INHERITANCE OF LOW PRODUCTION OF STRIGA GERMINATION STIMULANT IN SORGHUM

Host-plant resistance to the parasitic weed Striga (Striga spp. Lour.) is a manifestation of one or more potential mechanisms. One of the be tter understood mechanisms of resistance against Striga by sorghum [So rghum bicolor CL.) Moench] is low production of compounds by the host root that Striga seeds require as stimulants for germination. A recent ly developed, efficacious laboratory screening technique, the agar gel assay, distinguishes resistance to Striga among sorghum cultivars bas ed on the capacity of their root exudates to stimulate Striga seeds to germinate in a water agar medium. This study was conducted to determi ne the inheritance of low stimulant production in sorghum by the use o f the agar gel assay. F-1, F-2, and backcross progenies between resist ant sorghum line 'SRN-39' and three susceptible lines, 'Shanqui Red',' P-954063', and 'IS 4225', were evaluated for stimulant production. Seg regation ratios indicated that low stimulant production is inherited a s a single, nuclear, recessive gene which is largely additive in actio n.