Ammonium to Nitrate Ratio Affects Protocorm Like Bodies PLB Formation In vitro of Hybrid Cymbidium

Abstract

Carbon and nitrogen are the two elements that most affect plant organogenesis.<br /> In vitro, usually as part of the macronutrients. Some anecdotal evidence from the literature suggests that the ammonium (NH4+) to nitrate (NO3–) ratio may affect orchid organogenesis. In this study, to test this hypothesis, different NH4+: NO3– ratios were tested on the development of protocorm-like bodies (PLBs) of hybrid Cymbidium Twilight Moon ‘Day Light', when modified in Teixeira Cymbidium (TC) No.1 medium without plant growth regulators. More PLBs formed per half-PLB or per PLB tTCL when TC medium was used while TC from which PGRs or NO3–or NH4+ were removed (two controls) contained significantly less PLBs/explant. The same trend was observed forneo -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 fresh weight) than half-PLBs. The NH4+: NO3– ratio can be manipulated to increase the level of PLB production in the absence of plant growth regulators.