Iqbal, M., Ali, A. and Rizwanullah, M. (2005) Residual effect of tillage and farm manure on some soil physicalproperties and growth of wheat (Triticum aestivum L.). International Journal of Agriculture and Biology, 7: 54-57

Abstract

This study was conducted to investigate the residual effect of tillage and farm manure on soil physical properties and growth of wheat crop. Four tillage methods (Zero, Minimum, Deep and Conventional tillage) and three farm manure levels (control, FM @ 10 and 20 Mg ha-1) were used. Tillage methods significantly affected soil physical properties as they increased field saturated hydraulic conductivity while decreased bulk density of soil. Farm manure significantly affected the soil physical properties and growth of wheat as it increased field saturated hydraulic conductivity, 1000- grain weight, straw and grain yields of wheat and decreased bulk density of soil.

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INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY
1560–8530/2005/07–1–58–62
http://www.ijab.org Alleviation of NaCl-induced Effects on Chlorella vulgaris and
Chlorococcum humicola by Riboflavin Application
M.H.M. ABDEL-RAHMAN, R.M. ALI AND H.A. SAID
Botany Department, Faculty of Science, Cairo University, El Fayoum, Egypt
Corresponding author’s e-mail: mhm_abdelrahman@hotmail.com
ABSTRACT
The interactive effect of NaCl and riboflavin was investigated on the growth and other physiological parameters of Chlorella
vulgaris Beij. and Chlorococcum humicola (Näg.) Rab. Low to moderate salinities (50 and 100 mM NaCl) stimulated the
growth of both the species while higher levels (150-250 mM NaCl) reduced the growth of C. humicola only. Application of
riboflavin led to a significant increase in growth and biosynthesis of pigments in salt treated algae. Salinity decreased the
contents of carbohydrates and proteins while riboflavin treatments increased their contents in both tested algae. NaCl
treatments increased the accumulation of proline and other free amino acids while riboflavin treatment reduced their contents
in both studied algae. It was concluded that riboflavin treatment could alleviate the adverse effects of salinity on both algae.
Key Words: Algae; Riboflavin; Salinity
INTRODUCTION
Salinity represents one of the most important factors
which exert stress injury on the growth and metabolism of
plants. Many attempts have been undertaken to counteract
the adverse effects of salt stress on plants using organic or
inorganic solutes (Bejaoui, 1985; Radi et al., 1989; Shaddad,
1990; Hamed & Al-Wakeel, 1995; Ali, 2000). Vitamins (e.g.
ascorbic acid) were used as organic solutes for the
alleviation of salinity stress (Shaddad et al., 1990; Ahmed et
al., 1995). B-vitamins constitute a heterogeneous group of
organic compounds that acts as coenzymes, and whose
functions in microalgae are studied by several authors
(Gopala Rao & Sastry, 1972; Kodandaramaiah & Gopala
Rao, 1984). A survey of literature on B-vitamins showed
that they variably enhance growth and metabolism of
various plant species. Therefore, this work was conducted to
investigate the capability of riboflavin to counteract the
adverse effects of salinity stress on two selected algae
(Chlorella vulgaris and Chlorococcum humicola), isolated
from the Egyptian soils (Abel-Rahman et al., 2004).
MATERIALS AND METHODS
Test organisms. Axenic cultures of C. vulgaris and C.
humicola (two unicellular, non-motile, green algae) were
isolated from soil sites (El-Fayoum, Egypt), with salinity
range of 0.12 and 0.67 dS m-1, where they flourish nearly
round the year (Abdel-Rahman et al., 2004).
Culture conditions. All experiments were carried out in
250 mL conical flasks, contained 100 mL Bold's basal
medium (Bischoff & Bold, 1963) supplemented with sterile
compressed air and kept under fluorescent light (20 μmol m-
2s-1) with 16 h light period and at 25 ±2 ºC temperature.
Treatments. Exponential phase of growth of both
organisms were determined in cultures, where they were
grown for 14 d in media containing either NaCl at
concentrations 0, 50, 100,150, 200 or 250 mM or riboflavin
at concentrations 0, 0.06, 0.12 or 0.18 mM. In interactive
experiments, the starting cultures were adjusted to contain
0.125 cell x 106 mL-1 medium for both organisms.
Organisms were harvested (by centrifugation) after seven
days from cultures, which were treated with combinations
of the above mentioned concentrations of NaCl and
riboflavin. Reference controls contained NaCl
concentrations alone and absolute controls contained
untreated culture media. All treatments were replicated
thrice.
Measurements. Growth parameters included cell counts
and dry weights. The cell counts were taken using
haemocytometer slide or determination of optical density at
678 nm (Robert, 1979. Dry weight of cells was taken after
filtering and drying overnight at 105ºC. Chlorophylls,
carotenoids and total pigments were determined according
to Metzner et al. (1965). Soluble, insoluble and total
carbohydrates were determined by anthrone-sulfuric acid
method (Badour, 1959). Proteins were measured according
to the method of Lowry et al. (1951). Total free amino acids
and proline were determined according to Moore and Stein
(1948) and Bates et al. (1973), respectively.
Statistics. Data obtained were statistically analyzed using
the least significant difference test (L.S.D) at 1 and 5%
levels of probability.
RESULTS AND DISCUSSION
The growth of both organisms was significantly
increased at low levels of salinity (Fig. 1). With a rise in

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Fig. 1. Effect of different concentrations of NaCl (left) and riboflavin (right) on the growth (optical density) of
C. vulgaris vulgaris and C. humicola humicola
NaCl concentrations, the growth remained steady in C.
vulgaris but decreased in C. humicola. This indicated that
both the algae exhibit variable response to high salinity.
This conforms to the observations of Munns et al. (1983)
who report that the effect of salt on growth of micro-algae
varies dramatically between species. The salinity-induced
growth reduction may be attributed to the accumulation of
reactive oxygen species (Menezes-Benavente et al., 2004).
The growth of C. vulgaris was markedly elevated in
the media containing 0.06 or 0.12 mM riboflavin. However,
0.18 mM riboflavin was higher than the reference control.
However, the growth of C. humicola, was significantly
stimulated at all concentrations of riboflavin (Fig. 1). The
vitamins have been regarded as organic source for the
continual growth of phytoplankton species (Swift, 1980).
Under applied levels of NaCl or riboflavin, an exponential
phase of growth was evident for both algae, which reached
its maximum after seven days.
Riboflavin treatments, particularly at low and
moderate concentrations (0.06 & 0.12 mM), alleviated the
inhibitory effects of NaCl and enhanced growth and
pigment contents in both the algae as compared to the
reference controls (Fig. 2). Such an enhancement of pigment
biosynthesis has been reported in higher plants exogenously
supplied with vitamins (Shaddad et al., 1989). Gopala Rao
and Sastry (1972) reported that all B-group vitamins may be
related to chlorophyll synthesis.
Salinized cells of both algae treated with riboflavin
showed an increase in the contents (fractions & total) of
carbohydrates and proteins more than those subjected only
to salinity (Fig. 3). A stimulatory effect of riboflavin on
soluble carbohydrates was more pronounced than those of
the insoluble ones, and the increase in the protein fractions
was even more than the control cultures. However, the
response was greater in C. vulgaris than in C. humicola.
Other reports indicate that similar changes in carbohydrates
levels in response to vitamin treatments were related to an
increase in endogenous hormones (particularly cytokinin) or
to enzymes activities related to carbohydrate metabolism
(Back & San Pietro, 1968; Gopala Rao & Sundersanam,
1984). Makled (1995) reported that application of thiamin
(B1) similarly enhanced protein accumulation in C. vulgaris
vulgaris and Ankistrodesmus falcatus.
Fig. 4 shows that NaCl treatments increased the
accumulation of proline and free amino acids in both the
algae, and this accumulation was greater with increased

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60
NaCl concentrations. Our results are in agreement with
those obtained by Lin and Kao (1996) for rice. It is likely
that the accumulation of free proline and total free amino
acids could be one of the major mechanisms of salinity
tolerance in these algae. The role of riboflavin in modifying
the salt stress induced decrease in proline and other free
amino acids contents was also revealed for both algae (Fig.
4). Cells of both these salt stressed algae when exposed to
riboflavin exhibited the accumulation of carbohydrates and
proteins (Fig. 3) while free proline and total free amino acid
content were reduced (Fig. 4). This implies that the
incorporation of free amino acids into protein was markedly
enhanced by riboflavin treatment in both algae.
In conclusion, the application of riboflavin could
alleviate the adverse effects of salinity on C. vulgaris and C.
humicola. The stimulation of growth of C. vulgaris and C.
humicola by riboflavin may be attributed to induction of
some metabolic enzyme activities as has been noted for
Dunaliella tertioleca (Jahnke & White, 2003). However,
further studies are imperative on the effects of salinity and
other vitamins on certain other organisms so as to establish
Fig. 2. The interactive effects of NaCl and riboflavin on growth (left) and pigments (right) in C. vulgaris
vulgaris and C. humicola humicola. R = Reference control. Letters on the columns indicate the statistical
analysis of the original data where: n = Non significant and s = significant at least at P> 0.05

ALLEVIATION OF NACL-INDUCED EFFECTS BY RIBOFLAVIN / Int. J. Agri. Biol., Vol. 7, No. 1, 2005
61
the role of these factors on the levels of endogenous
vitamins and enzymes.
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