Journal of Food, Agriculture and Environment

Effect of maize lethal necrosis and its causative viruses (maize chlorotic mottle virus &  sugar cane mosaic virus) on the growth and yield of maize as influenced by varietal tolerance/susceptible levels and plant stage at time of inoculation

Author(s):

 James Karanja, John Derera,   Augustine Gubba, Stephen Mugo,  Anne Wangai

Recieved Date: 2019-10-03, Accepted Date: 2019-12-06

Abstract:

Like in other parts of continent, the population in Kenya continues to increase with decreasing of arable land size. A key problem is that most Kenyans rely on maize as a staple crop. The spread of plant pests and diseases has dramatically increased in recent years due climate change. These pests and diseases continue to cause huge losses to maize yield, threatening the livelihoods of vulnerable smallholder farmers and income in the high potential areas. Maize chlorotic mottle virus (MCMV) and sugar cane mosaic virus (SCMV) are known to infect maize. The synergistic association between the two viruses results to maize lethal necrosis (MLN) disease. Despite the development of maize lines and hybrids with improved resistance to MLN, little is known about the impact that these viruses has on yield loss.  A field study was conducted in 2015, 2016 and 2017, using 25 improved maize varieties to estimate the yield loss caused by MLN and its causative viruses by comparing uninfected and infected plants in the field. The maize varieties were mechanically inoculated with MCMV, SCMV and dual (MCMV+SCMV) at three growth stages; V₃,V₇, V_T.Disease severity scores, yield attributes and grain yield were determined. In the susceptible varieties, all measured variables were significantly reduced in V₃, V₇ and V_T  inoculations, with the greatest reductions occurring in the V inoculation stage. Among the yield components, the greatest reductions occurred on plant height, ear height, 50% days to anthesis, number of ears at harvest, rotten ears and grain yield. Hybrid KH500-33A was significantly affected in the MLN and SCMV treatments recording a yield reduction of 96.6 and 90.3%, respectively, with WE1101 recording 85.4% in MCMV. Hybrid CKLMLN146038 was the best performer across the 3 treatments recording the lowest yield reduction of 17.0%, 29.7% and 31.5% in MCMV, MLN and SCMV, respectively. The results from this study indicate that under field conditions, (i) MCMV tolerant maize hybrids are less affected by MLN, and (ii) dual inoculation of most of the hybrids with MCMV and SCMV exacerbates symptom expression and yield loss in MCMV susceptible hybrids. Percentage of yield loss is likely to be proportional to percentage of disease incidence and severity since plant densities in the experiment and farmers’ fields are probably too low to allow uninfected plants around the infected ones to compensate the yield losses of infected plants

Keywords:

MCMV, SCMV, MLN, maize,   yield loss

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Journal: Journal of Food, Agriculture and Environment
Year: 2020
Volume: 18
Issue: 1
Category: Agriculture
Pages: 23-29

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