Demand-Driven Technologies for Sustainable Maize ... - IITA

80Maize accounts for between 30 and 60% of food calories anddietary proteins in developing countries, especially in foods usedfor weaning infants. The grain is processed into several local dishesand drinks and consumed by both young and old. The protein innormal maize is, however, of poor nutritional value due to the limitedconcentrations of two essential amino acids, lysine and tryptophan.Maize varieties into which relatively high concentrations of these twoamino acids have been incorporated through breeding are referredto as Quality Protein Maize (QPM). Introduction of QPM into humandiet will help in alleviating the imbalance in maize protein, insuffi cientcalories, malnutrition, diseases and death among low income, maizeconsumingpopulations of WCA.Results of studies of genetic diversity, character association,heterosis and combining ability have been reported extensively inthe literature for various crops, including normal maize (Muppidathiet al. 1995; Choudhary 1997). However, QPM has received littleattention in these areas of study. Divergence studies are importantin gaining an understanding of the trend of evolutionary patterns,assessing the relative contribution of different components of yieldto total divergence and in determining the nature of associationsoperating at inter- and intra-cluster levels (Anand and Rawat 1984;Thakur and Zarger 1989). The objective of the present study was toassess the genetic divergence among introduced QPM lines, usinggenetic distance (D 2 ) analysis, with the goal of isolating divergent linesto be used in breeding programs.Materials and MethodsThe experimental plant materials were 63 QPM lines introduced intothe Institute for Agricultural Research (IAR), Samaru, Nigeria fromMexico, Ghana and Zimbabwe. The lines were sown on 20 June 2000,15 June 2001, and 18 June 2002, at IAR Research Farm (11 0 11’N;7 0 38’E, 686m above sea level). Each plot consisted of two 5m rowsspaced 0.75m apart with a spacing of 0.5m between plants (plot size= 7.5m 2 ). In each year, the experiment was laid out as a randomizedcomplete block design with three replications. All agronomic practicesrecommended for maize production in the savanna ecology werefollowed (IAR 1993). The lines were evaluated for 12 agronomic andnutritional traits in the three years of study. The traits were: days totassel (DT), days to silk (DS), days to physiological maturity (DPM),plant height (PH), ear height (EH), grain yield (GY), percentage protein(PRO), moisture content (MOI), carbohydrate content (CHO), ashcontent (ASH), fi bre content (FIB) and fat content (FAT).Data obtained for the 12 traits were subjected to the analysis ofvariance (ANOVA). The genetic divergence of the 63 QPM lines was