MSc

The study entitled “Enhancing nutrient use efficiency through nanofertilizers
in bush type vegetable cowpea (Vigna unguiculata subsp. unguiculata (L.) Verdcourt)
was carried out at College of Agriculture, Vellayani during 2020-2022 with the
objective of evaluating the effect of foliar applied nano-N and nano-Zn on growth,
yield and nutrient use efficiency, and working out the economics in bush type
vegetable cowpea.
The experiment was undertaken during January to March 2022 in Randomized
Block Design with ten treatments and three replications. In all the treatments half dose
of N, full dose of P and K were given as basal as per the KAU POP recommendation
(20:30:10 kg NPK ha-1
). Remaining N as nano-N and also nano-Zn were given as
foliar spray at different intervals. IFFCO Nano urea and Nano-Zn were used as the
sources of nano-N and nano-Zn at the rate of 2 mL L-1
respectively. FYM (20 t ha-1
)
and lime (250 kg ha-1
) were also applied at the time of land preparation. The
treatments were T1:50 per cent RDN + nano-N at 15 DAS, 30 DAS; T2:RDN + nanoZn at 30 DAS, 45 DAS; T3:50 per cent RDN + nano-N at 15 DAS + nano-Zn at 30
DAS; T4:50 per cent RDN + nano-N at 15 DAS + nano-Zn at 45 DAS; T5:50 per cent
RDN + nano-N at 30 DAS + nano-Zn at 30 DAS; T6:50 per cent RDN + nano-N at 30
DAS + nano-Zn at 45 DAS; T7:50 per cent RDN + nano-N at 15 DAS, 30 DAS +
nano-Zn at 30 DAS; T8:50 per cent RDN + nano-N at 15 DAS, 30 DAS + nano-Zn at
45 DAS; T9:50 per cent RDN + nano-N at 15 DAS, 30 DAS + nano-Zn at 30 and 45
DAS; T10:POP (½ N, full P and K basal and ½ N at 15 DAS). An absolute control was
also maintained. The variety of cowpea used for the field experiment was
Bhagyalakshmi.
The results revealed that plant height, number of branches, number of leaves
and leaf area per plant, and dry matter production were significantly influenced by
foliar application of nano-N and nano-Zn. However, the number of nodules remain
unaffected by the treatments. At 30 DAS, significantly taller plants were noticed in T2
(47.75 cm). At 60 DAS and at final harvest T7 produced the tallest plants (77.63 cm
and 82.08 cm respectively). The number of branches per plant recorded at 30 DAS
was found to be higher (2.72) in T10. At 60 DAS, and at final harveststage, the highest
85
number of branches per plant was seen in T5 (3.69) and T7 (3.95) respectively. The
number of leaves and leaf area per plant were significantly higher in T2 (13.08 and
458.23 cm2
, respectively) at 30 DAS. At 60 DAS and at final harvest, T5 resulted in
the highest number of leaves (19.42 and 17.92) and leaf area per plant (707.79 cm2
and 406.37 cm2
, respectively).
Leaf area index (LAI) and Leaf Area Duration (LAD) were also found to be
influenced significantly by the treatments. At 30 DAS, T2 (1.02) recorded the highest
leaf area index and it was on par with T10. At 60 DAS and at final harvest stage, the
highest leaf area index was obtained in T5 (1.57 and 0.90, respectively) and it was
found to be on par with T9, T2 and T7. From 30 to 60 DAS, the highest leaf area index
was noticed in T2 (37.35 days) whereas from 60 DAS to final harvest stage, it was the
highest in T5 (22.28 days). At 30 DAS, T10 (3.86 g per plant) recorded significantly
higher dry matter production while at 60 DAS and at final harvest stage, T5 resulted in
significantly the highest dry matter production of 24.89 and 37.36 g per plant
respectively which was on par with T2, T7, T9 and T10.
In case of yield and yield attributes, the treatment T7 resulted in the highest pod
weight (4.77 g). The highest number of pods per plant and pod yield per plant were
recorded in T5 (27.80 and 98.31g). The highest pod yield per hectare was observed in
T5 (7076 kg ha-1
) and it was found to be on par with T7, T9, T2 and T10. The treatment
T9 recorded the highest haulm yield per plant and haulm yield per hectare of 27.13 g
and 4522 kg ha-1
, respectively. Days to 50 percent flowering, pod length, pod girth
and harvest index were not considerably affected by the treatments.
At 30 DAS, chlorophyll content was found to be superior in T10 (2.88 mg g-1
)
whereas at 60 DAS and at final harvest stage, T5 resulted in significantly higher values
of 2.48 mg g-1
and 2.43 mg g-1
, respectively. Crude protein was found to be
significantly higher in T5 (35.29 %) and was on par with T9, T7 and T8.
Total N, P, K and Zn uptake were found to be significantly higher in T5 (297.28
kg ha-1
, 52.50 kg ha-1
, 66.28 kg ha-1
and 0.61 kg ha-1
, respectively). The treatment T5
recorded significantly higher agronomic efficiency values of 10.47 kg kg-1
, 16.92 kg
kg-1 and 10.47 kg kg-1 for N, P and K, respectively. Physiological efficiency was
86
significantly higher in T10 for P (79.94 kg kg-1
) and K (53.26 kg kg-1
) whereas for N, it
was not significantly influenced by nano-N and nano-Zn application. Apparent
recovery for N, P and K was superior in T5 (67.04, 24.90 and 21.93 per cent,
respectively).
Post experiment soil analysis revealed that treatments had no effect on soil
available N, P, K, Zn and organic C.
The highest net income (₹ 82,943 ha-1
) and B:C ratio (1.31) were obtained in T5
(50 per cent RDN + nano-N at 30 DAS + nano-Zn at 30 DAS) and it was found to be
on par with T10, T7 and T2.
From the study it could be concluded that application of half the recommended
dose of N (10 kg ha-1
), full P (30 kg ha-1
) and full K (10 kg ha-1
) as basal dose
followed by foliar application of N as nano urea and Zn as nano zinc each at the rate
of 2 mL L
-1
separately at 30 DAS could result in better growth, yield, nutrient use
efficiency and higher economic returns in bush type vegetable cowpea.