Characterization of maize testing locations in eastern and southern Africa

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Title: Characterization of maize testing locations in eastern and southern Africa
Author: Maideni, Francis W.
Abstract: The region of eastern and southern Africa is very diverse in environments and agronomic practices . The region has one of the highest per capita consumption of maize (Zea mays . L ) , which is predominantly produced by smallholder farmers . Some important constraints facing these farmers include drought and low fertility . For decades , the International Center for Wheat and Maize Improvement (CIMMYT ) has been involved in developing maize genotypes that have high grain yields and are tolerant to drought , low fertility and other important constraints . This germplasm is developed for wide adaptation . However , the development of superior germplasm is significantly affected by interaction between genotypes and the environment (i .e . , genotype by environment interaction , GEI ) . To estimate and understand GEI maize genotypes are evaluated in a range of environments representing as much variability of the target growing areas as possible . Because of dwindling resources needed to conduct testing in the region , it may not be possible to test in all potential target areas . Therefore , a careful process of site selection for testing is essential to improve efficiencies in cultivar testing and deployment . The objective of this research was to characterize the maize testing locations of the eastern and southern Africa region . Historical data from CIMMYT Regional Trials from 1999 to 2003 was used to characterize the environments and estimate genetic parameters . Environmnent and GEI showed consistently high contributions to the total variation observed among genotypes for grain yield . Environment contributed over 60 % and sometimes up to 85 % of total variation observed . Sequential retrospective pattern analysis (Seqret ) was conducted on the adjusted standardized grain yield . A total of 7 groups of environments were identified . Repeatabilites , a measure of the proportion of phenotypic variation that is due to genetic differences , was reduced under stress conditions . The relationship among traits showed that anthesis -silking interval (ASI ) is an important selective trait , which can improve selection efficiency for grain yield under stress conditions . Stability analysis provided an opportunity to observe the response and adaptation of genotypes to a wide range of environments . Variety ZM621 was a stable and high yielding genotype .
URI: http : / /hdl .handle .net /1969 .1 /3804
Date: 2006-08-16


Characterization of maize testing locations in eastern and southern Africa. Available electronically from http : / /hdl .handle .net /1969 .1 /3804 .

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