Phenotypic and genotypic characterization of white maize inbreds, hybrids and synthetics under stress and non-stress environments

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Title: Phenotypic and genotypic characterization of white maize inbreds, hybrids and synthetics under stress and non-stress environments
Author: Makumbi, Dan
Abstract: Maize is susceptible to biotic and abiotic stresses . The most important abiotic stresses in Africa are drought and low soil fertility . Aflatoxin contamination is a potential problem in areas facing drought and low soil fertility . Three studies were conducted to evaluate maize germplasm for tolerance to stress . In the first study , fifteen maize inbred lines crossed in a diallel were evaluated under drought , low N stress , and well -watered conditions at six locations in three countries to estimate general (GCA ) and specific combining ability (SCA ) , investigate genotype x environment interaction , and estimate genetic diversity and its relationship with grain yield and heterosis . GCA effects were not significant for grain yield across environments . Lines with good GCA effect for grain yield were P501 and CML258 across stresses . Lines CML339 , CML341 , and SPLC7 -F had good GCA effects for anthesis silking interval across stresses . Additive genetic effects were more important for grain yield under drought and well -watered conditions . Heterosis estimates were highest in stress environments . Clustering based on genetic distance calculated using marker data from AFLP , RFLP , and SSRs grouped lines according to origin . Genetic distance was positively correlated with grain yield and specific combining ability . In the second study , synthetic hybrids were evaluated at seven locations in three countries to estimate GCA and SCA effects under low N stress and optimal conditions and investigate genotype x environment interaction . GCA effects were significant for all traits across low N stress and optimal conditions . The highest yielding synthetic hybrids involved synthetics developed from stress tolerant lines . Synthetics 99SADVIA - # and SYNA00F2 had good GCA for grain yield across low N stress conditions . Heterosis was highly correlated with grain yield . Optimal environments explained more variation than stress environments . The third study evaluated the agronomic performance and aflatoxin accumulation of single and three -way cross white maize hybrids at five locations in Texas . Inbreds CML343 , Tx601W , and Tx110 showed positive GCA effects for grain yield . Significant GCA effects for reduced aflatoxin concentration were observed in lines CML269 , CML270 , and CML78 across locations . Differences in performance between single and three -way crosses hybrids were dependent mostly on the inbred lines .
URI: http : / /hdl .handle .net /1969 .1 /4188
Date: 2006-10-30

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Phenotypic and genotypic characterization of white maize inbreds, hybrids and synthetics under stress and non-stress environments. Available electronically from http : / /hdl .handle .net /1969 .1 /4188 .

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