Ammonium to Nitrate Ratio Affects Protocorm Like

Carbon and nitrogen are the two elements that most affect plant organogenesisin vitro, usually as part of the macronutrients. some anecdotal evidence from theliterature suggests that the ammonium (nh4+) to nitrate (no3–) ratio may affectorchid organogenesis. in this study, to test this hypothesis, different nh4+: no3–ratios were tested on the development of protocorm-like bodies (plbs) of hybridcymbidium twilight moon ‘day light’, when modified in teixeira cymbidium(tc) no. 1 medium without plant growth regulators (pgrs). more plbs formedper half-plb or per plb thin cell layer (ttcl) when tc medium was used whiletc from which pgrs or no3– or nh4+ were removed (two controls) containedsignificantly less plbs/explant. the same trend was observed for neo-plb (i.e.,newly formed plb) fresh weight. a high no3– ratio favoured neo-plb formation,but always less than tc medium, but significantly higher than the two controls.ttcls performed more poorly (i.e., fewer neo-plbs/explant and lower freshweight) than half-plbs. the nh4+: no3– ratio can be manipulated to increase thelevel of plb production in the absence of pgrs.