Epidemiology, Molecular Characterization and Yield Loss Assessment of Rice Due To Rice Yellow Mottle Sobemovirus in Northern Nigeria
Epidemiology, Molecular Characterization and Yield Loss Assessment of Rice Due To Rice Yellow Mottle Sobemovirus in Northern Nigeria.
ABSTRACT
Screenhouse and field experiments were conducted between 2008 and 2010 to quantify yield loss due to Rice yellow mottle virus (RYMV) in some selected rice cultivars.
determine the epidemiology of RYMV in relation to weather factors on the incidence of RYMV and insect vector population composition and identification studies; identify its alternative hosts.
determine serotypes of the pathogen; and molecular characterization of the strains and their distribution in the northern states of Nigeria.
The screenhouse experiment was arranged in a strip plot design with three replicates. Significant interaction between the effects of inoculation regimes and rice cultivars were found between the disease, growth and yield parameters.
The critical periods of RYMV infection for most of the rice cultivars used were within 4 – 8 Weeks after sowing (WAS). Paddy yield losses of 6.59 – 79.11 % and 3.65 – 81.67 % were recorded on the test cultivars in rainy and dry seasons, respectively.
Keeping the plants RYMV- free for up to 10 WAS resulted in grain yield almost similar to control. The epidemiology experiment was laid out in a randomized complete block design (RCBD) with three replicates.
Significant positive and negative correlations were recorded between RYMV incidence and severity index, some insect vectors and weather factors.
INTRODUCTION
Rice (Oryza sativa L.) Is a staple food for about one half of people in the world and is mainly harvested and consumed in Asia and Africa (Anonymous, 2005; Sun et al., 2006). In many regions, it is eaten with every meal and provides more calories than any other single food (Hynes, 2007).
It is not only consumed by humans and fed to livestock as it is also useful industrially for processing into acetic acid, glucose, and starch. Rice straw and stems are used by local farmers as bedding for animals and for weaving roofs, hats, baskets and sandals. The inedible rice hull is used as fuel, fertilizer, and insulation (Schalbroeck, 2001; Gao et al., 2004; Hynes, 2007).
Rice is produced in about 10% of all cropland (144 million hectares) in over 110 countries (Luth, 1980). It has the ability to adapt to diverse environmental conditions and is, therefore, grown in varied climatic conditions ranging from the Sahel to the Rainforest ecological zones (Luth, 1980) in every country in West Africa (WARDA, 1995).
The main production ecologies are rainfed lowland, rainfed upland, irrigated lowland, deep water/flooding and mangrove swamp (Onyishi et al., 2010). Nigeria cultivated 2.191 million hectares of land with rice paddy production of 3.28 million metric tonnes in 1999 while land area under rice production increased by 0.4 % with 3.30 metric tonnes in 2000 (Anonymous, 2001).
The potential land area for rice production in Nigeria is between 4.6 and 4.9 million hectares (Nwilene et al., 2009a). Despite the continuous increase in the land area that is cultivated with rice, Nigeria still imports rice annually (FAO, 2010). It was reported in order to meet local demand, Nigeria imported 1.7 and 1.8, million tonnes of rice in 2008/ 2009 and 2009/ 2010, respectively (FAO, 2010).
REFERENCES
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CSN Team.
