Combining ability of maize inbred lines resistant to stem borers evaluated in two agro-ecological zones of Kenya under artificial stem borer infestation
Karaya, H.
Combining ability of maize inbred lines resistant to stem borers evaluated in two agro-ecological zones of Kenya under artificial stem borer infestation - African Crop Science Society : 2011 - p. 89-90
Abstract only
Maize is an important food crop in sub-Saharan Africa. It constitutes the staple diet of many people in the region as evidenced by high average consumption levels of 79 Kg per capita in the continent and 125 Kg per capita in Kenya. Stem borers are the major insect pest of maize in Kenya and cause significant annual loss of maize yield estimated at 13.5% worth US$ 91 millions in Kenya. Information on combining ability is important to maize breeders and therefore, the objective of the present study were to examine the combining ability of the insect resistant maize inbred lines known to have resistance to Chilo partellus and Busseola fusca stem borers. Twenty inbred lines (females) were factorially mated using Design II with five males. The resulting F1s along with four commercial checks were evaluated in five sites (three in the lowlands and two in the mid- altitude area. Artificial infestation was done in 4 sites, where C. partellus were used for infestation in the lowlands and B. fusca in the medium altitude by placing five neonates in the maize whorl three weeks after planting. Leaf damage score (using a scale of 1-9 where: 1= No damage and 9= extremely damaged), number of exit holes, cumulative tunnel length, and grain yield were measured as resistance traits. General combining ability (GCA) and Specific combining ability SCA effects were calculated using line x tester analysis using SAS, where the females were considered as the lines and the males as the testers. GCA mean squares due to lines and testers were highly significant (P=0.001) for all traits. The ratio of GCA/SCA mean squares exhibited a predominance of additive gene effects in the inheritance of insect resistance traits as opposed to dominance gene effects. Most of the single cross hybrids performed well compared to the local checks and gave higher yield above 5 t/ha of which the trial mean was 4.2t/ha. Entry 19 was the most outstanding with a yield of 6.8 t/ha. The leaf damage and the tunnel length plant height ratio exhibited significance difference at P=0.001. With this respect, these inbred lines may provide a reliable basis for further evaluation and even development of new maize varieties, single cross hybrids, three way cross hybrids, double cross or even open pollinated maize varieties which can be grown by farmers thereby resulting in maize yield increment.
English
Combining ability
Maize
stem borers
Combining ability of maize inbred lines resistant to stem borers evaluated in two agro-ecological zones of Kenya under artificial stem borer infestation - African Crop Science Society : 2011 - p. 89-90
Abstract only
Maize is an important food crop in sub-Saharan Africa. It constitutes the staple diet of many people in the region as evidenced by high average consumption levels of 79 Kg per capita in the continent and 125 Kg per capita in Kenya. Stem borers are the major insect pest of maize in Kenya and cause significant annual loss of maize yield estimated at 13.5% worth US$ 91 millions in Kenya. Information on combining ability is important to maize breeders and therefore, the objective of the present study were to examine the combining ability of the insect resistant maize inbred lines known to have resistance to Chilo partellus and Busseola fusca stem borers. Twenty inbred lines (females) were factorially mated using Design II with five males. The resulting F1s along with four commercial checks were evaluated in five sites (three in the lowlands and two in the mid- altitude area. Artificial infestation was done in 4 sites, where C. partellus were used for infestation in the lowlands and B. fusca in the medium altitude by placing five neonates in the maize whorl three weeks after planting. Leaf damage score (using a scale of 1-9 where: 1= No damage and 9= extremely damaged), number of exit holes, cumulative tunnel length, and grain yield were measured as resistance traits. General combining ability (GCA) and Specific combining ability SCA effects were calculated using line x tester analysis using SAS, where the females were considered as the lines and the males as the testers. GCA mean squares due to lines and testers were highly significant (P=0.001) for all traits. The ratio of GCA/SCA mean squares exhibited a predominance of additive gene effects in the inheritance of insect resistance traits as opposed to dominance gene effects. Most of the single cross hybrids performed well compared to the local checks and gave higher yield above 5 t/ha of which the trial mean was 4.2t/ha. Entry 19 was the most outstanding with a yield of 6.8 t/ha. The leaf damage and the tunnel length plant height ratio exhibited significance difference at P=0.001. With this respect, these inbred lines may provide a reliable basis for further evaluation and even development of new maize varieties, single cross hybrids, three way cross hybrids, double cross or even open pollinated maize varieties which can be grown by farmers thereby resulting in maize yield increment.
English
Combining ability
Maize
stem borers