African Journal of Biotechnology Vol. 9 (9), pp. 1317-1324, 1 March, 2010 Available online at http://www.academicjournals.org/AJB DOI: 10.5897/AJB10.668 ISSN 1684–5315 © 2010 Academic Journals Full Length Research Paper Rootstock growth and development for increased graft success of mango (Mangifera indica) in the nursery Simon A. Mng’omba*, Festus K. Akinnifesi, Gudeta Sileshi and Oluyede C. Ajayi World Agroforestry Centre (ICRAF), Chitedze Research Station, P. O. Box 30798, Lilongwe 3, Malawi. Accepted 11 January, 2010 The graft success of seedlings depends on rootstock size and the skills of grafters. A study was carried out to evaluate the effects of rootstock diameter (at root collar), skills and experience of grafters on mango seedling thinning and grafting. Skilled and unskilled grafters were involved in grafting mango plants for at least three consecutive months. Different rootstock sizes based on root collar diameter of mango seedlings were assessed. The results showed significant differences in graft-take among three groups of nurserymen. The skills and experience of grafters had a significant effect on graft success. The late emerging seedlings showed higher increase in height and diameter after thinning. A higher survival (> 75%) and reduced time to graft-take (19 days) were achieved with thicker rootstocks (0.7 cm) than thinner rootstocks (0.3 cm). The early emerging plants produced more leaves than late emerging plants after grafted. It was concluded that a higher graft-take can best be achieved with skilled grafters and thicker rootstocks. Key words: Apomisis, Mangifera indica, nucellar, nurse, polyembryony, zygote. INTRODUCTION The supply of good quality and sufficient mango (Mangifera indica) planting materials in the tropics hinges on the development of good nursery management prac- tices which include propagation methods. Generally, improvement in the supply of good quality planting materials would ensure good tree survival and establish- ment in the field. Grafting is a common and preferred vegetative propagation method for mango trees (Bally, 2006). The graft success can be improved when root- stock selection is considered and based on desirable growth attributes of rootstocks (Simons, 1987), the skills and knowledge of grafters (Akinnifesi et al., 2008). Rootstocks play an important role for tree survival and establishment in the field, tree productivity and dwarfing of grafted fruit trees (Mng’omba et al., 2008). Seedling rootstocks with desirable attributes such as rapid growth (in height and diameter) could reduce the ‘waiting period’ to grafting time. Furthermore, proper alignment of scion *Corresponding author. E-mail: smngomba@cgiarmw.org. Tel: +265 1 707 329. Fax: +265 1 707 319. and rootstock cambium tissues could determine the graft success (Pina and Errea, 2005). The skills of grafters in aligning cambium tissues together are important in reducing graft failure. Mango possesses either polyembryonic (apomictic) or monoembryonic seed (Bally, 2006). A polyembryonic seed contains two or more embryos and they are zygotic (sexual) and nucellar (asexual or maternal) embryos. Monoembryonic seeds contain only a single zygotic embryo (a cross between maternal and paternal parents that is nurse or zygotic seedlings). According to Bally (2006), zygotic and nucellar seedlings are both used as rootstocks. The use of nucellar seedling rootstocks would ensure fruit orchard uniformity unlike nurse or zygotic seedlings. Nucellar seedlings are identical to the parent plant (Xiang and Roose, 1988; Garcia et al., 1999; Ruiz et al., 2000), but differences could be due to somatic variations (Frost and Soost, 1968). Identification of zygotic seedlings (referred to as off- type) from nucellar seedlings (true to type) is important for maintaining genetic homogeneity which ensures field uniform performance of rootstocks (Rao et al., 2008). However, this has not been easy in many polyembryonic seeds (Frost and Soost, 1968) and this includes mango