MSc

A study entitled “Impact of seed priming on physiological and
biochemical mechanisms under water stress condition in chilli (Capsicum
annuum L)” was undertaken with the objective assessment of the effect of
seed priming on physiological and biochemical mechanisms and yield
components under water stress condition in chilli. For both experiments I & II
seeds of the chilli variety ‘Vellayani Anugraha’ were primed with 2.5%
potassium nitrate (KNO3), 3% silicon dioxide (SiO2), and unprimed were
soaked in distilled water for 24 hours and subjected to control and water stress
levels at flowering stage.
The first experiment was carried out in a factorial completely
randomized design (FCRD) with the first factor being stress levels and the
second-factor being priming agents using different solutions replicated
thrice. The seeds primed with 2.5% KNO3, 3% SiO2, and unprimed seed
treatments were sown in protrays. Seedlings were transplanted to pots 35
days after sowing (DAS), irrigation, and other cultural practices were
followed according to KAU POP (package of practices). Water stress was
induced by withholding irrigation for three days where the relative water
content (RWC) of leaves reached 70% during the flower initiation stage. The
results of the first experiment revealed that seeds primed with 3% SiO2
resulted in early flowering and first fruiting.
Under water stress conditions, seeds primed with 2.5% KNO3 recorded
significantly higher values for RWC (69%), cell membrane stability Index
(CMSI) (42.16%), malonaldehyde (0.62 μmole ml-1), H2O2 (0.62 μmol g-1),
trehalose (0.15 μmol g-1 FW), α-amylase activity (14.68 μmol maltose formed
min-1 mL-1), specific leaf area (15.99 cm2 g-1) total chlorophyll content
(TCC) (1.92 mg g-1), superoxide dismutase (SOD) (491.3 units mg-1 of
protein), total soluble sugars (TSS) (1.53 mg/g) and total soluble protein
(TSP) (1.017 mg g-1) however 3% SiO2 primed seeds recorded significantly
higher values for total proline content (3.12 μmoles of proline g-1 of tissue).
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Under control conditions, 2.5% KNO3 primed seeds recorded significantly
high values for RWC (92%), trehalose (0.17 μmol g-1 FW), α-amylase
activity (16.76 μmol maltose formed min-1 mL-1), specific leaf area (20.88
cm2 g-1) total chlorophyll content (TCC) (4.54 mg g-1), superoxide dismutase
(SOD) (491.32 units mg-1 of protein), total soluble sugars (TSS) (3.22 mg g-1)
and total soluble protein (TSP) (2.06 mg g-1) however 3% SiO2 primed seeds
recorded significantly higher values for total proline content (1.31 μmoles of
proline/g of tissue) and CMSI (91.0%).
Under water stress conditions, capsaicin content was recorded
higher in seeds primed with 2.5% KNO3 (144.6 μg g-1), and ascorbic acid
was recorded the highest in seeds primed with 3% SiO2 (3.89 mg g-1). In
contrast, in control, both capsaicin content (224.0 μg g-1) and ascorbic acid
content (4.81 mg g-1) were recorded higher in seeds primed with 2.5%
KNO3.
Under water stress conditions, the yield components were higher in
seeds primed with 2.5% KNO3. The plant height (60 cm), number of flowers
plant-1 (24 number), number of fruits plant-1 (20 number), and fruit yield
(44.29 g), were recorded as significantly higher in seeds primed with 2.5%
KNO3. however, the seed yield (3.60 g) was recorded as significantly
higher in seeds primed with 3% SiO2, and the number of flowers plant-1 (22
number) was found the highest in unprimed seeds. Whereas in control, 2.5%
KNO3 primed seeds recorded significantly higher plant height (65.3 cm),
fruit yield (90.4 g), number of fruits plant-1 (23.4), and 3% SiO2 primed seeds
recorded significantly higher seed yield (4.03g).
The second experiment was carried out in a factorial randomized
block design (FRBD) with the first factor being stress levels and the second
factor being priming using different solutions which were replicated thrice.
the seeds primed with 2.5% KNO3, 3% SiO2, and unprimed seeds treatments
were sown in protrays. Seedlings were transplanted to the field 35 days after
sowing (DAS) and irrigation and other cultural practices were followed
according to KAU POP. Water stress was induced by withholding irrigation
for seven days where the (RWC) of leaves reached 70% during the flower
initiation stage. During this period, physiological parameters were taken
from the stress and control plants. The results revealed that seeds primed
with 3% SiO2 recorded early flowering whereas seeds primed with 2.5%
KNO3 recorded the first fruiting stage.
Under water stress conditions, seeds primed with 2.5% KNO3
recorded significantly high values for RWC (68.16%), CMSI (46.66%),
malonaldehyde (0.73 μmole ml-1), H2O2 (0.71 μmol g-1), trehalose (0.13 μmol
g-1 FW), α-amylase activity (13.93 μmol maltose formed min-1 mL-1),
Specific leaf area (13.47 cm2 g-1) TCC (1.93 mg g-1), SOD (520.03 units mg-1
of protein), TSS (1.55 mg g-1) and TSP (1.05 mg g-1) where 3% SiO2 primed
seeds recorded significantly higher values for total proline content (3.12
μmoles of proline g-1 of tissue). For control conditions, 2.5% KNO3 primed
seeds recorded significantly high values for (RWC) (79 %), trehalose (0.17
μmol g-1 FW), α-amylase activity (14.77 μmol maltose formed min-1 mL-1),
Specific leaf area (18.47 cm2g-1) TCC (3.86 mg g-1), SOD (405.60 units mg-1
of protein), TSS (3.16 mg/g) and TSP (2.0 mg/g) however 3% SiO2 primed
seeds recorded significantly higher values for total proline content (1.31
μmoles of proline/g of tissue) CMSI (91.16%).Under water stress conditions, capsaicin content was recorded higher in seeds primed with 2.5% KNO3 (90.5 μg g-1), and ascorbic acid was
recorded the highest in seeds primed with 3% SiO2 (3.78 mg g-1). In control,
capsaicin content (232.0 μg g-1) and ascorbic acid content (4.75 mg g-1) were
recorded higher in seeds primed with 2.5% KNO3.Under water stress conditions, the yield components were recorded
as higher in seeds primed with 2.5% KNO3 like plant height (55 cm),
number of flowers plant-1 (22.8 number), number of fruits plant-1 (19
number), and the fruit yield (45.3 g), were recorded as significantly higher in
seeds primed with 2.5% KNO3. The seed yield (3.16g) was recorded as
significantly higher in seeds primed with 3% SiO2, under, the control
condition, 2.5% KNO3 primed seeds recorded significantly higher plant
height (60 cm), fruit yield (84.93 g), number of fruits plant-1 (22.4) and 3%
SiO2 primed seeds recorded significantly higher seed yield (3.18 g).
According to our results, seed priming with 2.5% KNO3 and 3% SiO2
enhanced the capacity of the plant to absorb water by preserving the least
amount of cell damage and shielding the macromolecular structures from
membrane damage, Thus, seed priming with 2.5% KNO3 and 3% SiO2 can be
recommended.