PHYSIOLOGICAL AND BIOCHEMICAL VARIABILITY IN BLACKGRAM GENOTYPES (Vigna mungo (L.) HEPPER) FOR TOLERANCE TO LEAF CURL DISEASE
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Date
2021-12-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Acharya N.G. Ranga Agricultural University, Guntur
Abstract
The present study entitled “Physiological and biochemical variability in
blackgram genotypes (Vigna mungo (L.) Hepper) for tolerance to leaf curl disease” was
conducted at RARS, Lam, Guntur during late rabi 2018-19 and 2019-20 in a randomized
block design. The treatments included were 25 blackgram genotypes with three
replications.
Results obtained from the study revealed that significant difference was observed
among the genotypes for leaf curl disease incidence, thrips population, plant height,
number of branches, trichome density, leaf thickness, leaf area, SLA, SLW, LAI, SCMR,
total chlorophyll content, total phenols, tannins, total soluble sugars, free amino acids,
protein content, catalase activity, peroxidase activity and hydrogen peroxide content at
20, 40, 60 DAS and at maturity and CGR and NAR at 20 – 40 DAS, 40 – 60 DAS and 60
DAS to maturity during both the seasons. The twenty five genotypes evaluated were
grouped in to four different categories based on leaf curl disease incidence (%), 8
genotypes (LBG 884, LBG 888, GBG 1, VBG-13-3, TBG 129, PBG 32-2, TU40, GKB
3) under resistant category, 9 genotypes (LBG 623, LBG 806, LBG 808, LBG 818, LBG
881, GKB 1, GKB 2, GKB 4, VBG 14-16) as moderately resistant, 6 genotypes (LBG
752, LBG 787, LBG 822, LBG 828, LBG 951,PU31) were placed under moderately
susceptible category and 2 genotypes (TBG 125, TBG 104) were found susceptible.
The experiment was late sown during both late rabi 2018-19 and 2019-20 to
coincide with higher temperatures, lower relative humidity and high vector population
resulting in higher leaf curl disease incidence. Among the genotypes tested higher leaf
curl disease incidence (%) was observed in the susceptible genotypes TBG 104 (49%) and
TBG 125 (46.45%). Lower disease incidence was recorded in the genotypes TU 40
(5.43%) and LBG 884 (8.23%). Higher thrips population was recorded in the genotypes
LBG 623 (13.2 plant-1
) and GKB 4 (11 plant-1
). Leaf curl disease infection caused a
significant reduction in plant height, number of branches and leaf area in all the genotypes
and higher percent reduction was observed in susceptible genotypes compared to their
genotypic characters. Plant height in susceptible genotypes was reduced by 56.4%
whereas in resistant genotypes it was 33.7%. The percentage reduction in the number of
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branches was 65.3 in susceptible genotypes and 46.1 in resistant genotypes. The reduction
in the leaf area of susceptible genotypes was 82.9% and the resistant genotypes showed
only 52.8 % reduction in leaf area. Trichome density was observed to be maximum at 60
DAS and among the genotypes higher trichome density was observed in GKB 3 (27.67
per 10mm2
) followed by LBG 884 (27.22 per 10mm2
). Higher leaf thickness was observed
at maturity in all the genotypes and among the genotypes highest leaf thickness value was
recorded in TU 40 and GBG 1 (0.437 mm). The lower values of trichome density at 60
DAS and lower leaf thickness at maturity were recorded in the genotypes LBG 623 (12.09
per 10mm2
) and LBG 951 (0.377 mm) respectively.
Resistant genotypes accumulated higher dry matter compared to the genotypes of
any other category. The resistant genotype TU 40 showed higher values of leaf, stem, root
and pod dry weight at maturity with 5.274, 5.032, 1.485 and 3.696 g plant-1
respectively.
Lower SLA values were recorded at 60 DAS in all the genotypes and among genotypes
lower SLA values were observed in GBG 1 (105 cm2
g
-1
) grouped under resistant category
in GBG 1. Higher SLW values were also observed at 60 DAS in all the genotypes where
the resistant genotype GBG 1 (9.13 mg cm-2
) recorded the highest of all the genotypes.
Higher CGR values were recorded during 40-60 DAS in all the genotypes and among the
genotypes higher CGR value was recorded in the resistant genotype TU 40 (12.50 g m-2
ground area day-1
). Maximum NAR values were recorded during 20-40 DAS in all the
genotypes and the higher NAR value was recorded in PBG 32-2 (11.46 g m-2
leaf area
day-1
). Lower values of total dry matter at maturity, SLW at 60 DAS, CGR during 40-60
DAS and NAR during 40-60 DAS were recorded in the genotypes GKB 4 (8.46 g plant1
), TBG 104 (3.11 mg cm-1
), LBG 623 (5.16 g m-2
ground area day-1
) and TBG 104 (5.76
g m-2
leaf area day-1
) respectively.
Higher total phenolic and tannins content was observed at maturity in all the
genotypes and among them LBG 818 (73.11 µg g-1 FW) recorded higher total phenols
content and the genotypes TU 40 and GKB 3 (5.22 mg g-1 DW) recorded higher tannins
content. Whereas the lower values of phenols and tannins were recorded in the genotype
LBG 623 (51.47 µg g-1 FW and 4.01 mg g DW) The higher TSS content at 40 DAS was
recorded in the genotype LBG 623 (177 µg g-1 FW) whereas the lower value was recorded
in GKB 3 (90.23 µg g-1 FW). The higher FAA content at maturity was recorded in TBG
104 (1.132 mg g-1 FW) whereas the lower value was recorded in GKB 4 (0.543 mg g-1
FW). The higher protein content was recorded at 40 DAS in all the genotypes and among
them higher value was observed in VBG 13-3 (1.851 mg g-1 FW) and the lower value was
found in LBG 623 (1.396 mg g-1 FW).
Higher catalase and peroxidase activities were recorded at 40 DAS and 60 DAS
respectively in all the genotypes. Among the genotypes higher catalase activity was
recorded in TU 40 (74.85 ng min-1 mg-1 protein) and lower catalase activity was observed
in TBG 104 (33.33 ng min-1 mg-1 protein). Among the genotypes higher peroxidase
activity was recorded in TU 40 (80.72 ng min-1 mg-1 protein) and the lower peroxidase
activity was recorded in TBG 104 (40.83 ng min-1 mg-1 protein). The H2O2 content of all
the genotypes increased with the advancement in age and at 40 DAS the H2O2
accumulation was observed in response to the disease infection. Higher H2O2 content
among the genotypes was observed in TBG 104 (129.57 nmol g-1 FW) whereas lower
H2O2 accumulation was observed in TU 40 (71.27 nmol g-1 FW).
The leaf nitrogen content was observed to be decreased from 20 DAS to maturity
in all the genotypes. The genotype LBG 623 recorded higher N content at 20, 40, 60 DAS
and at maturity (2.92, 2.49, 1.74 and 1.49% respectively) and lower N content values were
recorded in the genotype TU 40 (1.83, 1.40, 0.64 and 0.55% respectively). The leaf
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phosphorus content of all the genotypes depleted from 20 DAS to maturity. Among the
genotypes higher P content values were recorded in the genotype TU 40 at 20, 40, 60 DAS
and maturity (0.456, 0.280, 0.276 and 0.216% respectively) whereas the lower values
were recorded in LBG 623 (0.309, 0.229, 0.183 and 0.174% respectively). The leaf
potassium content increased from 20 to 60 DAS in all the genotypes and decreased from
60 DAS to maturity among the genotypes higher K content value at 60 DAS was recorded
in the genotype LBG 806 (2.066%) whereas the lower value was record in LBG 623
(1.715%).
The leaf curl disease has severely affected the yield and yield component traits of
all the genotypes. The genotypes grouped under resistant category TU 40 (739 kg ha-1
),
VBG 13-3 (729 kg ha-1
) and PBG 32-2 (722 kg ha-1
) showed higher seed yield. The
character association studies has revealed that the morphological traits like leaf thickness
and trichome density showed highly significant negative correlation with thrips
population at 40 and 60 DAS both at phenotypic and genotypic levels. The physiological
traits like SLW, CGR and NAR showed highly significant negative association with leaf
curl disease incidence at both phenotypic and genotypic levels and SLA showed a positive
association. The biochemical traits such as catalase and peroxidase activities, phenols,
tannins, protein, phosphorus and potassium showed a highly significant negative
association with leaf curl disease incidence at both phenotypic and genotypic levels.
Whereas the traits TSS, FAA and H2O2 showed a highly significant positive association
with leaf curl disease incidence at both phenotypic and genotypic levels. Hence, It can be
concluded that the leaf curl disease resistance in blackgram is contributed by higher
antioxidant activities, K content and lower FAA and H2O2 contents.
Description
PHYSIOLOGICAL AND
BIOCHEMICAL VARIABILITY IN
BLACKGRAM GENOTYPES (Vigna
mungo (L.) HEPPER) FOR
TOLERANCE TO LEAF CURL
DISEASE