimate heritability, genetic advance and correlation for yield traits in rice genotypes, 7 parents and their 16 F2 populations were planted in a randomized complete block design with three replications at The University of Agriculture, Peshawar during 2012. Significant (p ≤ 0.05) differences among the genotypes were observed for days to 50 % heading, culm length, days to maturity, panicle length, primary and secondary branches panicle-1 and grain yield plant-1. Among the F2 populations Dokri-Bas/Bas-6129 produced early heading (94 days) and matured earlier (123.6 days). IR-8/NIAB-IR-9 displayed maximum primary branches panicle-1 (12.13) while Bas-6129/Dokri-Bas showed maximum secondary branches panicle-1(43.6). The highest grain yield (59.5 g) was recorded for Dokri-Bas/Pakhal. High heritability estimation was observed for all the studied traits associated with high selection response. IR-8/Shahdab-31 showed maximum heritability (0.92) and maximum selection response (6.91 cm) for panicle length. For primary branches panicle-1, maximumheritability (0.89) was displayed by Bas-6129/Dokri-Bas while maximum selection response (2.67) was observed for Bas-2008/TN-1. For secondary branches, Bas-2008/TN-1 had maximum heritability (0.97) and maximum selection response (19.82). The highest heritability (0.95) and selection response (25.60 g) was manifested for Dokri-Bas/DR-92 for grain yield plant-1. Positively significant phenotypic correlation of days to heading was observed with days to maturity, panicle length, and primary and secondary branches panicle-1. As a result of high heritability and high genetic advance for yield related traits, the populations IR-8/Shahdab-31, Bas-6129/Dokri-Bas, Bas-6129/Bas-370, Bas-2008/TN-1, IR-8/NIAB-IR-9, Dokri-Bas/DR-92 and Dokri-Bas/Pakhal could be utilized as progenitors in succeeding generations of rice breeding programs.

- by Habib Ullah
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- Maize Breeding

ARTICLE INFO ABSTRACT Maize (coefficient estimates and path analysis. This critical review discusses some systematic errors that have been observed in impacts on accuracy of path analysis. In a first moment, an approach about the maize crop, origin, characteristics and biometric models commonly used in genetic breed crop is presented. Some obstacles found in estimates of path coefficients and the methods used to adjust them are discussed. We also present evidences and a theoretical explanation that some data arrangement methods currently used, may be overe coefficients in scientific studies. Data from a literature search revealing the accuracy of path analysis of some research are presented and discussed. In a last moment, we present a future perspective about how the correct estima improve the accuracy of path analysis, underscoring the need for research directed to this objective.

- by Tiago Olivoto
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- Biometrics, Correlation, Error Analysis, Path Analysis

Los objetivos de este trabajo han sido= 1. Calcular el tiempo térmico a floración femenina y 2. Identificar genotipos de comportamiento estable. Se utilizaron veintidós híbridos simples experimentales de maíz de uso especial caracterizados por producir granos con almidón modificado y/ o alta lisina debido a la expresión de alelos nulos de los genes Waxy, Amylose-extender, Opaco-2 y su variante alélica Opaco-5. Los ensayos fueron conducidos durante cinco años consecutivos (2009/10 a 2013/14) en la localidad de Castelar ubicada en la Provincia de Buenos Aires. La combinación de localidad y años definió cinco ambientes de evaluación (C1, C2,...C5). Se utilizó un diseño de bloques completamente aleatorizados con 3 repeticiones. La unidad experimental fue una microparcela de 2,5 m de longitud debido a la naturaleza uniforme de las cruzas simples. La densidad de plantas a la cosecha fue de 83.000 plantas/hectárea. El tiempo térmico en grados Celsius (TT) hasta la fase de floración femenina (R1) fue calculado mediante el Método Residual modificado propuesto por Gilmore & Rogers en 1958. La estabilidad de los materiales ensayados se analizó mediante= coeficiente de variabilidad CVi (Francis & Kannenberg, 1978), varianza ambiental S2xi (Roemer, 1917) y los estadísticos Si(3) y Si(6) propuestos por Huhn (1979) y Nassar & Huhn (1987). El ANAVA reveló diferencias altamente significativas entre híbridos (F21:84= 4,64; p ≤ 0,01) y entre ambientes (F21:84= 11,08; p ≤ 0,01). Dado que el tiempo térmico necesario para alcanzar R1 varió entre 690,0 y 771,0 grados-día, los genotipos estudiados pueden clasificarse como ciclos FAO 300-400 (precoces) y 500 (intermedios). Los resultados obtenidos mediante los estadísticos paramétricos (CVi; S2xi) y no paramétricos (Si(3) y Si(6)) coincidieron en señalar a los híbridos HC53, HC66, HC71, HC85 y HC106 como de comportamiento casi constante y por lo tanto mayor capacidad tampón (homeostasis) para el carácter evaluado según esta perspectiva de análisis.

El germoplasma de maíz nativo de Tamaulipas es un recurso genético con alta variabilidad y adaptación a temperatura alta, para su uso adecuado como germoplasma base en un programa de mejoramiento, es necesario establecer la relación temperatura-tasa de desarrollo la cual es determinante para la distribución y adaptación de este germoplasma. El objetivo de este trabajo fue estimar las temperaturas cardinales de líneas derivadas de maíz nativo de Tamaulipas. Las líneas S3 derivadas de germoplasma nativo de Tamaulipas L1 y L3, se establecieron en 12 fechas de siembra durante los ciclos PV 2019, OI 2019-2020 y PV2020, en Güémez, Tamaulipas. Se estimaron las temperaturas cardinales de cada línea, mediante el análisis de regresión cuadrática entre la temperatura media diaria y la tasa de desarrollo (1/floración). La línea L1 tuvo una temperatura base de 15.1, optima 42.5 y umbral 47.7 °C, mientras que para L3 fueron de 16.6, 29.4 y 33.8 °C, respectivamente. La variación y los niveles de temperaturas cardinales entre las líneas evaluadas, demuestra la necesidad de la caracterización específica para cada cultivar y demuestra que el germoplasma de maíz nativo de Tamaulipas es una fuente valiosa de variación para tolerancia a estrés por temperatura alta.

- by Alejandro García Ramírez and +1
- •
- México, Maize, Temperature, Germplasm

The screening of forty eight maize in breds from International Maize and Wheat Improvement Center was carried out to estimate the genetic diversity and the results indicated presence of considerable diversity. The experiment was conducted in a randomized complete block design with three replication and phenotypic data were analyzed using twenty one agro-morphological traits. The forty eight maize in breds grouped into eleven clusters based on Mahalanobis D 2 (CAL1428) and cluster X (ZL154357, CAL1467, ZL153785, CAL1422, and ZL154346) and the hybrid in these cluster could be used as donor parents for new single cross maize hybrid development for improving yield.

- by Dr. Pavan Devesh
- •
- Plant breeding and genetics, Maize Breeding

Quality protein maize (QPM; Zea mays
L.) has effectively enhanced levels of the amino
acids, lysine, and tryptophan, over normal maize and
provided balanced dietary protein for the health and
development of monogastric animals and humans.
However, as in normal maize, QPM varieties are low
in provitamin A (ProVA), a precursor of vitamin A,which can lead to vitamin A deficiency in humans
when maize is a significant part of their diet. In this
study, maize inbred Hp321-1 carrying the favorable
alleles crtRB1-50
TE-2 and crtRB1-30
TE-1 that can
enhance levels of ProVA, was used as donor for
improving ProVA in QPM inbred lines CML161 and
CML171. Functional markers for identifying the
favorable alleles crtRB1-50
TE-2 and crtRB1-30
TE-1
were used in foreground selection, and simple
sequence repeat markers were used in background
selection for the BC1F1, BC2F1, and BC2F2 generations.
The background recovery rates were 77.4 and
84.5 % for CML161 and CML171 populations,
respectively, in the BC1F1 generation, and 89.9 and
92.1 % in the BC2F2 generation. With foreground
and background selection, the mean ProVA concentration
has been improved from 1.60 lg g-1 in the
parent of CML161 to 5.25 lg g-1 in its BC2F3
offspring, from 1.80 lg g-1 in the parent of CML171
to 8.14 lg g-1 in its BC2F3 offspring while maintaining
similar QPM characteristics of the recurrent
parents. The success from this study offers maize
breeders a procedure for increasing ProVA in QPM
lines, which will greatly mitigate vitamin A defi-
ciency and protein-energy malnutrition in developing
countries.

- by L. Liu and +2
- •
- Molecular Breeding, Plant Molecular Biology, Vitamin A, Maize

The aim of present investigation was to study the effect of foliar application of gibberellic acid (Progibb 40% WSG) spraying at 4-5 leaves stage of the maize crop. Two field experiments were conducted during kharif 2014 and rabi 2014-15 at Research Farm, Zonal Agricultural Research Station, Jhabua. Seven treatments (T = 20, T 30, T 40, T 50 T 60 gibberellic acid g/ha, Tricontanol 1 2= 3= 4 = 5= 0.1%= 250 ml/ha and control) were tested in randomized block design with three replications. Results showed that variation in different doses of gibberellic acid had significant effect on growth character (plant height and silking) and yield attributes (no. of cobs/plant, cob length, no. of grains/cob and cob weight/cob); grain yield and stover yield of maize in both the seasons. Higher values of plant height (197.33 and 205.5 cm) and silking (53.67 and 54.67) was recorded with the spraying of gibberellic acid @ 60 g/ha in both the seasons, respectively. Similarly the higher yield attributes viz., no. of cobs/plant (1.48 and 1.49), cob length (17.40 and 17.78 cm), no. of grains/cob (443.33 and 456.67) and cob weight/cob (93.2 and 97.32) were recorded with the application of gibberellic acid @ 50 g/ha in both the seasons, respectively. Application of gibberellic acid @ 50 g/ha produced highest grain yield (3522 and 4277 kg/ha) and stover yield (51.05 and 5413 kg/ha) which was statistically at par with doses of 40 g/ha, 60 g/ha and tricontanol 0.1% @ 250 ml. The maximum gross return (Rs. 56,347 and 65,854), net return (37,722 and 47,229), B: C ratio (3.03 and 3.54), production efficiency (32.49 and 37.19 kg/ha/day) and economic efficiency (339.84 and 410.69 Rs./ha/day) recorded with gibberellic acid @ 50 g/ha. Enhancing of production, productivity and profitability of maize under Jhabua Hill of Madhya Pradesh gibberellic acid applied @ 50 g/ha at 4-5 leaf stage of crop.

- by Journal of AgriSearch (JAS)
- •
- Maize Breeding

The aim of this paper was to determine que chemical composition of whole kernels as well as of flours and oils extracted from different value enhanced corn hybrids. From the growing-season 2012/13 to 2014/15, several field experiments were conducted at the Instituto de Genética E.A. Favret-INTA Castelar (Province of Buenos Aires, Argentina). By using controlled pollination to prevent contamination with foreign pollen several corn grain samples were obtained from twelve experimental hybrids (modified starch and high quality protein). Lipids, starch and protein content of whole kernels were measured using infra-red technology (NIRs) in transmittance mode. The content of crude protein (%) and extractable starch (%ES) was determined by Kjeldahl method and phenol-sulphuric anthrone methods respectively. The quality of the starch extracted from the endosperm was also analyzed using conventional lab techniques. The hybrids analyzed have a protein content ranging from 10,3 to 13,6%; 4,4 to 7,7% oil content and 67,1 to 69,8% starch content. The results obtained thru conventional techniques point out that the endosperm flours of these hybrids have 9,2 to 12,5% crude protein and 59,0 to 65,8% ES. A strong but negative relationship was found between oil and protein content as well as between oil and starch content. The double recessive hybrids (wxo2) are capable to synthetize up to 4,3 mg lyxine and 1 mg triptophan/100 mg endosperm protein. Hybrids with a high ( 42,5%) or very high oleic acid (52,0%) were also detected (termed as HC52 and HC152). Half of the materials studied yield kernels with 6,0% or more oil which makes of them a suitable and attractive alternative due to their nutritional and caloric contribution both for humans and animal feeding.

- by Victor Corcuera and +2
- •
- Analytical Chemistry, Food Science, Food and Nutrition, Food Chemistry

The prolificacy maize had been reported as a way to increase grain yield of maize. Theobjectives of this study were to; 1) improve inbred lineswith 2 ears per plant and 2) improve grain yieldper plant of F1 hybrid using the trait of two ears per plant. The cross was made between prolificacy tein corn (Ban-Kao) as male parent and a field corn (Agron29) as female parent. In the segregated progenies, selected plants were self-pollinated for two generationsto obtain S2 lines with 2 ears per plant. Then line x tester method wasmade between 16 lines and three testers (16 x 3). Yield trialsof the crosses and single ear commercial hybrids were conducted in a randomized complete block design with 2 replications at 7,111plants/rai. The results showed that grain yield of parents ranged from 206 -1,027 kg/rai and the average of ear per plant was about 1.71. The best grain yield was the cross of PLF13 x PLF18 giving yield about 1,705 kg/raiand had completely two fertile ears per plant.

- by Chawalit Jingjit
- •
- Plant Breeding, Maize Breeding

Twenty-five maize inbred lines were evaluated during rabi 2020-21 at AICRP on maize, Dharwad to assess the genetic diversity for different quantitative characters. The principal component analysis (PCA) identified first two principle components with more than 1.0 eigenvector and cumulatively explained 73.0 % of the total variance. The Tocher's cluster analysis was worked out wherein; the 25 inbred lines were grouped into eight different clusters. Cluster IV had a maximum of five inbred lines, while cluster VIII had only one entry. Mahalanobis D 2 analysis was performed to know inter and intra cluster distances. Cluster VII displayed maximum intra cluster distance of 133.59 among the clusters.The inter cluster distance was maximum with D 2

- by Bonipas Antony and +1
- •
- Maize, Genetics and Plant Breeding, Maize Breeding

A need exists for a reliable and nondestructive method
for identifying genotypes with rapid drydown rates in
segregating populations of maize (Zea moys L.). We designed
an electronic probe for this purpose and report
the results of its use. Correlation coefficients between the
moisture content estimated with the electronic probe and
the percent ear moisture obtained by the conventional
oven method were r = 0.90 in 1975 and r = 0.91 in 1976
(r = significant at 1% level). We concluded that the
electronic probe method would be useful to maize breeders
in identifying genotypes with rapid dry-down capabilities
and could be used by farmers in determining the optimum
harvest date.

- by Prof Manjit S Kang
- •
- Electronics, Moisture Content, Maize Breeding

Maize biofortification is adopted as strategy to circumvent the high risk of vitamin A deficiency, accentuated by
high incidence food losses due to storage insect pests in most developing countries where maize is an important
staple crop. This study was initiated to understand the mode of inheritance for resistance to storage weevils among
provitamin-A germplasm. A total of 72 provitamin-A maize testcross hybrids were evaluated for agronomic and
adaptive traits in three sites, Namulonge, Serere and Ngetta in Uganda during the main season of 2015. Based on
genotype x environment analysis of field traits, resultant grain from two divergent environments (Namulonge and
Serere) were screened for resistance against Sitophilus zeamais in a no-choice laboratory. Line by tester analysis
of combining ability indicated that both additive and non-additive gene effects were important in controlling the
resistance parameters, including adult mortality, F1 insects which emerged, Median Development Period, Index
of Susceptibility and Grain damage. Two provitamin-A inbred lines, CLHP0014 and CLHP0005 showed high GCA
effects for reduced infestation with storage weevil. Broad sense heritability was moderate (0.19 ≤ H2 ≤ 0.59)
and Narrow sense heritability (h2) was low ranging from 0.19 to 0.24. The two inbred lines with desirable GCA
effect for weevil resistance could be used in the development of resistant breeding population. However, the low
heritability of the trait observed, suggested that effective breeding methods be deployed to increase resistance
to storage weevil, concurrently with research efforts to develop high nutritional quality maize varieties.

- by Frejus K A Sodedji and +1
- •
- Genetics, Food Security, Maize Breeding, Plant Biofortification

Presentation made at AAAS- Washington DC- February of 2016

- by Walter Trevisan
- •
- Maize Breeding, Maize Germplasm

Abstract:
This research was conducted at The University of Agriculture, Peshawar and Cereal Crops Research Institute, (CCRI) Pirsabak, Nowshera, during spring and summer (2012-13) crop seasons. The testcrosses were developed from maize variety Azam at CCRI. All lines were de-tasseled prior to pollen shedding. At physiological maturity the test crosses were manually harvested and shelled individually. In spring (season 1) and summer (season 2) 2013, the resulting test-crosses were evaluated in a 12x12 partially balanced lattice square design at The University of Agriculture, Peshawar for different agronomical and yield related traits. Data had been taken on ear height (cm), ear length (cm), kernel rows ear-l, 100 kernels weight (g), and grain yield (kg ha-l). Non-significant differences were observed only for ear length, kernel rows ear-l and 100 kernels weight in seasons 1 while in season 2; non-significant differences were recorded for ear length and kernel rows ear-l. The remaining traits showed significant genetic variations among the testcrosses in both seasons. Low to moderate estimation of heritability and genetic advance was observed in both seasons. Maximum ear height was observed for TC-193 in season 1 and for TC-111 in season 2, whereas maximum kernel rows ear-1 was recorded for TC-226 in season 1 and for TC-251 in season 2. Test crosses TC-127 in season 1 and TC-251 in season 2, had maximum 100-grain weight, whereas TC-91 in season 1 and TC-107 in season 2, had maximum ear length. The TC-194, in season 1 and TC-95, in season 2, were observed to be the highest yielding test crosses and can be utilized as progenitors in succeeding generations of maize breeding programs.

- by Habib Ullah
- •
- Maize Breeding

Corn (Zea mays L.) genotypes with resistance to Aspergillus flavus Link ex Fr. are needed to reduce aflatoxin contamination of grain. The primary objective of this study was to determine if the pinbar inoculation technique was effective in separating hybrids for resistance and susceptibility to kernel infection by A. flavus and aflatoxin contamination of the grain at a number of locations, but other inoculation techniques were evaluated at individual locations. Two single crosses, MolSW X Mp313E and SC54 X Tx601, previously classified as resistant to kernel infection by A. flavus and two susceptible crosses, Mp68:616 X SC212M and GT106 X T202, were used. We found that hybrids previously classified as resistant to kernel infection by A. flavus had fewer kernels infected and lower aflatoxin concentration in the corn grain at harvest. However, these differences were not significant at all locations. Over six locations, resistant hybrids contained 58% less aflatoxin in the grain and 41% fewer infected kernels than susceptible hybrids. In addition to the pinbar, the side-needle, and to a lesser extent the knife inoculation technique, differentiated hybrid response to ear inoculation with A. flavus.

An investigation was taken up at Maize Research Station, Agricultural Research Institute, PJTSAU, Hyderabad during 2013-14. F1 material was generated by making crosses between BML 6 × CML 181 and BML 7 × CML 181for introgression of opaque 2 gene from Mexican donor CML181 through molecular breeding approach. The converted
quality protein maize BML 6 and BML 7 lines (designated as CB6 and CB7) with increased levels of lysine and tryptophan were crossed in various combinations to select a hybrid with increased lysine, tryptophan and high yield. The performance of elite maize genotypes, donor and derived QPM inbreds and their hybrid combinations were analysed
for yield and yield attributing characters. The experiment was designed with three replication following Randomized Block Design. Observations were recorded on twelve quantitative and qualitative traits. Hybrids recorded superior performance to parents with respect to plant height (cm), ear height (cm), number of kernel rows per ear, 100 kernel
weights (g), grain yield per plant (g) and tryptophan content (%). Two cross combinations CB6-36 × CB7-28 and CB6-36 × CB7-59 exhibited relatively higher tryptophan content and on par grain yield per plant compared to the standard check DHM 117. The hybrid combination CB6-36 × CB7-28 was shown excellent performance at All Indian Coordinate Research Project (AICRP) on Maize trails during the year 2015-16 and the yield was 6924 Kg/ha (BQPMH141) with higher tryptophan content and these hybrid parental lines need
to be further multiplied for commercial exploitation.

Maize ( coefficient estimates and path analysis. This critical review discusses some systematic errors that have been observed in impacts on accuracy of path analysis. In a first moment, an approach about the maize crop, origin, characteristics and biometric models commonly used in genetic breed crop is presented. Some obstacles found in estimates of path coefficients and the methods used to adjust them are discussed. We also present evidences and a theoretical explanation that some data arrangement methods currently used, may be overe coefficients in scientific studies. Data from a literature search revealing the accuracy of path analysis of some research are presented and discussed. In a last moment, we present a future perspective about how the correct estima improve the accuracy of path analysis, underscoring the need for research directed to this objective.

- by Tiago Olivoto
- •
- Biometrics, Correlation, Error Analysis, Path Analysis

Volatile organic compounds (VOCs) released by plants are generally involved in host recognition and host selection for many phytophagous insects. However, for leafhoppers and planthoppers, host recognition is mainly thought to involve a photo-tactic response, but it is not clear if a host plant could be selected based on the volatile cues it emits. In this study we evaluated olfactory responses in dual choice tests of two Hemiptera species, Dalbulus maidis (De Long) (Cicadellidae) and Peregrinus mai-dis (Ashmead) (Delphacidae), vectors of maize-stunting diseases, to three maize (Zea mays L.) germplasms, a temperate and a tropical hybrid and a landrace. VOCs emitted by the germplasms were collected and identified using gas chromatography-mass spectrometry. The temperate hybrid released significantly more VOCs than the tropical hybrid and the landrace, and its volatile profile was dominated by (±)-li-nalool. D. maidis preferred odours emitted from the temperate hybrid, whereas P. maidis preferred odours from the tropical hybrid and the landrace over the temperate one. In order to test if linalool plays a role in the behavioural responses, we assayed this compound in combination with the tropical hybrid, to provide other contextual olfactory cues. D. maidis was attracted to the tropical hybrid plus a 0.0001% linalool solution, indicating that this compound could be part of a blend of attractants. Whereas addition of linalool resulted in a slight, though not significant, reduction in host VOC attractiveness for P. maidis. Both hopper species responded to olfactory cues in the absence of supplementary visual cues.

- by Victoria Coll and +1
- •
- Insect-Plant Interactions, Planthoppers, Leafhoppers, Maize Breeding
- by Mahendra Tripathi and +1
- •
- Maize, Maize Breeding, Hybrid maize

- by eugene ojua
- •
- Plant Breeding, Environmental Pollution, Maize, Heavymetal Tolerance in Plants

The reliance of humanity on fossil fuels particularly petroleum hydrocarbons has been on the increase and had led to increased pollution of agricultural lands. This study was aimed at investigating the effect of crude oil concentrations on the vascular bundle sizes of two Zea mays varieties-Oba Super Zaria (OSZM) and SMZ 37 Kaduna commonly cultivated in the Southeastern Nigeria. The study was conducted in the green house in the State. The experiment was setup as a 2 × 4 factorial laid out in a Completely Randomized Design replicated three times with four treatment concentrations (0-control, 15, 30 and 45 ml) of petroleum crude and two maize varieties. Highly significant effects (P < 0.001) of the concentrations as well as the varieties were observed on the vascular bundles. The results showed a significant (P < 0.05) decrease in vascular bundle sizes with increasing concentration, with plants exposed to 45ml crude oil concentration having the smallest vascular bundle sizes. The vascular bundle sizes of Oba super Zaria decreased significantly (p < 0.05) with increasing concentrations of crude oil, while significant Original Research Article Ajuziogu et al.; IJPSS, 30(5): 1-6, 2019; Article no.IJPSS.52689 2 differences were also observed with the increasing concentrations in SMZ 37 Kaduna as compared to the control. Based on the results obtained from this investigation, OSZM appeared to be more susceptible to soils affected with crude oil.

- by eugene ojua and +1
- •
- Plant Breeding, Environmental Pollution, Maize, Heavymetal Tolerance in Plants

The genetic architecture underlying response to artificial selection has not been widely characterized so far. Elsewhere, an experimental framework has been proposed that combines association mapping and selection mapping (analysis of allele
frequency change) to characterize the genetic basis of crop improvement in recurrently selected populations. However, the approach has not yet been applied. This study concerns the performance of the association mapping component of the framework based on extensive computer simulation. Populations subjected to short-term recurrent selection have an evident basis for coancestry (family-level genetic relatedness), which needs to be controlled for during association analysis to limit false positive associations and minimize bias in the estimation of allele effects. Armed with the knowledge of a population’s founders, a founder-adjusted identity-by-state (FAIBS) estimator was proposed herein for calculating coefficients of coancestry specifically in closed breeding populations under recurrent selection. Weights based on IBS information of the founders were used to arrive at probabilities of identity-by descent for the derived population. A whole genome simulator was developed in R to mimic multi-generational plant breeding populations along with their genotypic and phenotypic values. Forward simulations were used to generate founders of a population based on demographic and evolutionary parameters specific to maize.
Using a specified single nucleotide polymorphism (SNP) allele-frequency distribution and under different selection intensities and trait heritabilities, closed-breeding populations under recurrent selection for a fixed number of generations were
generated from these founders. The SNP genotypic information for “metapopulations” formed from samples drawn across generations was used to compare the performance of FA-IBS and two other estimators of coancestry (simple IBS and
Loiselle) in terms of accuracy, precision, and correlation with the expected coancestry, along with the power of QTL detection and proportion of type-I errors. Results showed that selection had a marked impact on coancestry and on association mapping
inference. Relative to a defined expectation, FA-IBS and IBS produced similar results while Loiselle produced quite different results. Using FA-IBS, a maximum of ~85% power was observed in selected populations for QTL that explained the greatest
amount (15-18%) of genetic variation. However, selection also caused a corresponding increase in false positive associations relative to populations under pure drift. In general, association mapping was found to be applicable to closed breeding
populations under recurrent selection as long as the change in coancestry due to selection was accounted for. With further improvements in accuracy of coancestry estimates and consequently in model fit, better control over false positive associations could be achieved for selected populations.