Varietal responses of scion to stone grafting in mango for commercial propagation

Abstract

The present series of studies were carried out in the Department of Pomology and Floriculture, College of Horticulture, Vellanikkara during the period from May 1985 to December 1986 with the objective of studying the response of varieties of scion shoots with verying lengths for stone grafting in mango. Scion shoots of three different lengths viz., 6 cm, 8 cm and 10 cm collected from six vatieties of mango viz., Mulgoa, Priur, Banganappally, Mundappa, Banglore and Alphonso were used for grafting operation. Detailed anatomical studies of graft union of all the selected varieties were also conducted to find out the various stages of graft union and the possible reasons for graft failures. The results of the experiment on the response of varieties and length of scion indicated highest percentage of sprouting for the variety Benganappally with scion of lengths 8 cm and 10 cm and for Priur with scion of length 8 cm, while sprouting was poor for the variety Alphonso with scion of lengths 8 cm and 10 cm. The variety Priur recorded maximum survival with the scion of length 8 cm while the variety Mulgoa with the scion of length 6 cm recorded least survival. The experiment to find out the effect of varieties and length of scion on growth parameters revealed that the variety Mulgoa recorded maximum mean growth followed by the variety Banganappally up to 4th fortnight and that growth of scion was not influenced significantly by different lengths of scion used for grafting. The varieties had significant effect on girth of rootstock only during the initial stages of growth while girth of scion was influenced by varieties throughout the period of observations. With regard to these parameters there was no significant difference between scions of lengths 6 cm, 8 cm, and 10 cm. The maximum and minimum leaf production was noticed respectively for the varieties Banganappally and Banglora particularly during initial stages of growth. However, the use of scions with varying lengths did not reveal any significant difference with regard to this parameter. Anatomical studies of the successful grafts revealed four district stages in the healing process of graft union. Cambial bridge across the union was established 45 days after grafting and the union was completed three months after the grafting operation. In the unsuccessful grafts there was no callus formation even after 5 to 10 days of grafting. Very thick necrotic layers were to have developed in the wounded exposed surfaces of stock and scion. Irregular cut surface, wide gap between stock and scion and slow differentiation of callus were also observed. Moreover, some of the unsuccessful grafts initiated callus production only from stock side.