<Emphasis Type="Italic">Ex vitro</Emphasis> rooting using a mini growth chamber increases root induction and accelerates acclimatization of Kopyor coconut (<Emphasis Type="Italic">Cocos nucifera</Emphasis> L.) embryo culture-derived seedlings

Ex vitro rooting using a mini growth chamber to maintain relative humidity has been used to mass produce true-to-type Kopyor coconut (Cocos nucifera L.) seedlings through embryo culture. This new process was found to (1) improve the proportion of seedlings successfully transferred to soil (from 40 to 90% for seedlings with roots); (2) achieve this step in the shortest time possible (a reduction from 10 to 4 mo in in vitro culture); (3) improve root formation using indolebutyric acid (IBA; an improvement in the number of primary roots from 2 to 5); and (4) improve the vigor of seedlings ex vitro (improvements of fresh weight, shoot length, number of opened leaves, leaf thickness, amount of epicuticular wax, and stomatal density). The best ex vitro rooting and rapid acclimatization protocol was obtained when 4-mo-old seedlings with two opened leaves were kept in the mini growth chamber for 3 mo before being transferred into soil, and when the mini growth chamber was flooded with a quarter strength hybrid embryo culture (HEC) medium with 1 μM IBA but depleted of vitamins and sugar. This protocol was efficient in delivering high-value Kopyor seedlings to the field (90% success rate), with a decreased risk of contamination and lower labor cost. The improved process was found applicable to both tall and dwarf Kopyor and other coconut types.