Response to S1 recurrent selection for resistance to two stem borers, Busseola fusca and Chilo partellus, in two tropical maize populations

Abstract

Stem borers, Busseola fusca and Chilo partellus, are among the key devastating lepidopteran insect pests of maize causing grain yield losses. Recurrent selection studies for stem borer resistance in maize are limited. However, maize populations carrying resistance genes to these stem borers have not been exploited fully in breeding programmes. The objective of the study was to separately improve resistance to B. fusca and C. partellus stem borers for two maize populations CML395/MBR C5 Bc and CML444/MBR/MDR C3Bc and therefore grain yield after two cycles of S1 progeny recurrent selection. Cycle 0 and the advanced generations (cycle 1-susceptible, cycle 1-resistant and cycle 2-resistant) were evaluated at three locations in Kenya using a 35 9 12 a-lattice design with 2 replications. The net reductions in cumulative tunneling, number of exit holes and leaf feeding damage scores ranged from 0 to 69 % for both populations after two cycles of selection. In the two populations, each cycle of selection for borer resistance improved grain yield by 0.5-0.8 t ha . Actual net gains in grain yield with reference to cycle 0 were 43 % for population CML395/MBRC5 Bc under B. fusca infestation and 70 % under C. partellus infestation. For population CML444/MBR/MDR C3Bc, the actual net gains in grain yield were 25 % under B. fusca infestation and 36 % under C. partellus infestation. The reductions in the injurious effects attributable to leaf feeding damage, cumulative stem tunneling and number of exit holes contributed towards the 43 and 70 % net genetic gain in grain yield under B. fusca and C. partellus infestation respectively, for both populations. Broad sense heritability (H 2 ) for grain yield ranged from 2 to 98 % in both maize populations. The study showed that two cycles of S1 progeny recurrent selection was effective in accumulating favourable alleles for B. fusca and C. partellus stem borer resistance.

Increasing the Efficiency of Recurrent Selection for Yield in Maize

“…Asghar and Mehdi (2010) also showed that the estimates of broad-scense heritability, from S1 families, using an open pollinated sweet maize population, were (0.38) for grain yield, (0.77) for 100-kernel weight, (0.72) for cob length, (0.67) for plant height, and (0.57) for days to silking. Mwimali et al (2015) found that the broadscense heritability estimates from S 1 families for grain yield were 95.7, 93.5 and 98.4% for cycle 0, cycle 1 and cycle 2, separately, in the population CML395/MBRC5BC. These findings were higher than the present estimates however; estimates of heritability differ considerably from one study to another depending on the method of evaluation and number of replications.…”

Evaluation of tropical maize inbred lines for resistance to two stem borer species, Busseola fusca and Chilo partellus

“…Suitable maize germplasm should have resistance to both B. fusca and C. partellus. Recent reports indicate that climate change has led to C. partellus increasingly displacing B. fusca from the high altitude areas in Kenya (Mailafiya et al, 2011;Tefera et al, 2011;Mwimali et al, 2015). Furthermore, farmers exchange maize germplasm across agroecologies, therefore, the need to investigate the reaction of these tropical maize inbred lines for resistance to these borers becomes paramount.…”