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The study entitled “Yield maximization in bush type vegetable cowpea
(Vigna unguiculata subsp. unguiculata (L.) Verdcourt) was undertaken during
2019-2021 at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, with
the objective to find out the effect of foliar nutrition of water-soluble fertilizers, Zn
and B in maximizing the yield of bush vegetable cowpea.
Field experiment was carried out at Coconut Research Station,
Balaramapuram in Randomized Block Design with 13 treatments and three
replications during Rabi 2020 (12/11/ 2020 to 31/01/2021). The treatments were T 1
(POP recommendation [20-30-10 kg N, P and K ha -1 -half N, full P and K as basal
and half N at 20 DAS]), T 2 (T 1 + foliar application of 19:19:19 (0.5 %) at 45 DAS),
T 3 (T 2 + foliar application of 19:19:19 (0.5 %) at 60 DAS), T 4 (T 2 + foliar
application of ZnSO 4 (0.05 %)at 45 DAS), T 5 (T 2 + foliar application of solubor
(0.025 %) at 45 DAS), T 6 (T 2 + foliar application of ZnSO 4 (0.05 %) and solubor
(0.025 %) at 45 DAS), T 7 (T 6 + foliar application of 19:19:19 (0.5 %) at 60 DAS),
T 8 (T 1 + foliar application of KNO 3 (0.5 %) at 45 DAS), T 9 (T 8 + foliar application
of KNO 3 (0.5 %) at 60 DAS), T 10 (T 8 + foliar application of ZnSO 4 (0.05 %) at 45
DAS), T 11 (T 8 + foliar application of solubor (0.025 %) at 45 DAS), T 12 (T 8 + foliar
application of ZnSO 4 (0.05 %) and solubor (0.025 %) at 45 DAS) and T 13 (T 12 +
foliar application of KNO 3 (0.5 %) at 60 DAS). The variety used for the study was
Bhagyalakshmy.
Foliar application of macro and micro nutrients had no significant effect on
plant height. However, significant effect was observed on leaves per plant, branches
per plant, and dry matter production per plant at 60 DAS and final harvest.
Significantly higher number of branches at 60 DAS and final harvest was recorded
in treatment T 12 , the highest number of leaves per plant at 60 DAS in T 5 and T 8 at
final harvest. The highest dry matter production was observed in T 2 at 60 DAS
(27.45 g per plant) and T 5 at final harvest (39.51 g per plant).112
Nodule parameters were significantly influenced by foliar nutrition of
macro and micro nutrients. The highest number of nodules per plant (23.7 no.) and
fresh nodule weight per plant (1.35 g) were observed in T 5 and effective nodules
per plant in T 2 (16.7 no.).
Number of pods per plant, individual pod weight, green pod yield, dry
haulm yield and harvest index were significantly influenced by foliar application of
macro and micro nutrients. However, other yield parameters viz., days to 50 per
cent flowering, pod length and girth did not show any significant variations. Higher
number of pods per plant (30.88) was recorded in T 5 and the highest pod weight
(4.16 g) in T 2 . The highest green pod yield (106.54 g per plant and 7410 kg ha -1 )
was recorded in T 5 and it was statistically on par with the treatments T 2 , T 6 and T 11 .
The highest dry haulm yield (24.61 g per plant and 5470 kg ha -1 ) was observed in
T 13 and the highest harvest index in T 7 (0.419).
Significantly higher total chlorophyll content was observed in T 6 at 60 DAS
and in T 5 at final harvest. At 60 DAS, the highest LAI was recorded inT 8 and T 9 at
final harvest. The highest LAD was recorded in T 8 at both time intervals, 30-60
DAS and 60 DAS-final harvest. Crop growth rate was the highest in T 2 at 30-60
DAS and T 5 at 60 DAS-final harvest. However, the highest RGR was recorded in
T 6 at 30-60 DAS and T 5 at 60 DAS-final harvest.
Foliar application of macro and micro nutrients showed significantly higher
crude protein content in pods. The highest crude protein content of pod was noted
in the treatment T 7 .
Results on uptake of nutrients by crop showed that foliar application of
nutrients significantly enhanced the total uptake of N, P, K, Zn and B by crop. The
highest total uptake of N (337.17 kg ha -1 ), P (96.24 kg ha -1 ) and K (137.68 kg ha -1 )
were recorded in the treatment T 5 , however the highest Zn uptake was noted in T 9
and B uptake in T 11 .113
Available N, P, K, Zn and B status of post- harvest soil was significantly
influenced by foliar application of macro and micro nutrients. However, organic
carbon did not have any significant variation. The highest available N was observed
in treatment T 13 , available P in T 1 , T 3 and T 9 , available K in T 2 , available Zn in T 11
and available B in T 2 .
The highest net income (₹ 82651 ha -1 ) and B:C ratio (2.26) were recorded
in the treatment T 5 (POP + foliar application of 19:19:19 (0.5 %) and solubor (0.025
%) at 45 DAS) and it was followed by T 2 (POP + foliar application of 0.5 per cent
19:19:19 at 45 DAS). A yield enhancement of 55 percentage and 150 percentage
increase in net income were observed in T 5 over T 1 .
Considering the dry matter production, yield attributes, yield, total
chlorophyll content, CGR, RGR, net income and B:C ratio the treatment T 5 (POP
+ foliar application of 19:19:19 (0.5 %) and solubor (0.025 %) at 45 DAS) could be
adjudged as the best treatment for yield maximization in bush type vegetable
cowpea.