In Vitro Selection of Soybean Accessions for Induction of Germination of Striga hermonthica (Del.) Benth Seeds and Their Effect on Striga hermonthica Attachment on Associated Maize

Abstract

Production of maize in western Kenya is adversely affected by Striga hermonthica. Integrating legumes as intercrops is one way of reducing the density of S. hermonthica in the soil and improving the livelihood of subsistence farming communities. Legume species and varieties, however, vary in the ability to stimulate suicidal germination of S. hermonthica seeds. A study was conducted to select soybean (Glycine max) accessions with ability to stimulate germination of S. hermonthica seeds from western Kenya. The cut-root technique was used to screen 32 soybean accessions with Desmodium, Mucuna and maize varieties Nyamula, KSTP92 and WH502 as checks. Fourteen soybean accessions (selected from the cut-root experiment), Desmodium and Mucuna were grown in association with maize variety WH502 in pots inoculated with Striga seeds. There was a significant variation among soybean accessions in inducing germination of Striga. The relative germination of Striga seed by soybean accessions ranged from 8 to 66% compared to 70% for synthetic germination stimulant Nijmegen 1^®. Accessions TGx1448-2E, Tgm1576, TGx1876-4E and Tgm1039 had the highest relative germination percent. Most accessions that stimulated high germination of Striga seeds increased Striga attachment by 6–95%. There was a negative correlation (R ² = 0.7) between maize shoot dry weight and intercrop shoot dry weight. Accessions TGx1831-32E, Tgm944, Tgm1419 and Namsoy 4m had high stimulation but low attachment, hence making them potentially important trap crops.