Fig 3. Organic additives significantly increased PLB proliferation of the recalcitrant VKD orchid. (A) Tomato extract enhanced the proliferation of PLBs of VKD by providing sufficient nutrient supply. PLBs treated with the tomato extract appeared healthy, and tissue death due to the browning effect was rare. (B) The utilisation of nutrient and growth factors provided by tomato extract subsequently augmented the regeneration of PLBs into intact VKD orchid plantlets within eight weeks.