Effects of a 3-hr fumigation to 50 ppm ammonia on Abelmoschus esculentus Moench. var. Pusa Savni, Trigonella foenum-graecum L., Cyamopsis tetragonaloba Taub. var. Pusa Navbahar and Crotalaria juncea L., were studied. It was observed that the percentage and rate of seed germination were affected adversely in all the species and the fumigated plants had reduced root and shoot growth except in Abelmoschus where the effect appeared stimulatory. Visible symptoms of leaf injury were noticed within 24 hours after fumigation in Cyamopsis and Crotalaria. Chlorophyll contents were reduced in all the four species, maximum being in Trigonella and minimum in Abelmoschus. Growth performance studies revealed that a 30-day period after fumigation, was not enough for complete recovery of plants subjected to fumigation, as indicated by the low dry matter production, short shoot length, small number of nodes and small internodes in all ammonia exposed species.

INTRODUCTION

Ammonia has been implicated as an air pollutant at least since 1893 (Treshaw, 1970), but not in the usual sense. The damaging ammonia generally escaped from refrigerator precooling systems of cold storage rooms. Less frequently, anhydrous ammonia used as a ferti-lizer or escaped during its manufacture or nitric aciddamaged nearby vegetation. It is also found in the atmosphere of metropolitan areas, receiving pollutants from various combustion processes like domestic incineration, automobile engines, etc. Ambient concentrations of ammonia as high as 20 pphm from these sources have been reported ( Cholak, 1952 ) Zutshi (1971) estimated that around 5 tonnes of ammonia is liberated every year in the Bombay environment.

Sorauer summerized the knowledge regarding ammonia phytoxicity in 1914 (Treshaw, 1970) Symptoms consisted of dark or complete backening of leaves, bleaching of leaves of barley white rye. Wheat developed rust spots, especially along the leaf margins. Azalea chestnut leaves developed dark brown lesions between the veins which turned black next day and later dried up. Red azalea flowers developed white, wedge-shaped spots and white developed small brown spots. Old spruce seedlings became black, white young seedling become reddish yellow.

Ramsey (1953) and Brennan et al, (l962) have extensively studied the effects of ammonia plants. Thronton and Setterstrom (1940) found that ammonia fumigation at 40 ppm for one hour markedly injured tomato, sunflower, buckwheat and coleus plants. Concentration of 8.3 ppm for five hours produced slight injury. Mildest symptoms consisted of marginal chlorosis, with the remainder of the leaf remaining normal. The work presented here is an attempt to understand the sensitivity of some common plants to gaseous ammnia.

MATERIALS AND METHODS

Fumigation technique
Emission of gaseous ammonia : At N. T. P., 17 gm of ammonia occupies a volume of 22,400 ml, under laboratory conditions at 27°C temperature and 760 mm pressure, the volume occupied by 17 gm ammonia would be 24,640 ml. Accordingly, 11.5 ml of 1M freshly prepared liquor ammonia was necessary for occupying a chamber of 5.44 m3 capacity to produce a con-centrational reaction mixture to hasten the evolution of ammonia gas. Five mini fans were used for the circulation of gas within the chamber.

Estimation of gaseous ammonia : 30 minutes of evolution and filling of gas in the chamber, actual concentration of ammonia was estimated. The air from the chamber was sucked at the rate of 2 1/min by adjusting a flowmeter with the help of a pump and passed for 1-hr through a bubbler containing 0.02N H2S04.After addition of Nessler's reagent, absorbance developed was read on a spectronic- 20 photo-electric colorimeter at 370 nm wave- length. Calculations were done as per the follow- ing formula
(Leveggi et al., 1973 ) :
ug m3 NH3 = A x U. A. x E x 1000 x D
                          F x T

Where A.— Absorbance at 370 nm.
U. A.— Unit Absorbance
E— Efficiency
F— Flow rate
T— Time
and D— Dilution

It was found that at different times, the resultant concentration of ammonia in the chamber was around 50 + 10 ppm
( 30,000 ± 6,000 ug / ms3 ).

Seeds of Ablelmoschus esculentus Moench. Var. Pusa Savani, Trigonella foenum-graecum L.,Cyamopsis tetragonaloba Taub. var. Pusa Navbahar and Crotalaria juncea L. were soaked in distilled water and spread on filter paper in petridishes. A 50-seed lot for each species was then exposed to 50 ppm gaseous ammonia for 3 hr separately in a fumigation chamber. The seeds were then left for germination. The filter paper was kept moist with distilled water. Emergence of radical was taken as successful germination, which was noted every 24-hr for five consecutive days. Germination index (GI) values were calculated as per the method of Carley and Wafson (1968). Root and shoot lengths of seedlings from each species were recorded. A control without fumi- gation was run simultaneously, with the same number of seeds.

For each species 15-day old plants grown in pots under identical conditions, were exposed to 50 ppm ammonia for 3-hr in the fumigation chamber. After 24-hr of fumigation, the area and the number of damaged leaves on each plant were noted. The chlorophylls, total a and b were estimated in leaves of both control and fumigated plants (Arnon, 1949; Maclachlan and Zalik, 1963).

Some of the fumigated plants were allowed to grow in the garden. On the 30th day after fumigation they were harvested and studied with respect to their shoot length, number of nodes, length of fourth internode from the apex and oven dry weight of shoot.

RESULTS AND DISCUSSION

The seed germination was affected due to ammonia fumigation in all the species tested. The germination was reduced by 17% in Abelmoschus, 65% in Crotalaria, 61% in Cyamopsis and 74% in Trigonella ( Table 1 ).

The germination index figures indicated the reduction in the rate of seed germination due to fumigation.The GI values were reduced by 102 in Abelmoschus, by 588 in Crotalaria, by 382 in Cyamopsis and by 89 in Trigonella (Table 1 ).

Table 1 : Effect of a 3-hr fumigation with 50 ppm ammonia on germination of Abelmoschus, Crotalaria,Cyamopsis and Trigonella seeds

Name of the plant	% Germination  in 24-hr		Germination  index on 5th day		Root lengths, cm  (mean of 50 +s.d.) on 5th day		Shoot lengths,cm (mean of 50 +s.d.) on 5th day		Root, Shoot
	C	F	C	F	C	F	C	F	C	F
Abelmoschus	92	76	1436	1334	4.4 ±2.2	5.6±23	2.9 ±1.0	5.7±2.4	1.5	1.0
Crotalaria	98	34	1482	894	4.0±1.2	1.6±1.0	9.4±2.6	7.4±2.5	0.4	0.2
Cyamopsis	98	38	1482	1100	4.5±2.1	33± 1.8	8.9±1.1	4.3±0.9	0.5	0.8
Trigonella	78	20	1187	1098	4-2± 1.3	4.3± 1.5	4.3 ±1.9	4.4±0.8	1.0	1.0

C = Control       F = Fumigated       s.d = Standard deviation