1.1 Background of the study

Mango (Mangifera indica L.) is a tropical fruit known as “king of fruits‟ belongs to genus Mangifera, family Anac- ardiaceae which is grown almost all parts of the world. It is believed to have originated from South East Asia and more than 1000 varieties have been identified all over the world [1]. Currently, mango is produced in tropical and sub-tropical climates, in more than 85 countries worldwide [2]. Mango is known as the king of the fruits due to its excellent flavor, delicious taste and high nutritive values that makes the crop valued for both food and nutritional security especially for developing countries like Nigeria where the realization of food and nutritional security is still a challenge [3]. The crop can be consumed as a raw, canned, or juice which provides sufficient amount of dietary antioxidants, such as ascorbic acid, carotenoids, and phenolic compounds and additionally a remarkable amount of dietary fiber, and vitamin A [4]. Mango is one of the most widely grown among the fruit crops cultivated in Nigeria preceded only by banana in terms of economic importance [5]. In Northern region, the potential area for mango production is in estimated at about 118.2 hectare [4]. According to Mekonnen [6], an attractive and delicious tropical and temperate fruits including mango are much in demand in the local markets in Nigeria.

The productivity of mango in Nigeria is very low com- pared to the crop potential, about 20–30 ton/ha [7, 8]. Various factors govern crop productivity but, genetic and environmental are well known. Nowadays, the government has been introducing new improved varieties in Nigeria. However, as compared to different mango growing nations, varieties of improved mango seed- lings distributed to farmers for commercial production in Nigeria are few [9]. Moreover, the supply of suitable root-stock mango seedlings in Nigeria is very limited [10]. Consequently, nursery potting media believed to have contributed to low viability and productivity of mango in the region. Mango plants are multiplied asexually through grafting and each plant is made up of the rootstock which provides root system and the scion forming the tree canopy. Both of these parts play an equally vital role in the life of a tree. The rootstock has great influence on the vigour, longevity and productivity of the scion variety [11].

1.2 Statement of the problem
Mango is highly susceptible to russet-like physiological disorder that affects the stem during maturation, and is severe in humid weather, rendering the stem unfit for fresh fruit due to development of brown blemishes on the fruit peel. The resulting unattractive appearance disqualifies the fruit from the export market due to stringent quality requirements. Producers get low returns from such blemished fruits as the fruits are sold in the local market and to local juice processors. Due to a lack of locally validated information on best control options for mango russet, agribusiness oriented mango growers have tried use of broad-spectrum synthetic pesticides for its control, without success.

1.3 Objective of the study

The general objective of this study is to determine stem diameter (MM). The specific objectives are:

1. To determine the plant height

2. To determine the leaf number

3. To determine the root number

1.4 Justification of the study
Agriculture is the main occupation for 75% of Nigeria’s population. Increase in Nigerian population has resulted in less land that is classified as arable. However, there are huge tracts of unutilized land in Nigeria where commercial production of drought resistant crops like mango crop can be done. Good returns on agricultural investments will be realized by promoting commercial farming of high potential crops that grow well. Mango is such a high potential crop in terms of high demand in the domestic and export markets.