EVALUATION OF CERTAIN SORGHUM CULTIVARS FOR RESISTANCE TO RICE WEEVIL, Sitophilus oryzae (L.) AND IDENTIFICATION OF ATTRIBUTES OF RESISTANCE
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Date
2019
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
Sorghum, Sorghum bicolor L. Moench is the most important cereal crop grown in
India during both Kharif and Rabi seasons for multiple uses as food, feed, fodder and fuel
crop. Rice weevil, Sitophilus oryzae L. is the most important insect pest infesting sorghum
causing an annual loss of 25 – 40 per cent after six months of storage. Present study was
conducted for evaluation of sorghum cultivars against rice weevil to identify resistant
genotypes which could be used in longer storage conditions and also utilized for insect
resistance breeding programmes. Forty seven sorghum genotypes representing hybrids
(8), varieties (28), parental lines (3) and checks (8) were evaluated to identify least
susceptible genotypes based on adult emergence, oviposition, mean development period,
index of susceptibility, weight loss (per cent), germination (per cent) and biochemical
attributes (protein, fat and starch).
Based on mean adult emergence, the genotypes namely, N 13 (29.17), N 14
(38.67), 104 B (41.40), NJ 2647 (41.80) and CSV 13 (41.83) were found least susceptible.
Considering the adult weevil population and oviposition, the genotypes, viz., N 13, N 14,
104 B, NJ 2647, CSV 13, CSH 15 R, C 43 and CSH 13 were found recording low
susceptibility to S. oryzae. Among these genotypes, high protein (14.53 – 12.45 %), fat
(3.88 – 3.52 %) and starch (71.85- 70.84 %) were observed in CSH 15R, CSH 13, CSH
25, CSV 13, CSV 18, N 13, N 14, NJ 2647, NTJ 4 and rabi female parental line 104 B
recording low oviposition resulting in less weevil population showing the antibiosis
mechanism. Rabi female parental line (104 B) has recorded minimum rice weevil
population (41.40) with high protein (12.74 %), fat (3.67 %) and starch (71.85 %) contents
the storage for a period of 90 days.
Maximum mean development period of 48.91 days was observed in 104 B. Least
index of susceptibility was recorded in N 13 (6.72) when compared to the genotype, CSH
24MF (19.74). Less weight loss due to weevil infestation was recorded in 104 B (1.07 %)
and NJ 2647 (1.07 %). After 60 days of infestation maximum seed germination was
observed in the genotype, CSH 13 (78.67 %). Maximum grain hardness was observed in
sorghum genotype, NJ 2647 (6.44 kgf/mm2
) with low weevil population showing
antixenosis mechanism. Maximum test weight of 4.05 g was recorded in CSV 18 when
compared to other genotypes. Length breadth ratio ranged from 1.06 (CSH 35) to 1.33 (N
13).
The grain hardness was significantly negatively correlated with adult emergence
(r = -0.468) where seed size played an important role in determining the pest infestation
and adult emergence. The protein, fat and starch content in different sorghum genotypes
was significantly negatively correlated with adult emergence and oviposition.
From the present investigation, the sorghum genotypes, viz., N 13, N 14, 104 B,
NJ 2647, CSH 13, CSH 15R, CSV 13, C 43 and NJ 2446 were found promising which
could be utilized in rice weevil resistance breeding programme for further evaluation and
also safely stored for longer durations.
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D10,406