ABSTRACT
Some locally available yam (Dioscorea spp.) obtained from three
(3) different markets; Orie, Eke and Nkwo market at Afikpo. Fungal pathogens in
the samples were isolated using the method of Suleiman et al., (2015)
with the aid of Potato Dextrose Agar (PDA); isolated fungal pathogens were
identified usin the method of James and Natalie (2001); bacteria pathogens were
isolated using the method of Ogaraku and Usman (2008) and were subsequently
identified. The colony morphology and biochemical characteristics of bacteria
isolated from the specimens gotten from Orie, Eke and Nkwo market were
presented in the Chapter Four.
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
Yam
(Dioscorea spp.) belongs to the
family D*ioscoreceae and to the genus Dioscorea (Suleiman et al., 2015). The most cultivated yam species in Nigeria are the
White yam (Dioscorea rotundata),
Yellow Yam (Dioscorea cayenesis) and
Water Yam (Dioscorea alata). There
are also other species of wild yam grown and eaten in Nigeria during food
shortage (Amusa and Baiyewu, 1999). Yams are perennial herbaceous vine tubers
and valuable source of carbohydrate to the people of the tropical and
subtropical Africa, Central and South America, parts of Asia, the Caribbean and
Pacific Islands (Suleiman et al.,2015).
Dioscorea spp.constitutes a staple
food in the tropics (Amusa et al.,
2003). The FAO (2008) estimated that the world production is around 20 million
ton per year. Nigeria alone produces three quarter of the world total output of
yams. Out of the ten cultivated species, the six most important and valued in
Nigeria are White yam (Dioscorea
rotundata), Yellow Yam (Dioscorea
cayenesis) and Water Yam (Dioscorea
alata L.), Bitter Yam (D. dumetorum),
Chinese Yam (D. esculental) and
Aerial Yam (D. builbifera L.),
(Okigbo, 2004). Except their importance as food source, yams also play an
important and significant role in socio-cultural lives of those that produces
them. The ritual and superstition believe surrounding yam and utilization in
West Africa is a strong indication of the antiquity of the use of the crop
(okigb et al., 2015). Yam in Nigeria,
is also processed into various staple, intermediate and end product form (Amusa et al., 2003), which are used for
direct consumption by animals, used as the basicingredient for snacks or made
into flour used for baking instant puree (Morse et al., 2000). Despite the high quantity produced by Nigeria, the
demand for Yam tubers has always exceeded its supply. Howeverm it has been
estimated that an average of over 25% of the yield is lost annually to diseases
and pests (Ogali et al., 1991).
(Amusa et al., 2003) also reported that
over 50% of the yam tubers produced and harvested in Nigeria are lost in
storage.
1.2 Justification
of the Study
Yams are susceptible to many
microorganisms many have been reported in association with storage decay in yam
tuber. (Okigbo and Ikediugu, 2006). Chemicals have proved helpful in the
control of yam diseases, but one of the problem of frequent use of the
chemicals is resistance of those organisms. There is need for alternative
approach using plant extract as an indication that such plants could be used by
peasant farmers who cannot afford the chemicals to control the organisms,
diseases attack on the crops.
1.3 Objective
of the Study
To
identify the microorganisms associated with yam (Dioscorea spp.) rot in Ivo Local Government Area.
To
determine frequent occurrence of the organisms associated with yam (Dioscorea spp.) rot in Ivo Local Government Area.
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