STANDARDIZATION OF ROOTSTOCK IN MANGO

Abstract

Rootstocks in mango are always seedlings whether they are of zygotic or nucellar origin. Clonal nucellar seedlings rootstocks have many advantages over heterogenous monoembryonic seedling rootstocks. Clonal rootstocks have been selected for specific soil types and stress tolerance and behavior of the scion cultivar on clonal rootstocks is highly predictable. With the intensification of fruit production due to socio-economic considerations, the role of rootstocks in commercial fruit production has increased considerably in the recent past. Although rootstocks have several applications such as improving fruit quality, imparting adaptability to climatic and edaphic conditions and inducing dwarfing, the priorities of rootstocks selection in the tropics and subtropics have been focused mainly on vigour management and securing regular high fruit yields. Mango is an important fruit crop of the tropical and subtropical regions. The yield is less than 10 t/ha in most of the growing countries. Low planting densities based on the expected eventual tree size, propagation on seedling rootstocks of unknown pedigree and irregular bearing habits are some of major reasons for low orchard efficiency of mangoes in India. In India and Mexico, monoembryonic seedlings are generally used as rootstocks. Polyembryonic ‘Turpentine’ seedlings are used as rootstocks in Florida. Either polyembryonic ‘Saber’ or ‘13-1’ seedlings are used as rootstocks in Israel. In Australia, ‘Kensington’ seedlings are used as rootstock. Throughout South-East Asia polyembryonic seedlings are used for rootstocks. Use of nondescript mango stones for multiplication of rootstocks has led to enormous variation in the performance of mango clones in the orchards. Some attempts have been made to standardize the rootstocks for various scion cultivars including the use of polyembryonic cultivars for vigour management, salinity drought, stress tolerance, fruit yield and quality. There are relative advantages of polyembryonic rootstocks in mango. In many regions including India and Mexico scion cultivars are still being propagated on heterogenous monoembryonic seedling rootstocks despite the demonstrated advantages of clonal nucellar rootstocks. The potential of clonally propagated manoembryonic rootstock has not been properly investigated. Other Mangifera sp. also have interesting attributes and should be screened for graft compatibility with mango. The species that could be tested as rootstock for mango might extend mango cultivation to areas where abiotic and biotic stresses currently limit production and could provide a better source for dwarfing rootstocks for high density orcharding.