PG

The present study entitled "Nanoparticulate Seed Invigoration in Cowpea (Vigna
unguiculata (L.) Walp.)" was undertaken with the objective of assessing the effect of
nanopriming on seed germination, seedling vigour, plant growth, and yield in cowpea.
Seeds of the cowpea variety "Kanakamony" were primed with nano ZnO and nano MgO
(30 nm), which were taken in different doses of 100 (D1), 200 (D2), 400 (D3), and 600
(D4) mg L-1 with different durations of soaking 6 (S1), 8 (S2), and 10 (S3) hours.
Laboratory evaluation on the effect of nano ZnO and nano MgO were done in two
separate experiments in a completely randomized design (CRD), with different
concentrations of nanoparticles as the first factor and the duration of soaking as the
second factor and replicated three times.
The results of the first experiment (nanopriming with ZnO) showed a significant
difference from the control for seedling and germination parameters except for mean
germination time (MGT). Of all the doses D3 (400 mg L-1
) was found to be effective in
improving the germination and seedling parameters. In seed priming with nano ZnO
duration of soaking 6h was found to be effective. Priming with nano ZnO @ 400 mg L-1
and soaking duration of 6h recorded the highest values for the length of the seedling
(39.64 cm), root length of the seedlings (17.46 cm), shoot length of the seedlings (22.17
cm), fresh weight of the seedlings (11.30 g), catalase activity (659.26 n moles of H2O2
used min-1
g weight of sample -1
), peroxidase activity (2.39 units min -1mg of protein -1
),
Mean Germination Time (MGT) (4.87 days), Mean Daily Germination (MDG) (20.68
number day -1
), Vigour Index-Ⅰ (VI-Ⅰ) (3514.23), Vigour Index-ⅠⅠ (VI-ⅠⅠ) (66.15). But,
nano priming with ZnO @ 400 mg L-1
, soaking duration 8h gave significantly higher
values for dry weight of the seedling (0.68 g), gemination percentage (GP) (97.00),
speed of germination (SG) (19.83), Germination Index (GI) (670.00), Germination Rate
Index (GRI) (1931.96), Coefficient of Rate of Germination (CRG) (107.54).
The results of the second experiment too (nanopriming with MgO) showed
significant differences from the control for all the parameters except for MGT. Of all the
doses tested, D4 (600 mg L
-1
) and D3 (400 mg L
-1
), were found to be effective in
improving the germination and seedling parameters. Priming with nano MgO @ 400 mg
L
-1
, soaking duration of 8h recorded highest values for the length of the seedlings
(39.41cm), root length of the seedlings (15.93 cm), shoot length of the seedlings (23.48
cm), fresh weight of the seedlings (13.16 g), dry weight (0.58 g), catalase activity (626.94
n moles of H2O2 used min-1
g weight of sample -1
), peroxidase activity (2.40 units min -
1
mg of protein-1
), GP (93.33), MDG (23.08 number days-1
), VI-Ⅰ (3640.17), VI-ⅠⅠ (53.88),
SG (19.72), GI (660. 67), GRI (1972.06), CRG (92.33) and nano MgO @ 400 mg L
-1
,
soaking duration 6h recorded least MGT (4.75 days).
Six treatments (three best from each experiments) with control (hydropriming,
duration of soaking 10h) were included for field evaluation using RBD (Randomized
Block Design) with three replications. In the nano ZnO treatments, d3s1 (nano ZnO @
400 mg L-1
, soaking duration 6h), d3s2 (nano ZnO @ 400 mg L-1
, soaking duration 8h),
d4s1 (nano ZnO @ 600 mg L-1
, soaking duration 6h) were the three best treatments with
scores of 19, 24, 39 respectively. In the nano MgO treatments, d3s2 (nano MgO @ 400
mg L-1
, soaking duration 8h), d4s2 (nano MgO @ 600 mg L-1
, soaking duration 8h), d4s1
(nano MgO @ 600 mg L-1
, soaking duration 6h) were the three best treatments with the
scores of 15, 23, 31 respectively.
Nanoparticulate seed invigoration (nano ZnO and nano MgO) treatments showed
significant positive influence on all the parameters except for plant height, 100 seed
weight, days to 50% flowering in the field experiment. T1 (nano ZnO @ 400 mg L-1
,
soaking duration 6h ) recorded highest value for plant height (68.28 cm), number of
branches per plant (13.00), pods per plant (19.73), number of seeds per pod (16.93), 100
seed weight (11.80), days taken to 50% flowering (36.33), pod yield per plant (19.41 g),
seed yield per plant (21.79 g) in and T7 (control hydopriming, soaking duration of 10h)
recorded least value (58.33 cm, 6.40, 12.47, 10.47, 10.07 g, 45.33, 10.38 g, 11. 09 g)
respectively. With regarding to Zn content in seed, treatments T1 (nano ZnO @ 400 mg
L
-1
, soaking duration 6h), T2 (nano ZnO @ 600 mg L-1
, soaking duration 6h), and T3
(nano ZnO @ 400 mg L-1
, soaking duration 8h) were on par and significantly different
from T4 (nano MgO @ 600 mg L-1
, soaking duration 6h), T5 (nano MgO @ 400 mg L-1
,
soaking duration 8h ), T6 (nano MgO @ 600 mg L
-1
,soaking duration 8h), and T7 (control
hydopriming, Soaking duration 10h). Priming with all the doses of nano MgO showed
significantly higher content of Mg in seed in comparison with other treatments.
This study to evaluate the effect of seed nano priming with ZnO and MgO in
cowpea clearly indicated that seed nano priming can be advocated as a seed enhancement
tool in cowpea to produce superior seedling traits, crop growth, and yield. All the doses
evaluated in this study did not produce any phytotoxic effect on the plant. Seed
nanopriming with both ZnO and MgO had significant positive effect on germination and
seedling parameters. In nano priming with ZnO d3s1 (nano ZnO @ 400 mg L-1
soaking
duration 6h) can be recommended as the best and in nanopriming with MgO d3s2 (nano
MgO @ 400 mg L-1
soaking duration 8h) can be recommended as the best for superior
germination and seedling traits. Considering the effect on crop growth andyield seed
nano priming with dose nano ZnO @ 400 mg L
-1
, soaking duration of 6h can be
recommended for adoption by the farmer.