EFFECT OF ABSCISIC-ACID ON POLLEN GERMINATION AND TUBE GROWTH OF MAIZE GENOTYPES

As a preliminary step to using gametophytic selection to obtain genoty pes of maize, Zea mays L., differing for abscisic acid (ABA) content a nd/or sensitivity, the influence of ABA on the in vitro germination an d tube growth of maize pollen and the presence of genetic variability for these traits was investigated. In a first experiment, pollen sampl es of three genotypes were germinated on substrates containing increas ing amounts of ABA. Low ABA concentration (0.5 muM) significantly incr eased pollen germination and tube growth, while 500 muM ABA significan tly decreased both traits, thus indicating that ABA can influence the growth of maize pollen in vitro. In a second experiment, eleven inbred lines were screened for the in vitro reactivity of their microgametop hytes to ABA. The lines differed significantly for the response (% of control) of tube length, but not of pollen germination to ABA.