Effect of physiological pre-conditioning of explants and explant sources of Myristica fragrans Houtt. on Iinvitro culture establishment and growth

Abstract

The present study was conducted to standardise pre – treatments to induce large number of orthotropic shoots and to enhance the in vitro response of explants taken from nutmeg threes by standardising suitable basal media and by incorporating suitable growth hormones. Among the various physical methods of mother tree pre – treatments tried, pruning and pruning followed by etiolation induced four orthotropic shoots each. Pre – treating explant sources (parent trees) with BAP and kinetin each at 500 mg/1 and 1000 mg/1 induced 12 orthotropic shoots per tree. However, the in vitro response of all these newly induced shoots were more or less similar, except those taken from 50 mg/1 and 100 mg/1 of Ga3 infused parent trees. Surface sterilisation of the explants with – 0.1 per cent mercuric chloride for 10 minutes and addition of 0.01 per cent of a Carbendazim based fungicide in the culture medium helped to increase the rate of contamination free cultures. Pre – treating the shoot tips with 2 per cent sugar and 0.7 per cent PVP gave significantly superior results in eliminating phenolic interference. Pre – treating the shoot tip explants with CH at 500 mg/1 for 10 minutes gave significantly superior results in the culture establishment of nutmeg explants. The results also revealed the significantly superior influence of seedling explants over mature tree explants. Among the various basal media tried, AM at half strength of major nutrients and full strength of minor nutrients was found to be the best with a hormonal combination of BAP, NAA and 2, 4 – Dat 2 mg/1, 1 mg/1 and 0.5 mg/1 respectively, giving 67 per cent culture establishment. Phloroglucinol (40 mg/1) in combination with IBA (2 mg/1)gave significantly superior results in the induction of roots in established shoot tip cultures.