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oai:dspace.unza.zm:123456789/2502019-08-19T14:28:42Zcom_123456789_18col_123456789_81

Ngolwe, Kasaro R. Agness 2011-03-30T16:25:25Z 2011-03-30T16:25:25Z 2011-03-30 The purpose of the study was to compare the performance and relative stability of grain yield among four different maize (Zea mays L. ) types and also to investigate some agronomic traits and their relationship to overall yield stability. The four types of maize were compared in twelve environments, (3 locations x 4 management levels). Each type, i.e. single cross, double cross, three-way cross arid open pollinated, was represented by three entries. A split plot experimental design with three replications was used, the four management levels were the main plots and cultivars as subplots. The parameters measured were grain yield, plant height, shelling percentage and 100 kernel weight. The results showed that hybrids gave an overall higher yield performance compared to open pollinated varieties. Mean yields ranged from 145 kg/ha for MM 752 at Golden valley to 7482 kg/ha for MM 612 at Mansa. Among the hybrids, there were no significant grain yield differences between double crosses and three-way crosses, but there were significant differences P<_ 0.05 between single crosses and double crosses and between single crosses and three-" way crosses. In a step wise multiple regression, plant height and shelling percentage had the most contribution to the variation observed in grain yield. The linear regression o coefficient (b-value), the deviation from regression (Sd ) and the mean yield were used as stability parameters. All the hybrids IV had high linear response compared to the open pollinated varieties but among the hybrids, double cross hybrids were the most stable. They had high average yield, a regression coefficient closer to 1.0 and a low deviation mean square. The highest linear response was obtained by the single cross hybrid MM 601 while MMV 600, an open pollinated variety had the lowest linear response. Double cross variety MME 404 possessed the most desirable combination of stability characteristics. The commercial hybrids MM 601, MM 612, MM 603 which are widely grown in Zambia, exhibited good stability of performance. However, the open pollinated varieties showed low genetic potential for yield. The stability analyses for shelling percentage and 100 kernel weight explained some of the observed differences in yield stability. http://dspace.unza.zm/handle/123456789/250 en Agronomy Maize Maize variety performance under different management and environmental conditions Thesis