1.1 Introduction
Onion (Allium cepa L.) is one of the important vegetable crops grown globally, which belongs to the family Liliaceae. It is subdivided into three groups: Allium cepa, Allium aggregation, Allium prolilum, which are all diploids (Boukary, 2012). The crop is a biennial herb which originated from Central Asia with centers of diversity in Afghanistan, Iran and Pakistan. The crop is currently cultivated worldwide with other secondary centers of diversity identified over time (Brewster, 2008). Onion is ranked 4th among the most consumed vegetables after tomato, cabbage and watermelon with a global annual production of 2 million tonnes (Abdelkader et al., 2014).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research hypothesis and questions, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Onions are grown primarily for their use as food, adding flavors to food and taste (Megersa, 2017). The crop is also used for processing such as pickling, freezing, dehydration and oil extraction. Young and healthy green onion leaves with their white bases are eaten raw in salads. In addition to consumption, onions are produced for medicinal purposes such as prevention and treatment of blood and heart diseases (Cheema et al., 2003). The crop is also a rich source of Vitamin C and E (Elassi, 2007) and in Uganda, onions contribute to household income especially in highland areas where they are grown purposely for sale (Bua et al., 2017). In India, onion is being grown in an area of 0.83 million hectares with production of 13.57 million tonnes and the productivity is 16.30 ton ha-1 which is low. Maharashtra is the leading onion producing state followed by Karnataka, Gujarat etc (FAO et al., 2018).
In peri-urban areas of central Uganda, onion is becoming a major spice and vegetable produced by farmers in wetland areas. Consequently, strong help for smallholder producers to achieve potential yields to boost their income and secure their livelihood by providing high yielding and adapted onion genotype is critical. However, the present challenge in most onion growing areas is lack of well-adapted onion genotypes. As a result, varietal information to improve onion yield in production areas is inadequate. Additionally, research has not established a breeding program to develop improved varieties or even evaluated existing onion genotypes imported from outside Uganda to guide growers in selecting best yielding onion varieties to use. Evaluation of onion genotypes for their yield performance is considered as one approach to use in obtaining high yielding and adapted onion genotype.
Therefore, in Gada Local Government Area Sokoto State Nigeria where the research was carried out, the activities that was conducted is to know the Prevalence and Distribution of Nematode Species in Onion Farms.
1.3 Statement of Problems
Investigation reveals that onion production remains as low input and output crop with a national average yield of 5 ton ha-1 (FAO, 2012). However, the yield of the crop is far below the world average (19.7 ton ha-1) despite its being year- round production (FAO, 2012). The low onion yield in Uganda is partly attributed to farmers' exchange of planting materials (bulbs), they rarely purchase improved and well-adapted genotypes.
Furthermore, due to limited research on commercial production of onion, farmers rarely use improved production practices (Bewuketu et al., 2016). Common pests such as thrips decrease yield in the absence of timely pesticide application or resistant onion genotypes (Harsimran et al., 2015). Similarly, the ineffective post-harvest handling and storage practices used by farmers also contribute to about 25% losses (Harsimran et al., 2015). An ethnobotanical survey tells of the Fennoscandian multiplying onions as being a crop with reliable harvest, excellent storage ability, and good taste. Increased cultivation of this material on both household and commercial-scale should be possible (Leino et al., 2018).
1.4 Aim and Objectives of Study
The aim of the study is to determine the Prevalence and Distribution of Nematode Species in Onion Farms in Gada Local Government Area Sokoto State Nigeria. In achieving this aim, the following specific objectives were laid out as follows:
- To identify the best performing onion genotype with good storage under field and room conditions.
- To examine the prevalence of Nematode Species in Onion Farms
- To find out how Nematode Species in Onion Farms is distributed in Gada Local Government Area Sokoto State Nigeria
