Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges &
Opportunities during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
Unamended control; T2: 100% RDF; T3: 75% RDF + 20 kg S ha -1 ; T4: 100% RDF + 20 kg S
ha -1 ; T 5: 75% RDF + 30 kg S ha -1 ; T 6: 100% RDF + 30 kg S ha -1 ; T 7: 75% RDF + 40 kg S ha -
1 ; T 8: 100% RDF + 40 kg S ha -1 , replicated thrice. The crop was sown in 4.2 × 3.0 m 2 plots by
adopting a seed rate of 20 kg ha -1 and 30 cm row to row spacing. The RDF used was 20-40-0
kg NPK ha -1 and the entire quantity of fertilizers (NPK) were applied as basal before sowing.
The disease incidence (CLS) was observed at the time of flowering. Based on visual symptoms
of damage, CLS infestation levels were categorized into four grades of severity viz. grade 1
(healthy), grade 2 (low), grade 3 (medium) and grade 4 (severe). The biophysical parameters
(biomass, SPAD value and seed yield) were recorded under different severity grades. Canopy
reflectance data from mungbean (15 plants per each grade) were recorded with FieldSpec 3 Hi-
Res spectroradiometer (ASD 1999; spectral range: 350-2500 nm).
Results
The biophysical parameters of mungbean infested with CLS varied significantly under different
severity grades As mentioned in the table. With the increase in CLS incidence, the SPAD value
decreased by 22.9%. Fresh and dry biomass also varied significantly with CLS, however, the
trends were not consistent. The fresh and dry biomass of mungbean under severely infested
CLS was reduced by 30.1% and 38.5% compared to healthy plants. With increase in the
severity of CLS infestation the yield had declined significantly. The maximum yield loss was
observed in severely infested crop followed by medium CLS infestation compared to healthy
plants. The seed yield was reduced in infested plants by 38.1% (across three grades) compared
to healthy.
SPAD value, biomass and seed yield of mungbean under different grades of CLS
infestation
Severity Grade
SPAD value
Fresh biomass
(g plant -1 )
Dry biomass
(g plant -1 )
Seed yield
(g plant -1 )
Healthy 52.40 ± 5.69 a 42.42 ± 7.77 a 8.57 ± 2.11 a 2.02 ± 0.18 a
Low 45.10 ± 1.35 b 38.25 ± 8.93 a 7.66 ± 1.29 ab 1.49 ± 0.25 b
Medium 45.10 ± 1.35 b 35.93 ± 5.91 ab 6.84 ± 1.54 b 1.31 ± 0.15 c
Severe 40.37 ± 0.94 c 29.64 ± 7.59 b 5.27 ± 1.65 c 0.96 ± 0.10 d
Values are Mean ± SD, different superscript letters denote significant difference (p < 0.05)
Mean canopy reflectance of different CLS severity grades from the field based hyperspectral
radiometry studies showed a distinct difference between healthy and infested plants in the
figure at different levels of infestation as described in the figure. Reflectance from the CLS
infested plants compared to healthy was high in visible region (400-750 nm) and was lower in
near infra-red region (750-1100 nm). Healthy plants have higher reflectance in NIR region and
low reflectance in the visible region.
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