1
Introduction
India is an agricultural country and a major
user of water resource for irrigation. The scarcity of water is a major problem
in the arid and semi-arid regions of India.
The use of the industrial waste water for agricultural irrigation has
emerged in the recent past as an alternative source of water in these areas.
Pollution is an undesirable change in physical, chemical and biological aspects
of our environment. Among all kinds of pollution the problems of water
pollution due to the industrial effluent as well as sewage wastes have attained
the grater dimensions day by day in India [1]. Water pollution may be defined
as natural or induced changes in the quality of water which renders it unusable
or dangerous as regard to food, human and animal health, industry, agriculture
and fishing [2].
The most important effluent discharging
industries are thermal power plants, paper mills, textiles, distilleries,
fertilizer units, electroplating ,detergents, iron and steel industries,
pharmaceuticals, petrochemical, pesticide and herbicides, oil refineries ,
tannery and sugar mill industries. The industries are classified into three
categories such as red (high polluting industry), orange (less polluting
industry) and green (non-polluting industry) by Ministry of Environment and
Forests, New Delhi on the basis of the potentiality in creating pollution. In
our country, there are more than 20 types of industries coming under the red
category, which are highly polluting the environment. Indiscriminately discharged industrial
effluents contain organic and inorganic compounds, suspended solids and other
materials. The disposal of industrial
effluent into land or water bodies without prior treatment is a common practice
in India. The danger associated with heavy metals, toxic ions present in
untreated effluent and sewage have become great social and scientific threats.
Sugar industries
play a major role in creating the polluted environment. It falls under the red category. It plays a
major role in rural economy of our country. At the same time, it caused a
considerable amount of water and soil pollution by releasing a large amount of
waste water from the sugar mill. The effluent is discharged into nearby water
bodies making them polluted ones. The polluted water is being used for
irrigation by nearby farmers. Polluted water irrigation was directly affect
soil but also reduced agricultural yield [3]. The present research work has
been made to assess the physic-chemical characteristics of sugar mill effluent
and its effects on germination behaviour and seedling growth of hybrid brinjal
(Solanum melongena L. var. Pruthvi)
2
Materials and Methods
Effluent samples
The
effluent samples were collected in plastic containers from the out let of the
N.P.K.R. Co-operative sugar mill in Thalainayar, Mayiladuthurai Taluk, Tamil
Nadu and India. They were brought to the Ecology Laboratory, Department of
Botany and stored in refrigerator at 4oC for analysis purpose.
Seed material
Hybrid
brinjal (Solanum melongena L. var. Pruthvi) seeds were procured from
Authorized Private Agro Centre, Chidambaram, Cuddalore district, Tamil Nadu.
Analysis of sugar
mill effluent sample
The
collected sugar mill effluent sample was analysed for their various
physico-chemical properties in Ecology Laboratory,
Department of Botany, Annamalai University as per the routine standard methods
mentioned in American Public Health Association [4].
Preparation of different concentrations of effluent
The
collected effluent sample from the outlet of sugar mill industry was treated as
100 per cent raw effluent. Different concentrations (10, 25, 50, 75 and 100%)
of sugar mill effluent were prepared freshly by using distilled water whenever
necessary. They were used for germination studies.
Control : Distilled water
10% : 10 ml effluent + 90 ml water
25% : 25 ml effluent + 75 ml water
50% : 50 ml effluent + 50 ml water
75% : 75 ml effluent + 25 ml water
100% : Raw effluent
Germination studies
The
healthy and uniform sized hybrid brinjal seeds were selected and surface sterilized
with 0.1% HgCl2 for two minutes. They are thoroughly washed with tap
water to avoid surface contamination. Twenty seeds were placed equidistantly in
petridishes filled with sterilized soil. The seeds were irrigated with equal
quantity of different concentrations of effluent and the seeds irrigated with
distilled water treated as control. Five replicates were maintained for each
treatment including control. The germination percentage, seedling length,
seedling fresh weight and seedling dry weight were taken and recorded on the 21st
day’s seedlings. The values of vigour index and percentage of
phytotoxicity were also calculated. At the same time photosynthetic pigments (chlorophyll a, chlorophyll b and total chlorophyll)
and other biochemical analyses such as amino acids and starch were also
analyzed.
Germination
percentage
The
number of seeds germinated in each concentration was counted on the 21st
day and the germination percentage was calculated by using the following
formula
Germination
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Shoot and root
length (cm/seedling)
Five
seedlings were taken from each treatment and their shoot length and root length
were measured by using a cm scale and these values were recorded.
Fresh weight
(g/seedling)
Five
seedlings were collected from each treatment and their fresh weights were
measured with the help of an electrical single pan balance.
Dry weight
(mg/seedling)
The same seedlings used for fresh weight were kept in hot
air oven at 80°C
for 24 hours. Then, the seedlings were
taken from the oven and kept in desiccators for some time. Their dry weights
were taken by using an electrical single pan balance.
Vigour index
Vigour
index of the seedlings was calculated by using the [5].Vigour index =
Germination percentage ´ Length of seedling
Percentage of
phytotoxicity
The
percentage of phytotoxicity of effluent was calculated by using the formula
[6].
Percentage of phytotoxicity = _files/image004.gif){kind=small}
Biochemical
analysis
Estimation of chlorophyll
[7]
0.5 g of fresh leaf material was taken and ground with 10
ml of
80 per cent acetone in pestle and mortar. The homogenate was centrifuged at 800
rpm for 15 minutes. The supernatant was saved.
The residue was reextracted with 80 per cent acetone. The supernatant
was saved and utilized for chlorophyll estimation. Absorbance was read at 645,
663 and 480 nm in Spectrophotometer.
Total chlorophyll (mg g-1fr.
wt.) =
(0.0202) ´
(OD 645) + (0.00802) ´ (OD663)
Chlorophyll ‘a’ (mg g-1fr.
wt.) = (0.0127) ´
(OD 663) – (0.00269) ´
(OD 645)
Chlorophyll ‘b’ (mg g-1fr.
wt.) = (0.229) ´
(OD 645) – (0.00488) ´
(OD 663)
Carotenoid (mg/g
fr. wt.)
Carotenoid
content can be calculated (8).
Carotenoid
= (OD 480) – (0.114) ´ (OD 663) – (0.638) ´ (OD 645)
Estimation of amino
acid [9]
0.5
grams of plant material were ground well with 10 ml of 80 per cent ethanol in a
pestle and mortar. The homogenate was centrifuged at 800 rpm for 10 minutes and
the supernatant was saved. The
supernatant made upto 10 ml with 80 per cent ethanol. 1 ml of extract was taken
and 1 ml of ninhydrin reagent were added and mixed thoroughly in a Folin-Wu
tube and the content was heated for 20 minutes in a boiling water bath at 100°C. After 20 minutes, the content was removed
from the water bath and cooled under tap running water. The content was mixed
thoroughly made upto 10 ml with diluting solution. Then, the solution was read
at 570 nm in a Spectrophotometer.
Starch content [10]
The
ethanol insoluble residue left behind after alcoholic extraction of the
original material was taken for the extraction of starch.The residue was
dissolved in 6.5 ml of 52 per cent perchloric acid for one hour. It was
centrifuged and made upto 100 ml in a volumetric flask with distilled water.
One ml of this solution was further diluted with 5 ml of distilled water. To
this, 10 ml freshly prepared anthrone reagent was added. The content was heated
for 7 minutes at 100oC in a boiling water bath. The tube was then
cooled rapidly, shaken well and the appeared colour was read at 630 nm in Spectronic
– 20.
3
Results and Discussion
Physico-chemical
properties of sugar mill effluent are given in Table – 1. The analyses of sugar
mill effluent showed that it is acidic in nature with dull white in colour. It
contained high amounts of suspended solids and dissolved solids. It showed a
high value of Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).
The presence of considerable amounts of calcium, chloride, sulphate, nitrate,
fluoride, and silica were also noticed in the effluent. This is in conformity
with the earlier findings [11, 12, 13, 14, 15, 16, 17, 18]. The pollution load
of the effluent depends upon the nature of raw materials, chemicals used, the
processes involved in the factory and also the methods of treatments given to
the effluent before they discharged from the factory.
Table 1: Physico – Chemical properties of
sugar mill effluent
|
S. No. |
Properties |
Raw effluent |
|
1 |
Colour |
Dull
white |
|
2 |
Odour |
Decaying
molasses smell |
|
3 |
pH |
4.04 |
|
4 |
Electrical
conductivity (EC) |
4745
Mm- homs |
|
5 |
Temperature
(0C) |
33.0 |
|
6 |
Acidity |
1350.0 |
|
7 |
Suspended
solids |
180.0 |
|
8 |
Total
dissolved solids |
3725.0 |
|
9 |
Total
solids |
3905.0 |
|
10 |
BOD |
3480.0 |
|
11 |
COD |
7880.0 |
|
12 |
Chloride |
314.0 |
|
13 |
Sulphate |
290.88 |
|
14 |
Nitrate |
57.59 |
|
15 |
Fluoride |
1.88 |
|
16 |
Silica |
99.0 |
|
17 |
Calcium |
124.8 |
All parameters except colour, odour, pH,
EC and temperature are expressed in mg/l.
The effect of
different concentrations of sugar mill effluent on germination studies of
hybrid brinjal is presented in the above the figure -1. In the present investigation, the higher concentration
(25, 50, 75 and 100%) of sugar mill effluent did not help plant germination
because the presence of high salt content in the effluent at these
concentrations. Seed absorption water during germination and hydrolyse stored food
material and to activate enzymatic systems. During germination salts can
inhibit germination. The high salt concentration can slow germination by
several days or completely inhibit it [19]. The lower concentration of sugar
mill effluent (10%) promoted the germination. It may be due to presence of
optimum level of nutrients in this effluent concentration. Similar observation
was recorded in soybean [20, 21, 22].
Seedling growth and
their fresh and dry weight of hybrid brinjal seedlings increased at lower
concentration o f sugar mill effluent. It may be due to maximum uptake of
nitrogen, phosphorus and potassium by plants from this effluent concentration.
The improvement of vegetative growth may be ascribed to the role of potassium
in nutrient and sugar translocation in plants and turgor pressure in plant
cells [23]. However, the higher concentrations of sugar mill effluent decreased
in above the vegetative parameters of the brinjal plants. In higher concentrations of sugar mill
effluent contains high amount of organic and inorganic compounds, it becomes
toxic to plants. Similar observations were obtained by several workers [24,
25,26].
The above figure -2 denote the maximum
photosynthetic pigments such as chlorophyll a, chlorophyll b and total
chlorophyll of brinjal were observed at 10% concentrations of sugar mill
effluent may be due to the favourable elements such as magnesium, potassium
etc., present in the effluent on the pigment system. In higher concentrations
of sugar mill effluent become toxic to plants and a decrease in photosynthetic
pigments were observed above the figure
-2. The findings were also recorded by many researchers at different crops [27,
28, 29]. The increase in the amino acids and starch content of plants at lower
concentration of the effluent might be due to the favourable effects of organic
and inorganic elements which are present in their required quantities. But, the
higher concentrations of sugar mill effluent decreased the above mentioned
parameters. These results are in conformity with the results of some
researchers [30, 31, 32]. The 10% sugar mill effluent contains optimum content
of nutrients required for maximum vegetative growth of brinjal plant. While
studied the effect of various industrial effluents on germination studies of
some agricultural crops. The increase in germination study parameters at lower
concentration may be due to presence of growth promoting nature of nutrients in
the diluted effluent. The reductions in germination percentage and seedling
growth at higher concentrations of effluent are due to the presence of excess
amount of minerals present in the effluent. These excess amount of minerals
inhibit the germination and growth by interfering the metabolic activities
during germination and growth [33, 34].
4
Conclusions
The
physico-chemical parameters such as TDS, BOD and COD were observed to be higher
in sugar mill effluent and it severely affected the plant growth. From this
study, results that the lower concentration of sugar mill effluent (10%)
promotes the seed germination percentage, vegetative growth and biochemical of
hybrid brinjal seedlings and their higher concentrations of sugar mill effluent
inhibited the seed germination percentage, vegetative growth and biochemical of
hybrid brinjal seedlings compared to the control. It can also be concluded that
not only toxic metals but higher nutrients can also be toxic and inhibits the
seed germination and seedling growth. Therefore, dilution of the sugar mill
effluent is necessary to minimize the toxicity of sugar mill effluent and it
has the potentiality as organic fertilizer. However, the lower concentration of
effluent can be utilized for agricultural irrigation after suitable treatment
with appropriate dilution.
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