Micropropagation of Gerbera

Abstract

Gerbera is one of the popular flower crops in the world and is gaining importance in our country. Hardy upright flowers, leafless long stalks, numerous colours with long vase life have popularised gerbera. Availability of cheaper plant material is one of the major limitations in popularising this crop. The present investigations were carried out with varieties GJ-l, GJ-2 and OJ-3 to study shoot proliferation callusing and regeneration of leaf explant and rooting of in vitro developed shoots Half strength media of both MS and modified MS induced early shoot initiation and side shoot initiation but shoot number, shoot length and shoot weight was better in full strength media. The best treatment to produce higher shoot number with better growth was MS medium supplemented with 0.2 mg l-1 1AA and 1 mg 1-1 BAP in OJ-l and OJ-3. For GJ-2, MS medium supplemented with 0.1 mg 1-1 IAA and 2 mg l-1 BAP was best. It was noticed that the MS media supplemented with BAP induced higher multiplication rate with small plants and modified MS media supplemented with kinetin induced lower multiplication rate with good plant stature. Therefore, a protocol to obtain higher multiplication for a period of six weeks and transferring to kinetin supplemented modified MS media (5 mg 1 -1 kinetin for GJ-I and GJ-2, I mg l-1 kinetin for GJ-3) for a period of four weeks before rooting is suggested. Callus initiation was earlier in media supplemented with 2,4-D and BAP when compared to media supplemented with IAA and BAP in all the three varieties. (Maximum amount of callus was produced by 0.5 mg l -1 2,4-D with 4 mg 1-1 BAP, 1.0 mg 1-1 2,4-D with 3 mg l-1 BAP and 0.75 mg 1- l lAA with 2 mg l-1 BAP. Two distinct type of calli were produced by leaf explant. Creamy callus which was frothy in GJ-l and GJ-2 and friable in GJ-3 was produced by 2,4-D with BAP. Green/greenish white granular callus was produced by IAA and BAP. A higher cytokinin to auxin ratio in the media (IAA at 0.25, 0.5 or 0.75 with BAP at 3 mg 1 -1favoured regeneration from petiole tips of young leaves. The response was better with IBA than with NAA. Both IBA and NAA induced swelling of roots in GJ-2 and NAA induced callus production in GJ-3. GJ-2 was the only variety to show good response for ex vitro rooting. Best treatment for ex vitro rooting was IDA at 1000 ppm. When varietal responses to treatments were observed, NAA at 500 ppm was best for ex vitro rooting in GJ-2 and IDA at 1000 ppm for GJ-1.