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Mohan K. Shrestha / BIBECHANA 7 (2011) 70-75: BMHSS

BIBECHANA
A Multidisciplinary Journal of Science, Technology

and Mathematics

ISSN 2091-0762 (online)
Journal homepage: http://nepjol.info/index.php/BIBICHANA

Effect of Sewage and industrial effluents on flowering
behavior and yield of pea (Pisum sativum L. var. arkel)

Mohan Kumar Shrestha

∗∗∗∗
Dept. of Biology, Bhanu Memorial Higher Secondary School, Biratnagar, Nepal

Article History: Received 25 November 2010; Accepted 5 December 2010

Abstract

Municipality Sewage and effluents from Shah Udyog and Dairy Farming were taken to assess the

flowering behavior and yield of pea. The effluents from Dairy Farming initiated flowering earlier

than the other effluents while effluents of Shah Udyog retarded comparatively. The same trend

was followed for anthesis, withering and pod appearance. Duration of anthesis was found

increasing in the order: Dairy Farming, Municipality Sewage, Control and Shah Udyog

respectively. On the other hand, number of seed per plant and dry weight per seed was found in

decreasing order from Dairy Farming to Shah Udyog through Municipality Sewage.

Key words: Effluents; Flowering; Yield; Inhibition and promotion

1. Introduction

Discharge of waste unscientifically is a major problem in the large cities and industrial

area like Biratnagar (Lat N 26
0
29’, Long E 87

0
16’, altitude 72m).The industries viz. Textile ,

Sugar, Leather, Soap, Plastic, Iron rod, Stainless Steel, Liquors, Biscuits, Dairy, Oil seed

extraction mills etc. discharge their untreated waste directly into the natural environments thereby

polluting them [1-5].

The liquid waste of this city is discharged mainly to the Singhia River through municipal

sewage. The industrial effluents are discharged directly into the neighbouring water bodies or into

the agricultural land. The polluted water thus produced is being used by the farmers to irrigate

their crop land that adds plant nutrients to some extent and increases fertility of soil but also

includes toxicants that change soil fertility and micro-flora [6]. As it needs to investigate the

effects of effluents on the different parameters before using them in irrigation, an attempt has

been made to find out effect of effluents from Municipality Sewage, Dairy Farming and Shah

Udyog on flowering behavior and yield of pea (Pisum sativum L. var. arkel).

2. Materials and Methods

The seeds of pea were obtained from Siwani Seeds Selling Centre, Biratnagar and were

stored in air tight plastic bottle in dark room under ambient conditions. The Municipality Sewage

∗

Corresponding author: Mohan K. Shrestha, Dept. of Biology, Bhanu Memorial Higher Secondary School,

Biratnagar, Email:stha.mohan@yahoo.com

Mohan K. Shrestha / BIBECHANA 7 (2011) 70-75: BMHSS

was collected from the discharge point of the sewer of Biratnagar Municipality, located at the

bank of Singhia River. The effluents were collected directly from the outlet of the factories and

were stored inside the air tight polythene containers in dark room under ambient conditions. The

colour (visual appearance), pH (pH meter method), dissolved oxygen (Winkler’s method), solute

particles [7]and organic matter [8] were recorded within three days of effluent collection(table 1).

The concrete pots (diameter 44.5cm, depth 23.4cm) were filled with mixture of garden

soil, compost manure and sand in the ratio of 2:1:1 by volume. ¾ parts of them were buried in the

field. The seeds were sown in the pots and were irrigated daily with tap water. Each treatment

was carried out in triplicates.

The effluent treatment was started when the seedlings were 30 days old. Each pot for

particular effluent/control was irrigated with 500ml of 100% effluent/tap water at the interval of

10 days. The seedlings were irrigated with tap water daily except the day of treatment.

When the plants entered in reproductive phase, flowering behavior was observed daily

for each treatment/control, the number of plants having floral buds, number of flowers, withered

flowers and pods were recorded separately. The former two observations were recorded daily and

the rest were recorded at the intervals of twelve hours. For the observation of anthesis, withering

of flowers and pod appearance, 40 plants from each treatment were tagged randomly.

For each treatment/control, the smallest visible bud was tagged and the time taken for

anthesis was recorded. Three independent observations were carried out to calculate the mean

value.

After harvesting, the number of pod(s) per plant and number of seeds per pod were

recorded separately. The seeds from each treatment/control were oven dried at 80
0
C for 24 hours

and the dry weight per seed was calculated. The experiments were conducted in 1999.

3. Results and Discussion

The observation revealed that Dairy Farming and Municipality Sewage effluents initiated

reproductive phase earlier (fig.1). The rate of increase in number of flowering plants was initially

high in Municipality Sewage effluent but was leaded by Dairy Farming effluent in final days. The

Shah Udyog effluent delayed the initiation of reproductive phase and the rate was also low.

Comparatively, the Dairy Farming and Municipality Sewage effluents correlated in other

flowering and yield parameters i.e.; anthesis (fig.2, table 2), withering (fig.3 ), pod appearance

(fig.4 ), number of pods, seed set and dry weight of seed (table 3 ). The Shah Udyog effluent on

the other hand delayed all the parameters than the other effluents.

The Municipality Sewage receives the discharge of liquid waste of colleges, hospitals,

hotels, nursing homes and large number of household by-products that may contain high amount

of organic and inorganic toxicants and stimulants for plant growth and development. The Dairy

Farming effluent on the other hand may have less amount of inorganic toxicants but more organic

ones as it involves more biological action on the milk and its products. Similarly, Shah Udyog

effluent contains different classes of dyes including naphthol, sulphur, chromate, basic and direct

dyes used in cotton fabric production. Some of these contain toxic chemicals e. g; Chromium [9].

Shrestha and Niroula [10] reported that Municipality Sewage and Dairy Farming

effluents are inhibitory for seed germination while Shah Udyog effluent stimulated this

parameter. The inhibitory effect of the former two effluents on seed germination and stimulatory

effect in flowering and yield suggests that these effluents are not suitable for the earlier

developmental stages of pea but can be used to increase the yield after some chemical treatment.

The Shah Udyog effluent on the other hand, though stimulatory in earlier stages of development,

proved that it is not useful to get good yield of pea plant as it not only delayed the yield but the

seeds set inside the pods were not fully developed.

Plants show different degree of responses with effluents at different stages and also the

magnitude of toxicity depends upon species [2,5,11]. The present study also has shown that the

Mohan K. Shrestha / BIBECHANA 7 (2011) 70-75: BMHSS

inhibitory effect of the effluents on the same plant in earlier stages of development has changed to

stimulatory effect. To understand the exact nature and causes of different effluents/ sewage on the

tested plants, it still awaits detail physico-chemical analysis and further research in different

growth parameters.

Though the industrial and municipal sewage effluents may contain some useful organic

and inorganic nutrients required for plants, their more toxic nature than useful property suggests

not bringing them in use for irrigation without proper treatment. It is also indispensable to treat

the effluent chemically before discharge to the surrounding water bodies to minimize water

pollution and to save the quality of soil and surrounding air.

Table 1: Physico-Chemical Characteristics of Effluents and Tap water (control)

S.N.
Effluents /Tap

water
Parameters

Color
Solute

(g/l)
D.O.(mg/l) Organic matter pH

1. Dairy Farming Silvery White 1.4 3
Only Small

Amount
7.4

2.
Municipality

Sewage

Blackish

turbid
1.5 2.5 High 7.1

3. Shah Udyog Violet 1.7 3.6 Moderate 7.1

4. Tap Water ---------- 0.4 4.15 Negligible 6.9

Mohan K. Shrestha / BIBECHANA 7 (2011) 70-75: BMHSS

Table 2. Effect of Effluents on Duration of Anthesis of P. sativum.

S.N. Effluents/Tap Water Time (in hours)

1. Control 74.5

2. Dairy Farming 73.4

3. Municipality Sewage 73.6

4. Shah Udyog 76.1

Table 3. Effect of Effluents on Yield of P. sativum.

Seed
S.N. Effluents/Tap Water Pod Number / Plant

Number/Pod Dry weight seed (mg)

1. Control 1 1.2 66.7

2. Dairy Farming 1.2 1.4 87.1

3. Municipality Sewage 1.2 1.4 76.9

4. Shah Udyog 1.1 1.1 65.0

Acknowledgement

Author is grateful to P. G. Campus, Biratnagar, Nepal for providing laboratory facilities.

Mohan K. Shrestha / BIBECHANA 7 (2011) 70-75: BMHSS

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