R.N. Basu, N. Roychoudhury, B. Lahiri, P.K. Sen
Singh and Teaotia (7) and Sen et al (8) reported beneficial effect of IBA (r-indole butyric acid) on rooting of mango air layers. Recent studies in this laboratory (1) have indicated varietal difference in rooting of mango air layers and among four varieties studied, namely Langra, Himsagar, Bombai and Gulabkhas. Langra has been found to be a shy rooter and Gulabkhas a good rooter with Himsagar and Bombai giving moderate rooting performances. In all these varieties IBA application improved rooting and ultimate survival of rooted layers. Basu et al (3) indicated that improved rootability of air layers treated with IBA was associated in part with changes in amino acid metabolism.

The present investigation was undertaken to further elucidate the physiology of root formation in mango air layers by following the changes in carbohydrates and nitrogen fractions including free amino acids, and rooting factors during regeneration. One single Langra tree in full vigour and bearing condition (about 30 years old) was selected for the study. Air layering was done on 13.7.66, IBA at 3000 ppm in Lanolin was applied at the time of ringing in the region just above the ring cut.

Total nitrogen was estimated by the micro-kjeldahl method and soluble nitrogen was estimated in the same way after successive extraction with 10% and 5% trichloroacetic acid. The carbohydrates were estimated by the methods described by Basu et al (2) and amino acids following the procedure standardised by Das Chaudhuri et al (5). Rooting factors were assayed following the method of Hess (6) with some modifications (2). Concentrated ethanolic solutions containing 2.5 g equivalent of fresh material were loaded on chromatograms for bioassay of rooting factors.

In the present studies 80 per cent of IBA treated layers rooted with an average of 2.8 roots per layer against 40 per cent rooting and 0.6 roots per layer under control layers not treated with the chemical.

There was very little change in the contents of different carbohydrates and nitrogen fractions in non-layered shoots during the 34 days' period of study. But a progressive increase in carbohydrate constituents took place in bark and wood under the treatments L and L/IBA.

There was little difference in the contents of different carbohydrate fractions under these two treatments at the pre-callusing stage but at callusing and root emergence stages treatment L was found to contain relatively greater quantities of available carbohydrates than L/IBA, where the degree of callusing and root formation was greater (table 1).

The relatively high concentrations of reducing and non-reducing sugars in bark and wood of layers suggest the importance of easily available soluble carbohydrates in the metabolism of regenerating tissues.

Basu, R.N., Roychoudhury, N., Lahiri, B. and Sen, P.K. (1972). BIOCHEMICAL CHANGES DURING ROOT FORMATION IN MANGIFERA INDICA L. AIR LAYERS. Acta Hortic. 24, 64-71
DOI: 10.17660/ActaHortic.1972.24.9

Acta Horticulturae