© The Authors, 2021, Published by the Universidad del Zulia*Corresponding author: ramon.jaimez@utm.edu.ec
Luis F. Fernández-Zambrano
1
Liliana Corozo Quiñonez
2
Álvaro Monteros Altamirano
3
Francisco Arteaga Alcívar
2
Ramón E. Jaimez
2
*
Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912
ISSN 2477-9407
DOI: https://doi.org/10.47280/RevFacAgron(LUZ).v39.n1.12
Crop Production
Associate editor: Dr. Jorge Vilchez-Perozo
Keywords:
Growth
Nitrogen
Pepper
Drought tolerance
Morphological and physiological responses of two species of Capsicum (Capsicum annuum L.
and Capsicum chinense Jacq.) under conditions of water decit
Respuestas morfológicas y siológicas de dos especies de Capsicum (Capsicum annuum L. y
Capsicum chinense Jacq.) bajo condiciones de décit de agua
Respostas morfológicas e siológicas de duas espécies de Capsicum (Capsicum annuum L. y
Capsicum chinense Jacq.) sob condições de décit de água
Abstract
Drought and water scarcity, effects from ongoing climate change, are
between main limitations in agricultural production. In this sense, this
study aimed to compare the differences morphological and physiological
responses between local cultivars of Capsicum annuum L. and Capsicum
chinense Jacq under WD conditions. After 20 days of being transplanted and
maintained with adequate irrigation and fertilization, in a randomized block
design, plants of four local cultivars (2 of C. annuum and 2 of C. chinense)
were subjected to two treatments: WD consisting of 14 days without
irrigation, and plants watered every three days. The relative water content
(RWC), root volume, leaf area, specic leaf area, dry weight of the different
organs and leaf nitrogen concentration were measured. The results show that,
under conditions of WD, plants of C. annuum and C. chinense decreases
signicantly leaf RWC, root volumes, total growth and leaf nitrogen
concentration. In the case of C. annuum, the WD affected production, which
varied between cultivars. It seems that the mobilization of photoassimilates
towards fruits is a strategy for a higher production for some cultivar of C.
annuum as demonstrated in the cultivar ECU-2254b, however, it was the
cultivar that showed the lowest RWC in both conditions of water availability.
The cultivar of C. chinense ECU-2241, showed a better tolerance to WD
presenting greater root growth and greater RWC.
1
Ministerio de Agricultura y Ganadería. Ecuador.
2
Universidad
Técnica
de
Manabí.
Facultad
de
Ingeniería
Agronómica. Provincia Manabí Ecuador.
3
Instituto
Nacional
de
Investigaciones
Agropecuarias.
Estación Experimental Santa Catalina
Recibido: 31-08-2021
Aceptado: 19-11-2021
Published: 21-12-2022
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912. January - March. ISSN 2477-9407.
2-7 |
Resumen
La sequía y la escasez de agua, producto del cambio climático
en curso, están entre las principales limitaciones en la producción
agrícola. En este sentido, esta investigación tuvo como objetivo
comparar las diferencias en las respuestas morfológicas y siológicas
entre cultivares locales de Capsicum annuum L. y Capsicum chinense
Jacq en condiciones de décit hídrico. En un diseño de bloques al
azar, luego de 20 días de ser trasplantadas y mantenidas con riego
y fertilización adecuada, plantas de cuatro cultivares locales (2 de
C. annuum y 2 de C. chinense) fueron sometidas a dos tratamientos:
décit hídrico consistente en 14 días sin riego, y plantas regadas cada
tres días. Se midió el contenido relativo de agua (RWC), volumen de
raíces, área foliar, área foliar especíca, peso seco de los diferentes
órganos y concentración de nitrógeno foliar. Los resultados muestran
que, en condiciones de décit hídrico, las plantas de C. annuum y C.
chinense disminuyen signicativamente el RWC foliar, el volumen de
raíces, el crecimiento total y la concentración de nitrógeno foliar. En
el caso de C. annuum, el décit hídrico afectó la producción, que varió
entre cultivares. Al parecer la movilización de fotoasimilados hacia frutos
es una estrategia para una mayor producción en algunos cultivares de C.
annuum como se demuestra en el cultivar ECU-2254b, sin embargo,
fue el cultivar que presentó menor RWC en ambas condiciones de
disponibilidad de agua. No hubo diferencias signicativas entre
cultivares en la concentración de nitrógeno foliar en condiciones
de décit hídrico El cultivar de C. chinense ECU-2241, mostró una
mejor tolerancia al décit hídrico al presentar mayor crecimiento
radicular y mayor RWC.
Palabras claves: crecimiento, nitrógeno foliar, pimiento, tolerancia
a la sequía
Resumo
A seca e a escassez de água, efeitos das mudanças climáticas
em curso, são as principais limitações na produção agrícola. Nesse
sentido, o presente trabalho visa comparar as diferenças nas respostas
morfológicas e nas relações hídricas entre locais, cultivares de
Capsicum annuum L. e Capsicum chinense Jacq sob condições de
décit hídrico. Após 20 dias do transplante e manutenção adequada
de irrigação e fertilização, plantas de quatro local cultivares (2 de C.
annuum and 2 de C. chinense) foram submetidas a dois tratamentos:
décit hídrico de 14 dias sem irrigação e plantas irrigadas a cada três
dias, em um delineamento de blocos ao acaso. Foram avaliados o
conteúdo relativo de água (RWC), o volume da raiz, a área foliar, a área
foliar especíca e o peso seco dos diferentes órgãos e concentração
de nitrogênio na folha. Os resultados mostraram que, em condições
de décit hídrico, as plantas de C. annuum e C. chinense diminuem
o RWC na folha, no volume das raízes, no crescimento total e na
concentração de nitrogênio na folha. No caso de C. annuum, o décit
hídrico afetou a produção, que variou entre as cultivares. Parece que
a mobilização de fotoassimilados para os frutos é uma estratégia para
uma maior produção de C. annuum como demonstrado pelo cultivar
ECU-2254b, porém foi a cultivar que apresentou o menor RWC
em ambas as condições de disponibilidade hídrica. A cultivar de C.
chinense ECU-2241, apresentou melhor tolerância ao décit hídrico
por apresentar maior crescimento radicular e maior RWC.
Palavras-chave: crescimento, nitrogênio foliar, pimenta, tolerância
à seca
Introduction
As a result of the increase of greenhouse gases in the atmosphere,
an
increase
in
global
temperature
is
predicted,
which
may
lead
to
the
desiccation
of
many
regions
due
to
increases
in
evaporation
and
decreases
in
total
annual
precipitation
(Kunapala
et
al.,
2020
Kweku
et al., 2018). Drought and water shortages are one of the main
limitations
in
agricultural
production,
as
a
consequence,
today
it
is
important
to
understand
the
adaptation
and
tolerance
responses
of
different cultivars to these conditions. The water decit (WD) reduces
stem and root growth, leaf area, specic leaf weight and plant biomass
(Gray & Brady, 2016) and leads to changes in physiological aspects
(Lawlor & Tezara, 2009). The responses of plants under conditions of
WD are complex and diverse and although physiological studies at
various scales are conducted to understand the mechanisms involved,
these have not been fully elucidated (Zandalinas
et al., 2018), so the
information
that
can
be
obtained
is
basic
in
breeding
programs
in
order to achieve cultivars tolerant to water deciencies.
The
Capsicum
genus is made up of about 35 species, of which ve
species
(Capsicum
annuum
L.,
Capsicum
frutescens
L.,
Capsicum
pubescens,
Capsicum
chinense
Jacq
and
Capsicum
baccatum
L.)
have
been
domesticated
(Bosland
&
Votava,
2012).
The
Food
and
Agriculture Organization of the United Nations (FAO) for the year
2019 reported that the area sown with chili and peppers worldwide
amounted to about 2 million ha with an approximate production of 38
million t. Of this, 238.271 ha were planted in the American continent
producing 4.942.458 t (FAO, 2021).
C. annuum
and
C. chinense
are
among the most widely cultivated species in the American continent.
Several species of
Capsicum
are sensitive to WD (Jaimez
et al.,
2000; Gonzalez-Dugo
et al., 2007, Macias-Bobadilla
et al., 2020) and
the effect of this decit considerably reduces production if it occurs
in the owering period and the beginning of fruit formation (Jaimez
et al., 2000, Yang
et al., 2018). In addition, in the seedling stage in
open eld conditions, the decrease in water availability considerably
affects growth and can even lead to plants´
death. In the
Capsicum
genus, the low availability of water in the soil causes a decrease in
plant
height,
basal
diameter,
root
volume
and
biomass
(May-Lara
et al., 2011) signicant reductions in leaf water potential and yield
(Jaimez
et
al.,
1999;
Jaimez
et
al.,
2000;
Mardani
et
al.,
2017;)
reductions of CO
2
assimilation and electron transport rates (Campos
et al., 2014, Martinez-Acosta
et al., 2020) and reductions of nitrogen
(N) uptake that inuences the reduction of amino acids involved in
different metabolic pathways (Serret
et al., 2018).
In relation to
C. annuum
and
C. chinense
there is information on
responses to the WD of commercial cultivars, but little information
exists
on
local
cultivars,
which
limits
the
understanding
of
the
variations of response to WD as a function of the genotypic variability
in
these
species.
Therefore,
it
is
necessary
to
understand
the
morphological responses and nutrients intake in conditions of WD of
these species, in order to be considered in future breeding programs.
Then, the objective of this study was to evaluate the morphological
and
physiological
differences
response
of
local
cultivars
of
C.
annuum
L. and
C. chinense
Jacq. under conditions of WD in order to
select possible drought tolerant cultivars.
Materials and methods
The experiment was carried out under greenhouse conditions in
the experimental Campus “La Teodomira” of the Technical University
of
Manabí,
Province
of
Manabí,
Ecuador
(01
°
09’51”S
and
80
°
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Fernández-Zambrano et al. Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912
3-7 |
23’24” W) at an altitude of 60 m.a.s.l. The average temperature in the
greenhouse was 25 °C and a relative humidity of 82%.
Local cultivars: Two cultivars of C. annuum L. and two of C.
chinense Jacq.) were evaluated. The seeds of the cultivars were
obtained from the Genebank of the National Institute of Agricultural
Research (INIAP) of Ecuador. The cultivars of C. annuum were the
ECU-2254b and ECU-2254c collected in the province of El Oro and
for C. chinense Jacq the cultivars ECU-2239a and ECU-2241 were
collected in the province of Manabí (name of cultivars are codes
of INIAP). The selection of cultivars was made based on previous
information of high productions (greater than 2000 kg.ha
-1
) (Loor &
Muñoz, 2019). The seeds were sown in plastic trays with 32 cells
(54 cm long x 28 cm wide and 5.52 cm deep) using peat as substrate.
Subsequently, they were transplanted 28 days after sowing to 40
cm high x 30 cm with polyethylene bags with previously prepared
substrate with a mixture of 50% organic matter based on bovine
manure, 25% sowing soil and 25% from a carbonated source (crushed
peanut shell from the region). Polyethylene bags were located in a
randomized block design, which consisted of eight treatments;
2 irrigation (plants irrigated and plant without irrigation) x four
cultivars (two C. annuum cultivars and two cultivars of C. chinense)
and 4 repetitions (blocks) with a total of 160 plants in an area of 120
m². Each experimental unit had 5 plants.
Before inducing the treatments, the seedlings were watered every
two days and each plant was fertilized 10 days after transplantation
(dat) with 40 g of compound commercial fertilizer (12 N - 11 P - 18 K)
and in a leaf way with a water-soluble fertilizer (24 N - 18 P - 13 K) in
proportions of 0.5 g.L
-1
of water every three days. At 20 days after
transplanting (dat) the treatments began: WD that consisted of 14
days without irrigation and watered every three days to maintain soil
close to eld capacity.
Fourteen days after starting the water experiment, 4 plants
were taken per treatment for physiological and morphological
measurements. The relative water content of the leaf (RWC) was
determined from leaf cuttings (10 squares of leaves were cut from
the plants of each cultivar) and weighed (fresh weight, FW) in an
analytical balance. Once weighed, they were placed to saturate in
petri dishes with distilled water for a time of four hours; after this
period, leaf cuttings were taken out the surface moisture was removed
with an absorbent paper were weighed (saturation weight, SW) and
placed in an oven for 48 hours at 65 °C, later the dry weight (DW)
was determined. The RWC was calculated as follow: (FW-DW/SW-
DW) *100 (Sanders & Arndt, 2012). The volume of roots (RV) was
determined by carefully taking the roots out of the substrate, removing
the soil and introduced them into a cylinder of known volume of water
-the displaced water content determined the volume of the roots. The
leaf area (LA) was measured for each genotype with a model LI-3100
leaf area meter. The determination of the specic leaf area (SLA) was
calculated by dividing the leaf area between the dry weight of the
leaf. The dry weight of root (PR), stem (PT) and leaves (PH) was
determined by separating each of its parts and placed in an oven at
65 ° C for 72 hours and once dried they were weighed. The Kjeldahl
method was used for the determination of the N concentration in the
leaves.
A one-way analysis of variance was performed. For the
comparison of means, the Tukey test was used at 0.05%. The data
were expressed as mean values ± standard error. Linear relationships
were made between some variables.
Results and discussion
Relative water content (RWC)
The analysis of variance shows that there was a signicant effect
on the irrigation factor for all traits with exception of SLA while for
cultivar factor there was signicant differences for RWC, root weight
(RW) and stem weight (SW) (table 1). The non-irrigated plants of
all cultivars presented lower signicant RWC, in relation to the
irrigated plants (gure 1). In plants without irrigation the variations
were between 37% (cultivar ECU-2254b) and 53.9% (cultivar ECU-
2254c). In irrigated plants there were no signicant differences
between cultivars, the values ranged between 61.8% and 80%.
There is a tendency that the cultivars with the highest RWC in
irrigated plants are those that also present the highest RWC in the
treatment without irrigation; this variable could be evaluated in other
cultivars. Other results differ about the effect of the WD on the RWC
probably due to the fact that the number of days in WD changes e.g.
Serret et al. (2018) found no signicant differences in the RWC of C.
annuum due to the WD, probably because the decit was evaluated
in plants that were watered every 3 days, and in the case of our study
the length of the decit was 14 days. On the other hand, signicant
reductions in RWC in C. annuum and C. chinense have been obtained
as the availability of water in the soil decreases both in the vegetative
stage and in owering and fruiting, however C. chinense showed
higher RWC (Okunlola et al., 2017).
Table 1. Analysis of the variance for relative water content (RWC), specic leaf area (SLA), root volume (RV), root weight (RW), stem
weight (SW), leaf weight (LW) and percentage of leaf nitrogen (N).
F.V. RWC SLA RV RW SW LW N
Model 5946.67* 40380.56 872.08** 17.48 148.37* 127.21* 12.40*
Block 44.85 1570.55 14.08 0.29 11.07 0.13 0.03
Irrigation 4719.85* 11359.47 486** 5.9* 51.33** 101.27** 11.67*
Cultivar 1078.47* 10161.4 360.67** 8.59 72.13** 13.14 0.20
Irrigation*Cultivar 103.5 17289.15 11.33 2.7 13.83 12.66 0.42
Error 728.9 58143.76 171.25 13.65 42.25 47.81 0.83
Total 6675.57 98524.32 1043.33 31.13 190.62 175.02
13.23
The displayed value is the sum of squares. Signicance a ** P <0.001. * P <0.05
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912. January - March. ISSN 2477-9407.
4-7 |
Figure 1. Relative leaf water content (RWC) in cultivars of
Capsicum annuum (ECU-2254b and ECU-2254c)
and Capsicum chinense (ECU-2239a and ECU-2241)
with irrigation (black bars) and without irrigation
(gray bars). Lines in bars are the standard errors.
Different letters are signicant differences (P <0.05)
according to Tukey test.
Specic leaf area
The analysis of variance shows that there are no differences in
the effects of irrigation and cultivars (table 1). However, there is a
tendency for cultivars to present lower SLA with WD (gure 2). For
example, the SLA of ECU-2239a decreased by 40%, while ECU-
2241 the decrease was 27% and ECU-2254c only 9% with respect
to the SLA of irrigated plants.
The results suggest that C. chinense cultivars have the tendency
to present lower SLA than C. annuum cultivars, as a strategy to
avoid greater areas of transpiration, Okunlola et al. (2017) and
Serret et al. (2018) reported signicant decreases of SLA in C.
annuum under moderate conditions of WD (irrigation every three
days). Although Martinez-Acosta et al. (2020) found in C. annuum
plants under soil WD between 75 and 25%, that the weight and the
leaf area decreased, however, the decrease in weight was greater,
maintaining higher SLA until the 80 days. Subsequently, the
decrease in SLA is similar and signicantly lower in both conditions
with respect to plants with 100% water availability. When the WD
develops slowly, changes occur in development processes that have
various effects on growth. Although the leaf area is important,
since a greater light uptake depends on it, a high leaf expansion can
negatively affect adaptation to the low availability of water due to a
greater transpiratory surface (Wang et al., 2017).
0
50
100
150
200
250
300
2239a 2254b 2241 2254c
AFE (cm
2
g
-1
)
Cultivar
A
A
A
A
A
A
A
A
Figure 2. Specic leaf area (SLA) in cultivars of Capsicum
annuum (ECU-2254b and ECU-2254c) and Capsicum
chinense (ECU-2239a and ECU-2241) with irrigation
(black bars) and without irrigation (gray bars). Lines
in bars are the standard error. Different letters indicate
signicant differences (P <0.05) according to Tukey test.
Root volume
The available water content in the soil for the plants, inuenced
the signicant responses both for cultivars and for the irrigation
factor (table 1). The cultivar of C. chinense ECU-2241, was the one
that presented the highest volume of roots in both conditions of water
content, while the cultivar of C. annuum ECU-2254b the lowest
(gure 3). In the conditions of WD, all the cultivars decreased the
root volumes, being only signicant for the cultivar of C. chinense
ECU-2239a. The cultivar presenting the greatest decrease in root
volume (57%) was C. chinense ECU-2241, while the cultivar ECU-
2254b the least (46%). Under irrigation conditions, C. chinense
cultivars presented the highest root volumes. A linear relationship
(r
2
= 0.76%) was found between root volume and RWC (gure 4).
The linear relationship between the volume of roots and the
RWC seems to indicate that in Capsicum a greater surface of root
contact with the soil ensures a greater amount of water in the leaves
and therefore apparently a lower water stress. This trend of greater
amount of root volume could be used as a variable that indicates
a greater tolerance to WD. It is also known in other Solanaceae
species (tomato) that the WD leads to a reduction in the area of the
root xylem, decreasing the water potential and lead to decreases
in the leaf stomatal conductance (Hernandez-Espinoza & Barrios-
Macias, 2020). The evaluation of several root variables could then
be used as a criterion for improvement programs; studies with larger
number of cultivars should be carried out to verify these trends.
0
20
40
60
80
100
2239a 2254b 2241 2254c
RWC (%)
Cultivar
AB
A
A
BC
BC
C
C
A
0
5
10
15
20
25
30
35
40
2239a 2254b 2241 2254c
Volume of roots
Cultivar
A
ABC
ABCD
BCD
CD
D
AB
Figure 3. Volume of roots in cultivars of Capsicum annuum
(ECU-2254b and ECU-2254c) and Capsicum chinense
(ECU-2239a and ECU-2241) with irrigation (black
bars) and without irrigation (gray bars). Lines in the
bars are the standard errors. Different letters indicate
signicant differences (P <0.05) according toTukey test.
0
10
20
30
40
50
60
70
80
90
0 5 10 15 20 25 30
RWC (%)
Volume of roots (cm3)
y=0.2442x+28.31
R
2
= 0.76
2254c
2254c
2254b
2254b
2241
2241
2239a
2239a
Figure 4. Relationship between root volume and relative water
content (RWC) in cultivars of Capsicum annuum
(ECU-2254b and ECU-2254c) and Capsicum chinense
(ECU-2239a and ECU-2241) with irrigation (black
dots) and without irrigation (no ll). Vertical and
horizontal lines are the standard errors.
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Fernández-Zambrano et al. Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912
5-7 |
could ensure a greater amount of water intake. Thus, C. chinense
plants maintain the development of their roots in search of water
in deeper areas of the soil (Potters et al., 2007). However, this will
depend on the efciency of the water intake by the roots (Hernandez-
Espinoza & Barrios-Macias, 2020). Cultivars of C. annuum, on the
contrary, have a greater investment towards the growth of the aerial
part (leaves and stems). It seems that both species have different
initial strategies for the distribution of assimilates, an aspect that
should be corroborated with a greater number of cultivars in both
species. In the cultivars of C. chinense, the percentage distribution
of weight between the organs remained similar in both conditions of
water availability, which indicates that despite the decrease in water,
a sink force was maintained the same as in conditions of irrigation.
These results are similar to those reported by Jaimez (2000), where
cultivars of C. chinense under conditions of different irrigation
Total biomass
The local cultivars of C. chinense presented the lowest
accumulations of total biomass under irrigation conditions,
presenting ECU-2239a, with the least signicant accumulation
(gure 5). Under conditions of WD there were no signicant
differences in the dry weight reached between the cultivars, while
those of C. annuum, despite presenting the highest accumulation of
biomass, were the most affected by the WD. Cultivars ECU-2254b
and ECU-2254c under the decit treatment only reached 55 and
58% and their decreases were signicant (P <0.05) with respect to
the total dry weight obtained under irrigation conditions, while the
cultivars of C chinense ECU-2239a and ECU-2241 reached 87 and
60% respectively of the dry weight in WD conditions in relation to
the irrigated plants.
Figure 5. Total dry weight of Capsicum annuum cultivar
plants (ECU-2254b and ECU-2254c) and Capsicum
chinense (ECU-2239a and ECU-2241) with
irrigation (black bars) and without irrigation (gray
bars). The lines are the standard errors.
Weight of the different organs
In relation to the weight distribution among the different organs,
no signicant differences were found (P <0.05) due to the effects of
the irrigation factor or cultivar for the RW or LW, but signicance
was found in the SW for both the cultivar and for irrigation (table
1), where the least signicant weight of the watered plants was
presented by the cultivar ECU-2239a (gure 6 A). The leaves in
all cultivars maintained the highest amounts of weight in both
conditions of water availability, followed by the stem and the root
(gure 6 A, B). C. annuum cultivars presented fruit production,
being ECU-2254b the one with the highest signicant production
both under irrigation conditions and in WD (gure 6 A, B).
All organs presented lower weight under conditions of WD
(gure 6 B) e.g. fruit production in C. annuum cultivars was the
most affected, with decreases close to 80% in both cultivars with
relation to production in irrigated plants (gure 6 A, B). The lower
productions also implied an increase in the weight distribution
towards leaves and stems in both cultivars of C. annuum under
WD. The WD did not inuence the distribution of assimilates
between the area and the roots in any of the cultivars (gure 7).
In the cultivars of C. chinense
, the lowest values were presented
in the aerial part/root weight ratio in the two conditions of water
availability (gure 7).
Although the WD did not inuence the distribution of assimilates
between the aerial parts and the roots in any of the cultivars, in the
cultivars of C. chinense
the lowest values were presented in the
relation weight aerial part / root weight under the two conditions
of water availability, which indicates that in this species a greater
investment of photoassimilates towards root growth is likely, which
0
5
10
15
20
25
30
35
40
2239a 2254b 2241 2254c
Total dry weight (g)
Cultivar
A
A
A
B
B
B
B
B
Figure 6. Final dry weight of root leaf, stem and fruit of
Capsicum annuum (ECU-2254b and ECU-2254c)
and Capsicum chinense (ECU-2239a and ECU-
2241) with irrigation (A) and without irrigation (B).
Lines in the bars are the standard errors. Different
letters indicate signicant differences (P <0.05).
0
5
10
15
20
25
2239a 2254b 2241 2254c
Aerial part/root ratio
Cultivar
B
B
B
B
A
A
A
A
Figure 7. Relationship between aerial part weight (stems and
leaves) and root weight in cultivars of Capsicum
annuum (ECU-2254b and ECU-2254c) and C
Capsicum chinense (ECU-2239a and ECU-2241)
with irrigation (black bars) and without irrigation
(gray bars). Lines in the bars are the standard errors.
0
2
4
6
8
10
12
14
16
2239a 2254b 2241 2254c
Weight (g)
Cultivar
ROOT LEAF STEM FRUIT
A
AB
B
A
A
A
A
A
A
A
A
A
A
B
A
0
2
4
6
8
10
12
14
16
2239a 2254b 2241 2254c
Weight (g)
Cultivar
ROOT LEAF STEM FRUIT
A
A
A
A
A
A
A
A
A
A
A
A
A
B
B
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2022, 39(1): e223912. January - March. ISSN 2477-9407.
6-7 |
frequencies (every 3, 6 and 9 days) presented a trend of greater
accumulation of dry matter with greater irrigation frequency, but the
distribution of dry matter to the different organs remained relatively
constant, independent of the frequency of irrigation. It seems
that the greater investment towards root growth offers a greater
possibility of water uptake to C. chinense plants and therefore they
are less affected in terms of growth.
All organs presented lower weight under conditions of WD, which
implies that there were lower rates of photosynthesis (Martinez-
Acosta et al., 2020). Under WD condition, fruit production in C.
annuum cultivars was the most affected, with decreases close to
80% in both cultivars. Similar trends of water-decient and irrigated
plants have been reported by Dorji et al. (2005). The decreases in
fruit production may be due to a higher number of oral abortions
and small fruits. Drought stress has been shown to decrease yield,
and at the same time produce senescence of leaves (Vashi et al.,
2020). A higher fruit production of the ECU-2254b initially under
water limitations indicates a greater investment of photoassimilates
towards fruit production, an important characteristic at times of less
water availability. It is probable that in the ECU-2254b a greater
quantity of photoassimilates is distributed towards fruits, which
gives it greater productivity both under irrigation conditions and
under WD.
The lower productions in WD also implied an increase in the
weight distribution towards leaves and stems in both cultivars of C.
annuum. Both cultivars of C. chinense did not show fruit production,
so it is necessary to evaluate the changes in the distribution of
assimilates under conditions of WD. It is known in C. chinense that
under eld conditions at average temperatures of 28ºC and without
water limitations, the fruits have the highest relative growth rates
between 76 and 86 days after transplanting (Jaimez & Rada, 2016).
In this experiment, the plants were kept up to 60 days; therefore, it is
important to carry out future experiments including the production
phase.
Leaf nitrogen concentration (N)
The analysis of variance showed that there is a signicant effect
of irrigation on the leaf N concentration (table 1). Under conditions
of WD, the N content in plants decreased signicantly (P<0.05).
The four cultivars showed signicantly lower concentrations of
N with respect to irrigated plants (gure 8). However, there are
no differences between cultivars for each of the water conditions
evaluated.
The lower signicant concentrations of N in plants without
irrigation indicate that under limited water conditions in all
cultivars there was also a lower uptake of N, probably due to lower
transpiration rates (Ismail, 2010). González–Dugo et al. (2007)
explain that in general lower concentrations of N have been found
in crop plants that are subject to WD. It is probable that lower
availability of water in the soil led to a partial stomatal closure,
which inuenced lower rates of CO
2
assimilation and transpiration
rates reported in both species (Jaimez et al., 1999; Serrat et al., 2018;
Martinez -Acosta et al., 2020) leading to a lower rate of uptake
of N and also lower growth rates. The lower concentrations of N
inuence decreases in the photosynthetic capacity, which leads to
lower growth rates. In three of the cultivars, the effect of the decit
led to reductions of 43% in the leaf N concentration. Only cultivar
ECU-2254b had reductions of 32% and maintained the highest fruit
production in WD.
Conclusions
The most important aspects standing out from this research
are: The higher root volume leads to a better adaptation in terms of
maintaining higher RWC in irrigated and non-irrigated conditions,
with the trend that cultivars with higher RWC and root volume in
watered plants are those that also present the highest root volume
and RWC values in the treatment without irrigation.
There is a greater distribution of assimilates towards the roots
in cultivars of C. chinense, while cultivars of C. annuum mobilize
more quantity of assimilates to the stem and fruit formation in both
conditions of water availability (WD and without WD). Although
there is lower growth due to the WD, the differences between
cultivars in the aerial / root biomass ratio did not change. The
decrease in root growth during periods of WD also inuences a
lower uptake of N that consequently inuences lower growth rates.
The cultivar of C. annuum ECU-2254b could be selected for
having a higher production under WD while the cultivar of C.
chinense ECU-2241, shows a better tolerance to WD by presenting
greater root growth and greater RWC in decit conditions hydric.
The responses in Capsicum appear to vary between cultivars within
the same species and between species.
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