Screening of maize genotypes for low <i>Striga Asiatica</i> stimulant production using the 'agar gel technique'

Abstract

One of the best characterized mechanisms of resistance to the parasitic weed ( Striga ) is low germination stimulant exudation by host plants. Using a simple and rapid agar gel assay, 112 maize genotypes were tested for low stimulant production and haustorium initiation of Striga asiatica (L.) Kuntze. Most of the genotypes induced high level of germination of Striga seeds at distances more than 1.3 cm, from the crop seedling root to the furthest germination Striga seed. Germination distance highly correlated with rate of germination and was used as a quick way of determining the level of haustorial germination induced by the test genotypes. Some breeding lines such as PR 91A 496-13 and PR 91A 496-25 induced moderately low germination. B 37.91-952-1 induced the least germination distance (0.87cm). This is comparable to that of highly resistant sorghum varieties. The commercial varieties induced high level of germination. A similar procedure was followed to observe the rate of haustorium initiation. Despite the tendency to stimulate considerably high germination, some entries permitted very low haustorium initiation. The best three lines in terms of low haustorium initiation were PR 496-45, PR 91B 5323 33x34 and PR 91A 496-17. There was no relationship between germination distance and haustorium initiation.