Improvement of embryogenic callus induction and shoot regeneration of buffalograss by silver nitrate

Addition of the ethylene antagonist, silver nitrate (AgNO3), into callus induction medium significantly enhanced embryogenic callus production (both induction frequency and callus growth) of field-collected male immature inflorescence cultures of buffalograss NE84-45-3 and 'Texoka'. No stimulatory effect of AgNO3 was observed on embryogenic callus induction for female immature inflorescence culture of a female genotype `609' and `Texoka'. Calli initiated on AgNO3-containing media had more shoot-regenerating calli than those initiated on AgNO3-free media, when they were transferred to the regeneration media. Benzyladenine at 2.2 μM gave the best response for regeneration, regardless of the callus source. Although average number of shoots regenerated per callus was lower for calli initiated on AgNO3-containing media, total number of shoots regenerated was higher. The stimulatory effect, however, was environment and genotype dependent. While the addition of AgNO3 significantly stimulated embryogenic callus induction of NE84-45-3 immature inflorescences collected in Fall 1995 and May 1997, it only slightly increased the embryogenic callus induction frequencies in May 1996 when rainy conditions occurred. For male inflorescences of `Texoka' collected in early May, AgNO3 significantly enhanced embryogenic callus production consistently over the two-year period (1996, 1997).