Physiological and reproductive behaviour of summer Mungbean [Vigna radiata (L.) Wilczek] under terminal heat stress
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Date
2015
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CCSHAU
Abstract
The present investigation was carried out on three mungbean genotypes viz. MH 421, MH 318 and
Basanti in the screen house during 2012-13 and 2013-14. High temperature induced changes for plant water
status i.e. water potential (yw), osmotic potential (ys) and relative water content (RWC %), relative stress
injury (RSI %), physiological parameters viz. total chlorophyll, chlorophyll stability index (CSI), chlorophyll
fluorescence and canopy temperature depression (CTD), biochemical like malondialdehyde (MDA), total
soluble carbohydrate (TSCs), proline accumulation, nitrogen content, antioxidant enzymes and protein
profile were studied 3 and 7days after exposure (DAE) to high temperature (>35oC) and reproductive
changes, yield attributing character, seed quality studies were taken at harvesting stage.
The yw and ys of leaves became more negative from -0.66 to -1.97 and -1.01 to -1.87 MPa
respectively, with increasing the days after exposure (DAE) to high temperature (>35°C). In the genotype
MH 421, the value of yw (-1.59) and ys (-1.69) of leaf were more negative than MH 318 and Basanti. With
the increased DAE, RWC of leaf declined from 73.65% to 63.41%. Total chlorophyll content (17.27 to
11.31 mg g-1 DW), SPAD (48.64 to 46.02) readings, CTD (-5.78 to -4.37: °-C) and CSI (81.01% to 67.36%)
decreased with increased DAE to high temperature and decrease was more in Basanti and MH 318 than MH
421. RSI increased with increased DAE to high temperature; the increase more in Basanti (41.34%)
followed by MH 318 (40.72%) than MH 421 (34.88%). MDA (21.75 to 34.44), TSCs (23.58 to 33.65 g g-1
DW) and proline content (3.11 to 17.77 mg g-1 DW) increased in all genotypes with increased DAE; the
increase MDA, being more in leaves of Basanti (30.66 μ mol g-1DW) followed by MH 318 (28.97) than MH
421 (28.26). The TSCs and proline content were maximum in MH 421 (33.83 mg g-1 DW and 25.21 mg g-1
DW) followed by MH 318 (30.08 and 23.75) than Basanti (28.26 and 22.19) respectively. Moreover the
RWC (%) and Osmotic adjustment (OA) were also better in MH 421under high temperature stress.
High temperature induced the specific activity of antioxidant enzymes such as superoxide
dismutase (SOD) (3.37 to 5.67), catalase (CAT) (7.40 to 11.48), peroxidase (POX) (10.09 to 21.95),
ascorbate peroxidase (APX) (0.35 to 1.56), Glutathione peroxidase (GPX) (0.39 to 0.61), Glutathione
transferase (GST) (0.22 to 0.80). The antioxidant i.e. total glutathione (409.49 to 513.09) and hydrogen
peroxide (H2O2) (1.53 to 1.82) were enhanced while ascorbic acid (AAC) (25.20 to 16.88) and caroteonoid
content (4.61 to 2.30) were decreased with increased DAE to high temperature. The specific activity of
above said enzymes was maximum in MH 421 followed by MH 318 and minimum in Basanti at all the
DAE to high temperature. The total glutathione, ascorbate and caroteonoid content were higher in MH 421
as compared to other genotypes while reverse trend was seen for H2O2 content.
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Keywords
genotypes, planting, biological phenomena, proteins, tolerance, enzymes, irrigation, developmental stages, yields, sowing