STUDIES INTO THE EFFECTS OF FORCED SHOOT ETIOLATION AND DIFFERENT MEDIA ON THE ROOTAGE OF MANGIFERA INDICA L. CUTTINGS

There is immense variability within a clone of mango because of the faulty use of heterozygous seedling rootstocks. Recently work has been started on the standardization of rootstocks in different parts of India. Cuttings seemed to be one of the easiest methods of propagation. The effects of growth regulator, etiolation and invigoration of shoots by heading back on the rooting of mango cuttings have been emphasized by Mukherjee et al (7). The importance of different media on the rooting of cuttings has also been emphasized by many workers (1, 3, 5, 6, 8, 14) in both temperate and tropical plants but the same have not been tested for mango cuttings. The present paper deals with some of these aspects.

The cuttings were prepared following the technique of Mukherjee et al (1967) and these were planted in pots containing different media. The pots were kept under mist created by hand spraying. The date on the percentage success and survival of different types of cuttings are presented in table 1. Forced cuttings rooted and established better than those of unforced type in all the five media irrespective of the years of experimentation. The percentage of rooting and the corresponding establishment were further increased when both types of cuttings were given etiolation treatment. Out of the five media used peat moss and sand (1:1) proved to be the best regarding rooting of forced and etiolated cuttings (figure 1). The survival of rooted cuttings was also highest (86%) under this treatment. These results confirm the findings of earlier workers in other crops (3, 5, 6). The chemical analysis of the different types of cuttings revealed a higher percentage of moisture in the forced shoots as compared to that in the unforced shoots. Etiolation treatment increased the moisture content of both types of shoots within a narrow range. Etiolation treatment had an increasing effect on the total carbohydrate content of the shoots. However, a negative trend was observed when content of total nitrogen was considered. The C/N ratio was much higher in the unforced shoots as compared to that in the forced shoots (table 2).

According to a number of earlier workers (2, 9, 11, 12 & 13) a high carbohydrate content was associated with easy rooting of cuttings. Recently, Sen and Basu (10) working on Justicia gendarusa also found that the presence of an abundance of soluble carbohydrates in comparison to nitrogenous reserves is significantly beneficial for root initiation