THEMEDA QUADRIVALVIS (Linn.) O

SOME OBSERVATIONS ON THE AUTECOLOGY OF THEMEDA QUADRIVALVIS (Linn.) O. Ktze. Var. QUADRIVALVIS

BY S. C. PANDEYA (Department of Botany, University School of Sciences, Gujarat University, Ahmedabad-9, India) Received August 3, 1966 (Communicated by Professor T. S. Sadasivan, r.A.SC.)

ABSTRACT Therneda quadrivalvis var. quadrivalvis has restricted geographical distribution. It, otherwlse, dominates in low-lying areas at Sagar, M.P. (where the studies were undertaken). The grass community is kept fenced during the growth period. Underlying soils are stabilised, and moderately moist. The study "reveals that the restricted distribution of the species is perhaps due to low migration capacity and low ecological amplitude. Success of the species to form almost pure stands, in its area of distribution, may be due to almost no seedling mortality and formation of simple aggregates. Further, the species yields a good bulk of hay. It has optimum feed value during the month of September.

INTRODUCTION Themeda quadrivalvis (Linn.) O. Ktze. var. quadrivalvis is the dominant grass on loots of hills and hillocks and low-lying areas at Sagar, M.P. (where the "studies were conducted) forming Themeda quadrivalvis association (cf. Pandeya, 1961, 1964a, 1964b). Underlying soils are stabilised and moderately moist. The excellence of the soil on which the species grows is attested by the closeness of the surrounding land utilised for crop production. During the growth period the grassland stands are either fenced with cut thorny bushes or otherwise protected from grazing. T. quadrivalvis is a tall (1.5 to 3 m.), deep-rooted grass. The plants are annual to perennial. In the T. quadrivalvis association it covers 80 to 95% of the ground. The grasses of the association are maintained for hay and are cut in the month of October, every year. The plants start growth from old root-stocks and seeds in the month of June, after a few heavy showers. The vegetative growth is vigorous, With the clos0 of monsoon, in the month 63 64 S.C. PA~DEYA of September, the plants start flowering. Even if the plants are not cut for hay in the month of October, they naturally completely dry up by the close of the month of November. T. quadrivalvis belongs to the tropical and sub-tropical regions of Old World, chiefly Indo-Malayan (cf. Blatter and McCann, 1935). In India it occurs in North-West India, Madhya Pradesh, Western Peninsula, Bihar (Haines, 1924), and Naga Hills (Bor, 1960). Hitchcock (1951) describes it as an introduced grass in U.S.A.; established on bottam land, near Oplousas, St. Landary Parish, La. Also introduced in the West Indies and East Indies. This excellent fodder grass thus has restrictred distribution. The present investigations have been undertaken to understand the causes for the restricted distribution of the species and to work out the optimum feed value of the grass when it may be harvested for hay.

RESULTS AND THEIR INTERPRETATION

I. Seed and its Germination (i) Size, shape and weight.--The seeds are oblong-lanceolate in shape. Length of the seeds varies from 4-12mm to 7.88mm (Mean 6.25mm; Standard Deviation (S.D.) -4- 0.9068). The breadth varies from 0-91 mm to 1.12mm (Mean 1-014mm; S.D. I0'0831). The weight of a single seed varies from 1-7812mg to 2.1534mg (Mean 1.9375 mg S.D. ± 0. 1249). (ii) Seed output.--Seeds ripe from down upwards. Average seed output, calculated in 30 stands of the association, is 1,332 per plant (Minimum 624; Maximum 2,000). (iii) Germh~ation.--Seeds were collected in the month of October and put for germination immediately. There was no dormancy. Germination experiments were set in the months of April-May in the subsequent year but before the seeds would otherwise germinate in nature. Following treatments Were given to the seeds: (a) In different light exposures. (b) Sulphuric acid scarification. (c) Electric shock of 8 volts for ½ hour. Germination was effected in petri-dishes in between wet filter-papers. Three replicates were set for each treatment. Autecology of Themeda quadrivalvis vat. quadrivalvis 65 (a) In different light exposures.--One set of three petri-dishes was put separately under the following light exposures: Continuous light (during night, light was supplied from a 40-watt bulb placed at a distance of 1½ ft.-45 cm, and interposed with a water jacket). Continuous darkness. Alternate exposures of 12 hours of light and 12 hrs. of darkness. Alternate exposures of 6 hours of light and 6 hrs. of darkness (first six hours in light). Figure 1 gives the percentage germination under different light exposures. From the figure it is seen that germination is first set under alternate 12 ho~rs light and 12 hours darkness. It is highest under the treatment. As compared to the control (which is: 14%, under natural day conditions) the germination appears to be retarded under continuous darkness and alternate 6 hours light and 6 hours darkness. In continuous light, although the germination is set earlier, but percentage germination remains low.

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(b) Sulphuric acid scarification.--Three batches of 100 seeds each were separately treated with concentrated sulphuric acid for one minute. After proper washing, each batch of the seeds was put for germination in petri- S. C. PANDEYA dishes, separately. Results are presented in Fig. 2. It is seen from the figure that the germination is accelerated under the treatment. (c) Electric shock of 8 voltsfor ½hour.--Three batches of 100 seeds each were put separately in beakers half-filled with water (distilled). Two drops of concentrated hydrochloric acid were next put in the water in beakers so as to make it conductive to electric current. Electric current of 8 volts from a step-down transformer was allowed to pass for ½ hour through water by two copper electrodes dipped in the beaker. Seeds were next washed several times with water and then put for germination in petri-dishes. Results are set in Fig. 2. It is seen that germination could not be much accelerated by this treatment.

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Under (b) and (c) treatments, petri-dishes were kept at room temperature in front of a window alongside the control. The mode of germination is "hypogeal". II. Reproductive Capacity According to Salisbury (1942), the reproductive capacity of a species is as much a characteristic as any other specific feature and one moreover of the greatest ecological importance. He defined reproductive capacity as the product of the average seed output and the fraction represented by the average % germination. It can be formulated as: Seed output × % germination 100 = Reproductive Capacity. Autecology of Themeda quadrivalvis var. quadrivalvis 67 In the present case of T. quadrivalvis it works out to:

1332 × 28 = 372"96. 100

A comparison of seed size, weight, ~o germination and reproductive capacity of some important species is given in Table I.

TABLE [

A comparison of seed output, size, weight, % germhzation and reproductive capacity of some grasses worked out in lndia

; Mean size in mm Mean ~b Mean w eight Repro- germina- Species Author seed ...... in ductive Distri bution tion output Length Breadth I mg capacity

Botkriockloa Pandeya 3,505 2.738 0"477 0.0058 43.3 1,517 Eastward from Arabia to S.E. ~trtvra (Linn.) (1950-5I) A~ia and Tropical Africa; A. Camus widespread in India DidtantMum Pandeya 0,0082 ,56 Widespread in India and Burma annulatum ( 1950-51 ) ] and also common in Tropical (Forssk.) Stapf. ] J and North Africa ltdlffaa antttepho- I Pandeya 463 I. 650 1.055 1.0560 29.0 134 Restricted in India in parts of roides DC. i (1966-- : Madhya Pradesh, i in press) ! Maharashtra, South India J and rare elsewhere Ari:tida funicu- Varshney ., .... 3,0000 .. 422 Restricted to hottest and driest lata Trin. et (1966-- parts of N.-W. India Rupr. in press) i Tlu~da vuadri- Author ' "--~,3--~- 6.250 1.014 1.9375 28.0 373 "Restricted in Indo-Malayan; in valvix (Linn) India occurs N.-W., Madhya O. Ktze. j Pradesh, W. Peninsula, Bihar, Naga I-Iill.~

III. Dispersal of Seeds The seeds of the species, being heavy, are not effectively dispersed by wind. They have been observed to be dispersed by the callus of the spikelets (bisexual) piercing the skin or becoming otherwise attached to animals. The seeds may also be carried to some distances by water current.

IV. Environmental Factors 1. Climate.--T. quadrivalvis grows in areas having salubrious climate. The climate of a typical area--Sagar, M.P.,--is given in Table IL B3 68 S. C. PANDEYA

TABLE II Rainfall and temperature data of Sagar, Madhya Pradesh (Values are averages of last 10 years)

Temperature in ° C. Rainfall in mm

Months Mean Mean Highest Lowest Total Hi.ghest Number maxi- mini- maxi- mini- for a m a of rainy mum mum mum mum month day days

January .. 25.0 11.1 29.5 6.5 3 1 1

February .. 29.0 14.5 34-6 10.0 25 12 6

March .. 33.0 17.0 38.7 11.3 2 1 3

April ...... 38.8 22.6 41.5 18.0 1 1 1

May ...... 40.5 24.3 43.6 23.5 0 0 0

June ..... 34 "2 23.6 41 "2 21.7 225 82 11

July ..... 29- 8 22.5 36.6 20- 8 402 157 19

August .~ 27.1 22.1 30.5 20.1 327 92 22

September ... 28.4 22.0 33- 3 19- 0 204 56 10

October _ 32.4 20.1 34.8 14.7 25 7 5

November _ 28.5 13.5 30.3 11.0 0 0 0

December _ 24.5 12.5 30.0 9.5 38 12 4

By courtesy of the MeteorologicalLaboratory, University of Saugar, Sagar, M.P.

2. Lithology.--The underlying rocks at Sagar, as also in the surrounding areas, is basalt (Deccan trap). 3. SoiL--As a result of geological erosion, Sagar has undulating land surface consisting of chains of flat-topped hills wi~h a system of st reams connect- ing the depressions so that the entire surface is well drainei]. The drainage pattern has led to the formation of three types of basic soils in the area, viz., (i) laterite soil, (ii) Stabilised 'black cotton soil ', locally called as ' regur ', and otherwise " Chernozem" type, (iii)Freshly weathered products. Of these, the first and third types are developed on hill tops only; the second Autecology of Themeda quadrivalvis var. quadrivalvis 69

type is formed in low-lying areas or level grounds. The stabilised 'black cotton soil' are so formed under the process like" calcification " (cf. Pandeya, 1966). The soils underlying T. quadrivalvis are stabilised 'black cotton soils' No exception was recorded to this. Characters of the soils where the species grows and dominates are set in Table III. It is seen from the table that the species grows in soils which are stabilised, base rich and which are kept moderately moist throughout the growth period.

TABLE III Soil characters--Analysis of 12 stands of T. quadrivalvis association. In each stand 10 soil samples (from a depth of 10 cm) were drawn

Analysis (in % dry weight of soil) Mean Standard deviation

1. Soil Moisture, as on about 15th September 21.0833 _ 5.7680 2. pH value ...... 7.39 __+ 0.14 3. Organic carbon, in mg per 100 g dry soil 585"42 +34"55 4. Total nitrogen ...... 0.1152 _.+ 0.0050 5. Carbonate content ...... 2.4827 __ 4.3139 6. Exchangeable calcium .... 0.5888 ___ 0.4239 7. Exchangeable sesquioxides .... 0.1688 + 0.0810 8. Total sesquioxides ...... 17.7800 _ 1.6279

V. Seasonal Productivity As has been mentioned earlier, T. quadrivalvis is kept for hay and is not allowed to be grazed. Generally, it is harvested in the month of late October. In order to ascertain the best period of harvesting the grass, total vegetational cover by the grass of comparable quadrat (area: 0.16 sq. m.) was clipped every month. Fresh weight and percentage contents of crude fibres and proteins were estimated for each instalment. The results are given graphically in Figs. 3 and 4. It is seen from the figure that the fresh weight per quadrat increases in the beginning up to the month of September and later shows a decline. Pro- ~0 S.C. PANDEYA

tein contents are at the maximum just before flowering, followed with a decrease. Crude fibres, on the other hand, continue to increase up to fruiting. Results thus indicate that the best period for harvest would be at the time of flowering during the month of September when the fresh weight and proteins are at the maximum and crude fibres are moderate in quantity. When the crude fibres are highest the plants are hard and not palatable to cattle.

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• . . , • .... , . J A S 0 N D J F M A M J J A 5 0 H D J F M A M MONTHS MONTHS FIG. 3 FIo. 4 FIG. 3. Monthly variations in fresh weight yield of Themeda quadrivalvis (Lima.)O. Ktze. var. quadrivalvis per 0" 16 sq. m. FIG. 4. Monthly variations in total nitrogen and etude fibre contents of Themeda quadrivalvis var. quadrivalvis starting from the month of June with the sprouting of seeds.

VI. Biotic Factors The grass is highly susceptible to grazing. It, therefore, does not invade the highly grazed association at Sagar, viz., Bothriochloa-Dichanthium association (cf. Pandeya, 1964b), which has otherwise similar type of underlying soil (cf. Pandeya, 1966). Indeed, upon fencing, the said association tends to pass on to T. quadrivalvis type (as observed in an exclosure experimen0. The results of the exclosure study are given in Fig. 5. Although the area Autecology of Themeda quadrivalvis var. quadrivalvis 71 was fenced for just one year the invasion by T. quadrivalvis was found significant.

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BIOTIC AFTER ONE STABLE COMMUNITY YEAR OF FENCING GRASSLANDS FIG. 5. Exclosure Experiment: Result of I year of fencing the highly grazed Bothrioehloa- Diehanthium association, which is otherwise situated on similar physiography (low-lying areas) and soil type. The said grassland association tends to pass on to 2". quadrivalvistype upon removing the anthropogenic factors. To judge the relative importance of the various species, Coverx. Frequency index was worked out for each species. Behaviour of only important species is shown in the figure. (Relative importance can be formulated as: % Canopy Cover x % Frequency/100).

VII. Culture Experiments It was observed that T. quadrivalvis grows on soils which are stabilised and moderately moist. Next to soil moisture, exchangeable calcium seems to be an important soil factor for the growth of the grass. This is because the distribution of the species is restricted to soils having exchangeable calcium from 0.575 to 0.754%. Therefore, the following culture experiments were set up to see the effects of lime-dressing on the growth of the species: 100 seeds were sown under each of the following conditions: 1. Garden soil having 0.5 % of exchangeable calcium. 2, Lime-dressed garden soil (½ kg. of lime per kg. of soil). 72 S.C. PANDEYA

Monthly records of the growth of the plants in both the cases were taken. Results are given in Table IV. From the table it is seen that an increase in calcium content of soil brings about an overall reduction in the growth of the plants. Thus, the emergence of the seeds in case of lime-dressed soil is delayed by two days and the number of seeds germinated out of 100 is also reduced. The monthly yield of the plants is also less in case of the lime- dressed soil and is the average height of the plants.

TABLE IV Culture experiments--Effect of lime dressing of soil on the growth of Themeda quadrivalvis

Soil type Garden loam Lime-dressed soil (½ kg. lime: kg. soil)

No. of seeds sown ... 100 100 Time of emergence ... 3rd day 5th day Total number of seeds germinated ..... 33 24 Number of plants survived 33 22 Date of observation .. 15 July 15Aug. 15Sept. 15Oct. 15July 15Aug. 15Sept. 15Oet. Mean height of plants in m: .... 0.45 1.05 1.75 1.80 0.20 0.8 1.25 1.20 Average fresh weight per plant in g: .... 2.10 6.80 10.50 10.00 1.20 3.2 7.40 7.10

Note.--Seeds sown on 15th of June; subsequentreadings taken on 15th of each month.

DISCUSSION I. The causes resulting into development of vegetation are migration ecesis, aggregation and competition (cf. Weaver and Clements, 1938). Viewing the behaviour of Themeda quadrivalvis in this context the following points emerge from the present study, which are perhaps responsible for its restricted distribution :-- 1. Migration.--Appears to be a weak factor in the present species. This is because (a) the mobility (via heavy and not wind-dispered seeds) is inefficient, (b) seed production is low, Autecology of Themeda quadrivalvis var. quadrivalvis 73 2. Ecesis follows migration. It is the adjustment of the plants to new home. Germination, growth and reproduction are the three essential processes in it. The first critical phase in ecesis is germination. The average percent, germination in T. quadrivalvis is only 28, with as low as 392.96 of reproductive capacity (cf. Table I). Germination rises to 62% in sulphuric acid scarified seeds, indicating that impervious seedcoat is the main cause for low germination. Under ' growth ', the fate of seedling is the next crucial point. As has been shown under culture experiments (Table IV), the seedlings do not have mortality. This may indicate that the plants are able to withstand intra- specific competition. Further, in general, even a short period of drought after germination is often disastrous in many species. However, in the present case, since the grass grows only on moderately moist soils situated in low-lying areas, the drought will not be a factor at all. With further growth and increase in the size of individuals, the demands become correspondingly greater. This would add to the competition pressure and only those species would dominate which stands competition. The success of T. quadrivalvis to invade a highly grazed area upon fencing and under similar soil conditions (exclosure experiment) would attest the competition capacity of the species. 3. ";Ecological amplitude" of the species.--Nevertheless, the species shows a narrow range of tolerance with respect to the factors of soil. The Iow ecological amplitude of the species is further shown by its great susceptibility to grazing. The restricted distribution of the species may thus be due to: (a) Low migration capacity, and (b) Low ecological amplitude. The success of the species to form almost pure stands in specialised habitat may be due to: (a) No seedling mortality, (b) Formation of simple aggregates by falling of the heavy seeds near their own abode. II. Themeda quadrivalvis has been shown to have its optimum feed value (as measured in terms of its maximum nitrogen content and low crude fibres) during the month of September, just before flowering. At this period, the grass should be normally harvested for hay. 74 S.C. PANDEYA SUMMARY The paper deals with some observations on the autecology of Themeda quadrivalvis (Linn.) O. Ktze. var. quadrivalvis. The species has restricted geographical distribution. It, otherwise, dominates in low-lying areas at Sagar, M.P. (where the studies were undertaken). The underlying soils are stabilised and moderately moist. The grass-stands are kept fenced during the growth period (from the month of June to October) and are harvested as hay in the month of October. The investigations were undertaken to understand the causes for the restricted distribution of the species and to work out the optimum feed value of the grass when it may be harvested for hay. The causes resulting into development of any vegetation are migration, ecesis, aggregation and competition. The present study reveals that, of these factors, the restricted distribution of the species may be due to: (a) Low migration capacity via heavy seeds which have low seed output and are without any efficient means of dispersal. (b) Low ecological amplitude for some factors of the environment. The success of the species to form almost pure stands in specialised habitat may be due to: (a) No seedling mortality, (b) Formation of simple aggregates by falling of the seeds near their own abode. The species yields a good bulk of hay. It has optimum feed value during the month of September, as measured in terms of its maximum nitrogen content and low crude fibre.

ACKNOWLEDGMENT I am greatly indebted to Prof. R. Misra, F.N.I., Head of the Depart- ment of Botany, Banaras Hindu University, Varanasi-5, for the painstaking guidance, valuable criticisms and suggestions throughout the course of this study.

REFERENCES Blatter~ E. and McCann, C. The Bombay Grasses. Imp. Counc. Agri. Res. Sci. Mono.) 1935, 5, Delhi. Autecology of Themeda quadrivalvis var. quadrivalvis 75

Bor, N.L. .. The Grasses of Burma, Ceylon, lndia and Pakistan. Intern. Set. of Mono. on Pure and Applied Biol., Pergamon Press, Oxford, London, New York, 1960, 1, 767, Haines, H. H. .. The Botany of Bihar and Orissa. Adlard and Sons and New Man, London, 1924. Hitchcock, A. S. .. Manual of the Grasses of United States. United States Dept. of Agri. Misc. Pub. No. 200, United States Government Printing Office, Washington. Revised by A. Chase, 1951 Pandeya, S.C. .. "Notes on the Autecology of Bothriochloa pertusa Willd. and Dichanthium annulatum Stapf.," BM1. bot. Soc. Univ. Saugar, 1950-51, 3, 4-10. .. "Ecology of grasslands of Sagar, Madhya Pradesh," J. Indian bot. Soe., 1961, 40 (4), 592-600. .. "Ecology of grasslands of Sagar, Madhya Pradesh. II A. Composition of the fenced grassland associations," Ibid., 1964 a, 43 (4), 577-605. "Ecology of grasslands of Sagar, Madhya Pradesh. IIB. Composition of the associations open to grazing or occu- pying special habitat," Ibid., 1964b, 43(4), 606--39. "Ecology of grasslands of Sagar, Madhya Pradesh. HI. Edaphie factors in the distribution of the grassland associations," Sym. Intern. Soc. Trop. Ecol. on Food, Fodder, Fuel, etc., 1966, in press. and Dubey, M. D. .. "Soil-profiles of Jabalpur," J. Indian bot. Soc., 1964, 43(1), 49-61. Salisbury, E. L .. The Reproductive Capacity of Plants. C. Bell and Sore. Ltd., London, 1942. Varshney, C. K. .. "Aute~ological observations on Aristida funiculata Trin. et Rupr.," 1966, Unpublished,. Weaver, J. E. and Clements, Plant Ecology. McGraw-Hill Book Co., Inc., New York and F.E. London, 1938.