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Validation of a major QTL for salinity tolerance on chromosome 1 of rice in three different breeding populations

Authors:
Validation of a major QTL for salinity tolerance on chromosome
1 of rice in three different breeding populations
M.R. ISLAM1,*, G.B GREGORIO2, M.A. SALAM1, B.C.Y. COLLARD2, E. TUMIMBANG-
RAIZ2, D.L. ADORADA2, R.D. MENDOZA2, R.K. SINGH2, L. HASSAN3*
1 Plant Breeding Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh
2 Plant Breeding, Genetics and Biotechnology Division, International Rice research Institute DAPO Box
7777 Metro Manila, Philippines
3 Genetics and Plant Breeding Department, Bangladesh Agricultural University, Mymensingh, Bangladesh
Keywords: microsatellite marker, QTL, rice, salinity tolerance, validation
I. – Rice (Oryza sativa L) is one of the most important
food crops of the world. It is the staple food of South and Southeast Asia
and widely consumed in South America and Africa. Eighty five percent
of rice production is devoted for human consumption (I, 1997). It
occupies almost one-fifth of the total world area. The world population
grows over 80 million per year and is predicted to reach 10 billion within
2050 (K et al, 1997). For these increasing people now need to
increase the rice production for fulfill their demands.
Salinity is the most common abiotic problem in rice growing areas of
the world (S, 1987). Millions of hectares in the tropics, arid and
semi-arid region are technically suitable for rice cultivation but they are
left idle or cultivated with low yielding varieties due to the lack of suitable
tolerant high yielding varieties. About 400-950 million hectares land of the
world is affected by different levels of salinity (L et al, 1998). More than
54 million hectares of rice land in Asia are affected by salinity; another
9.5 million hectares of saline soils can be managed by large-scale irriga-
tion and drainage schemes and by chemical treatment of soil, but the scale
of problem makes these solutions too costly (G et al, 2002). The
rice plant is one of the most suitable crops for saline soils, although it is
considered moderately sensitive to salinity (M and K, 1987).
Salt tolerance is a complex, quantitative, genetic character controlled
by many genes (S, 1985; Y and F, 1986). Using con-
ventional breeding methods, plant selection for salt tolerance is not easy
because of the large environmental effects and low heritability of salt toler-
Agrochimica, Vol. LV - N. 6 November-December 2011
*Corresponding author: lutfulhassan@yahoo.co.uk
Received 04 August 2011 – Received in revised form 06 October 2011 – Accepted 22 October 2011
M.R. ISLAM ET AL.
356
ance (G and S, 1993; G, 1997). DNA/molecu-
lar markers are widely accepted as potentially valuable tools for crop
improvement of rice, especially abiotic stresses (M et al 1999).
Despite the importance of developing rice varieties with salinity
tolerance, only a small number of quantitative trait loci (QTL) mapping
experiments have been conducted. QTLs for salinity tolerance in rice
have been mapped using Amplified Fragment Length Polymorphism
(AFLP), Restriction Fragment Length Polymorphism (RFLP), and mic-
rosatellite or simple sequence repeat (SSR) markers in different popula-
tions (G, 1997; L et al, 2000; T et al, 2000; B
et al, 2002, N, 2004). Microsatellite markers have been useful for
tagging and mapping of genes/QTLs associated with salinity tolerance
(L et al, 2001). A major QTL for salt tolerance was mapped at chro-
mosome 1 by using F8 recombinant inbred line (RIL) of Pokkali/ IR29
cross (G, 1997). This QTL was designated as the SalTol QTL.
The segment of chromosome 1 contained a QTL that controlled the Na+
- K+ absorption ratio and accounted for 64.3 to 80.2% of the phenotypic
variation in salt tolerance with LOD> 14.5. This chromosome 1 segment
was further saturated in RFLP and SSR markers using the RIL popula-
tion by B et al. (2002). The identified Na+, K+ and the Na+ - K+
absorption ratio QTLs accounted for 39.2, 43.9 and 43.2% of the pheno-
typic variation with LOD > 6.7 (B et al, 2002). This segment of
the chromosome 1 was confirmed by fine mapped by using near isogenic
lines (NILs) of the backcross of Pokkali/ IR29. Using interval mapping
analysis, two LOD peaks were detected: one peak is associated with
four microsatellite markers within 4.3 cM distance; CP03970, RM8094,
RM493 and CP6224 and another one is with RM140 (N, 2004).
Prior to marker-assisted selection (MAS), QTLs and tightly-linked
markers should be validated by testing their effectiveness in determining
the target phenotype in independent populations and different genetic
backgrounds (C et al., 2003; C et al., 2003). In this study, the
SalTol QTL on chromosome 1 was validated in three different F2 popula-
tions to test if this QTL was present in different genetic backgrounds by
using microsatellite markers. QTL results were then further confirmed
using F3 derived population using the same parental genotypes.
M  . – Plant materials. – The three F2 populations were: (1)
‘BRRI dhan40’/ ‘IR61920-3B-22-2-1’ (population 1) where ‘BRRI dhan40’ was a popu-
lar variety cultivated in Bangladesh and susceptible at seedling stage and IR line was
highly tolerant to salinity and released as salinity tolerance variety in the Philippines;
VALIDATION OF A MAJOR QTL FOR SALINITY TOLERANCE
357
(2) ‘BRRI dhan28’/ ‘IR50184-3B-18-2B-1’ (population 2) where ‘BRRI dhan28’ was a
very popular variety for irrigated ecosystem cultivated in Bangladesh highly susceptible
and IR line was moderately tolerant to salinity and.(3) ‘Kajalshail’/ ‘IR52713-2B-8-
2B-1-2’ (population 3) where both of the parents were tolerant to salinity. Significant
marker-QTL associations detected in the F2 populations were subsequently confirmed
using F3 derived population.
Screening for salt tolerance. Screening of 300 F2 and 600 F3 plants of each cross
was done under controlled environment conditions following the method described by
G et al. (1997). A nutrient solution was used as described by Y et al
(1976) for growth media. The salinity of EC 12 dSm-1 was applied. The screening test
was conducted in IRRI Phytotron Glass house maintained at 29°C/ 21°C day night tem-
perature, a relative humidity of 70% during the day and natural daylight.
A modified standard evaluation score (Tab. 1) was used in rating the symptoms of
salt damage. Score 1 is representing normal growth and no leaf symptoms and considered
as highly tolerant; similarly score 3 for nearly normal growth, but leaf tips or few leaves
whitish and rolled and considered as tolerant; score 5 for growth severely retarded; most
leaves rolled; only a few are elongating and considered as moderately tolerant; score 7 for
complete cessation of growth, most leaves dry, some plants dying and known as suscep-
tible and finally score 9 was revealed for almost all plants dead or dying and known as
highly susceptible. In the scoring, odd number from 1-9 was used and no even number was
used to discriminate clearly among the classification. Scoring was done three weeks after
salinization or after the death of the susceptible check (IR29).
Molecular marker analysis. Twenty SSR and two EST markers from 49.6 to 87.1
cM position of chromosome 1 segment (according to Gramene database (www.gramene.
org) (W et al, 2002) including the markers were used for fine mapping by N
(2004) were tested for polymorphism. Genomic DNA was extracted using the CTAB
method described by Z et al. (1995). Microsatellite analysis was performed using the
methods described by T et al (2000). PCR was carrying out in a PTC-100 dyad
thermocycler machine (MJ Research), and was placed the 384-well plate. Amplification
products (2-3 µl) were resolved by polyacrylamide gel electrophoresis (8%, 10% or 12%
gels). The gel was run for 2-5 hrs at 100 volts. The gels were stained with ethidium bro-
mide staining solution and visualized under UV light.
Linkage and QTL Analysis. – Linkage analysis was performed using the Map
Manager/QTX computer program (M et al., (2001) using the Kosambi function using
a linkage evaluation of P = 0.001. The ripple command was used to verify the marker
order. The newly constructed linkage maps were compared with the existing maps.
QTL analysis was performed using Windows QTL Cartographer version 2.0
(B et al., 2001). For interval mapping analysis (IM), a LOD threshold score of 2.5
was selected. The proportion of the total phenotypic variation explained by each QTL
was calculated as R2 value (R2 = ratio of the sum of squares explained by the QTL to
the total sum of squares). For more accurately determining QTL positions, composite
interval mapping (CIM) was performed with default parameters.
R. Phenotypic Scoring. Among the 288 plants in
population 1, around 150 plants were scored as moderately tolerant
(Fig. 1(a)). 125 were classified as tolerant to highly tolerant and more
M.R. ISLAM ET AL.
358
than 15 plants were scored as susceptible to highly susceptible to salin-
ity. In Population 2, among the 281 plants, 185 plants were scored as
susceptible to highly susceptible to salinity tolerance and around 80
plants were scored as moderately tolerant and only few were scored as
tolerant (Fig. 1(b)). Population 3 showed that among 292 plants more
than 230 were scored 3 and around 20 plants scored 1, which indicated
that most of the plants of this cross were highly tolerant to salinity
(Fig. 1(c)). Around 40 plants were scored as moderately tolerant and
there was no susceptible.
Construction of linkage map. In population 1, seven PCR based
markers were used, among them six markers found in one linkage group
to saturate the target region of the chromosome 1 where the major salin-
ity tolerance gene was located (Fig. 2). RM6681 marker was unlinked
with others. Figure 2 shows the linkage map of different markers and
their interval distances for population 1, population 2, population 3
and the previous fine map. In population 2, seven markers were used
for constructing linkage map but only four markers could be scored.
The four markers gave one linkage group and constructed SSR map. In
population 3, five markers were used and found all the five markers in
one linkage group and construct SSR map.
Quantitative trait loci (QTL) analysis. The results using single
marker analysis are summarized for all the three populations in Table 2.
In population 1, RM8094 was found to be strongly associated with salin-
ity tolerance with significant on P<0.001. Other four markers RM1287,
RM3412, RM493 and CP03970 also gave significantly association with
salinity tolerance (P<0.05).
The graph derived from IM and CIM are shown in Fig. 3. The QTL
was tightly linked with the marker RM8094 with the LOD score of
2.81 and R2 value was 0.0535. A LOD peak was found from IM and
CIM line graph which was located near RM8094, between the flanking
markers RM8094 and RM3412. In populations 2 and 3, none of the
four microsatellite markers was significant in single marker analysis
(Tab. 2).
Reconfirmation in the F3 population. Among the 575 plants that
were tested, total 320 plants were scored as 3 and only 4 scored 1, these
were considered as tolerant and highly tolerant to salinity, respectively
(Fig. 4). 188 plants were scored as moderately tolerant to salinity and
63 plants were scored as susceptible to highly susceptible to salinity.
The frequency distribution of the salinity reaction was continuous and
slightly skewed towards tolerance.
VALIDATION OF A MAJOR QTL FOR SALINITY TOLERANCE
359
F. 1. – Phenotype variation of salinity tolerance for three F2 populations.
A
B
C
M.R. ISLAM ET AL.
360
F. 2. – Results of Linkage Map analysis for three F2 populations with previous fine map.
T 1. Modified standard evaluation score (SES) of visual salt injury at seedling
stage.
Score Observation Classification
1 Normal growth, no leaf symptoms Highly tolerant
3 Nearly normal growth, but leaf tips or few leaves
whitish and rolled
Tolerant
5 Growth severely retarded; most leaves rolled;
only a few are elongating
Moderately tolerant
7 Complete cessation of growth; most leaves dry;
some plants dying
Susceptible
9 Almost all plants dead or dying Highly susceptible
All of the markers were found in one linkage group flanking the
SalTol region on chromosome 1. The markers sequence of this linkage
map and linkage map from F2 population of the same cross was similar
but interval distances slightly changed. RM8094 was found to be strong-
ly associated with salinity tolerance with significant (P<0.0001) using
single marker analysis (Tab. 3). The four markers RM1287, RM3412,
RM493 and CP03970 were also found to be significantly associated with
salinity tolerance (P<0.01).
IM and CIM analysis showed that there was one QTL associated in
this segment of chromosome 1 associated with salinity tolerance. The
RM8094 marker was tightly linked with the QTL with the LOD score of
VALIDATION OF A MAJOR QTL FOR SALINITY TOLERANCE
361
T 2. – Single marker analysis for three F2 populations.
Markers Population I Population II Population III
F-value P- value F-value P- value F-value P- value
RM8132 -- -- -- -- 0.23 0.636
RM8045 3.42 0.065 0.04 0.834 0.20 0.653
RM1287 6.22 0.013* 2.69 0.102 2.92 0.089
RM8094 13.34 0.000*** -- -- -- --
RM3412 4.64 0.033* -- -- -- --
RM493 5.81 0.017* 2.42 0.121 2.72 0.100
CP3970 5.74 0.018* 2.79 0.096 2.27 0.133
RM6681a0.24 0.658 -- -- -- --
-- Marker gave monomorphism
* Significance at 5% level
** Significance at 1 % level
a Unlinked Marker
Note: Parents gave polymorphism in population II but F2 progenies gave like susceptible parent
(BR28) for RM8132, RM3412 and RM6681
Fig. 3. – Interval Mapping (IM) and Composite Interval Mapping (CIM) curve for Population 1 of F2
population.
3.7086 and its R2 value was 0.0222 (Fig. 5). The LOD peak was found
from IM and CIM line graph which was located near RM8094 between
flanking markers RM8094 and RM3412. The IM and CIM results were
identical.
M.R. ISLAM ET AL.
362
D. – Phenotypic Scoring. – The phenotypic or trait data
were taken on the basis of leaf injury symptoms. Leaf injury is highly
correlated with salt effect to the plants reactions as tolerant or susceptible.
The established classification of susceptible, moderate and tolerant based
on field, laboratory and Phytotron glass house was clearly related to visual
injury symptoms rating and Na+/ K+ absorption ratio (G, 1997).
In population 1, 288 seedlings were tested. After three weeks of
salinization (or death of the susceptible check, ‘IR29’) phenotypic scor-
ing was done for salinity tolerance or susceptibility. In population 1,
the frequency distribution of the tested plants was continuous while the
frequency distribution of population 2 showed continuous and skewed
T 3. – Single marker analysis for F3 population.
Markers F3 population
F-value P- value
RM8045 3.47 0.630
RM1287 9.85 0.002**
RM8094 17.66 0.000****
RM3412 9.03 0.003**
RM493 8.17 0.004**
CP3970 7.74 0.006**
Fine Map
(IR29/Pokkali)
Population 1
(IR61920/BRRI
dhan40)
Population 2
(IR50184/BRRI
dhan28)
Population 3
(IR52713/Kajalsail)
Fig. 4. – Phenotypic variation of salinity tolerance for F3 Population.
VALIDATION OF A MAJOR QTL FOR SALINITY TOLERANCE
363
towards the right (susceptibility). In population 3 the frequency distri-
bution of the tested plants showed continuous and skewed towards left
(tolerance). This was consistent with the phenotypes of both parents (i.e.
tolerant to salinity).
Molecular and QTL analysis.Linkage analysis showed that all of
the markers formed a single linkage group except RM6681, which was
unlinked. This map covered only from 52.4 to 66.5 cM of chromosome 1
segment according to Gramene data base. Although there are some dif-
ferences of marker positions from the previous map, the F2 maps were
very similar to the previous fine-map by N (2004) except for slight
difference in distances between markers.
The three methods single marker analysis, interval mapping (IM)
and composite interval mapping (CIM) for each of the three F2 popula-
tions were used to found the more accurate association and position of
the QTL. Three methods of QTL analysis (single marker analysis, IM
and CIM) were used in order to confirm QTL results and because some
differences in results are sometimes obtained using different methods.
From single marker analysis in population 1, RM8094 was found to be
strongly associated with salinity tolerance with significant on P<0.001.
Four markers RM1287, RM3412, RM493 and CP03970 were also
Fig. 5. – IM and CIM curve for F3 population.
M.R. ISLAM ET AL.
364
significantly associated with salinity tolerance (P<0.05). These results
revealed that there was important QTL for salinity tolerance in this
region of the chromosome 1 segment.
To more precisely determine the location of the identified QTL for
salt tolerance by single marker analysis, IM and CIM analysis was per-
formed. The LOD plot of IM and CIM was very similar. A LOD peak
was found from IM and CIM line graph which was located at RM8094
and flanking between RM1287 and RM3412. From this result it was
assumed that a QTL was tightly linked with the marker RM8094 with
the LOD score of 2.81 and R2 value was 0.0535. N (2004) also
reported that a QTL for salinity tolerance was present in this region of
chromosome 1 segment and the position of QTL was between the marker
loci CP6224 and RM8094 (1.5 cM) by using NILs (BC3F4) of the cross
of Pokkali/ IR29. B et al (2002) saturated this segment of chro-
mosome 1 with RFLP and microsatellite markers using the RIL popula-
tion and reported that two microsatellite markers, RM23 and RM140
flanked the SalTol QTL with 16.4 and 10.1 cM distance, respectively.
The source of salinity tolerance in population 1 was from IR61920-3B-
22-2-1 (NSIC106) for this study which was donated by the ancient par-
ent of this variety TKM6, Kitcheli Chamba or Vallaikar. The source of
salinity tolerance of the NILs and RIL populations was used by N
(2004) and B et al (2002) was Pokkali, which has been the most
commonly-used source of salinity tolerance in rice to date. Interestingly,
a QTL was detected in the same region of chromosome 1.
Using the F3 population derived from population 1, RM8094 was
found to be strongly associated with salinity tolerance (P<0.0001). Four
other markers RM1287, RM3412, RM493 and CP03970 were also found
to be significantly associated with salinity tolerance (P<0.01). These
results confirmed our previous result in the F2 population that there was
a QTL for salinity tolerance in this region of the chromosome 1 segment.
IM and CIM were identical. The maximum LOD score value of 3.7086
and its R2 value was 0.0222 which was slightly higher compared to the
maximum LOD score value in the F2.
In populations 2 and 3, none of the markers were significant using
single marker analysis. However, the most tightly-linked markers associ-
ated with the SalTol QTL were not polymorphic in both of these popula-
tions. The failure to detect a QTL in population 2 was unexpected because
of the difference in phenotype between both parents and that one parent
(IR50184) was derived from Pokkali. In population 3 it was found that
VALIDATION OF A MAJOR QTL FOR SALINITY TOLERANCE
365
most of the plants were tolerant; this result was obtained may be due to the
effect of both parents, because both of the parents were salinity tolerant.
This population was included for validation in this study because previous
IRRI data indicated that the Kajalshail parent was susceptible. However,
in this study, this variety was clearly tolerant. These results revealed that
the population of those crosses of ‘BRRI dhan28’/ ‘IR50184-3B-18-2B-1’
and ‘Kajalshail’/ ‘IR52713-2B-8-2B-1-2’ may not be suitable for the
introgression of the SalTol QTL using marker assisted selection.
The QTL analysis results confirmed the presence of a QTL at the
SalTol locus in an independent population. This was interesting because
the pedigrees of the tolerant parents used were different. The results in this
study also indicated the importance of verifying QTLs in three different
populations, even if the large QTL effects were previously reported. For a
marker assisted breeding program for introgressing the SalTol QTL, par-
ents that differ widely in phenotype should be selected (i.e. highly tolerant
and highly susceptible or susceptible genotypes to salinity).
A. – We thank Poverty Elimination through
Rice Research Assistance (PETRRA), Generation Challenge Program
(GCP) and Challenge Program for Water and Food (CPWF) project
for providing funds for this research. We also thank to BRRI and IRRI
authorities to allow us to do this research and technical supports.
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N, J.M.: Fine mapping of the salinity tolerance gene on chromosome 1 of rice (Oryza sativa L.) using near
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MC, S.R.: Mapping and genome organization of microsatellites sequences in rice (Oryza sativa L.).
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Tuan, V.D., F, Y., T, M. and B, T.: Mapping quantitative trait loci for salinity tolerance in rice.
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C, K., C, S., S, L.D. and MC, S.R.: Gramene, a tool for grass Genomics. Plant
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International Rice Research Institute (IRRI), Los Banos, The Philippines (1976).
Z, K., H, N., B, J. and K, G.S.: PCR-based marker assisted selection in rice breeding.
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S. – The effect of a major quantitative trait locus (QTL) for salinity tole-
rance in rice, designated as SalTol in a previous study, was tested using three F2 bree-
ding populations. The populations were derived from the following F1 hybrids: ‘BRRI
dhan40’ (susceptible)/ ‘IR61920-3B-22-2-1’ (highly tolerant); ‘BRRI dhan28’ (highly
susceptible)/ ‘IR50184-3B-18-2B-1’ (moderately tolerant); and ‘Kajalsail’ (tolerant)/
‘IR52713-2B-8-2B-1-2’ (tolerant). Targeted mapping of the chromosome region con-
taining SalTol (49.6 to 87.1 cM) on chromosome 1 was conducted using 20 SSR and
two EST markers. Comparisons of linkage maps of the three populations were very
similar to the previous QTL map that identified SalTol. A QTL was only detected for
‘BRRI dhan40’/ ‘IR61920-3B-22-2-1’ population. The SSR marker RM8094 was the
most tightly-linked marker (P<0.001); four other markers, RM1287, RM3412, RM493
and CP03970, were also significantly associated with salinity tolerance (P<0.05). An
F3 population of the cross ‘BRRI dhan40’/ ‘IR61920’ was used to reconfirm this result.
This was interesting because the tolerant parent in this population was not related to the
tolerant parent used for the original mapping population. QTLs were not detected at the
SalTol locus for either of the other two populations. This was consistent with the phe-
notypes of the parents used to construct these populations, and indicates that the SalTol
QTL may only be effective in specific populations.
INDEX VOL. LV (2011)
N.A. A, M. A - Improvement in growth, chlorophyll pigments
and photosynthetic performance in salt-stressed plants of sunflower
(Helianthus annuus L.) by foliar application of 5-aminolevulinic acid .... pag. 94
E. C, S. M, A. F, J.P. S -
Accumulation and translocation capacity of As, Co, Cr, and Pb
by forage plants ............................................... » 105
C. D C, E. P, C. C, S. L, M. D Z,
F. M, R. Á - Nitrogen fixation by soybean in the Pampas:
relationship between yield and soil nitrogen balance .................. » 305
A. E, B. C, R. P - Effects of Cd on ectomycorrhizal
fungal growth. Efficacy of in vitro screening experiment .............. » 85
L. G, M. R C, M. B, C. G -
Nanoparticles effects on growth and differentiation in cell culture of carrot
(Daucus carota L.) ............................................ » 45
R. G, M.R. G, P. M - Effects of ethephon on vegetative
growth and fruit composition of ‘Verdejo’ grapevines . . . . . . . . . . . . . . . . » 139
S.V. G, M.V. F, L. Y, M. Cş,
A. P, C.J. S, M. Tć, M. A
č
ć
- Revitalization
of urban ecosystems throught vascular plants: preliminary results from the
BSEC-PDF project ............................................ » 65
F. H, M. A, M. Y A, T.M. Q, A U H,
A. N - Evaluation of phosphoric acid as a phosphate fertilizer for wheat
production on salt-affected soils .................................. » 297
M.R. I, G.B. G, M.A. S, B.C.Y. C,
E. T-R, D.L. A, R.D. M, R.K. S, L. H -
Validation of a major QTL for salinity tolerance on chromosome 1 of rice
in three different breeding populations ............................. » 355
B. M, M.S. V, R. S - Long term effect of land use
systems on phosphorus adsorption behaviour under acidic alfisol
of Meghalaya, India ........................................... » 233
M-K, A. S, A.K. P, T.J. P, K.M. M,
R. R - Elevated CO2 and temperature effects on phosphorus dynamics
in rhizosphere of wheat (Triticum aestivum L.) grown in a typic haplustept
of subtropical India ............................................ » 313
T. M, N. M - Seasonal changes in micronutrients concentrations
in leaves of apricot tree influenced by different interstocks . . . . . . . . . . . . » 1
M. M, M.E. P, K. S R, R.C. D, A. S R,
N.W. M - Modelling N mineralization from high C:N crop residues . » 178
2
A. N, L. G, C. K, A. M-S, E. D’I,
A. P - Response of fresh cut kiwifruits and tomatoes to cold storage » 54
M.M. N A, N.M. H - Regulation of glutathione in tolerance
of Triticum aestivum to isoproturon ............................... » 147
D.I. O, R.S. L - Heavy metal accumulation in geranium
(Pelargonium hortorum) and effects on growth and quality of plants . . . . » 116
M. P, G.P. M, L. L - Stability of the main Aloe
fractions and Aloe-based commercial products under different storage
conditions ................................................... » 288
C. P, C. C, R. T, M. L, S. M,
B. G, J. B - Metal defence against biotic stress; is it real? . » 29
C. R, M.L. R-M, A. B-C - Mineralization
and nutrient release of leaf litter and fallen bromeliads in a pine-oak forest
in Oaxaca, Mexico ............................................ » 218
C. S, C. P, R. I - The role of dietary chlorophylls:
an EPR study on the antioxidant activities of tomato lipid extracts ...... » 249
V. S, S. S, K.R. S - Potassium quantity intensity
parameters of soils under predominantly rainfed mango (Mangifera indica)
orchards ..................................................... » 261
J. S, R. K, P. S, B. S K,
S.K. B, V. A K, T. C, M. V C -
Effect of sewage sludge application on accumulation of Cd, Cr, Ni and Pb
in forage maize (Zea mays L.) ................................... » 332
P. S, Š. P, D. B, T. Vě - Uranium uptake
and stress responses of in vitro cultivated hairy root culture of Armoracia
rusticana .................................................... » 15
J.C. T, R.S. Y - Hydrolysis of P fractions by phosphatase
and phytase producing fungi ..................................... » 275
D. T, A. G - Influence of compost amendment and
maize root system on soil CO2 efflux: a mesocosm approach ........... » 161
E. V, M. V - Biomass production in a extremely acid soil treated
with various calcareous amendments .............................. » 129
W.Z. Z, X.Q. C, J.M. Z, H.Y. W, C.W. D, F.Q. G -
Effects of humic acid on the adsorption and fixation of ammonium
and potassium ions on montmorillonite ............................ » 203
A. Z, F. V, G. A - Time evolution of phenols
extractions from Sangiovese grapes with and whitout the addition of solid
carbon dioxide ................................................ » 193
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A Typic Palexerult in the rana formations of the northern plateau in the province of León (Spain) was subject to acidity correction field tests over a period of two years. The experimental crop was a local rye variety and the amendments included gypsum, dolomite, limestone and sugar foam waste, all at a 6000 kg ha -1 rate as CaCO 3. General analyses were integrated with specific tests for soluble and easily exchangeable Al forms (Al-CaCl 2) in addition to KCl, BaCl 2 and CuCl 2 extracted Al, adsorbed Al (NH 4AcO) and amorphous Al. Two different multiple linear regression equations (OLS) for production were used. One included all general soil variables and those corresponding to the fractionation of the different Al forms. As shown here, pH water, adsorbed Al, CEC, AI-KCI, Al-CaCl 2 and Al-CuCl 2 were the individual variables most strongly correlated with production, with R 2 = 0.626, within the topmost 12 cm of the soil layer receiving the calcareous amendments. A principal component analysis exposed a substantial share of pH-dependent charge in organic matter on the cation exchange capacity of the soil.
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The aim of the work was to estimate the impact of fallen bromeliads extraction on the dry matter deposit at soil and nutrient cycling in a pine-oak forest. Leaf litter and fallen bromeliads were collected over a period of 12 months from two sites in the forest, and their dry weight as well as their nitrogen, phosphorus, calcium and magnesium content were recorded. In microcosms, the mineralization rate of each type of material from both sites was analyzed. Leaf litterfall rates were found to be 3.63 and 4.09 Mg ha -1 y 1 and bromeliad litterfall rates were found to be 0.046 and 0.021 Mg ha -1 y -1; the latter represent 1.27% and 0.52%, respectively, of leaf litterfall. The leaf litterfall dynamic showed seasonal behavior; the bromeliad litterfall dynamic did not. The contribution of fallen bromeliads to the nutrient deposit on the forest floor was 0.85% for nitrogen, 0.48% for phosphorus, 0.62% for calcium and 0.60% for magnesium, relative to the leaf litter contribution. Leaf litter was found to be more recalcitrant to mineralization than bromeliads.