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Title: Impact of nutrient management, soil type and location on the accumulation of capsaicin in Capsicum chinense (Jacq.): One of the hottest chili in the world
Author: Subhasish Das

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Scientia Horticulturae 213 (2016) 354–366

Contents lists available at ScienceDirect

Scientia Horticulturae
journal homepage: www.elsevier.com/locate/scihorti

Impact of nutrient management, soil type and location on the
accumulation of capsaicin in Capsicum chinense (Jacq.): One of the
hottest chili in the world
Subhasish Das a , K. Charan Teja b , Buddhadeb Duary b,∗∗ , Pawan Kumar Agrawal c ,
Satya Sundar Bhattacharya a,∗

Soil & Agro Bio Engineering Lab, Department of Environmental Science, Tezpur University, Tezpur 784028, Assam, India
Department of Agronomy, Soil Science, Agricultural Engineering, Plant Physiology and Animal Science (ASEPAN), Institute of Agriculture, Visva Bharati,
Sriniketan, 731236 West Bengal, India
National Agricultural Science Fund (NASF), Room No. 707, Krishi Anusadhan Bhavan-I, Pusa, New Delhi 110 012, India

a r t i c l e

i n f o

Article history:
Received 2 June 2016
Received in revised form 26 October 2016
Accepted 28 October 2016
Available online 4 November 2016
Capsicum chinense

a b s t r a c t
Capsicum chinense (Jacq.) cv. Borbhut a highly pungent and strictly endemic landrace is found in Northeast
India. Information regarding scientific cultivation of this crop is not available. In the present investigation, we formulated a few organic based integrated nutrient management schemes to standardize the
pungency and hotness of the crop in two widely apart locations. Here we assess the impact of the management schemes on capsaicin accumulation in C. chinense grown in two types of soil (alluvial and lateritic)
falling in two states of India (Assam and West Bengal). Some vital nutritional (crude protein, fibre, sugar
and acid contents) and phytochemical features (␤-carotene, lycopene) were also evaluated. Chilies grown
in Assam soil (alluvial) exhibited significantly higher capsaicin content and pungency than those grown
in the West Bengal soil. Application of vermicompost alone resulted in higher fruit yield, soluble sugar,
protein, fibre, and lycopene contents in plants of Assam; whereas in West Bengal the maximum fruit
yield and nutritional attributes were observed in plants grown under NPK + Vermicompost. However,
vermicompost based nutrient management scheme efficiently elevated the pungency level in “Borbhut”
irrespective of soil types.
© 2016 Elsevier B.V. All rights reserved.

1. Introduction
Capsicum chinense (Jacq.) cv. Borbhut, a member of the
solanaceae family is a rare, indigenous, and endemic plant found
only in the hills and plains of Northeast India (Meghvansi et al.,
2010). This wild species evolved after natural cross pollination
between C. frutescens and C. chinense followed by adaptation to
different microclimatic conditions prevalent in this region (Islam
et al., 2015). Earlier, this species was designated as the “hottest
chili” in the world (Guinness World Records, 2006). Interestingly, the hotness recedes due to strong endemism of the crop;
thus greatly restricting the agronomic expansion of the species

∗ Corresponding authors: Department of Environmental Science, Tezpur University, Assam, 784028, India.
∗∗ Corresponding author at: Dept. of ASEPAN, Institute of Agriculture, Visva Bharati,
Sriniketan, 731236, West Bengal, India.
E-mail addresses: bduary@yahoo.co.in (B. Duary), satyasundarb@yahoo.co.in,
satya72@tezu.ernet.in (S.S. Bhattacharya).
0304-4238/© 2016 Elsevier B.V. All rights reserved.

in varied agroclimates. In Northeast India, this crop is traditionally cultivated in home gardens and there exists a sizeable genetic
variability among the landraces (Bhagowati and Changkija, 2009).
Capsaicin (N-vanillyl-8-methyl-6-nonenamide; C18 H27 NO3 ; mol
weight: 305.41) is a phenylalkylamide alkaloid that is responsible
for the pungency as well as the hotness in chilies. It is formed by
the condensation of vanillylamine and 8-methyl-6-nonenoyl-CoA
(Keyhaninejad et al., 2014). Capsaicin plays an important role in
suppressing gastric ulcer by selective stimulation of the afferent
nerves in the gastric mucosa thereby inhibits the acid secretion,
enhances the mucus secretions and mainly hastens the gastric
mucosal blood flow which aids in prevention and healing of ulcers
(Kang et al., 1996). Hence, the compound has enormous pharmacological properties, therapeutic potential and high market value
(Prasad et al., 2005). So far, there is no alternative agrotechnology to standardize the hotness in “Borbhut” irrespective of growing
Among all environmental factors, soil is the most important
attribute which significantly influences plant physiology (Chludil

S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

et al., 2008). However, use of chemical fertilizers in large amount
leads to instantaneous nutrient release inducing crops to grow at
maximum rate, and exhaust all photosynthetic products in the
growth process; leaving only a minimal amount for the production
of secondary metabolites (Stamp, 2003). In this juncture, organic
based nutrient management scheme can be a useful proposition.
Organic farming is a rapidly growing practice as it promises food
safety and soil health. Nevertheless, strategies like Integrated Nutrient Management (INM) where both organic and inorganic inputs
are supplied in conjunction ensure sustainable crop productivity and soil health (Mukhopadhyay et al., 2013). Incorporation
of exogenous organic amendments as part of organic agriculture has acquired lot of attention in recent years (Herencia et al.,
2008). In similar experimentations under organic conditions, a
tenfold increase in quercetin (flavonoid) levels in spinach, Chinese cabbage, and Welsh onion has been reported (Ren et al.,
2001). Similar reports by Ibrahim et al. (2013) recorded 12and 22%
increment in total phenol and flavonoid contents in organically
cultivated Labisia pumila. Among various organic inputs, vermicompost (VC) is an efficient plant growth promoter, as it abounds
in hormone-like moieties, organic acids, beneficial microflora and
major nutrients (N, P, K, S) in bio-available form (Sahariah et al.,
2015; Najar et al., 2015). During vermicomposting, earthworms
greatly enhance humification of organic matter through microbial
activation, thereby enhancing activity of several plant hormones
(auxin, gibberellin and cytokinin) (Atiyeh et al., 2002). Additionally, the humic substances contributed by VC in soil may trigger
secondary metabolic pathways in plants (Zandonadi et al., 2013).
However, there is a significant research gap in regard to studies on
influence of VC on plant phenolic compounds in varied soil types.
“Borbhut” is almost a wild landrace cultivated by a small group
of farmers in traditional manner, with no scientific support. The
wider adaptability of the crop would likely render a unique chilli
to the world, whose medicinal application is yet to be explored
adequately. Under these contexts, for the first time, we developed organic based nutrient management schemes to stabilize
capsaicin production and hotness without hampering the yield
of the crop over the regions. Under these perspectives the key
hypotheses of the present investigation were: (a) VC improves pungency and capsaicin content in “Borbhut” (Capsicum chinense); (b)
the endemity of the “Borbhut” landrace in regard to expression
of capsaicin and other phenolics can be stabilized through vermicompost based nutrient scheduling irrespective of soil types. We
verified our hypotheses through a two year field experiment in
two widely situated locations with diverse soil types. Our major
rationale was to identify the major soil attribute(s) responsible for
capsaicin content and pungency without hampering the yield of
this chili species. Nutrient schemes comprising of inorganic fertilizers+ VC, inorganic fertilizers+ farmyard manure (FYM), as well
as only VC and FYM were applied to cultivate C. chinense. Furthermore, we were interested to know whether the overall plant quality
attributes like crude protein, crude fibre, total soluble sugar and
titratable acidity, lycopene, and ␤-carotene in Bhut jolokia fruits
gets changed in response to the applied treatments.

2. Materials and methods
2.1. Experimental locations
Two diverse locations, L1-Sonitpur (Assam, Northeast India;
26.7008◦ N, 92.8303◦ E) and L2-Birbhum (West Bengal, East India;
23.6700◦ N, 87.7200◦ E) with varying agro-climatic conditions were
selected for the field experiments. The climate in L1 is sub-tropical
humid marked by heavy rainfall, moderately hot summer and winter spells. Conversely, a tropical dry climate is characteristic in L2


with less precipitation. The soil of L1 is dark in color with clay-loam
texture (Typic Endoaquepts) and L2 has a red sandy-loam soil (Typic
Haplustal). Details of climate (mean monthly ambient temperature,
sum of precipitation and relative humidity during the crop period)
have been provided in Table 1.
2.2. Vermicompost and farmyard manure
The VC was prepared following a standardized technique
demonstrated by Goswami et al. (2013). A feedstock was formulated mixing vegetable waste, crop residue (rice straw and husk),
cow dung and weeds in a proportion of 4:2:3:1 and poured in a
vermi-bed. Earthworm species, Metaphire posthuma was added to
it at the rate of 20 worms per kg. The mixture was regularly churned
and watered to ensure better aeration and moisture respectively.
We recorded an ambient temperature range of 24–29 ◦ C during
vermicomposting. The FYM was procured from a local agricultural
farm (Tezpur, Assam) and it comprised of rice straw (10%), cattle
dung slurry (15%), tree leaves (10%), and cow dung (65%). VC and
FYM were transported and used identically in both L1 and L2.
2.3. Experimental design and treatments
A two-year field experiment during 2013 (August–November)
and 2014 (August–November) was conducted in both the locations
using randomized block design (RBD) with four replications. The
detail climatic condition which prevailed during the growing seasons in both the years is presented in Table 1 and average climatic
conditions have been described in the previous section. The maximum and minimum monthly ambient temperature was higher in
L2 as compared to L1 during the growing season; whereas, the
amount of rainfall and average relative humidity were higher in
L1.Water soaked seeds were sown in a raised bed nursery during August in both the years and seedlings at 6–8 leaf stage were
collected after 25 days, cautiously packed and subsequently transplanted to field in the month of September in L1 and L2. As this
landrace is not commercially cultivated, we followed the cultivation package for C. anuum with some modifications. The N, P2 O5 ,
and K2 O content in FYM and VC was analyzed before calculating
the quantities to be applied. We recorded 1.5% N, 0.65% P2 O5, and
0.70% K2 O in VC; while FYM contained 0.80, 0.40 and 0.50% of N,
P2 O5 , and K2 Orespectively. The quantity of FYM and VC were computed and applied on the basis of nitrogen equivalent and nutrient
requirement per plant. Accordingly the quantity of P2 O5 and K2 O
supplied from the required quantity of FYM and VC for 50% RDN
(recommended dose of N) supply was calculated. The rest of the
required P2 O5 and K2 O were supplemented through inorganic fertilizers (P2 O5 and K2 O) for T2 and T3 only; whereas for T4 and T5
no additional P2 O5 and K2 O were supplied through inorganic fertilizer. The details of various treatment combinations are provided
in Table 2a.
Recommended dose of N, P (P2 O5 ) and K (K2 O) was at
120:80:80 kg ha−1 and the FYM and VC were applied as shown
above. Twenty raised beds were prepared for transplanting the
seedling with dimensions: l × b × h = 4m × 3m × 1m. In each plot,
six (6) pits were dug and all the treatments were applied there.
On the basis of the recommended dose of fertilizer and plant
population the required quantity was calculated per plant basis.
Accordingly, half of the required N (at 120 kg ha−1 ) and full of P2 O5
(at 80 kg ha−1 ) and K2 O (at 80 kg ha−1 ) were applied as basal dose
in each pit receiving inorganic fertilizers. Similarly, for supplying
N, P2 O5 and K2 O through organic source the requirements of FYM
and VC were also computed per plant basis prior to dispensing. The
remaining half of N requirement was applied in the form of water
emulsion (top dressing). Urea, Single Super phosphate, and Muriate
of potash were used as inorganic sources of N, P, and K respectively.


S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

Table 1
Climatic data recorded for Sonitpur and Birbhum during 2013 and 2014.



Rainfall (mm)



Relative humidity (%)









L1: Sonitpur, Assam, L2: Birbhum, West Bengal.

Table 2
Detailed inventory of (a) treatment combinations and (b) used resources under the study.
(a) Apportionment of N, P2 O5 , and K2 O from organic and inorganic sources
Recommended dose

T1: Control
T2: NPK50% + FYM50%
T3:NPK50% + VC50%
T4:FYM only
T5:VC only

Quantity of FYM/VC (t ha−1 )



P2 O5

K2 O

120 (kg ha−1 )

80 (kg ha−1 )

80 (kg ha−1 )













(b) Basic characteristics of soil, vermicompost and farmyard manure

Bulk Density (g cc−1 )
Water holding capacity (WHC) (%)
Available N (mg kg−1 )
Available P (mg kg−1 )
Available K (mg kg−1 )
Total organic carbon (TOC) (%)
Humic acid C (%)
Fulvic acid C (%)
Microbial biomass C (␮g C g−1 )
Urease activity (␮g g−1 h−1 )
Phosphatase activity (␮g g−1 h−1 )



5.3 ± 0.03*
1.13 ± 0.32*
66.00 ± 4.16*
119.2 ± 25.2**
110.2 ± 35.8**
75.5 ± 19.5**
1.77± 0.48**
0.36 ± 0.13*
0.72 ± 0.15*
43.8 ± 9.76**
41.3 ± 7.51**
87.8 ± 11.9**

6.1 ± 0.05*
1.34 ± 0.26*
51.30 ± 4.16*
71.7 ± 18.2**
67.7 ± 12.8**
115.6 ± 21.9**
0.84± 0.18**
0.18 ± 0.09*
0.50 ± 0.16*
18.48 ± 2.64**
19.7 ± 4.14**
52.1 ± 5.61**


Farm yard manure (RS + CDS + TL + CD)*

5.9 ± 0.1
0.42 ± 0.02
87.6 ± 11.7
99.3 ± 23.1
187.5 ± 10.7
108.1 ± 24.9
12.9 ± 0.9

107.7 ± 22.5
63.9 ± 14.7
116.6 ± 26.8

6.5 ± 0.1
0.69 ± 0.08
72.0 ± 14.6
85.7 ± 11.3
168.6 ± 14.8
65.2 ± 15.7
8.6 ± 0.22

78.6 ± 13.4
52.1 ± 17.8
87.5 ± 19.1

Significantly different @ p < 0.01 (**), p < 0.05 (*); L1: Sonitpur, Assam; L2: Birbhum, West Bengal. *RS = rice straw; CDS = cattle dung slurry; TL = tree leaves; CD = cow dung.

The seedlings were transplanted in the pits (size: 30 cm deep
and 20 cm wide) after surface sterilization with 0.2% mancozeb
(Bavistin). Other Agronomic operations like irrigation and weeding and plant protection measures were undertaken uniformly in
all the plots to ascertain homogeneity in both the locations.

and Bremner, 1969). For estimating soil urease activity the method
of Kandeler and Gerber (1988) was followed with slight modification. Soil microbial biomass C was enumerated following the
chloroform fumigation technique as per Jenkinson (1988).

2.4. Soil sampling and analysis

2.5. Plant sampling, fruit yield and yield attributing features of C.

The soil sampling was carried out at two intervals, once before
applying treatments (basic soil) and once after crop harvest (harvest soil). Samples were drawn from 0 to 15 cm soil depth near
the root zone and also from other parts of the plots and subsequently mixed together to form composite soil samples for each
plots assigned to various treatments. The samples were air-dried,
cleared-off of stones, pebbles, debris like roots, leaves, twigs etc.,
and ground mechanically to pass through a 2 mm sieve mesh and
subsequently used for analysis. The soil samples were analyzed
for pH, bulk density, water holding capacity, soil organic C, total
Kjeldahl nitrogen, available P, available K, fulvic acid C, humic acid
C and soil respiration following the analytical procedures of Page
et al. (1982). Soil phosphatase activity was determined after extraction with 0.5 M CaCl2 and determined spectrophotometrically at
440 nm after incubation with p-nitro phenol phosphate (Tabatabai

The crop was harvested in three phases within 95–120 days
after transplanting; the final harvest was obtained at 120 days after
transplanting. Numbers of fruits per plant and fruit weight were
recorded to enumerate the final yield. Fruit samples were packed,
transported to laboratory and stored at −80 ◦ C for analysis. Yield
attributing parameters, viz. crude protein, crude fibre, titratable
acidity, and total soluble sugar were determined in the fruit samples to ascertain the quality of the fruits. Modified Kjeldahl method
was used to enumerate crude protein content (Cottenie et al., 1982).
Crude fibre contents were determined using the standard chemical analytical protocols of the AOAC (1995). The fruit sample of
10 g was homogenized in 90 ml distilled water and filtered. About
2–3 drops of phenolphthalein was added in an aliquot of 10 ml and
titrated with 0.1 N NaOH to determine titratable acid percentage in
“Borbhut” fruits (Antoniali et al., 2007). The total soluble sugar was

S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

determined as o Brix in a refractometer as per the manufacturer’s
protocol (Atago, Japan).
2.6. Capsaicin quantification and pungency determination in the
About 500 mg of fruit was extracted in 10 ml acetone for 3 h on a
mechanical shaker. The resultant mixture was spun at 10,000 rpm
for 10 min in a centrifuge (REMI R-8C, India). The supernatant was
evaporated on a water bath and the residue was re-dissolved in
5 ml of 0.4% NaOH and 3 ml of 3% phosphomolybdic acid solution.
The contents were shaken, filtered and absorbance was measured
at 650 nm in a UV–vis spectrophotometer (Agilent Cary 60, USA).
Capsaicin standard (Sigma Aldrich, USA) was used for preparation of the standard curve and the results were presented as
mg per 100 g fruit (Siddiqui et al., 2013). The pungency of the
samples was calculated following Todd et al. (1977) as shown
Pungency(SHU) = Capsaicincontent(mg 100 g−1 FWchili)
× 1.6 × 107

2.7. Determination of lycopene and ˇ-carotene content in the
For estimating lycopene and ␤-carotene, 1 g of sample was pulverized in 16 ml of acetone and n-hexane (4:6, v/v). The mixture
was set to stand for 30 min till the two phases of the mixture separate. The aliquot from the upper layer was taken and read at 663,
645, 505 and 453 nm (Nagata and Yamashita, 1992). The following
equations were utilized for enumerating lycopene and ␤-carotene

Lycopene mg g− = −0.0458 × A663+0.204 × A645+0.372
×A505 − 0.806 × A453

␤ − Carotene mg g−1 = 0.216 × A663 − 1.22 × A645 − 0.304


3. Results and discussion
3.1. Properties of vermicompost, farmyard manure and the soils
of two locations
Table 2b presents the physico-chemical characteristics of VC,
FYM, and the soil. Two types of organic manure (VC and FYM) were
used as the major components of the nutrient scheme used in this
work. Although VC was more acidic compared to the FYM, the low
bulk density and high water holding capacity of the materials justify the benefit of using VC over FYM as soil conditioner (Singh
et al., 2010). As such, total organic C content, microbial biomass C
and enzyme activity (urease and phosphatase) were considerably
greater in the VC than FYM; therefore, availability of N, P, and K
was also significantly higher in the VC as compared to the FYM. All
these properties advocate the overall advantage of VC application
in soil for improvement of soil health and crop productivity. The
results are in good agreement with some previous findings (Atiyeh
et al., 2002).
Soil pH of L1 and L2 were 5.3 ± 0.3 and 6.1 ± 0.5 respectively.
High rainfall and undulating topography probably resulted in
washing out of soluble bases from the topsoil in L1 which in turn
made the soil acidic (Raychaudhuri et al., 2014). The availability of
N and P was significantly higher in L1 (N: 119.2 ± 25.2 mg kg−1 ; P:
110.2 ± 35.8 mg kg−1 ) than L2, while, K availability was higher in
L2 (115.6 ± 21.9 mg kg−1 ) as compared to L1 (75.5 ± 19.5 mg kg−1 ).
This may be attributed to the high K content in the parent
material of the soil of Birbhum district, West Bengal (Tandon,
1995). However, TOC level was considerably higher in the
soil of L1 (1.77 ± 0.48%) than L2 (0.84 ± 0.18%). Alluvial soils
are very productive with significantly high soil organic C pool
(Bhattacharyya et al., 2013). Soil of L1 exhibited significantly high
microbial biomass C than L2 (p < 0.001). Urease and phosphatase
activities were also higher (urease = 41.3 ± 7.51 ␮g g−1 h−1 ;
phosphatase = 87.8 ± 11.9 ␮g g−1 h−1 )
(urease = 19.7 ± 4.14 ␮g g−1 h−1 ; phosphatase = 52.1 ± 5.61 ␮g g−1 h−1 ).
Generally, alluvial soils are substantially richer in soil organic C
pool as compared to lateritic soils (Bhattacharyya et al., 2013). In
addition, high rainfall and humidity in L1 probably supports soil
microbial activity thereby facilitates soil organic C build up in the
area (Table 1).
3.2. Effects of various treatments on bulk density, water holding
capacity and pH of the soils

×A505 + 0.452 × A453

2.8. Statistical analysis
Considering three factors (treatment, location, and year) that
might have influenced various soil and crop attributes, full factorial analysis of variance (ANOVA) was performed with a significance
level of P < 0.05. We adopted Duncan’s multiple range test (DMRT)
to compare the means of treatments, year, and location. Moreover, multiple regression analyses were conducted based on the
following hypotheses:
a. The influence of soil physico-chemical properties differs
between locations with respect to Capsaicin content in Chilli.
b. Soil organic C, microbial biomass C, humic acid C, fulvic acid C,
and soil enzymes largely trigger capsaicin production irrespective of locations.
c. Bioavailability of NPK in soil has had greater impact on capsaicin
content in L2 than L1.

The changes in bulk density, water holding capacity, and pH
of soil under various treatments are presented in Table 3. The pH
did not vary over two years (ploc × yr = ns).The effect of time on
pH change due to organic manuring is seldom observed in studies spanning less than five years. However, the soil pH was reduced
significantly under various treatments and greatly varied between
the locations (ptrt = 0.000; p loc × trt = 0.001). Significant reduction
in pH was observed in soil when treated with T3 and T4. This may
be ascribed to the prevalence of several organic acids in the VC
added to the soil system which probably influenced the soil reaction (Deka et al., 2011). On the other hand, the bulk density of the
soil reduced substantially under T3, T4, and T5 compared to the initial values and the changes were significantly higher in L1 soil than
L2 (ptrt = 0.000; ploc = 0.000). These results are in good agreement
with some previous findings (Saikia et al., 2015).
Concurrently, water holding capacity significantly improved
over the years under VC and FYM treated soils (ptrt = 0.000;
pyr = 0.003; ptrt × yr = 0.004). Although we observed noteworthy treatment × year interaction in regard to water holding
capacity, the interaction effects were insignificant between location, year (time), and treatments (ploc × yr = ns; ploc × trt = ns;


S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

Table 3
Effect of various treatments on soil pH, bulk density, and water holding capacity.
BD (g cc−1 )


p(loc × trt)
p(loc × yr)
p(trt × yr)
p(loc × trt × yr)

WHC (%)

Year 1

Year 2

Year 1

Year 2

Year 1

Year 2

5.40 ± 0.01c
5.31 ± 0.03d
5.29 ± 0.02d
5.38 ± 0.05 cd
5.39 ± 0.03 cd

5.36 ± 0.04 cd
5.33 ± 0.04d
5.32 ± 0.05d
5.41 ± 0.01c
5.37 ± 0.04 cd

1.15 ± 0.13e
1.09 ± 0.04g
1.05 ± 0.04h
1.03 ± 0.01h
1.04 ± 0.04h

1.17 ± 0.08de
1.12 ± 0.11f
1.07 ± 0.07gh
1.02 ± 0.09h
1.03 ± 0.03h

74.31 ± 2.41 cd
77.15 ± 1.49c
82.30 ± 1.04b
84.63 ± 2.08ab
83.03 ± 2.22ab

71.11 ± 2.32d
74.15 ± 1.72 cd
80.12 ± 2.68bc
86.19 ± 1.17a
86.29 ± 2.15a

6.11 ± 0.01ab
6.03 ± 0.02b
6.03 ± 0.04b
5.91 ± 0.01bc
5.96 ± 0.04bc

6.20 ± 0.03a
6.08 ± 0.05ab
6.09 ± 0.05ab
5.93 ± 0.04bc
5.98 ± 0.04bc

1.41 ± 0.02a
1.37 ± 0.01ab
1.27 ± 0.05bc
1.25 ± 0.13c
1.24 ± 0.02 cd

1.39 ± 0.13ab
1.35 ± 0.09b
1.25 ± 0.08c
1.25 ± 0.08c
1.21 ± 0.16d

48.58 ± 7.42i
53.43 ± 4.17g
56.04 ± 4.96f
54.25 ± 1.30fg
61.17 ± 4.94e

50.02 ± 2.19h
55.13 ± 5.7f
57.24 ± 1.44f
56.5 ± 4.22f
63.17 ± 2.40e

T1 = Control, T2 = 50% of Recommended dose + 50% of RDN through FYM, T3 = 50% of Recommended dose + 50% of RDN through VC, T4 = FYM only, T5 = VC only; L1: Sonitpur,
Assam, L2: Birbhum, West Bengal. Similar letters represent non-statistical difference as per Duncan’s Multiple Range Test (DMRT) post-hoc analysis (p < 0.05).DMRT was
performed considering three factors: location, year of cultivation, and treatment.

ploc × trt × year = ns). As such, application of organic amendments
improve soil environment through the humification process
(Schaeffer et al., 2015). VC being a porous and stable substrate elevates moisture retention in the rhizosphere through stabilization
of aggregation and increment in porosity. The results are in good
agreement with recent findings (Saikia et al., 2015).
3.3. Changes in soil organic C, fulvic acid C, humic acid C,
microbial biomass C and soil respiration in soil
The impact of FYM and VC based nutrient management on the
soil organic C, fulvic acid C, humic acid C, microbial biomass C
and soil respiration in both the soil types was assessed to evaluate the role of organic amendments in binding C stock in soils
(Table 4). According to the statistical analyses, significant variations
among treatments, locations, and years for all these attributes were
observed. Moreover, in most cases, second (loc × trt, loc × yr, and
trt × yr) and third order interactions (loc × trt × yr) were highly significant. Such variation between the locations was primarily due
to inherent properties of the two soil types. However, changes
in soil organic C, obstinate C fractions (humic acid C and fulvic
acid C), and microbial biomass over the years were probably an
outcome of the treatment effects; indicating ecological benefits
of organic manuring for longer duration (Saikia et al., 2015). It is
worthwhile to mention that soil organic C level was significantly
higher in soil treated with VC without chemical fertilization (T5) in
L1 (ptrt = 0.000). Whereas, VC + NPK (T3) treatment showed highly
significant impact on soil organic C of L2 (ptrt = 0.000). Significantly
higher value of fulvic acid C was recorded under T3 (VC + NPK) in
L1, while humic acid C was the highest under T5 in L2 (ptrt = 0.000).
Interestingly, about 35.7and 66.6% gains in fulvic acid C and humic
acid C contents respectively were recorded in T5 treated soils of L1
as compared to the initial value. The humic acid C and fulvic acid
C richness in soil indicate formations of stable humic substances,
vital to sustain soil health and plant growth (Li et al., 2013). As such,
the gain in humic substances should also facilitate microbial diversity and activity in soil, which is clearly evidenced in the results
for microbial biomass C and soil respiration in the soil (Table 4).
Originally, microbial biomass C and soil respiration were higher in
L1 than L2 because of edaphic and climatic conditions. Although
microbial biomass C was significantly higher in L1 as compared to

L2 after two year of VC based cultivation, about 2.92-3.17 fold increment in microbial biomass C was evidenced in L2 under the same
nutrient management scheme. VC application in soil greatly facilitates microbial diversity and activity in varied soil types through a
steady supply of energy sources for microorganisms (Atiyeh et al.,
2002). At the end of the study the treatments in regard to microbial biomass C and soil respiration may be arranged in the order:
T3 = T4 ≥ T5 > T2 > T1 and T5 ≥ T3 = T4 > T2 > T1 respectively. Similarly, soil respiration in soil also increased over time under various
treatments and such increment was significantly higher in T5, followed by T3 and T4 in L1; whereas T4 and T5 showed significant
impact on SR in L2 (ptrt = 0.000).
3.4. Changes in bioavailability of N, P, K and enzyme activity in
Table 5 represents the effect of various treatments on N, P, and
K availability in soil over the two year period of cultivation. N availability increased by 1.35–1.58 fold in Sonitpur soil (L1) and by
1.85–2.63 fold in Birbhum soil (L2) due to the application of FYM
and VC. Significantly high N availability was recorded in L1 soil
treated with NPK + VC (T3) followed by NPK + FYM (T2); whereas in
L2, N bioavailability was in order: T2 > T3 > T5 > T4 > T1 (ptrt = 0.000).
Moreover, location played a vital influence on bioavailability of
N, and we observed a significant difference in available N content among the two soil zones amended with similar treatments
(ploc = 0.005). Although treatment × year and location × year interactions were significant, similar effects of treatment × location
and treatment × year × location interactions were absent (Table 5).
Hence, the time factor (year) had some additive influence on
the treatment effects, but the location variations might not have
major impacts on the nutrient schemes in regard to N nutrition in soil. Similarly, P availability of soil was significantly high
under T2 followed by T3 in Sonitpur (L1). However, in Birbhum
(L2) soil, only VC (T5) application resulted in significant enhancement of P availability in soil (ptrt = 0.000; pyr = 0.000). K availability
was also significantly higher under T3 (NPK + VC) followed by T2
(NPK + FYM) in both the soil types (ptrt = 0.000; ploc = 0.000). Application of organic amendments, especially VC considerably enhance
activity of N fixing, P solubilizing microorganisms and promotes
release of several endogenous and exogenous enzymes in soil;

S. Das et al. / Scientia Horticulturae 213 (2016) 354–366


Table 4
Effect of various treatments on soil organic C, fulvic acid C, humic acid C, microbial biomass C and soil respiration.
SOC (%)

p(loc × trt)
p(loc × yr)
p(trt × yr)
p(loc × trt × yr)

FAC (%)

MBC(␮g g−1 )

HAC (%)

SR(␮g g−1 h−1 )

Year 1

Year 2

Year 1

Year 2

Year 1

Year 2

Year 1

Year 2

Year 1

Year 2

1.79 ± 0.62d
2.17 ± 0.16c
2.10 ± 0.14c
2.21 ± 0.26b
2.56 ± 0.46ab

1.82 ± 0.15d
2.2 ± 0.31c
2.12 ± 0.21c
2.23 ± 0.71b
2.67 ± 0.41a

0.75 ± 0.05d
0.87 ± 0.11c
0.96 ± 0.08b
0.94 ± 0.15bc
1.10 ± 0.12a

0.79 ± 0.07d
1.03 ± 0.18ab
0.97 ± 0.14b
0.98 ± 0.085b
1.14 ± 0.80a

0.52 ± 0.05c
0.92 ± 0.12b
0.98 ± 0.60ab
0.96 ± 0.09ab
1.02 ± 0.15a

0.58 ± 0.02c
0.95 ± 0.02b
1.02 ± 0.10a
1.04 ± 0.17a
1.08 ± 0.03a

18.24 ± 1.97i
86.15 ± 3.10c
92.3 ± 1.18b
91.12 ± 2.09b
90.31 ± 3.13b

21.64 ± 2.73h
93.95 ± 8.60b
97.83 ± 2.61a
97.71 ± 6.59a
94.62 ± 7.91ab

10.36 ± 0.08d
12.03 ± 0.17 cd
14.13 ± 0.07b
13.52 ± 0.26c
15.27 ± 0.11ab

11.62 ± 0.51d
14.41 ± 0.11b
15.87 ± 0.24ab
15.21 ± 0.56ab
16.07 ± 0.31a

1.22 ± 0.28h
1.73 ± 0.23ef
1.89 ± 0.32e
1.34 ± 0.17gh
1.61 ± 0.16f

1.25 ± 0.61h
1.71 ± 0.18ef
1.92 ± 0.72e
1.33 ± 0.23gh
1.64 ± 0.32f

0.55 ± 0.09f
0.80 ± 0.04d
0.80 ± 0.01d
0.62 ± 0.14d
0.73 ± 0.19e

0.58 ± 0.12f
0.83 ± 0.06 cd
0.85 ± 0.09c
0.67 ± 0.18d
0.78 ± 0.05de

0.21 ± 0.01f
0.32 ± 0.04ab
0.30 ± 0.07e
0.38 ± 0.05de
0.40 ± 0.03d

0.23 ± 0.01f
0.38 ± 0.02de
0.33 ± 0.05e
0.40 ± 0.06d
0.42 ± 0.05d

17.42 ± 1.82j
54.70 ± 2.24f
50.31 ± 2.02fg
52.15 ± 0.55g
54.23 ± 4.05f

19.14 ± 3.38hi
58.70 ± 8.08d
56.63 ± 4.52de
54.01 ± 1.15g
56.62 ± 4.25e

4.86 ± 0.09j
7.02 ± 0.12h
7.13 ± 0.61gh
8.03 ± 0.21f
8.11 ± 0.08ef

5.72 ± 0.28i
7.19 ± 0.02g
7.18 ± 0.19g
8.29 ± 0.26e
8.16 ± 0.33ef

T1 = Control, T2 = 50% of Recommended dose + 50% of RDN through FYM, T3 = 50% of Recommended dose + 50% of RDN through VC, T4 = FYM only, T5 = VC only; L1: Sonitpur,
Assam, L2: Birbhum, West Bengal. Similar letters represent non-statistical difference as per Duncan’s Multiple Range Test (DMRT) post-hoc analysis (p < 0.05).DMRT was
performed considering three factors: location, year of cultivation and treatment.

Table 5
Effect of various treatments on available N, P, and K in soil of both locations.
N (mg kg−1 )

p(loc × trt)
p(loc × yr)
p(trt × yr)
p(loc × trt × yr)

P (mg kg−1 )

K (mg kg−1 )

Year 1

Year 2

Year 1

Year 2

Year 1

Year 2

117.00 ± 17.51f
172.00 ± 14.56ab
180.00 ± 29.64a
159.00 ± 31.10c
158.00 ± 47.72c

126.00 ± 18.25e
184.00 ± 25.02a
188.00 ± 22.07a
168.00 ± 39.60b
164.00 ± 51.72b

105.14 ± 10.65c
138.16 ± 13.20a
130.17 ± 13.41a
120.83 ± 12.05b
122.65 ± 4.88b

113.54 ± 3.15c
141.46 ± 12.20a
136.67 ± 12.23a
123.33 ± 2.45b
126.25 ± 4.93ab

70.21 ± 1.14e
81.21 ± 0.95b
83.05 ± 3.75b
73.53 ± 2.82d
74.97 ± 1.22d

73.17 ± 3.92d
84.52 ± 1.17b
89.25 ± 1.05b
77.08 ± 1.02 cd
81.19 ± 1.38b

66.00 ± 11.00g
185.00 ± 24.51a
157.00 ± 23.41c
127.26 ± 20.22e
131.00 ± 27.21d

68.00 ± 14.00g
189.00 ± 36.16a
163.00 ± 29.14b
129.26 ± 31.0de
135.00 ± 7.92d

69.03 ± 1.21f
82.31 ± 7.56de
84.12 ± 5.09de
75.80 ± 12.e
83.11 ± 6.136de

71.62 ± 2.11f
88.21 ± 11.56d
89.03 ± 7.09d
78.21 ± 2.35e
89.28 ± 7.06d

108.2 ± 4.54ab
117.31 ± 3.68a
120.13 ± 5.03a
109.19 ± 2.17ab
105.8 ± 5.19ab

113.15 ± 9.41a
121.9 ± 3.16a
127.30 ± 2.68a
115.78 ± 2.37a
118.4 ± 5.19a

T1 = Control, T2 = 50% of Recommended dose + 50% of RDN through FYM, T3 = 50% of Recommended dose + 50% of RDN through VC, T4 = FYM only, T5 = VC only; L1: Sonitpur,
Assam, L2: Birbhum, West Bengal. Similar letters represent non-statistical difference as per Duncan’s Multiple Range Test (DMRT) post-hoc analysis (p < 0.05).DMRT was
performed considering three factors: location, year of cultivation and treatment.

thereby greatly increase N, P, and K availability in soil (Goswami
et al., 2013).
Interestingly, the data for soil enzyme activities (urease and
phosphatase) also substantiate the increment in N, P and K availability in soil (Table 6). Urease activity was significantly high
under T5 followed by T4 and T2 in L1; while in L2, soil urease
activity was in the order of T2 = T3 = T4 = T5 > T1. Urease activity
in soil depends on abundance of urea and urea-like substrates
in the organic matter (Albiach et al., 2000). Similarly, soil phosphatase activity was in the order: T5 > T2 = T3 = T4 > T1 in L1 and
T2 = T3 = T4 = T5 > T1 in L2 respectively. VC application in soil stimulates phosphatase activity through augmentation of P solubilizing
microorganisms in soil (Goswami et al., 2013; Uz and Tavali, 2014).
In the second year all treatments recorded a significant rise in
urease activity both in L1 (3.00–7.41 folds) and L2 (2.30–5.06
folds) soil compared to the first year (pyr = 0.003). Moreover, the

full factorial ANOVA highlighted significant effect of the second and third order interactions (ploc × trt = 0.002; ploc × yr = 0.004;
ptrt × yr = 0.002; ploc × trt × yr = 0.002) between locations, treatments,
and years; indicating the additive effects of location and time on
the response of various nutrient management schemes in regard
to improvement in soil phosphatase activity. Probably, the FYM
and VC used in this study enriched the soil microflora that in
turn boosted the soil enzyme activities over time. Our observation is in agreement with a recent finding (Uz and Tavali, 2014).
These results imply that though the L1 soil responded better to
the adopted nutrient schemes as compared to the L2, the overall nutrient recovery was also noteworthy in the latter. Therefore,
the response to organic manuring largely depends on the inherent soil quality as well as adoption of such schemes for long


S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

Table 6
Phosphatase and Urease activities in soil of L1 and L2.
Phosphatase activity (␮g g−1 h−1 )

p(loc × trt)
p(loc × yr)
p(trt × yr)
p(loc × trt × yr)

Urease activity (␮g g−1 h−1 )

Year 1

Year 2

Year 1

Year 2

71.21 ± 1.29d
80.43 ± 1.59b
80.05 ± 4.50b
81.15 ± 3.26b
89.29 ± 5.34a

78.62 ± 2.09c
83.25 ± 3.54ab
84.13 ± 1.20ab
85.53 ± 4.06ab
92.29 ± 2.32a

40.88 ± 0.09e
61.44 ± 0.19bc
56.33 ± 0.31c
62.30 ± 0.29b
68.31 ± 0.19a

40.88 ± 0.09e
61.44 ± 0.19bc
56.33 ± 0.31c
62.30 ± 0.29b
68.31 ± 0.19a

48.52 ± 1.25f
60.31 ± 1.19e
61.24 ± 2.13e
68.55 ± 2.15d
67.21 ± 1.46de

53.58 ± 2.82ef
62.17 ± 1.49e
62.48 ± 3.01e
69.05 ± 2.44d
69.51 ± 1.31d

23.02 ± 0.23h
37.23 ± 0.83f
35.14 ± 0.22g
40.73 ± 0.10e
43.18 ± 0.38de

25.22 ± 0.23h
36.87 ± 0.18g
36.38 ± 0.38g
42.16 ± 0.13de
45.33 ± 0.22d

T1 = Control, T2 = 50% of Recommended dose + 50% of RDN through FYM, T3 = 50% of Recommended dose + 50% of RDN through VC, T4 = FYM only, T5 = VC only; L1: Sonitpur,
Assam, L2: Birbhum, West Bengal. Similar letters represent non-statistical difference as per Duncan’s Multiple Range Test (DMRT) post-hoc analysis (p < 0.05).DMRT was
performed considering three factors: location, year of cultivation and treatment.

3.5. Influence of various treatments on fruit yield, crude protein,
crude fibre, titratable acidity and total soluble sugar in C.
We observed remarkable differences in fruit yield and yield
attributing features (crude protein, crude fibre, titratable acidity,
and total soluble sugar) of C. chinense between two locations under
various treatments (Fig. 1). The factorial ANOVA output for all these
attributes is presented in Table 7. Interestingly, a steady and significant increase over the years was observed for these attributes
(Table 7).Overall, the fruit yield including other quality attributes
(crude protein, crude fibre, total soluble sugar, and titratable acidity) were significantly higher in Sonitpur (L1) than in Birbhum (L2).
We observed significant location × treatment and treatment × year
interactions in regard to fruit yield. These imply that the locational
variation highly affected treatment effects and such effects also varied over the years. The VC treatment (T5) produced significantly
greater yield compared to other treatments irrespective of locations (ptrt = 0.000). Interestingly, if we consider L2 as a case, the
T3 (NPK + VC) exhibited higher yield than the other treatments,
which indicates the importance of chemical supplements in poorly
fertile soils (Fig. 1). The improvement in nutrient availability, C
enrichment, and microbial activity probably enhanced fruit yield
under VC based nutrient schemes (T3 and T5). VC are generally
rich in diverse microbial populations which are capable of producing phyto-hormones like auxin and gibberellin which support plant
growth and yield (Arancon et al., 2004). Our results imply that effectiveness of nutrient schemes in regard to production of greater fruit
yield, is highly location specific, i.e. it depends on the inherent soil
quality and time duration of the cultivation. Similar results have
been reported by Kunicki et al. (2010).
Similarly, crude protein content was generally higher in L1 than
L2 and significant location × treatment and treatment × year interactions in regard to protein contents in fruits were also observed
(Fig. 1; Table 7). However, protein levels were significantly higher
under combined application of VC and inorganic fertilizers (T3)
than only VC (T5) and other treatments. Crude protein content
in the fruits was higher in T3 by 27.12 and 19.25% in L1 and L2
respectively as compared to the control (ptrt < 0.001). Application
of VC increases protein and N-rich substances in soil which boost
protein formation in plants (Lima et al., 2009). However, varia-

tions in NO3 :NH4 ratio in soil greatly influences protein content
in fruits (Borgognone et al., 2013). As such, the organic + inorganic
(VC + NPK) sources supply N more in highly mineralized form
(NO3 − ); which probably induced higher protein levels in C. chinense
(Fallovo et al., 2011).
Crude fibre content was significantly higher under T5 irrespective of location and the increment in fibre contents under T5
was highly significant over the years (pyr < 0.001).Moreover, crude
fibre content ranged between 1.5–3.8% in L1 and 2.1–3.5% in L2
which was substantially higher than commercial chili (C. annuum)
(0.58–0.67%) (Januˇskeviˇcius et al., 2012).Interestingly, the location × treatment interaction and the location × treatment × year
interaction were significant; which imply that the effects of various treatments on fibre content in “Borbhut” were significantly
influenced by both location and year factors. Hence, our results
suggest that vermi-based nutrient schemes (T3 and T5) were tenable at different locations with varied soil types (Crude protein:
ploc × trt < 0.001; crude fibre: ploc × trt < 0.05). This may be due to the
contribution of VC in formation of stable C stock in soil which in turn
probably facilitated fibre formation in plants through accelerated
C assimilation (Srivastava et al., 2012).
Soluble sugars and titratable acidity are two important respiration substrates in fruits and major components of the soluble solids
which significantly enhance the storage potential of horticultural
produce (Tigist et al., 2013). Titratable acidity represents the total
acidity of the fruits that develops due to occurrence of citric, ascorbic and malic acids (Samira et al., 2013). The rates of sugar and acid
consumption in fruits largely control the duration of fruit respiration. Reduction in titratable acidity induces ripening of fruits and
thus may reduce the storage potential of the fruit, while total soluble sugar value indicates ripening and senescence of fruits (Samira
et al., 2013). Both titratable acidity and total soluble sugar of the
“Borbhut” fruits was significantly higher in L1 than L2 suggesting an
intense role of soil fertility on the fruit quality (ploc < 0.001). Organic
manuring enhances the carbohydrate content and organic acids in
fruits (Zhang et al., 2011).
We also detected significant location × year and location × treatment × year interactions. In addition, the relatively
hotter climate in L2 might be another reason behind lower concentration of total soluble sugar and titratable acid in the “Borbhut”
fruits than those grown in L1 (Table 1). Ambient temperature

S. Das et al. / Scientia Horticulturae 213 (2016) 354–366


Fig 1. Changes in fruit yield and other yield attributing parameters (crude protien, crude fibre, titrable acidity and total soluble sugar) under various treatments in both
locations. Bars with similar letters are not statistically different from each other as per Duncan’s Multiple Range Test (DMRT) post-hoc analysis (p < 0.05). DMRT was performed
considering three factors: treatment, location, and year of cultivation. (T1 = Control, T2 = 50% of Recommended dose + 50% of RDN through FYM, T3 = 50% of Recommended
dose + 50% of RDN through VC, T4 = FYM only, T5 = VC only; L1: Sonitpur, Assam, L2: Birbhum, West Bengal).

Table 7
The ANOVA output of mean square and level of significance for all three factors (location, treatment, and year) and their interactions in regard to Capsaicin, pungency,
lycopene, ␤-carotene, crude protein, crude fibre, titrable acidity, total soluble sugar and fruit yield.
source of variation


mean square

loc × trt
loc × yr
trt × yr
loc × trt × yr







4.87E + 16
1.11E + 17**
1.53E + 14*
1.20E + 16*
6.56E + 14*
8.92E + 13*
2.13E + 14ns
9.15E + 13









2.91E + 17**
2.56E + 17**
1.17E + 16**
8.98E + 15**
4.25E + 15*
5.83E + 14ns
8.72E + 14ns
3.67E + 14








Loc = location, trt = treatment, yr = year; cap = capsaicin, pun = pungency (superscripts 1 and 2 mean fruits and placenta respectively), lyc = lycopene, ␤-car = ␤-carotene,
CPrt = crude protein, CFib = crude fibre, TA = titratable acidity, TSS = total soluble sugar. ns = non-significant.
p < 0.05.
p < 0.001.

invariably controls the sugar content and acid percentage in fruits
(Stenzel et al., 2006). Generally, high ambient temperature coupled
with low precipitation causes moisture deficit in the root zone
of plants; which in turn reduces acid and sugar contents in fruits
(Nomura et al., 2005). In general, organic manuring stabilizes soil

aggregates and thereby enhances moisture retention capacity of
the soil in the long run (Wang et al., 2016). Moreover, adequate
N and K availability in soil greatly regulate organic acid and sugar
contents in horticultural crops.


S. Das et al. / Scientia Horticulturae 213 (2016) 354–366

3.6. Effect of various treatments on capsaicin content, pungency,
and hotness of C. chinense
Fig. 2 represents the data on the variability in capsaicin concentration pungency in fruits and placenta under various treatments
during two years of “Borbhut” cultivation. In general, both capsaicin
and pungency were significantly higher in plants grown in L1 than
L2. We recorded significantly highest capsaicin content in plants
grown under T5 (VC only) in both L1 (29.2 ± 0.16 mg 100 g−1 ) and
L2 (18.8 ± 0.17 mg 100 g−1 ) (ptrt < 0.001). A noteworthy improvement in both capsaicin content and pungency in fruits harvested
from plants grown under T3 and T4 in L2 during second year. This
indicated that the use of VC and FYM supplemented with inorganic
NPK was capable improve these traits in “Borbhut” grown in nutrient fatigue soils. We also detected significant treatment × year and
location × year interactions for capsaicin (fruits). The results are
in conformity with some previous findings (Siddiqui et al., 2011;
Saikia et al., 2015).
Interestingly, capsaicin content and pungency in the placental
tissue were remarkably higher than the whole fruit irrespective
of treatments and locations (p < 0.05; Fig. 2). In general capsaicin
content was 1.1–1.4 folds higher in placenta, while pungency
was 2–4 folds higher in placenta than fruits. However, the effects
of inorganic + organic nutrient management did not have additional benefit with regard to placental pungency in both the
locations. Nevertheless, the location × treatment, location × year,
and treatment × year interactions were highly significant for placental pungency.Canto-Flick et al. (2008) reported similar results
of 8–10 fold higher capsaicin content in the placenta than the
whole Habanero chillies of Yucatan. The placenta hosts the
capsaicin glands that secrete capsaicinoids which in turn accumulates in the placental vacuoles; thus making it the major site
of capsaicin production and accumulation (Prasad et al., 2006).
Interestingly, capsaicin content in the studied landrace “Borbhut” was considerably higher than most of the cultivated chilli
(C. annuum) varieties in India like CCH (1.705 mg 100 g−1 ± 0.13),
Arka Abhir (0.292 mg 100 g−1 ± 0.006), Bayadagi Kaddi (0.608 mg
100 g−1 ± 0.12) and in Mexican Habanero (2.59 mg 100 g−1 ± 0.85)
(Cisneros-Pineda et al., 2007; Tilahun et al., 2013). Aminifard et al.
(2012) reported a 59% increase in capsaicin content under organically cultivated C. annuum plants. In our study, capsaicin content
was 46.7–57.9% and 34.5–50% higher than control in L1 and L2
Multiple regression analysis of the data for capsaicin (n = 30)
were performed to quantify its relation with different soil quality attributes in both the locations. Our major aim was to identify
the most influencing soil quality factors for capsaicin production
in chilli. When we regressed capsaicin content of both locations
with all studied soil parameters the co-efficient of regression (R2 )
was weak (L1: R2 = 0.59, L2: R2 = 0.95), although statistics showed
good significance (p = 0.04). This indicates that some of the studied attributes may or may not have greater impact on capsaicin
content in C. chinense. Interestingly, when the regression was performed removing pH, bulk density and water holding capacity,
the R2 sharply increased [R2 = 0.73 (L1) and 0.99(L2)]. However, in
Sonitpur (L1) maximum R2 values (0.89) was achieved when we
regressed capsaicin content with only soil organic C, fulvic acid
C, humic acid C, soil respiration, microbial biomass C, and soil
enzymes (urease and phosphatase) (Table 8). Hence, formation of
stable C compounds and acceleration of microbial activity in soil is
supposed to trigger capsaicin levels in chilli cv Borbhut rather than
N, P, and K enrichment in naturally fertile soil like L1. Our results
are in good agreement with some previous findings (Perner et al.,
2011; Borgognone et al., 2013).In contrast, strong R2 values (0.99)
were achieved in Birbhum (L2) when N, P, and K were included with
soil organic C, fulvic acid C, humic acid C, soil respiration, microbial

biomass C and soil enzymes (Table 9). Hence, N, P, and K levels were
important supplementary factors along with soil organic C levels
and microbial growth with respect to capsaicin content in poorly
fertile soil (L2). Thus, the variations in soil quality are vital attributes
that regulates biosynthesis of metabolites in plants (Dong et al.,
2011).Overall, the multiple regression analyses suggested that location and soil type were the key factors along with soil organic
C pool, nutrient availability, and soil microbial activity that control capsaicin content in C. chinense cv Borbhut. Canellas et al.
(2015) stated that humic substances interact with plant membrane
transporter proteins, modulate the signal transduction mechanisms thereby influencing production of secondary metabolites in
“Borbhut” is a highly pungent landrace and we observed a significant variation in its pungency under various treatments (Fig. 2).
Pungency is a major factor of chilli pepper that determines its quality and market value (Gangadhar et al., 2012). In our study, the order
of pungency was found to be as: T5 > T4 = T3 = T2 > T1 (ptrt < 0.001)
both in L1 and L2. Pungency of the chillies grown under T5 (VC
only) was significantly higher than other treatments both in L1
(4.67 × 106 SHU) and L2 (3.02 × 106 SHU). A comparison regarding
the hotness index of “Borbhut” with the popular Habanero from
Yucatan (Mexico) and some other widely cultivated chilli varieties
in India has been presented in Table 10. The comparative index
showed a 25–80% more heat in “Borbhut” fruits than other cultivated varieties. Pungency in pepper chillies varies greatly with soil
type particularly depending on soil osmotic properties and nutrient
content (Soria Fregoso et al., 2002). Humic substances are prolific
biostimulants that play a crucial role in activation of genes responsible for various secondary physiological processes in plants (Nardi
et al., 2015).
3.7. Impact of nutrient management on lycopene and ˇ-carotene
in C. chinense fruits
Caroteinoids viz., lycopene and ␤-carotene suppress cancer and
eye disorders (Johnson, 2002). Measurement of lycopene and ␤carotene in C. chinense fruits in this study revealed significant
variations between locations as well as within treatments (Fig. 3).
Location played an important factor influencing the production of
significantly higher lycopene and ␤-carotene in L1 grown “Borbhut” than L2 (ploc < 0.001). Generally, caroteinoid synthesis initiates
during the ripening stage of crops and is strongly influenced by
agricultural practice (Perez-Lopez et al., 2007). In this experiment, fruits grown under T5 (VC only) contained significantly high
(ptrt < 0.001) lycopene and ␤-carotene irrespective of locations.
Exogenous application of organic manure in soil usually increases
lycopene and anti-oxidant content in fruits. Our results corroborate some previous findings (Riahi and Hdider, 2013; Verma et al.,
Generally, nutrient (especially N) enrichment in soil induces ␤carotene in many plants; the reason behind such phenomenon is
still ambiguous (Becker et al., 2015). In this study, we recorded
highest ␤-carotene in C. chinense fruits under T5 (VC only) followed by T4 (FYM only) and T3 (NPK+ VC) in both the locations
(ptrt < 0.001) while, VC and FYM harbour C, N, P, K, S, and microbial
inoculums in balanced amount (Arancon et al., 2004). Therefore,
the enhancement in ␤-carotene was probably due to the balance in C and N nutrition obtained from VC and FYOliveira et al.
(2003) advocated the significant role of soil characteristics on
caroteinoid production in fruits. Additionally, a highly significant
location × treatment interaction was seen in regard to ␤-carotene
enhancement in fruits of “Borbhut” which establishes the effectiveness of the treatments in different soil types. Similar observations
have also been made by previous workers (Caris-Veyrat et al.,
2004).Moreover, “Borbhut” grew in L1 under considerably lower

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