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| Article Socio Eco |
Agronomic practices and disease severity
Rice
(Oryza sativa L.) is the major
agricultural crop of the world. And it is grown throughout the world once or
twice within a year. It is also the main agricultural crop of Nepal. Its
cultivation is maximum in terai region. Hilly region and Himalayan region also
favor rice cultivation but comparatively lesser than that to terai region.
Although
rice is the main crop of the world it is infected by different groups of
pathogens, but main is fungal group. Blast disease caused by fungal pathogen Pyricularia oryza has threatened the
world causing crop loss and food security. The pathogen infects on leaves,
stem, neck, clums and panicles.
Different
factors cause the crop to be infected by pathogens and cause blast disease.
Among them agronomic practices is one of them. Different agronomic practices
like tillage, irrigation, date of sowing, fertilization, method of planting,
etc.
A
survey had been done in Hemza village of kaski district in year 2012. In that
survey, effect of some agronomic practices like hand weeding times, date of
sowing and type of planting on blast disease severity was explored. From the
survey:
Blast disease severity on different
times of hand weeding
Rice
blast disease severity decreases with increased time of hand weeding as
in table 1. But the severity increases with increasing days after
transplantation. The field which was hand weeded only for one time has severity
after 25, 35 & 45 days of transplantation (DAT) as 15.97%, 32.98% and 36.9%
respectively. Similarly, the field hand weeded for two times showed severity
after 25, 35 & 45 (DAT) as 14%, 26.11% and 26.55% respectively. And that
for field hand weeded for three times showed severity as 10%, 15% and 12%
respectively.
Disease
severity form the field that was had hand weeded for two and three times was
compared with severity of field which was hand weeded for only one time.
Analysis from t-test indicates significant relation between times of weeding
i.e. p value less than 0.005.
Blast disease severity on different
dates of sowing
Dates
of sowing rice seeds also affects the severity caused by blast disease. Blast
severity increases with late sowing of rice seeds. Disease severity in early
sowed rice field showed comparatively lesser than that in late sowed field. As
in table 2 the field which have been sowed on 25th Jestha showed the
disease severity at 25, 35 and 45 days after sowing as 20.5%, 28.13% and 40.15%
respectively. Similarly, with the field which have been sowed on 5th
Aswin showed severity as23.7%, 33.86% and 44.87% at 25, 35 and 45 days after
sowing respectively. And that for fied sowed on 25th Aswin showed
severity at 25, 35 and 45 days after sowing as 28.86%, 36.31% and 44.87%
respectively. On the other hand severity increases with increasing age of crops
(rice).
Disease
severity of late sowed field (sowed on 5th Aswin and 25th
Aswin) was compared with severity of early sowed field (25th
Jestha). Data analysis from t test indicates significant effect of date of
sowing on disease severity in rice due to blast i.e. p value > 0.005.
So,
the result reveal that different agronomic practices has effect on blast
disease severity and crop loss due to blast.
