Rooting of microshoots and ex vitro establishment of plantlets of bael (Aegle marmelos (L.) Corr.

Abstract

Studies were conducted on “Rooting of microshoots and ex vitro establishment of plantlets of bael (Aegle marmelos (L.) Corr.)” for evolving techniques for in vitro rooting, ex vitro rooting and ex vitro establishment of plantlets of bael during 2003-2005 in the Department of Plantation Crops and Spices and Department of Plant Biotechnology, College of Agriculture, Vellayani, Thiruvananthapuram. The in vitro propagation techniques in bael have already been standardised. The microshoots 3.00 to 5.00 cm long with 3.00 to 4.00 leaves were taken from the cultures of previous study maintained in the Plant Biotechnology Laboratory, College of Agriculture, Vellayani, Thiruvananthapuram. The highest rooting of the microshoots (50.00 per cent) occurred in two treatments namely, MS basal medium supplemented with IBA 2.50 mg l-1, sucrose 30.00 g l-1 and agar 6.00 g l-1 and on the same basal medium supplemented with NAA 1.00 mg l-1, sucrose 30.00 g l-1 and agar 6.00 g l -1. The microshoots took the least number of days (8.00) for root initiation in full strength MS basal medium supplemented with IBA 0.50 mg l-1, sucrose 30.00 g l-1 and agar 6.00 g l-1. The highest number of roots (2.67) was obtained in full strength MS basal medium supplemented with IBA 2.50 mg l-1, sucrose 30.00 g l-1 and agar 6.00 g l-1. The best pre-treatment identified for ex vitro rooting was IBA 1000.00 mg l-1 for 20 s (quick dip) which gave the highest survival rate (50.00 per cent), number of roots (1.67) and length of roots (0.63 cm), compared with IBA 50.00 mg l-1 (slow dip). Different potting media like sand, soilrite, sand and soil (1:1), sand, soil and coirpith (1:1:1) and sand, soil and leafmould (1:1:1) were compared to study their effect on ex vitro establishment.. Sand was found to be the ideal potting media for ex vitro establishment. The highest survival rate (50.00 per cent), leaf number (4.67), plant height (3.67 cm), fresh weight (0.6501 g), dry weight (0.25 g), stomatal conductance (0.1165 cm S-1), leaf area index (0.1370) and crop growth rate (0.0291 mg cm-2 day-1) were obtained when planted out in sand than in other potting media. The effect of VAM (Glomus etunicatum and Glomus fasciculatum) in different potting media were also studied in the ex vitro establishment of plantlets. It was observed that mycorrhiza inoculated plants in a potting media of sand showed higher survival rate (66.67 per cent) than control (50.00 per cent). The highest values for number of leaves (6.00), plant height (4.30 cm), number of roots (2.33), fresh weight (0.6908 g), dry weight (0.2847 g), stomatal conductance (0.0383 cm S-1), leaf area index (0.1478) and crop growth rate (0.9921 mg cm-2 day-1) were obtained for the mycorrhiza treated plantlets in sand, compared to other mycorrhizal treated potting media. In the present investigation, protocols were evolved for the in vitro rooting of microshoots of bael (Aegle marmelos (L.) Corr.). But ex vitro rooting and ex vitro establishment gave only limited success. However, few plantlets could be acclimatized and were transferred to mud pots containing sand, soil and cowdung in the ratio 1:1:1 for observing further growth and establishment.