dc.description.abstract |
Rice (Oryza sativa L.) is one of the most paramount staple foods of the world.
It occupies a unique position in cereal crops with respect to area under cultivation and
more than 2.7 million populations depending on rice. In Pakistan, rice is an important
food and cash crop and has the status of second staple food crop after wheat and the
second major exportable produce after cotton. Despite much development in rice
production technology research and developments, the yield of rice crop in Pakistan is
very low as compared to other rice growing countries. One of the major yield limiting
factors is the attack of insect pests and diseases. Among these, leaf folder (LF)
Cnaphalocrocis medinalis (Gu.) and bacterial leaf blight (BLB) of rice are of
economic importance and cause irreparable yield losses every year. A comprehensive
survey was conducted to investigate the farmers’ perception regarding leaf folder and
bacterial leaf blight and factors which boost up the infestation of leaf folder and
incidence of bacterial leaf blight and their management practices in rice crop. A
questionnaire was developed; minimum of 50 farmers were interviewed in selected
five districts of Punjab, Pakistan. Majority of the farmers (62%) responded that LF
attacked their crop first while 30% farmers were of the opinion that BLB attacked
first. Eight percent informed that crop was attacked by LF and BLB simultaneously.
As most of the farmers (72%) responded that those fields in which LF attacked first,
the incidence of BLB was high, while 64% farmers told that LF enhanced the severity
of BLB. Furthermore, the interaction among leaf folder and bacterial leaf blight was
also studied. Total damage area (TDA) in the combined treatment (LF+Xoo) was
significantly higher (72.08±1.57) than in the combined treatment (Xoo+LF), single LF
treatment and single Xoo treatment on rice variety Basmati 385 and same trend was
followed by 2nd week and 1st week. This implies a synergistic interaction of LF and
xiv
Xoo when Xoo was inoculated after LF infestation. However combined treatment of
(Xoo+LF) showed a significantly lower TDA (59.28±1.47) compared with other
combined treatment (72±1.57) and single LF and Xoo treatments. The data regarding
yield contributed factor and yield losses due to leaf folder and bacterial leaf blight
alone and combined were also recorded. The data revealed that maximum 1,000 grain
weight loss due to BLB was 13.22% and 6.79% for years 2012 and 2013 respectively,
on Super Basmati followed by Basmati 515 and Basmati 385. The highest 1,000 grain
weight loss due to LF was 7.09% and 1.20% on Super Basmati followed by Basmati
515 and Basmati 385. The maximum 1,000 grain weight loss due to combined
treatment (LF and BLB) was 20.06% and 7.07% on Super Basmati followed by
Basmati 515 and Basmati 385 during 2012 and 2013 respectively. The maximum
yield loss due to BLB was 20.62% and 10.55% on Super Basmati followed by
Basmati 515 and Basmati 385. The yield loss due to LF was 10.32% and 3.48% on
Super Basmati followed by Basmati 515 and Basmati 385.The yield loss due to
combined (LF and BLB) was 27.05% and 11.02% on Super Basmati followed by
Basmati 515 and Basmati 385. The leaf damage data revealed that two wild species,
Oryza rufipogon and Oryza brachyantha were resistant to LF. Fourteen genotypes
were moderately resistant (MR), ten were moderately susceptible (MS), fourteen were
susceptible (S) and ten were highly susceptible (HS) against leaf folder. Similarly
results exhibited that one wild species (O. rufipogon) was found highly resistant (HR)
whereas one species (O. brachyantha) showed resistance (R) response. Two rice
genotypes showed moderately resistant (MR) response; nine rice lines represented the
moderately susceptible (MS) response, thirty three were represented susceptible
response (S) and four were found highly susceptible (HS) against bacterial leaf blight.
These identified resistant germplasm can be used in breeding program of rice crop to
develop resistant varieties against leaf folder and bacterial leaf blight disease. |
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