Introduction
The life cycle of
plants is subjected to adverse environmental conditions that limit the
development of plants and their chances of survival. One of these adverse
conditions is water deficit. As a consequence of this specific environmental
condition, plants can respond with the reduction of the water potential and
leaf turgescence with closure of the stomata and, consequently, a lower
photosynthetic rate that reflects in the cell elongation (Nogueira et al.
2005) and cell growth (Jaleel et al. 2009). Therefore, the characteristics of the internal
structure of the leaves of plants may be important to determine the level of
tolerance to water stress (Batista et
al. 2010), as well as to detect
the anatomical modifications of plants subjected to treatments that involve
water conditions in a phase prior to leaf wilting (Oliveira
et al. 2014).
Plants present several
modifications to adapt to the stressful conditions, such as increases in the
thickness of the epidermis, number of trichomes, deposition of the cuticle, and
stomatal density in cavities and stomatal crypts (Castro
et al. 2009), as well as a reduction in stomatal size.
In addition to leaf
growth and modifications in leaf anatomy, water deficit may generate oxidative
damage, caused by energy from excitation of the chlorophyll molecules not being
used in photosynthesis or eliminated in the form of heat. This causes the
production of reactive oxygen species (ROS), which can react with any cell
molecule, causing damage to the cells and organs (Barbosa et al. 2014; Morales and Munné-Bosch 2016). Several studies have
shown the induction of oxidative stress by water deficit and antioxidative
enzyme activity, such as superoxide dismutase (SOD) and peroxidase (POD) (Wang et al. 2016; Rosa et al. 2017; Reis et al.
2018; Gupta et al. 2018).
However, it is important
to emphasize that the effects of water deficit on plants are quite variable,
because the effects depend on the intensity and speed of stress imposition and
the developmental stage at which it happens (Pimentel 2004). In addition, the genetic capacity of plants and their
recovery potential are determinant factors for the development and survival of
each species.
Campomanesia xanthocarpa O. Berg.
(Myrtaceae) is a deciduous tree, popularly known as “Guabirobeira” or
“Guabiroba” and according to review of Luz and Krupek (2014) it is a heliophyte and selective hygrophyte plant, with
occurrence in the “capoeiras and capoeirões” on moist soils and well drained
capons and gallery forests, both in flat areas and on hillsides and near water
ways. It has good adaptability and may occur in dry, compact, and low-fertility
soils.
The
economic importance of C. xanthocarpa comes
mainly from its use in beekeeping, human food, and medicinal products. The
plants’ fruits, when ripe, are rich in vitamin C and appreciated in natural
consumption and industrialization in the manufacture of liqueurs and ice creams
(Carvalho 2006).
The seedlings of C. xanthocarpa cultivated under water
deficit shows reduction of the leaf water potential and all the characteristics
of photosynthetic metabolism, which reaches close to zero only 20 days after
the suspension of irrigation. However, after resumption of irrigation, the
seedlings show to recover (Bento et
al. 2016). No information is
available on the protective mechanisms or morphoanatomical modifications that
could allow this recovery after the water deficit.
Considering the
occurrence of C. xanthocarpa in both
moist soils and environments with low water availability, we hypothesize that
this species shows plasticity in its morphoanatomical and biochemical responses
that enables its survival in environments subject to temporary water deficits
and allow for its recovery after irrigation restoration.
This study aims to
evaluate the growth, antioxidant enzyme activity, leaf anatomy, and recovery
potential of C. xanthocarpa seedlings
subjected to water deficit.
Materials and Methods
Plant
and cultivation material
Fruits of C. xanthocarpa
O. Berg. were
collected in remaining Cerrado areas, located near the municipality of
Dourados/MS, Brazil. After collection, the fruits were processed manually, and
the seeds were washed in running water to eliminate the remnants
of pulp and dried with Germitest® paper.
Fig. 1: Experimental
scheme of the distribution of C. xanthocarpa plants in the two water regimes (Control-C
and water deficit-WD) and in the six evaluation periods: T0 beginning of the
experiment; 1st and 2nd P0 - first and second
photosynthesis zero, 1st and 2nd REC - first and second
recovery, and the END evaluation
Table 1: Water potential (Ψw) due to the evaluation periods between irrigated
seedlings of C. xanthocarpa and
subjected to water stress conditions
Treatments |
T01 |
1st
P0 |
1st
REC |
2nd
P0 |
2nd
REC |
END |
Control |
-0.1 Aa* |
-0.1Aa |
-1.3 Ba |
-0.1 Aa |
-1.9 Ca |
-1.9 Ca |
Water deficit |
-0.1 Aa |
-2.6 Db |
-2.7 Da |
-2.3 Cb |
-2.3 Ca |
-1.9 Ba |
Uppercase letters
buy the different evaluation time in the same water condition and lowercase
letters bought the different hydric conditions at the same evaluation time. (1)T0
beginning of the experiment; 1st and 2nd P0 - first and
second photosynthesis zero, 1st and 2nd REC - first and
second recovery, and the END evaluation |
The seedlings were produced from sowing in tubes 50 x
190 mm to one centimeter of depth containing Dystroferric Red Latosol, sand,
and commercial substrate Bioplant® in the proportion of 1:1:1,
placing one seed per tube. The seedlings were transplanted to pots with the
same soil and capacity of 5 kg when reached approximately 15 cm, having been
acclimated for 30 days, with water retention capacity in the substrate soil of
70% and kept in a greenhouse under 40% shade. During the experiment, the plants
were protected from rainfall by a plastic cover.
At the beginning of the experiment (T0), the pots were
distributed in two groups: Group 1 (control (C), where plants were irrigated
periodically in order to maintain 70% of the water retention capacity of the
substrate, and group 2 characterized by water deficit (WD), where irrigation
was suspended until the photosynthetic rate reached close to zero, at which
time the plants were re-hydrated with daily irrigation for one week at a rate
and maintained a water retention capacity of the substrate to 70%.
The plants were evaluated in six periods: T0 (beginning
of the experiment); 1st P0 (first photosynthesis zero), when the seedlings
under suspension of irrigation showed photosynthetic rate close to zero (28
days); 1st REC (first recovery),when the seedlings were re-irrigated
until the photosynthesis values approached the control (seven days); 2nd
P0 (sec photosynthesis zero) when the seedlings were subjected to the sec cycle
of suspension of irrigation and showed photosynthetic rate close to zero (nine
days); 2nd REC (sec recovery), when the seedlings were re-irrigated
until the photosynthesis values reached the control in the sec cycle of
irrigation suspension (seven days); and the end evaluation occurred at 172 days
of experiment (Fig. 1).
Plant
measurements
Growth characteristics were evaluated by collecting three seedlings of
each treatment and evaluated for the number of leaves (NL), shoot length (SL),
and root length (RL). For the analysis of antioxidant enzyme activity, an
extract was obtained from the homogenization of 1 g of the leaves and roots,
removed from each treatment, fragmented in mortar in the presence of liquid
nitrogen. Next, 2 ml of extraction solution was added, consisting of EDTA 0.1
mM in potassium phosphate buffer 0.1 M, pH 6.8, containing 20 mg of
polyvinylpyrrolidone. Homogenized solution was centrifuged for 20 min at 4000
rpm and the supernatant collected, which was then used in the evaluations of
peroxidase - POD (Macedo et al. 2005) and superoxide dismutase - SOD (Beauchamp
and Fridovich 1971; Giannopolitis and Ries 1977;
Longo et al. 1993).
Free-hand para dermal and
transversal cuts were made in the median region of completely expanded leaves
of each treatment (n=8). Cross-sectional cuts were performed free-hand with a
steel blade in fresh material being stained with astra blue and safranin,
according to Bukatsch’s (1972) proposal modified and assembled between lamina
and laminula in glycerinated gelatin. From this
cross-sectional sections, the thickness of the cuticle adaxial
(CAd; µm)
and abaxial (CAb; µm), epidermis adaxial (EAd; µm) and abaxial (EAb; µm), palisade (PP; µm), and lacunous (PL; µm)
were determined.
Fig. 2: Number of leaves - NL (A) root length – RL (B) and shoot length - SL (C) between irrigated seedlings of C. xanthocarpa and water deficit
conditions. Lowercase letters compare the different water regimens
in the same period of evaluation by the T test (P < 0.05). Uppercase letters compare the control treatment in
the different evaluation periods. Uppercase letters in italics compare the
stress treatment in the different evaluation periods, both by the Scott–Knott
test (P < 0.05)
The paradic impressions were
prepared in the morning, between 8:00 and 11:00 h, with Super Bonder®
glue of samples from the median region of the limbus on the adaxial and abaxial
surfaces, being determined: polar diameter (PD µm) and equatorial diameter of the stomata (ED µm), ostiolar aperture (OA µm),
stomatal functionality (considered the polar diameter/equatorial diameter ratio
of stomata), and stomatal index (SI%) calculated using the formula proposed by Salisbury (1928). The laminary obtained was
photographed with the aid of a Moticam 2000 digital camera coupled to the
optical microscope by means of the MoticImage 2000 program and adjusted scales
in the appropriate optical conditions.
Experimental design and
statistical analysis
The experimental design was completely randomized in a factorial scheme
with 6 evaluation periods (T0, 1stP0, 1st REC, 2nd P0, 2nd REC, and END) and 2
water regimens (control and water deficit) with four replications, where each
repetition corresponded to a seedling.
The data were subjected to analysis of variance.
Significant effects on the means of the water regimens were compared by the T
test with a 5% probability and on the averages of the evaluation periods were
compared by the Scott–Knott test at 5% probability.
Results
Effects on Water potential (Ψw)
The interaction was observed for water potential between evaluation
time and water regimens (Table 1). In the first and sec cycle of photosynthesis
close to zero (1st and 2nd P0), significant reductions
were observed for Ψw. At the end of the experiment, the stressed seedlings
did not differ from the control.
Effects on Growth
characteristics
Fig. 3: Antioxidant activity of
superoxide dismutase (SOD - U of SOD) enzymes in leaves (A) and roots (B); and
Peroxidase (POD - μmol g FM-1) in leaves (C) and roots (D) between irrigated seedlings of C. xanthocarpa and water deficit
conditions
The seedlings of C. xanthocarpa
under water deficit conditions showed reduction in the number of leaves (NL) in
the first cycle of suspension/resumption of irrigation when compared to control
(Fig. 2A). However, at the end of the experiment, the NL of seedlings under
water deficit did not differ from control.
Under water deficit, root length (RL) showed an increment
during the 1st P0 period (Fig. 2B); however, at the end of the
experiment, this increment was lower than the control. The shoot length (SL)
was reduced during 1st REC, 2nd P0, 2ndREC,
and at the end of the 90 days of irrigation resumption (Fig. 2C).
Effects on antioxidant enzyme
activity
The enzymatic activity of superoxide dismutase (SOD) and peroxidase
(POD) was influenced by the interaction between the control and stress
treatments (Fig. 3). Water deficit showed an increase in the enzymatic activity
of SOD in the leaves during periods of 1st P0 and 2nd P0,
respectively. A significant increase in the activity of this enzyme was also
observed in control seedlings in the first cycle of suspension/resumption of
irrigation and at the end of the experiment (Fig. 3A). However, the SOD
activity in the root was higher in the 1st REC periods and at the
end of the experiment (Fig. 3B).
In relation to POD activity in the leaves, an increase
was observed during the 1st P0 and 2nd P0 periods and at
the end of the experiment in the seedlings under water deficit (1.18 mM, 0.99 mM, and 1.29 mM, respectively) (Fig. 3C). In the roots, this increase was seen in
the1st P0, 1stREC, and 2nd P0 periods (Fig.
3D).
Leaf
anatomy
The leaf anatomy of C.
xanthocarpa seedlings was influenced by irrigation conditions (Fig. 4). The
seedlings under water deficit showed significant reductions in the thickness of
the cuticle of the adaxial face from the 1st P0 period and remained
same until the 2nd REC period. At the end of the experiment, the
previously stressed seedlings showed an increase in the thickness of the
cuticle of the adaxial face (Fig. 4A). For the cuticle of the abaxial face, the
seedlings under water deficit showed an increase in thickness in 2nd
REC period (Fig. 4B).
In relation to the epidermal faces, the adaxial and
abaxial faces showed an increase in the thicknesses due to the water deficit.
For the epidermis of the adaxial face, this increase was observed in the 2nd
P0 and2nd REC periods and at the end of the experiment (Fig. 4C) and
for the epidermis of the abaxial face, in the periods of 1st P0 and
at the end of the experiment (Fig. 4D).
Fig. 4: Cuticle adaxial – Cad (A) and abaxial
- CAb (B),
epidermis adaxial – Ead (C) and abaxial
– Eab (D),
palisade parenchyma – PP (E) and lacunous – PL (F) of
leaf structures/tissues between irrigated seedlings of C. xanthocarpa and water deficit
conditions
As for the brackets, the seedlings under water deficit
showed reductions in the thickness of the palisade parenchyma in the 1st P0
period and at the end of the experiment (Fig. 4E). However, in the 2nd
P0 period, an increase in thickness with a value of 19.3 µm was observed. For
the lacunous parenchyma, reductions in the thickness were observed during the 1st
REC and 2ndREC periods and at the end of the experiment in seedlings
subjected to water deficit when compared with the control seedlings (Fig. 4F).
Effects on stomatal
characteristics
The ostioles aperture and the polar diameter of the stomata were
influenced by irrigation conditions (Fig. 5). For the ostioles aperture,
reductions observed were found in the periods of higher water stress:1st P0 and 2nd P0 (Fig.
5A). In relation to the polar diameter, a reduction was seen in the 1st F0;
however, in the 2nd P0 period, an inversion in the behavior was
observed, with an increase in the polar diameter of the stomata in the stressed
seedlings seen compared to control (Fig. 5B).
The equatorial diameter was influenced by the factors
alone, and they were smaller in seedlings subjected to water deficit, reduced
from the first cycle of suspension/resumption of irrigation and remaining with
an average value of 2.96 µm until the end of the evaluation period (Fig. 5C,
D).
The stomatal index in the seedlings under water deficit fluctuated
throughout the experimental period, as seen through reductions in the index
during the1st P0, 2nd P0, and 2nd REC periods,
and through increases in the 1st REC period and at the end of the
experiment (Fig. 5E).
It was only possible to observe stomatal functionality
(PD/ED) differences promoted by the water deficit from the 2nd P0
period, (Fig. 5F) in which the seedlings under deficit showed a value for this
parameter superior to that observed for the control seedlings, which remained
until the end of the experiment.
Discussion
In this study, the seedlings of C.
xanthocarpa under water deficit showed a reduction in water potential
(Ψw 2.4 MPa) when the photosynthetic rate was reduced to values close to
zero. After the resumption of irrigation, there was recovery of the Ψw of
the seedlings previously maintained under water restriction, reaching values
close to of the control plants, as observed for other tree species (Bento et
al. 2016; Rosa et al. 2017; Reis et al. 2018).
Fig. 5: Ostiolar aperture - OA (A), polar diameter - PD (B) and equatorial diameter of the
stomata - ED (C, D), and stomatal
index – SI (E) stomatal
functionality – PD/ED (F) (polar
diameter/equatorial diameter ratio of stomata) of leaf
structures/tissues between irrigated seedlings of C. xanthocarpa and water deficit
conditions
The water deficit negatively affected the growth of
seedlings of C. xanthocarpa, as
evidenced by the reduction in the new leaves even after the first cycle of
suspension/resumption of irrigation, likely reflecting the reduction of cell
division and expansion caused by the low availability of water (Martins et al.
2010).
However, in the 2nd REC cycle, the seedlings
maintained under water deficit produced a higher new leaves. This phenomenon is
known as “hardening”, which allows the plant a greater osmotic adjustment when
it has already undergone a first cycle of stress due to lack of water. The
solutes accumulated in the first water deficit are not readily assimilated and
allow a higher osmotic accumulation and adjustment in the sec cycle of water
deficit (Kramer and Boyer 1995), allowing the continuity of the development
processes.
As a response to the water deficit (1st P0),
the seedlings showed higher root production as a strategy to adapt to stress,
since the aerial part of the plant showed reduced growth. This may be related
to the recognition and signaling of stress, through the production of abscisic
acid and reactive oxygen species (ROS) (Gupta et al. 2018), both of which induce root growth and stimulate the
emergence of lateral roots while suppressing growth of the aerial parts.
However, after the 1st P0 period, the
stressed seedlings ceased the growth of roots and reduced the aerial portion of
the plants, a state that remained until the end of the experiment. This
behavior can justify the reduction of leaf water potential in this period and
signals the sensitivity of C. xanthocarpa
to water deficit. We emphasize that the effects of water deficit on seedling
growth are due to alterations in metabolism, with observed reductions of
stomatal conductance, transpiration rate, and photosynthesis (Bento et al.
2016).
The decrease in water availability affects the growth of
plants by controlling the opening of the stomata (Ashraf 2010), which blocks
the influx of CO2 into the leaves, thus, affecting photosynthetic
activity and biomass production.
In the face of environmental stresses, plants which
exhibit tolerance tend to minimize damage to their metabolism through the
regulation of enzymatic activity, showing an increase in the activity of these
enzymes that inactivate and/or transform ROS immediately after stress.
Oxidative stress can act as an important regulator of vegetative growth,
reproduction, defense, and survival of the plant (Morales and Munné-Bosch
2016).
In present study, the highest SOD activity was recorded
in the periods of higher water deficit (1st P0 and 2nd
P0). This behavior proves that an increase in enzymatic activity is a
protective response to oxidative stress that C. xanthocarpa presents in the face of increased levels of ROS.
This response is produced because of water deficit, since SOD efficiently
performs the removal of hydrogen peroxide (H2O2), which
generates the toxic superoxide radical (O2-) (Silva et al. 2012; Hura et al. 2015).
In addition to SOD, high POD activity was observed in
the leaves of seedlings under water deficit for the same periods of high water
deficit. This high POD activity is associated with an increase in the intracellular
level of H2O2 owing to removal of the superoxide radical
(Pereira et al. 2012; Taiz et al. 2017). The POD has high affinity
for H2O2 when at low concentrations (Gechev et al. 2006; Jaleel et al. 2009; Locato et al.
2010).
It should be emphasized that the increase in the
activity of these antioxidant enzymes was also found in the young plants of Jatropha curcas (Arcoverde et al. 2011; Silva et al. 2012), Copaifera
langsdorffii Desf. (Rosa et al. 2017) e Calophyllum
brasiliense Cambess. (Reis et
al. 2018), in which such behavior was related to the occurrence of a
favorable adjustment of the activity of antioxidant enzymes or new synthesis of
proteins (Jin et al. 2009) as a form
of defense and tolerance of plants against stress.
Hydrogen peroxide is a species of ROS that may play two
important roles in plants. In low concentrations, H2O2 acts
as a molecular sign involving signaling acclimatization, triggering tolerance
to various biotic and abiotic stresses. At high concentrations, it causes the
programmed death of the cell (Scandalios 2005; Bhattacharjee 2012; Taiz et al. 2017). Thus, the log of the SOD
and POD activity in the seedlings of C.
xanthocarpa, outside the periods of water restriction, is likely related to
the presence of O2- and H2O2 formed
according to the stressful environmental conditions recorded in the previous
periods, at levels harmful to the plants.
The activity of SOD and POD enzymes was inferior in the
roots of the plants to the leaves. This is because the enzymatic activity may
vary in the different organs of the plants dependent on the diversified sites
of activity of each enzyme (Gechev et al.
2006; Jaleel et al. 2009; Maia et al. 2012). Furthermore, the
production of H2O2 in peroxisomes and leaf chloroplasts
during environmental stresses may be 30–100 times faster than in mitochondria
(Foyer and Noctor 2003; Bhattacharjee 2012). The greater activity of enzymes in
the leaves than in the roots before the water deficit indicates that the
signaling for defense against this stress in C. xanthocarpa is exercised first in the leaves and then translated
into other parts of the plant.
The observation of the antioxidant activity of SOD and
POD in the roots of the stressed seedlings in the 1st REC period is
related to the reduction of the relative humidity of the air recorded during
this period (data not presented). It is known that some enzymes are
constitutively expressed while others are induced by environmental stresses, as
shown in studies of low stress activities which result in less severe symptoms
and high stress activities that result in more severe symptoms (Barbosa et al. 2014). Thus, the environmental
conditions recorded for the 1st REC period induced a continuity of
protection from oxidative damage provided by the enzymes on the seedlings, in
the face of the production of new toxic molecules.
The water deficit promoted morpho-anatomical
alterations, reflected in the reduction of ostiolar aperture in the polar and
equatorial diameters. Such modifications (density, index, aperture, size, and
diameters) are related to the regulation of gas exchanges under stressful
situations (Castro et al. 2005, 2009;
Souza et al. 2010). During such
situations, leaves that have smaller stomata and are under water deficit
conditions have greater capacity for efficiency in water use due to smaller
stomatal pore size, thus, conditioning a lower loss of water due to
transpiration (Boeger and Wisniewski 2003). In case of C. xanthocarpa, the reduction in the size of the stomata was
another strategy adopted by the plant to avoid water loss in the face of
stress. This may indicate that the decrease observed for ostiolum opening had a
greater effect on the diffusion of water than of CO2, thereby
maintaining the influx of CO2 and lower loss of water by
transpiration (Taiz et al. 2017).
The alterations evidenced in stomata size, index, and
functionality, along with other modifications in the leaf structures, indicate
that C. xanthocarpa can be subjected
to severe water restriction situations. However, some of these alterations
occur on a structural and irreversible level and therefore require time (Casson
and Gray 2008), as evidenced from the 1st REC by the increase of the
stomatal index.
In present study, the increased functionality of the
stomata observed for the stressed plants demonstrate that the stomata acquired
a more elliptical morphology in relation to the plants maintained under
irrigation, which favored the low water loss (Melo et al. 2014).
This emphasize that these alterations may serve as an
indicator of plant tolerance response to their hydric state and can prove the
adaptive value of the plant in investing in the protection of chlorophyllous
tissues and reduce transpiration. It is interesting to note that the assessed
values of some anatomical characteristics of the stressed plants were not
restored to the values of the control until the end of the experiment. These
results indicate that the initial priority of the species is the maintenance of
turgescence, even if reduced, as a way of maintaining metabolism, and that,
perhaps with a longer period of evaluation, the plants can increase metabolism
or completely recover the evaluated parameters. Similar behavior was observed
in other species (Arcoverde et al. 2011; Melo et al. 2014; Bento et
al. 2016; Reis et al. 2018).
C. xanthocarpa
showed morpho-anatomical and metabolic changes which
favored minimizing water loss. This behavior can justify the occurrence of this
species in environments with low water availability, proving our hypothesis
that the species has plasticity to adjust to temporary water deficit.
Conclusion
The C. xanthocarpa is a
native species sensitive to water deficit but presents strategies to adapt to a
temporary water restrictive environment. The seedlings of C. xanthocarpa
showed leaf morphoanatomical alterations as survival strategies to temporary
water deficit. The species showed an active antioxidant system with increased
activity of the enzymes superoxide dismutase and peroxidase in both the shoots
and roots, allowing the recovery of seedlings after resumption of irrigation. This
information is important because it can assist viverists or farmers, minimizing
the mortality rates of seedlings and consequently the costs of production. It
will also favor the success of management practices in projects of the recovery
of degraded areas.
Acknowledgements
We
acknowledge the CNPq (Conselho Nacional de Desenvolvimento Científico e
Tecnológico) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
(CAPES) for the financial support and scholar ship.
Author Contributions
Larissa FB Araújo,
Ferenanda S Junglos and Mário S Junglos collected data, Larissa FB Araújo and
Daiane M Dresch conducted statistical analysis, Fernanda S Junglos e Rosilda
Mara Mussury conducted leaf anatomy, Silvana de Paula Quintão Scalon supervised
the experimental work and all authors wrote the article.
References
Ashraf M (2010). Inducing drought
tolerance in plants: Some recent advances. Biotechnol Adv 28:169‒183
Barbosa MR, MM Araújo, SL Willadino, C Ulisses,
TR Camara (2014). Plant generation and enzymatic detoxification of reactive oxygen
species. Cienc Rur 44:453‒460
Batista LA, RJ Guimarães, FJ Pereira, GR
Carvalho, EM Castro (2010). Leaf anatomy and water potential in the coffee cultivars tolerance
to water stress. Rev Cienc Agron
41:475‒481
Beauchamp C, I Fridovich (1971). Superoxide dismutase: improved assays
and assay applicable to acrylamide gels. Anal
Biochem 44:276‒287
Bento LF, SPQ Scalon, DM
Dresch, ZV Pereira (2016). Potential
for recovery of Campomanesia xanthocarpa Mart. Ex
O. Berg seedlings from water deficit. Afr
J Agric Res 11:2775‒2785
Bhattacharjee S (2012). The language of reactive
oxygen species signaling in plants. J
Bot 2012; Article 985298
Boeger MRT, C Wisniewski (2003). Comparison of leaf
morphology of tree species from three distinct successional stages of tropical
rain forest (Atlantic Forest). Braz J Bot 26:61‒72
Bukatsch F (1972). Bemerkungen zur doppelfärbung
astrablau-safranin. Mikrokoscos 61:255
Carvalho PER (2006). Espécies Arbóreas Brasileiras, p:627, DF: Embrapa Informação Tecnológica: Colombo, PR:
Embrapa Florestas, Brasília
Casson S, JE Gray (2008). Influence of environmental
factors on stomatal development. New Phytol 178:9‒23
Castro EM, FJ Pereira, R Paiva (2009). Histologia Vegetal: Estrutura e Função dos
órgãos Vegetativos, UFLA, Lavras, Brazil
Castro EM, JEBP Pinto, HC Melo, AM Soares, AA
Alvarenga, ECL Júnior (2005). Anatomical and
physiological aspects of guaco plants submitted to different photoperiods. Hortic Bras 23:846‒850
Foyer CH, G Noctor (2003). Redox sensing and signaling associated with reactive
oxygen in chloroplasts, peroxisomes and mitochondria. Physiol Plantarum
119:355‒364
Gechev TS, FV Breusegem, JM Stone, I Denev, C Laloi (2006). Reactive oxygen species as signals that modulate
plant stress responses and programmed cell death. BioEssays 28:1091‒1101
Giannopolitis CN, SK Ries (1977). Superoxide dismutases: I- occurence in higher plants.
Physiol Plantarum 59:309‒314
Gupta DK, JM Palma, FJ Corpas (2018). Antioxidants and Antioxidant Enzymes in Higher
Plants. Springer USA
Hura T, K Hura, A
Ostrowska, K Dziurka (2015). Rapid plant rehydration initiates permanent and
adverse changes in the photosynthetic apparatus of triticale. Plant Soil 397:127‒145
Jaleel CA, P Manivannan, A Wahid, M Farooq, J
Al-Jaburih, R Somasundaram, R Panneerselvam (2009). Drought stress in plants: A
review on morphological characteristics and pigments composition. Intl J Agric Biol 11:100‒105
Jin X, Y Huang, F Zeng, M Zhou, G Zhang (2009). Genotypic difference in response of
peroxidase and superoxide dismutase isozymes and activities to salt stress in barley.
Acta Physiol Plantarum 31:1103‒1109
Kramer PJ, JS Boyer (1995). Evolution and agriculture.
In: Water Relations of Plants and Soils,
pp:377‒404. Academic Press San Diego, USA
Locato V, MC Pinto, A Paradiso, LD Gara (2010). Reactive oxygen species and ascorbate-glutathione
interplay in signaling and stress responses. In: Reactive Oxygen Species and Antioxidants in Higher Plants, pp:45‒64. Science Publisher, Enfield, New
Hampshire, USA
Longo OTD, CA Gonzáles, GM Pastori, VS Trippi (1993). Antioxidant defenses under hyperoxygenic
and hyperosmotic conditions in leaves of two lines of maize with differential
sensitivity to drought. Plant Cell
Physiol 34:1023‒1028
Luz IJ, RA Krupek (2014). Reproductive phenology, fruit and
seed biometry of Campomanesia xanthocarpa
O. Berg. (Myrtaceae).
Estud Biol 36:115‒124
Macedo
GA, Pastore GM, Sato HH, Park YK (2005) Bioquímica experimental dos
alimentos, p:187. Livraria Varela, São Paulo, Brazil
Maia JM, SLF Silva, EL Voigt, CEC Macedo, LFA
Ponte, JAG Silveira (2012). Activities of antioxidant
enzymes and root growth inhibition in cowpea seedlings exposed to different
salt levels. Acta Bot Bras 26:342‒349
Martins MORJ, MC Nogueira, ADA Neto, MG Santos (2010). Growth of the neem (Azadirachta indica A. Juss. - Meliaceae)
seedlings under water deficit. Rev
Árv 34:771‒779
Melo EF, CN Fernandes-Brum, FJ Pereira, EM
Castro, A Chalfun-Júnior (2014). Anatomic and physiological modifications in seedlings
of Coffea arabica cultivar siriema
under drought conditions. Cienc Agrotechnol
38:25‒33
Morales M, S Munné-Bosch (2016). Oxidative stress: A master regulator of plant
trade-offs? Trends Plant
Sci 21:996‒999
Nogueira RJMC, MB Albuquerque, EC Silva (2005).
Aspectos ecofisiológicos da tolerância à seca em plantas da caatinga. In: Estresses Ambientais: Danos e Benefícios em Plantas,
pp:22‒31. UFRPE, Imprensa
Universitária, Recife, Brazil
Oliveira NK, EMD Castro, RJ Guimarães, LM Pieve,
DP Baliza, JL Machado, T Freitas (2014). Foliar anatomy of coffee plants
implanted using hydro retainer polymers. Coffee Sci 9:258‒265
Pereira JWL, PAM Filho, MB Albuquerque, RJMC
Nogueira, RC Santos (2012).
Biochemical changes in peanut
genotypes submitted to moderate water stress. Ver Cienc Agron 43:766‒773
Pimentel C (2004). A Relação da Planta Com a Água. Seropédica: Edur, 2004.191p:il, Rio de Janeiro, Brazil
Reis LC, AC Foresti, SPQ Scalon, DM Dresch, ZV Pereira (2018). Effect of water deficit and
abscisic acid on photosynthetic and antioxidant metabolism in seedlings of Calophyllum brasiliense (Cambess.).
Cerne 24:387‒396
Rosa DBCJ, SPQ Scalon, T Cremon, F Ceccon, DM Dresch (2017). Gas Exchange and antioxidant activity in seedlings of
Copaifera langsdorffii Desf. under different water conditions. Ann Braz Acad Sci 89:3039‒3050
Salisbury EJ (1928). On the Causes and Ecological
Significance of Stomatal Frequency, with Special Reference to the Woodland. Phil Trans Roy Soc Lond
Ser B 216:1‒65
Scandalios JG (2005). Oxidative stress: Molecular perception and
transduction of signals triggering antioxidant gene defenses. Braz J Med Biol Res 38:995‒1014
Silva EN, RV Ribeiro, SLF Silva, SAVieira, LFA
Ponte, JAG Silveira (2012).
Coordinate changes in photosynthesis, sugar accumulation and antioxidative
enzymes improve the performance of Jatropha
curcas plants under drought stress. Biomass Bioener 45:270‒279
Souza TC, PC Magalhães, FJ Pereira, EM Castro,
JMS Junior, SN Parentoni (2010).
Leaf plasticity in successive selection cycles of ‘Saracura’
maize in response to periodoc soil flooding. Pesq Agropec Bras 45:16‒24
Taiz L, E Zeiger, IM Møller, A Murphy (2017). Fisiologia e Desenvolvimento Vegetal, 6th
edn, p:858. Artmed, Porto Alegre, Brazil
Wang W, MX Xia, J Chen, R Yuan, FN Deng, FF Shen (2016). Gene expression characteristics and regulation mechanisms of
superoxide dismutase and its physiological roles in plants under stress.
Biochemistry 81:465–480