Phalaenopsis spp. is one of rare flowers which have best viewing merit and regarded as"the Queen of Tropical Orchid". Tissue culture is the main progenitive method of it,but Tissue browning which hamper cell differentiation affects the whole process of tissue culture, and also restrict the industrial product of Phalaenopsis. This study researched on the changes in cytology and physiology and biochemistry of explants when browning , The main results are as follows :1 As showed as followed by light microscope, the cellularity was destroyed,cell wall had obvious crimple and rupture,after that,There were a mass of black substances deposited in cell after explant browning.2 Qualitative and quantitative deterimation of 9 phenolic acids were studied before and after browning of phalaenopsis(R4) by High Performance Lequid Chromatography (HPLC). The results showed that chlorogenic acid, catechol, catechuic acid, caffeic acid correlated with browning, and the influence of chlorogenic acid and catechol on browning was the most important.3 The browning rate was the lowest at pH6.5 or 20℃. Under the same temperature(25℃),The PPO activity and total phenolic content didn't have direct ratio with the bulk of pH, and there was no significant correlation between PPO activity and total phenolic content, but there was significant correlation between browning rate and total phenolic content at pH 5.0; Under the same pH(6.0), PPO activity ,total phenolic content and browning rate increased as the temperature rose, and there were the best significant correlation between browning rate and PPO activity at 20℃, significant correlation between browning rate and total phenolic content at 20℃and 30℃.4 Browning of explant decreased when cultured under 1000lx and 3000lx, while browning become serious when cultured under 2000lx and the activity of PPO was much higher than the others, but three treatments had no significant difference of total phenolic content. There were no significant correlation between browning and PPO but significant correlation between browning and total phenolic content when cultured under 1000lx and 2000lx. Darkness pretreatment may decrease browning, especially of pretreatment for 10d, browning rate was the most and the activity of PPO was the biggest when explant without... |