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Gas exchanges and water use efficiency in the selection of tomato genotypes tolerant to water stress


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Water stress can affect the yield in tomato crops and, despite this, there are few types of research aiming to select tomato genotypes resistant to the water stress using physiological parameters. This experiment aimed to study the variables that are related to the gas exchanges and the efficiency in water use, in the selection of tomato genotypes tolerant to water stress. It was done in a greenhouse, measuring 7 x 21 m, in a randomized complete block design, with four replications (blocks), being five genotypes in the F2BC1 generation, which were previously obtained from an interspecific cross between Solanum pennellii versus S. lycopersicum and three check treatments, two susceptible [UFU-22 (pre-commercial line) and cultivar Santa Clara] and one resistant (S. pennellii). At the beginning of flowering, the plants were submitted to a water stress condition, through irrigation suspension. After that CO2 assimilation, internal CO2, stomatal conductance, transpiration, leaf temperature, instantaneous water use efficiency, intrinsic efficiency of water use, instantaneous carboxylation efficiency, chlorophyll a and b, and the potential leaf water (Ψf) were observed. Almost all variables that were analyzed, except CO2 assimilation and instantaneous carboxylation efficiency, demonstrated the superiority of the wild accession, S. pennellii, concerning the susceptible check treatments. The high photosynthetic rate and the low stomatal conductance and transpiration, presented by the UFU22/ F2BC1#2 population, allowed a better water use efficiency. Because of that, these physiological characteristics are promising in the selection of tomato genotypes tolerant to water stress.
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Genetics and Molecular Research 16 (2): gmr16029685
Gas exchanges and water use efciency in the
selection of tomato genotypes tolerant to water
M.E.A. Borba, G.M. Maciel, E.F. Fraga Júnior, C.S. Machado Júnior,
G.R. Marquez, I.G. Silva and R.S. Almeida
Instituto de Ciências Agrárias, Universidade Federal de Uberlândia,
Campus Monte Carmelo, Uberlândia, MG, Brasil
Corresponding author: G.R. Marquez
Genet. Mol. Res. 16 (2): gmr16029685
Received March 24, 2017
Accepted May 5, 2017
Published June 20, 2017
Copyright © 2017 The Authors. This is an open-access article distributed under the terms of
the Creative Commons Attribution ShareAlike (CC BY-SA) 4.0 License.
ABSTRACT. Water stress can affect the yield in tomato crops and,
despite this, there are few types of research aiming to select tomato
genotypes resistant to the water stress using physiological parameters.
This experiment aimed to study the variables that are related to the
gas exchanges and the efciency in water use, in the selection of
tomato genotypes tolerant to water stress. It was done in a greenhouse,
measuring 7 x 21 m, in a randomized complete block design, with four
replications (blocks), being ve genotypes in the F2BC1 generation,
which were previously obtained from an interspecic cross between
Solanum pennellii versus S. lycopersicum and three check treatments,
two susceptible [UFU-22 (pre-commercial line) and cultivar Santa
Clara] and one resistant (S. pennellii). At the beginning of owering,
the plants were submitted to a water stress condition, through irrigation
suspension. After that CO2 assimilation, internal CO2, stomatal
conductance, transpiration, leaf temperature, instantaneous water use
efciency, intrinsic efciency of water use, instantaneous carboxylation
M.E.A. Borba et al.
Genetics and Molecular Research 16 (2): gmr16029685
efciency, chlorophyll a and b, and the potential leaf water (Ψf)
were observed. Almost all variables that were analyzed, except CO2
assimilation and instantaneous carboxylation efciency, demonstrated
the superiority of the wild accession, S. pennellii, concerning the
susceptible check treatments. The high photosynthetic rate and the
low stomatal conductance and transpiration, presented by the UFU22/
F2BC1#2 population, allowed a better water use efciency. Because of
that, these physiological characteristics are promising in the selection
of tomato genotypes tolerant to water stress.
Key words: Abiotic stress; Drought tolerance; Tomato; Wild accession
The tomato cropping has an economical and social relevance in Brazil and all over the
world. The South American country is among the top 10 tomato producers (AGRIANUAL,
2016), evidencing the relevance of the crop. The tomato [Solanum lycopersicum (L.)] adapts to
different climatic conditions (Neves et al., 2013), and despite this, the abiotic stress occurrence,
like water stress, is one of the biggest problems that the crop presents (Morales et al., 2015b).
Predominantly, in the arid and semi-arid regions, the conicts for the water use are
a limiting factor. However, it is also observed in regions that have abundant water resources
but are incapable to supply the high demand (Telles and Costa, 2010). Beyond that, crops
that require a large irrigation system present elevated energy costs. In this sense, developing
genotypes that are tolerant to water stress has become a low-cost and more efcient strategy
in regions with water decit (Girotto et al., 2012).
The process of tomato domestication caused a shortage of genotypes that are tolerant
to water stress (Alvarenga, 2013). However, there are wild species that have a better water use
efciency than the commercial cultivars. The wild accession LA-716 (S. pennellii) is one of
them and, although it does not present good agronomic characteristics, the wild species uses
water more efciently than the cultivated plants (Rocha et al., 2016). With the plant breeding,
it is possible the rescue of important agronomic characteristics, through an interspecic cross
followed by backcrossings with a background of interest (Maciel et al., 2011).
Direct methods, used for selection genotypes tolerant to water stress, are expensive and
demand more time, which makes the indirect methods more viable. Many types of research have
proven the efciency of genotype selection from different techniques, like visual symptoms,
soil water balance, the ow of sap, and gas exchange analyses (Aksic et al., 2011; Celebi, 2014;
Begun et al., 2012; Rocha et al., 2016). However, the use of these techniques is scarce.
Because of that, this experiment aimed to study the variables related to gas exchange
and the water use efciency in the selection of tomato genotypes tolerant to water stress.
The experiment was conducted at the Experimental Horticulture Station
(18°42.0'43.19''S and 47°29.0'55.8''W, 873 m above sea level) and at the Genetic Resources
Laboratory of the Federal University of Uberlândia - UFU, Monte Carmelo Campus, in the
period of May 2013 to August 2016.
Tomato genotypes tolerant to water stress
Genetics and Molecular Research 16 (2): gmr16029685
The genetic material utilized was originally from the germplasm bank of UFU. The
segregating populations evaluated were, previously, obtained from an interspecic cross
between UFU-222 (S. lycopersicum) versus wild accession LA-716 (S. pennellii). UFU-222 is
a pre-commercial line that has small fruits (>18 g), 9° Brix and is susceptible to water stress.
The wild genotype also presents small fruits (15 g) but is tolerant to water decit (Morales et
al., 2015b; Rocha et al., 2016).
To select genotypes tolerant to water stress, ve F2BC1 populations, originated from
self-fertilization of the rst backcrossing, were utilized: UFU22/F2BC1#8, UFU22/F2BC1#9,
UFU47/F2BC1#11, UFU22/F2BC1#2, UFU22/F2BC1# and three check treatments, being two
susceptible (cv. Santa Clara and UFU-222) and one resistant (S. pennellii).
The genotypes were sown on May 5, 2016, in polystyrene trays of 200 cells, lled
with commercial coconut ber substrate. Thirty-ve days after sowing, the plants were
transplanted into pots (5-L volume), containing the same substrate that was used for seedling’s
production. The tomato plants were cultivated in a bow-type greenhouse, measuring 7 x 21 m
and ceiling 4 m, covered with transparent polyethylene lm of 150 microns, protected against
ultraviolet rays, and curtain side of white and anti-aphid scream. The cultural dealings were
made according to the tomato crop recommendations (Alvarenga, 2013). The experiment was
set up in a randomized complete block design, with three replications (blocks), totalizing 24
plots (8 genotypes x 3 blocks). Each plot consisted of one plant.
The climatic conditions, in the greenhouse, were monitored with the aid of an
automatic weather station. The ux density (W/m-2) of the global solar radiation was estimated
through the equipment Silicon Photodiode Pyranometer (NRLITE - Campbell Sci.), and the
temperature (°C) and relative humidity (%) were estimated using the Vaisala Sensor (HMP45C
- Campbell Sci.). The equipment was installed in the center of the greenhouse and above the
plants, and it was connected to a data acquisition system (Datalogger CR1000 - Campbell
Sci.). The data were stored every 15 min.
Tensiometers were installed in each plot, 20 days before the evaluation (98 days after
sowing, DAS), to evaluate the water tension on the substrate. The irrigation was done in a
controlled manner, keeping the substrate humidity in great conditions (-10 kPa). On the beginning
of the owering (116 DAS), the tomato plants were submitted to a water stress condition, where
the water potential was putten closed to -30 kPa through irrigation suspension. The evaluations of
the gas exchange, chlorophyll index, and leaf water potential were made on August 31 (118 DAS).
The parameters of the gas exchange were checked using three leaets of the middle
third of each plant, during the morning (approaching 8 h), using the equipment InfraRed Gas
Analyzer (IRGA, model LCA-4, analytical development Co., Hoddesdon, England). The
parameters obtained were: CO2 assimilation (A), internal CO2 (Ci), stomatal conductance
(Gs), transpiration (E), and leaf temperature (T). The instantaneous water use efciency was
calculated from the ratio between CO2 assimilation and leaf transpiration (A/E), the intrinsic
efciency of water use was calculated from the ratio between CO2 assimilation and the stomatal
conductance (A/Gs), and the instantaneous carboxylation efciency was estimated from the
ratio between the CO2 assimilation and internal CO2 (A/Ci).
The chlorophyll (a and b) levels were estimated through two leaets of each plant
of the middle third, using a chlorophyll meter (CFL-1030, Falker). The equipment estimates
the concentration of photosynthetic pigments with high precision, without needing chemical
reagents that are commonly used for this and saving time (Rigon et al., 2012). The values were
summed, and the mean of each plot was obtained.
M.E.A. Borba et al.
Genetics and Molecular Research 16 (2): gmr16029685
The potential leaf water (Ψf) was measured before sunrise (±5:00 am), with the aid
of a pressure chamber, type Scholander (Soil Moisture Model 3000), and ve leaets of the
middle third of each plant were used for it. The values were also summed and the mean of each
plot obtained. The statistical analyses were done with the aid of the GENES computational
program (Cruz, 2013).
The water availability of the substrate was not restrictive for the water demand of the
plants (-10 kPa), until the decit beginning. After 2 days of the water decit imposition, during
the physiologic evaluations, the substrate was submitted to a moderate matricidal potential
(below -25 kPa) (Figure 1). Guida et al. (2017), when submitting tomato plants to a water
stress, observed that the soil matricidal potential below -28 kPa promotes a reduction in the
stomatal conductance, affecting the crop yield.
Figure 1. Water matricidal potential (kPa) of the substrate from August 18, 2016 to August 31, 2016.
Analyzing the climatic conditions in the greenhouse, it was found that the average
temperature was 23.4°C, which is close to the ideal temperature (18°-24°C), for the tomato
crop, according to Duarte et al. (2011). The mean relative humidity of the period was 60.3%,
presenting a variation of 33.5-86.4%. The average of the global solar radiation and vapor
pressure decit were, respectively, 167 W/m2 and 1.38 kPa (Figure 2).
Figure 2. Temperature (°C), relative humidity (RH, %), global solar radiation (Qg, W/m2), and vapor pressure
decit (kPa), monitored on August 31, 2016.
Tomato genotypes tolerant to water stress
Genetics and Molecular Research 16 (2): gmr16029685
Analyzing the leaf temperature, it was found that the cv. Santa Clara showed a
temperature 20% higher than the wild accession (S. pennellii). The genotypes of the UFU22/
F2BC1#9 and UFU47/F2BC1#11 populations and the pre-commercial line UFU-222 showed a
similar behavior to the cv. Santa Clara, while the genotypes of the UFU22/F2BC1#8 population
were similar to the wild accession (Table 1).
Table 1. Averages of leaf temperature (T leaf) (°C), stomatal conductance (Gs) (molm-2s-1), transpiration
(E) (mmolm-2s-1), internal CO2 (Ci) (mmolm-2s-1), CO2 assimilation (A) (µmolm-2s-1), instantaneous water
use efciency (A/E) (mmol CO2/mol H2O), intrinsic efciency of water use (A/Gs) (mmolm-2s-1 H2O), and
instantaneous carboxylation efciency (A/Ci), in tomato genotypes, F2BC1, submitted to a water stress.
*Means followed by the same letter in the column do not differ, signicantly, from each other by the Tukey test (P < 0.05).
T leaf
cv. Santa Clara
Solanum pennellii
Overall average
Morales et al. (2015a) afrmed that the variations in the leaf temperature could be used
to estimate the water stress of plants. The reduction of water soil availability causes an increase
in the leaf temperature, due to a reduction in the transpiration that is the main mechanism
responsible for the plant cooling (Morales et al., 2015a), even though this relation was not
observed in the present experiment probably due to a disturbance in the plant physiology.
One of the rst reactions that plants show in response to water stress is the stomatal
closure (Wang et al., 2012). The pre-commercial line UFU-222 presented the higher stomatal
conductance (Gs) and did not differ, signicantly, from the cv. Santa Clara. On the other
hand, the wild accession, S. pennellii, showed Gs lower (54%) than the cv. Santa Clara.
The genotypes of the UFU22/F2BC1#8, UFU22/F2BC1#2, and UFU22/F2BC1#3 populations
presented Gs similar or higher than the wild species.
The reduction in the stomatal conductance, due to a stomatal closure, reduces the waste
of water by transpiration. Even though this strategy affects the photosynthetic rate because it
complicates the CO2 diffusion, which is extremely vital for the process of photosynthesis.
Therefore, an effective regulation of the stomatal opening is primordial for the plant’s
development under water stress conditions (Santos et al., 2013).
The mean transpiration (E) observed was 1.36 mmolm-2s-1, and the highest were
observed in the genotypes Santa Clara, UFU22/F2BC1#8, and UFU-222. The genotypes of
the UFU22/F2BC1#2 and UFU47/F2BC1#11populations presented the lowest transpiration
rate, and the last one did not differ, signicantly, from the genotypes of the UFU22/F2BC1#3
population and the wild accession S. pennellii.
The lowest transpiration rate of the wild accession, S. pennellii, makes it capable of
tolerating the water stress. Because of this, the wild genotype can develop in arid regions
(Easlon and Richards, 2009), being, therefore, a promising material for the tomato breeding
that aims to nd genotypes tolerant to water stress. Low transpiration (E) might be associated
with nonstomatal factors, as variations on the leaf cuticle allow the water loss by transpiration.
M.E.A. Borba et al.
Genetics and Molecular Research 16 (2): gmr16029685
The increase in thickness and mesophyll’s density are described as adaptive responses to water
stress (Poorter et al., 2009).
Evaluating the internal CO2, it was found that the genotypes of UFU22/F2BC1#8,
UFU22/F2BC1#9, and UFU22/F2BC1#3 populations did not differ from each other and had
similar behavior to the wild accession S. pennellii, presenting an average higher than the
overall of the experiment. A signicant difference was found between the wild genotype and
cv. Santa Clara, even though the genotypes UFU22/F2BC1#2 and UFU-222 did not differ from
cv. Santa Clara being all in the worst group.
High values of internal CO2 indicate that the genotype can provide more CO2 for the
ribulose-1,5-bisphosphate carboxylase-oxygenase (rubisco). However, this did not happen in
the present study, probably due to a decrease in the activity of enzymes involved in the CO2
xation process (Table 1).
Analyzing the CO2 assimilation (A) of the genotypes, it was found that the cv. Santa
Clara was 24% higher than the wild accession S. pennellii. However, both check treatments
were better than the rest of the genotypes. Furthermore, the other check treatment UFU-222 was
also better than the rest of the genotypes and showed a similar behavior to both susceptible and
resistant checks. Besides this, the genotype UFU22/F2BC1#9 highlighted showing a similar
behavior to the wild accession (Table 1).
The mean value of CO2 assimilation that was observed in the present experiment is
lower (4.11 µmolm-2s-1) than the results in other experiments under excellent water conditions
(15.6 µmolm-2s-1) (Galmés et al., 2012). However, it is similar to results found by Morales
et al. (2015b), when the photosynthesis decreased from 8.61 to 4.18 µmolm-2s-1, when the
water stress was submitted. A low CO2 assimilation proves that the water stress might affect
physiological and biochemical processes of the vegetables, such photosynthesis (Farooq et al.,
2009; Jaleel et al., 2009).
A higher instantaneous water use efciency, observed in the wild genotype (S.
pennellii), about the other treatments, is related to its low transpiration (E). Among the
evaluated genotypes, UFU22/F2BC1#2 highlighted, being the one that most resembled the
wild accession. On the other hand, S. pennellii was 2.2 more efcient in water use than the cv.
Santa Clara, which is possible the main result, proving its resistance to water stress. Similar
results were found by Machado et al. (2010), correlating the amount of transpiration water
with the dry matter production.
Analyzing the intrinsic efciency of water use, it was found that the overall average
was 59.82 mmolm-2s-1 and this high value was found in the UFU22/F2BC1#2 genotype
followed by the wild accession S. pennellii. On the other hand, the lowest intrinsic efciency
of water use was found in the UFU22/F2BC1#8 and UFU47/F2BC1#11genotypes. It was
also found that the wild accession was 64% more efcient than the cv. Santa Clara. High
photosynthetic rate associated with low stomatal conductance (Gs) are characteristics nd in
plants with tolerance to water stress, which also has a higher intrinsic efciency of water use
(Pazzagli et al., 2016). In environments with limited water resources, the positive magnitude
of these parameters becomes essential for the adequate functioning of plants and also for
demonstrating the physiological plasticity of the species to abiotic factors (Funk and Vitousek,
2007; Li et al., 2008; Silva et al., 2008).
Evaluating the instantaneous carboxylation efciency, the check treatment cv. Santa
Clara highlighted presenting the high value, i.e., 72% higher than the wild accession S. pennellii.
On the other hand, the lowest instantaneous carboxylation efciency was observed for the
Tomato genotypes tolerant to water stress
Genetics and Molecular Research 16 (2): gmr16029685
UFU22/F2BC1#8 and UFU47/F2BC1#11 genotypes. According Silva et al. (2015), the relation
between internal CO2 (Ci) and CO2 assimilation (A), which is the instantaneous carboxylation
efciency, is a characteristic that makes possible to estimate non-stomatal factors that could be
affecting the photosynthetic process and, consequently, the biological yield.
The potential leaf water (Ψf) indicates the energy status of plants, where values
closely to zero indicate that the plant is not under water stress. However, high negative values
indicate an intense water stress (Morando et al., 2014). The mean value of leaf water potential,
observed in the experiment, was -0.635 mPa (Table 2). The lowest value was found in the cv.
Santa Clara, being 7.7 times smaller than the wild accession S. pennellii, which makes the
commercial genotype to be considered susceptible to water stress. The genotypes UFU22/
F2BC1#8, UFU22/F2BC1#9, UFU47/F2BC1#11, UFU22/F2BC1#2, and UFU-222 were the ones
that most approached to the S. pennellii, for the potential leaf water, even though they were
four times inferior compared to the wild genotype.
Table 2. Potential leaf water (Ψf, mPa), chlorophyll a, chlorophyll b, and total chlorophyll in tomato genotypes
F2BC1 submitted to water stress.
*Means followed by the same letter in the column do not differ, signicantly, from each other by the Tukey test (P < 0.05).
Ψf (mPa)
Chlorophyll a
Chlorophyll b
Total chlorophyll
cv. Santa Clara
Solanum pennellii
A relation between transpiration and the stomatal opening is related by Firmano et
al. (2009), where the higher is the stomatal conductance, stronger is the transpiration. Under
moderate stress conditions, plants remain with the stomata closed, to maintain greater water
potential and ideal turgor pressure, which is an important indication of tolerance to water
stress (Lawlor and Tezara, 2009).
During the experiment, the average chlorophyll a content was 37.53 mg/L, with a
coefcient of variation relatively low (4.29%) (Table 2). The genotypes UFU22/F2BC1#8,
UFU22/F2BC1#9, UFU47/F2BC1#11, and UFU22/F2BC1#2 highlighted presenting the highest
values and not differing, signicantly, from the wild check treatment, S. pennellii. The
lowest chlorophyll a content was observed in the plants of the pre-commercial line, UFU-
222. According to Rego and Possamai (2011), the chlorophyll content, in a plant, varies in
function of climatic conditions and an increase in this pigment reects in an increase in the
photosynthetic rate.
Almost all the genotypes that were evaluated showed a similar behavior related to the
specic chlorophyll b content. The lowest value was found in the genotype UFU-222, which
did not differ, signicantly, from the cv. Santa Clara. Furthermore, the genotypes UFU22/
F2BC1#8, UFU22/F2BC1#9, UFU47/F2BC1#11, UFU22/F2BC1#2, and UFU22/F2BC1#3 did
not differ, signicantly, from the check treatments cv. Santa Clara and S. pennellii (Table 2).
Analyzing the total chlorophyll, it was found an overall average of 51.24 mg/L. The
lowest content was observed in the pre-commercial line UFU-222, which differed signicantly
M.E.A. Borba et al.
Genetics and Molecular Research 16 (2): gmr16029685
from all the genotypes that were evaluated. On the other hand, the highest values were found
in the genotypes S. pennellii, UFU22/F2BC1#9, and UFU47/F2BC1#11. Besides that, these
three genotypes did not differ, signicantly, from the genotypes UFU22/F2BC1#8, UFU22/
F2BC1#2, and UFU22/F2BC1#3 (Table 2).
Low chlorophyll content might be associated with climatic conditions, mainly
related to high leaf temperature. Plants with a C3 metabolism, like tomato, have a better
photosynthetic behavior under temperatures between 20° and 25°C. When submitted to a water
stress conditions, the plants may present, in addition to stomatal closure, alterations in the
chlorophyll synthesis, functional and structural alterations in chloroplasts, and disturbances in
the processes of accumulation, transport, and distribution of assimilates.
All the variables analyzed, except CO2 assimilation and instantaneous carboxylation
efciency, evidenced a superiority of the wild accession S. pennellii, regarding the susceptible
check treatments.
The high photosynthetic rate, low stomatal conductance, and transpiration are
promising physiological characteristics that could be used in the selection of tomato genotypes
tolerant to water stress.
Conicts of interest
The authors declare no conicts of interest.
The authors would like to thank the Federal University of Uberlândia, CNPq, and
FAPEMIG for the nancial support of this research project.
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... Net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration (E), internal leaf CO 2 (ICO 2 ), vapor pressure deficit (VPD) and internal leaf temperature (LT) were evaluated using a portable photosynthesis system (LI-COR, LI-6400XT, NE, USA) in the morning (08:00-11:00) under a fixed blue-red light-emitting diode (LED) light source. Later, the water use efficiency (WUE) was obtained through the ratioof Pn/E, and the carboxylation efficiency index (CEI) using the ratio Pn/ICO 2 [25]. Three measurements were made for genotype on a fully expanded leaf, being the 4th or 5th leaf from apical meristem, at 120 days after planting (DAP). ...
... The least efficient genotype was a genotype from high altitude, 0516-503.CLD (1749 masl) with 0.0737. Efficiency in the carboxylation process may be associated with the ability of Rubisco to increase its affinity for CO 2 fixation with respect to intracellular O 2 and, thus, reduce photorespiration rates and increase Pn [25,46]. Consistently, the genotypes that presented the highest Pn reached the highest values for CEI also. ...
... This behavior is conditioned by the plant response, throughstomatal closure mechanism, which reduces dehydration [9,41,51,57]. In this way, it is evident that when the Gs was reduced, the diffusion of CO 2 was affected, also implying an effect on Pn [25]. ...
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Sweet potato is a crop with a wide capacity to adapt to adverse conditions. To study the tolerance of the sweet potato to a low-altitude environment, 34 genotypes comprising three groups from different altitude conditions ranging from 18-599, 924-1298, 1401-2555 meters above sea level were evaluated. These genotypes were evaluated through ecophysiological parameters: net photosintetic rate (Pn), stomatal conductance (G S), transpiration (E), leaf internal CO 2 (ICO 2), vapor pressure deficit (VPD) and leaf internal temperate (LT). sSubsequently, water use efficiency (WUE) and carboxylation efficiency index (CEI) were estimated. Simultaneously, morpho-agronomic characterization of the genotypes was conducted including descriptors and morpho-colorimetric parameters. A wide ecophysiological variability was found among genotypes from high, intermediate and low altitudes, when those were evaluated under low altitude conditions. The genotypes that presented major soil coverage efficiency and leaf size showed greater Pn, WUE and CEI, and Low VPD and E, aspects that benefited the ability to form roots the under low-altitude environment. The altitudinal origin of the genotypes influenced the ecophysiological response under low altitude conditions. The capacity of certain sweet potato genotypes to tolerate low altitude conditions were due to to different mechanisms, such as certain morphoagronomic traits that allowed them to adjust their physiological processes, especially those related to photosynthesis.
... High Pn associated with low gs was observed in water stress tolerant plants which had higher iWUE (Pazzagli et al., 2016). Borba et al. (2017) reported high Pn and low gs and E, and better water use efficiency in F 2 BC1 population of Solanum pennellii x S. lycopersicum cross. Both A1-63/79 and Man-63/79 were better than their respective parents with respect to iWUE. ...
... The high Pn, low E and high iWUE make the inbred lines capable of tolerating water stress. High Pn, low gs and low E were found to be promising in selecting water stress tolerant tomato genotypes (Borba et al., 2017, Zeist et al., 2018. Selection for increased photosynthetic efficiency per se was mostly successful in maize (Crosbie et al., 1977). ...
Safflower (Carthamus tinctorius L.), a multipurpose oilseed crop is the only cultivated species in the Carthamus genus. Carthamus spp. have been explored for resistance to biotic and abiotic stresses but not for physiological efficiency. Photosynthetic traits of ten wild and ten cultivated species and six interspecific inbred lines were studied to understand the expression of the photosynthetic traits among them, and for trait introgression from wild species in interspecific derivatives. Relations among some physiological traits in interspecific inbred lines differed from those observed in wild and cultivated species. The high photosynthesis (Pn), low transpiration (E) and high intrinsic water use efficiency (iWUE) could be introgressed from the wild species, C. lanatus and C. turkesthanicus into safflower cultivars. Inheritance of photosynthetic traits from wild to cultivated species indicated that wild species are exploitable for safflower improvement. This study suggests the utilization of wild species for their high Pn, low E and iWUE characteristics for developing abiotic stress-tolerant safflower cultivars.
... These measures were gathered using the LI-6800 portable photosynthesis system from 8:00-11:00 am. Additional compound parameters were computed as follows, (8) iWUE: instantaneous water use efficiency was measured as the relation A/E, (9) inWUE: intrinsic efficiency of water use computed as the relation A/gs, and (10) iCE: instantaneous carboxylation efficiency was measured as the relation A/Ci [21]. Measurements were made on three plants per genotype on a fully expanded leaf from the upper third part of the plant. ...
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Heat and drought are major stresses that significantly reduce seed yield of the common bean (Phaseolus vulgaris L.). In turn, this affects the profitability of the crop in climatic-vulnerable tropical arid regions, which happen to be the poorest and in most need of legume proteins. Therefore, it is imperative to broaden the sources of heat and drought resistance in the common bean by examining closely related species from warmer and drier environments (i.e., Tepary bean, P. acutifolius A. Gray), while harnessing such variation, typically polygenic, throughout advanced interspecific crossing schemes. As part of this study, interspecific congruity backcrosses for high temperature and drought tolerance conditions were characterized across four localities in coastal Colombia. Genotypes with high values of CO2 assimilation (>24 µmol CO2 m−2 s−1), promising yield scores (>19 g/plant), and high seed mineral content (Fe > 100 mg/kg) were identified at the warmest locality, Motilonia. At the driest locality, Caribia, one intercrossed genotype (i.e., 85) and the P. acutifolius G40001 control exhibited sufficient yield for commercial production (17.76 g/plant and 12.76 g/plant, respectively). Meanwhile, at southernmost Turipaná and Carmen de Bolívar localities, two clusters of genotypes exhibited high mean yield scores with 33.31 g/plant and 17.89 g/plant, respectively, and one genotype had an increased Fe content (109.7 mg/kg). Overall, a multi-environment AMMI analysis revealed that genotypes 13, 27, 82, and 84 were environmentally stable with higher yield scores compared to the Tepary control G40001. Ultimately, this study allows us to conclude that advanced common bean × Tepary bean interspecific congruity backcrosses are capable of pyramiding sufficient polygenic tolerance responses for the extreme weather conditions of coastal Colombia, which are likely to worsen due to climate change. Furthermore, some particular recombination events (i.e., genotype 68) show that there may be potential to couple breeding for heat and drought tolerance with Fe mineral biofortification, despite a prevalent trade-off, as a way to fight malnutrition of marginalized communities in tropical regions.
... The measurements obtained were thereafter adjusted for each leaf area measured. From the default measurements, photosynthetic water use efficiency (A/E) for each plant was calculated (Borba et al. 2017). Thereafter, all plant material was collected and separated into roots, stems and leaves and the fresh mass (g) and root length (cm) determined. ...
Calobota sericea is a native legume of South Africa, confined to the water-limited rangelands, and it has recently been prioritised for additional characterisation regarding its pasture potential. In this study, we examined the growth characteristics of C. sericea under glasshouse conditions where water limitation was implemented at different plant ages, and for different durations. Results indicate that preferential resource allocation to the roots, as well as reduced stomatal conductance and transpiration, were early responses to water limitation, irrespective of the age at which water limitation was imposed, or the duration of water limitation. Under water-limited conditions, increased production of protective pigments, such as carotenoids and anthocyanins, was also observed, which helped in recovery after rewatering. It was concluded that after rewatering, all negative impacts of water limitation on morphology and physiology of C. sericea plants were generally returned to well-watered levels. This suggests that C. sericea plants employ a wide range of phenotypic adjustments in response to water limitation, which makes the plants well adapted to areas with high rainfall variability.
... Stomatal conductance and leaf water potential are the indicators of plant water regime, but also can be used for selection of tomato-resistant genotypes to drought conditions [12]. Literature data confirm that drought stress induced stomatal closure and causes decrease of turgor and water potential in tomato plants [13,14]. ...
Conference Paper
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The reaction of leaf growth to drought stress is controlled by various hormones, among which ABA is one of the most important. The aim of this study was to examine the effects of ABA deficiency on tomato leaf response under severe drought stress. Therefore, ABA-mutant (flacca) and wild type (Ailsa Craig) were selected for research and in the stage of second flower truss anthesis plants were exposed to severe water deficit. The effects of severe drought on wild-type leaves and flacca mutant showed that, as a result of reduced ABA concentrations, flacca plants were exposed to a higher degree of stress than wild-type leaves, which had a negative impact on the examined physiological and biochemical parameters. Severe drought caused stomatal closure, decreased water potential, specific leaf area, and chlorophyll concentrations in the leaves in both genotypes, but this was more pronounced in the mutant. Wild-type plants have accumulated more vitamin C and ABA and have a higher total antioxidant capacity in the leaves in dry conditions than flacca mutants, which contribute to their better adaptive response to stress. Based on this, it can be assumed that the ABA mutation has led to a decrease in the capacity for oxidative stress products caused by severe drought stress.
... Diante disso, aprimorar novas metodologias de seleção no melhoramento genético do tomateiro para tolerância à seca é de fundamental importância. Há relatos de métodos eficientes de seleção direta (Nahar & Ullah, 2006;Shamim et al., 2014;Rocha et al., 2016;Borba et al., 2017) e indireta em tomateiro (Aazami et al., 2010;Morales et al., 2015) visando avaliar a tolerância ao déficit hídrico, no entanto, tais procedimentos demandam maior período de tempo, custos elevados e exigem mais mão de obra para execução. ...
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A seleção de genótipos tolerantes ao déficit hídrico pode beneficiar a cultura do tomateiro favorecendo maiores produtividades. O objetivo do trabalho foi avaliar a potencialidade de solução osmótica de manitol como simulador de deficiência hídrica para seleção de genótipos de tomateiro. Adotou-se o delineamento inteiramente casualizado (DIC) com quatro repetições. Avaliou-se a melhor concentração de manitol capaz de identificar dois genótipos contrastantes (acesso selvagem LA-716, pertencente a espécie Solanum pennelliie cv. Santa Clara) tolerante e suscetível ao estresse hídrico, respectivamente. O potencial osmótico de -0,3 MPa obtido a partir da utilização de 22,29 g L-1 de manitol apresentou maior eficiência para seleção de genótipos do tomateiro. Esta concentração foi utilizada para seleção em sete genótipos segregantes F2RC1, provenientes de cruzamento interespecífico (S. pennellii versus S. lycopersicum) comparando com a testemunha resistente, acesso selvagem LA-716 e suscetível, cv. Santa Clara. O genótipo UFU80 - F2RC1#1 se destacou entre os demais, sendo superior em relação à testemunha suscetível ao déficit hídrico. O potencial osmótico de -0,3 MPa obtido por manitol foi eficiente na seleção indireta de genótipos segregantes de tomateiro tolerantes ao déficit hídrico.
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O objetivo do estudo foi compreender as alterações fisiológicas do girassol, em fase reprodutiva, quando submetido a estresses hídrico e salino. O estudo foi conduzido em ambiente protegido, aplicando-se 4 níveis de irrigação (25%, 50%, 75% e 100% da evapotranspiração da cultura) e 2 níveis de condutividade elétrica da água de irrigação (0,6 e 3,0 dS m-1) no cultivar Charrua. O delineamento foi o de blocos ao acaso em esquema fatorial 4 x 2 com 3 repetições. Foram avaliados parâmetros de trocas gasosas e fluorescência. Para as trocas gasosas avaliou-se a taxa fotossintética (A), taxa transpiratória (E), condutância estomática (Gs), concentração interna de CO2 (Ci) e as razões Ci/Ca, A/Ci, A/Gs e A/E. Para a fluorescência da clorofila A foram mensurados o rendimento quântico efetivo do fotossistema II (ϕ PSII), o rendimento quântico potencial do fotossistema II (Fv/Fm) o quenching fotoquímico (qP) e o quenching não-fotoquímico (qNP). A fluorescência da clorofila A não sofreu alterações significativas com os tratamentos. A Charrua demonstrou adaptabilidade aos efeitos dos estresses, resultando em diminuição da abertura estomática, aumento de Gs, da A, da eficiência instantânea de carboxilação e eficiência do uso da água quando submetido aos menores níveis de irrigação e condutividade elétrica.
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The selection of genotypes with agronomic potential associated with drought tolerance is considered of high complexity. An alternative could be the use of selection indexes that can evaluate multiple characteristics simultaneously. This study aimed to select tomato genotypes with agronomic potential and drought tolerance by selection indexes. The experiment was conducted in a randomized block design with three replications. Ten treatments were evaluated: seven genotypes F2RC3, donor genitor (Solanum pennellii), recurrent genitor (UFU-040), and cv. Santa Clara. The irrigation was suspended until the substrate reached a matric potential of ≤-25 kPa for water stress simulation during the tomato cycle at 45, 60, 80 and 100 days after sowing. The control treatment (donor genitor) and cv. Santa Clara, were resistant and susceptible to water deficit, respectively. The UFU-102-RC3#91335 genotype presented agronomic potential and satisfactory tolerance level to water deficit and presented 58.2% higher production than the recurrent genitor (UFU-040). The genotype-ideotype distance selection index was the most appropriate for the selection of tomato genotypes for agronomic potential allied to drought tolerance.
– This study associated data of performance, gas exchange and morphometric analysis of the root system using the WinRhizo software. The main objective was to verify how the modifications in the root system contribute to maintain the photosynthetic rates and productivity in sorghum hybrids divergent regarding tolerance to water deficit. The 1G 282 tolerant hybrid presented higher tolerance to desiccation of the leaves, higher grain productivity (68.33%) and maintained its photosynthetic rate 2.13 times higher compared to the sensitive BRS 332 during the water deficit. Both hybrids presented responses related to desiccation prevention, characterized by modifications of the root system that are capable to benefit absorption of water and nutrients under stress. Besides, 1G 282 showed more developed and responsive root system, especially due to a higher superficial area of very fine roots (42.67%), volume of fine roots (36.90%) and very fine roots (53.18%) under water deficit when compared to the sensitive BRS 332 at the same conditions.Keywords: Sorghum bicolor, roots, WinRhizo, photosynthesis. MODIFICAÇÕES DO SISTEMA RADICULAR, TROCAS GASOSAS E PRODUTIVIDADE EM HÍBRIDOS DE SORGO CULTIVADOS SOB DÉFICIT HÍDRICO RESUMO – O estudo em questão associou dados de rendimento, trocas gasosas e morfometria do sistema radicular utilizando o software WinRhizo. O principal objetivo foi verificar como modificações do sistema radicular contribuem para a manutenção da taxa fotossintética e produtividade em híbridos de sorgo divergentes para tolerância ao déficit hídrico (WD), sendo um tolerante (1G 282) e outro sensível (BRS 332). O híbrido tolerante 1G 282 apresentou maior tolerância à desidratação do tecido foliar, além de manter uma taxa fotossintética 2,13 vezes maior e maior rendimento de grãos (68,33%) em relação ao sensível BRS 332 durante o WD. Ambos os híbridos apresentaram respostas de prevenção à seca, caracterizada por modificações do sistema radicular capazes de favorecer a absorção de água na condição de estresse. No entanto,1G 282 demonstrou possuir um sistema radicular mais desenvolvido e responsivo, especialmente por exibir maior área superficial de raízes muito finas (42,67%) e volume de raízes finas (36,90%) e muito finas (53,18%) em condição de WD, quando comparado com o sensível BRS 332 nas mesmas condições de cultivo.Palavras-chave: Sorghum bicolor, raízes, WinRhizo, fotossíntese.
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The objective of this study was to evaluate the physiological behavior of different tomato genotypes to assist in the selection of plants with tolerance to drought stress. It was used three blocks random and ten treatments: Eight genotypes F2RC1 [UFU80- F2RC1 #1 (3.5); UFU102- F2RC1 #7 (13.4); UFU102- F2RC1 #7 (13.3); UFU102- F2RC1 #7 (16.8); UFU102- F2RC1 #3 (2.7); UFU80- F2RC1#1 (11.8); UFU102- F2RC1 #7 (16.7); UFU102- F2RC1 #3 (14.5)], UFU-650 and LA-716. The experiment was conducted in a greenhouse with monitoring the flux density (W m-2), solar radiation (Qg), air temperature (°C), relative humidity (%) and the matric potential in the substrate (kPa). The collected physiological characteristics were: leaf temperature (Tleaf), internal CO2 (Ci), transpiration (E), stomatal conductance (gs) and CO2 assimilation (A), determined by portable gas analyzer infrared - IRGA. It was observed that the wild tomato S. pennellii was 6.96 times lower than the recurrent parent UFU-650 (pre-commercial line, susceptible to drought). The stomatal conductance (gs) showed significant values among genotypes. The results contribute to physiological characterization access S. pennellii (drought tolerant) and can assist in the selection of F2RC1 plants resistant to drought.
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Comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on xylem pH, ABA, and ionic concentrations of tomato (Lycopersicon esculentum L.) plants were investigated in two split-root pot experiments. Results showed that PRI plants had similar or significantly higher xylem pH, which was increased by 0.2 units relative to DI plants. Nitrate and total ionic concentrations (cations+anions), and the proportion of cations influenced xylem pH such that xylem pH increases as nitrate and total ionic concentrations decrease, and the proportion of cations increases. In most cases, the xylem ABA concentration was similar for PRI and DI plants, and a clear association between increases in xylem pH with increasing xylem ABA concentration was only found when the soil water content was relatively low. The concentrations of anions, cations, and the sum of anions and cations in PRI were higher than in the DI treatment when soil water content was relatively high in the wetted soil compartment. However, when water content in both soil compartments of the PRI pots were very low before the next irrigation, the acquisition of nutrients by roots was reduced, resulting in lower concentrations of anions and cations in the PRI than in the DI treatment. It is therefore essential that the soil water content in the wet zone should be maintained relatively high while that in the drying soil zone should not be very low, both conditions are crucial to maintain high soil and plant water status while sustaining ABA signalling of the plants.
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RESUMOA berinjela tem grande importância nutricional e socioeconômica, sendo cultivada e comercializada em vários países, principalmente em ambiente protegido; sua produção, assim como a de inúmeros cultivos agrícolas, é dependente de fatores como água, nutrientes e luz; propôs-se, assim, com este trabalho, avaliar as trocas gasosas, fluorescência da clorofila a e temperatura foliar de berinjela cultivada em ambiente protegido em diferentes lâminas de irrigação. O estudo foi realizado em casa de vegetação utilizando-se delineamento inteiramente casualizado, com 5 tratamentos e oito repetições, totalizando 40 unidades experimentais. Os tratamentos constaram de cinco lâminas de irrigação: 33, 66, 100, 133 e 166% da ETc, as quais corresponderam a 133, 266, 403, 536, 669 mm planta-1 ciclo-1, respectivamente. A taxa fotossintética das plantas de berinjela aumenta com o acréscimo da reposição hídrica. Os valores mais expressivos de trocas gasosas (A, E, gs, Ci, EiUA e EiC) nas plantas de berinjela, de forma geral, foram observados quando se utilizaram, na irrigação, lâminas estimadas entre 123,52 e 166% da ETc. A fluorescência da clorofila aumentou com o aumento das lâminas de irrigação e a temperatura foliar diminuiu em função do aumento da água.
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O trabalho foi realizado com o objetivo de avaliar o potencial agronômico de híbridos de tomateiro a partir da linhagem TOM-687, rica em acilaçúcares e de resistência comprovada a pragas. O experimento foi instalado na HortiAgro, município de Ijaci, MG. Foi constituído de 30 genótipos (5 híbridos comerciais, 1 linhagem pré-comercial (TOM-687), e 24 híbridos nos quais TOM-687 foi utilizada como um dos pais), os quais foram conduzidos em tutoramento com haste dupla, no espaçamento de 1,30 x 0,50 m, totalizando 15.385 plantas por hectare. Foram realizadas nove colheitas, entre as datas de 01/11/08 a 28/11/08. Foram avaliadas as características de massa média por fruto (g fruto-1) e produção por hectare (t ha-1). Os 24 híbridos que tiveram TOM-687 como um dos pais apresentaram potencial produtivo similar ao das testemunhas comerciais Débora Max, Bravo, Bônus, Kombat e Atyna. Dos 24 híbridos experimentais, quatro (TEX-298, TEX-310, TEX-315 e TEX-316) foram avaliados quanto à resistência à traça-do-tomateiro (Tuta absoluta) e mostraram-se mais resistentes do que as testemunhas comerciais.
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Abstract Celebi, M., 2014. The effect of water stress on tomato under different emitter discharges and semi-arid climate condition. Bulg. J. Agric. Sci., 20: 1151-1157 The aim of this study was to determine the effect of water stress on tomato. The experiment was conducted in a loamy soil under semi-arid climate conditions of Konya in 2010 and 2011. Irrigation water was applied using Class A pan evaporation (Kpc = 0.60, 0.80, 1.00, and 1.20) with six days irrigation intervals and with two different emitter discharges ratios. Drip irrigation laterals were arranged for every row. Significant differences in fruit yields were found among all treatments (p<0.01). Maximum marketable fruit yield (83.8 - 73.9 t ha-1) was obtained under conditions of AS1 and BS1 applications, respectively. Maximum irrigation water applied of the mention applications were determined as 507.1 mm and 365.1 mm and seasonal evapotranspiration were determined as 657.0 mm and 538.1 mm, respectively. The crop yield response factor was 2.28 - 2.04 under conditions of BS1, and 1.45 - 1.53 under conditions of AS1 by years, respectively. Hand harvest tomato varieties (Lycopersicon esculentum cv.H2274) responded to water restraint with a significant proportional decrease on yield under semi-arid climate conditions. In addition, water stress increased the susceptibility of plants to attack by pathogens. Key words: Crop yield response factor, water restraint, emitter discharges ratios, evapotranspiration, tomato Abbreviations: WUE=water use efficiency; IWUE= irrigation water use efficiency; ky= crop yield response factor; EDR= emitter discharges ratio; IRc= irrigation water / cumulative pan evaporation; = Relative yields decrease; =relative evapotranspiration deficits; A= 4 Litter hour-1 emitter discharges treatment; B= 2 Lh-1 emitter discharges treatment; S= kpc treatments according to water deficit
Drought is the major environmental stress that adversely affects crop productivity in the Mediterranean region. Adopting water saving strategies, such as deficit irrigation or even no irrigation (rain-fed) and using drought-tolerant genotypes and/or landraces may represent effective tools to save water without substantial reduction of yield. An experiment was conducted in two consecutive growing seasons (2013 and 2014), to assess soil water content and matric potential of soil, physiological parameters, growth, yield and fruit quality of two Italian long-storage tomato landraces: " Locale di Salina 6 " (LS; 2013 and 2014) and " Piennolo del Vesuvio " (PV; 2014) under rain-fed (RF) and full irrigation (FI) conditions. Leaf water potential, CO 2 assimilation, stomatal conductance, photosynthetic efficiency and growth were moderately impaired under rain-fed conditions, while intrinsic water use efficiency slightly increased. The marketable yield of LS in both growing seasons, and PV in 2014 under RF conditions was slightly reduced (by 6%) as compared with the FI treatment, indicating a drought tolerance of both landraces. In the 2014 experiment, the marketable yield was significantly higher by 55% in PV than in LS landrace. When averaged over landraces, the fruit quality traits in particular fruit dry matter, total soluble solids and total ascorbic acid contents increased by 21, 33 and 55%, respectively under RF compared to FI. The results can play an important role in selecting tolerant genotypes for use under limited water supply in order to save water and improve fruit quality without affecting the crop productivity.
We investigated the effects of elevated CO2 concentration ([CO2]), different irrigation regimes, and their interactions on leaf gas exchange, water relations, biomass production, and water use efficiency in tomato plants. In spring 2014, two tomato cultivars (CV1, which is potentially drought tolerant, and CV2 which is potentially heat tolerant) were grown in two separate greenhouse cells at [CO2] of 380 and 590 μmol L−1 (ppm) located at the experimental farm, Taastrup, Denmark. Plants were either irrigated to 18% of volumetric soil water content (FI, full irrigation), or irrigated with 70% water of the fully-irrigated control, delivered to either the whole pot (DI, deficit irrigation) or alternately to only half of the pot (PRD, partial root-zone drying). The experiment was a completed factorial design with four replications per treatment. The two cultivars showed a similar response to soil water deficits, but their water consumption responded differently to high [CO2]. Intrinsic water use efficiency (WUEi, photosynthetic rate/stomatal conductance) and plant water use efficiency (WUEp, aboveground biomass/plant water use) were both significantly increased by reduced irrigation treatments and elevated [CO2], although no significant reduction of stomatal conductance was detected under high [CO2]. There was a positive interaction between CO2 enrichment and water deficits on plant water use efficiency. Root water potential was negetatively affected by reduced irrigation but positively influenced by elevated [CO2], while leaf water potential was significantly decreased only by reduced irrigation. CO2 enrichment increased flower number without affecting fruit number, thereby reducing fruit set. Reduced irrigation in combination with elevated [CO2] caused a significant improvement in plant water use efficiency in both tomato cultivars.
Water is a limited agricultural resource, so this study has been related to rational use of water in the intensive tomato growing technology. The two-year investigation was carried out by a biological procedure - through field trials in the conditions with irrigation of tomato hybrid Amati F1, on alluvium soil type, in the river valley of Southern Morava, near Nish. The experiments were set in random complete block design with four replications, where three irrigation variants were involved (SWP of 20 kPa, 30 kPa, 40 kPa) together with the unirrigated control. Observing both investigation years, the highest fruit yield was reached at the variant with SWP of 30 kPa, while in variants with higher (SWP of 20 kPa) and lower (SWP of 40 kPa) soil moisture fruit yield decreased. The greatest tomato fruit yield was observed when the average water consumption for ETP amounted 584 mm, so this value could be regarded as tomato's demand for water in south Serbia. The highest values of WUE and IWUE for tomato were reached in the variant with SWP of 30 kPa, meaning rational water consumption was enabled at this SWP value. The study results have shown that, using tensiometer, tomato irrigation regime can be successfully kept at SWP of 30 kPa, on alluvium soil type in south Serbia.
Com o objetivo de avaliar os efeitos de períodos de sombreamento sobre o crescimento inicial e concentrações de clorofila em mudas de jequitibá- rosa (Cariniana legalis), foi instalado um experimento no viveiro de pesquisa da Embrapa Florestas, em Colombo, PR. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos e quatro repetições. Os tratamentos estabelecidos foram: 100 % (pleno sol); 70 %; 64 %, 44 % e 34 % de radiação solar incidente. A altura e diâmetro do coleto foram monitorados em intervalos de 30 dias, dos 60 aos 180 dias após a emergência (DAE). O peso da matéria seca total, aérea e radicial, área foliar, clorofila a e b e clorofila total, foram medidos aos 180 DAE. O percentual de 63,07 % de RFA (radiação fotossinteticamente ativa) proporcionou o maior crescimento em altura das mudas. As maiores médias de diâmetro do coleto ocorreram com as mudas submetidas a pleno sol. O oposto foi observado com a área foliar, onde observaram-se as maiores médias quando as mudas foram submetidas ao maior percentual de sombreamento (34 % de luminosidade). O acúmulo de matéria seca total foi estimado para 54,40 % de RFA. Os teores de clorofila a e b foram maiores nas folhas das mudas sombreadas. Concluiu-se que mudas do jequitibá-rosa, em sua fase inicial, apresentam bom crescimento quando cultivadas na faixa de 54 % a 64 % de luminosidade.