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Ecological and Physiological Studies on Two Species of Solanum
Flora, Bd. 155, S. 486-496 (1965) Botanical Institut, University of Saarland
Ecological and Physiological Studies on Two Species of Solanum II. Factors Controlling the Ecological Distribution of S. Xanthocarpum ScHRAD & WENDL
By J. L. WAKHLOO With 3 figures in the text (Received August 6, 1964)
The report covers a part of the investigations on the ecological distribution and physiology of some Indian medicinal plants carried out at Benaras and Bhagalpur during the last few years (WAKHLOO 1963; 1964a, b, c). S. xanthocarpum is almost confined to the southern hemisphere, having been reported from Ceylon, Malaya, tropical Australia and Polynesia. Indian sub- continent, including Pakistan and Burma, happen to be the only regions in the northern hemisphere where the species is found (HooKER 1885). In In.dia it has been reported from practically all the places, except the higher altitudes in Himalayas, as its altitudinal limit is 2000 meters. Methods employed in these investigations, including the green-house experiments, have been described in an earlier report (WAKHLOO 1963; 1964 c). Field observations were mainly recorded in the state of Utter Pradesh and Bihar during 1957-1961. Observations recorded elsewhere have been cited wherever relevant.
Observations
Habit and Habitat: The species is found usually in waste, open situations, such as dry sandy river banks, occasionally in cultivated fields, as a winter-summer weed, where less irrigation is practiced. The plant is very prickly, diffuse, procumbent herb, both annual and perennial, reaching a spread of 2 to 3 meters, under favourable conditions of growth, and has an extensive tap root. The young branches, and the leaves on both surfaces, are clothed with deciduous stellate hairs. Later the upper leaf surface becomes glabrous and shiny, remaining, however, armed with a myraid of prickles on both the surfaces. Phenology: S. xanthocarpum seedlings begin to appear during the rains in July and continue to appear in large numbers till the later part of monsoon, when the heavy showers are few and far between and the temperatures remain around 30 °C.
Ecological and Physiological Studies on Two Species of Solanum.
487
During the light winter rains stray seedlings have been observed following occasional short rise in temperatures, but the plants produced are feebly developed which usually perish upon exposure to the desiccative westerlies which start in March. However, seedlings appearing during this season in cultivated fields which are lightly irrigated may thrive. The roots develop faster than the shoot and soon reach deeper layers of soil. An adult plant may have a straight tap root 2 meters or more in length. Flowering begins when the plants are 8 to 10 weeks old and continues all the year round, except during the heavy and prolonged rains. A considerable number of flowers have been observed to be sterile, falling off soon after opening. Such flowers are morphologically distinguishable from the fertile ones by their relatively smaller diameter, smaller ovaries and shorter styles (Fig. 1). In summer, from March to June, the species thrives and is at its best, attaining a considerable spread, In regions where the rains are heavy and prolonged and in low lying areas, such as North Bihar and Bengal, the species behaves as an annual, disappearing completely in JulyAugust. In regions where rainfall is less and long intervals elapse between showers, the species behaves as a perennial attaining a spread of 3 meters or more and flowers throughout the year. In areas where winter is severe, such as Kashmir valley and Simla, the plant is small beginning its life in May-June and ending by November.
Fig. 1. Top: A fertile flower and the gynoecia of fertile flowers. Bottom: A sterile flower and the gynoecia of sterile flowers.
488
J. L.
WAKHLOO
Stomatal Frequency and Index: Stomata, mostly of the anisocytic, occasionally of the diacytic type, are found on both the leaf surfaces, being about 24 and 34 per sq. mm. on the upper and the lower surfaces respectively. The stomatal index shows a similar relation, being 21 and 28 in the upper and the lower surfaces respectively. A stomatal frequency gradient is observed from the mid-rib to the margin of a single leaf, but no such gradient is observed in the stomatal frequencies of fully developed leaves from different nodes of the stem even though great care was taken to get the epidermal peelings from precisely corresponding portions of the leaf surfaces (Table 1) Environmental Factors
Edaphic: The species grows on silty and sandy loams and on sand, thriving in soils with low water retaining capacities. The nutrient status, textural and other analytic data regarding the soils are given in Table 2. pH varies from moderately acidic (6.05) to considerably alkaline (9.2). Organic carbon ranges from 0.295 to 0.985 per cent, which also indicates that the plants grow in soils relatively poor in nitrogen. Carbonate content is very low varying from 0.01 to 1.0 per cent. Exchangeable calcium ranges from 4.2 to 13.88 m. e. (milliequivalent) per cent, potassium from 1.12 to 9.21 m. e. per cent and magnesium from 0.448 to 4.936 m. e. per cent. Acid soluble phosphorus ranges from 0.017 to 0.310 per cent of the dry weight. A noteworthy feature of the soils, supporting the species, is their relatively high potassium content, a wide range of hydrogen ion concentration and the very low carbonate content. Table 1
No. of Stomata per unit area of leaf surface of S. xanthocarpurn. (Mean of 100 readings from 50 plants) Position of the leaf; node no.
Leaf surface
III
Upper Lower Upper Lower Upper Lower Upper Lower
IV
v VI
Stomata per unit area
28 34
27 35
27 33
26 35
Biotic: The species is subjected to considerable biotic influences. Goat and the buffalo browse at the young shoots rarely, only when there is nothing else around to feed upon. In cultivated fields it is often weeded out. The real menace to the species is from two insect pests viz. a beetle, Epilachria dodecastigma (Coccinellidae), and a
Ecological and Physiological Studies on Two Species of Solanum
489
larva (which could not be identified). The latter is exclusively restricted to this species while the former is found on many other species. These two pests are responsible for complete annihilation of large healthy plants in a matter of hours (Fig. 2.) They thrive in warm humid weather during monsoon. What one day is a luxuriant growth is reduced to a mere mass of prickly stems in a day or two. The egg~ being laid on the stems and leaves, the nymphs and grubs developing, feed on the foliage and flowers. The attack is repeated on the same plant several times, devouring any new growth that may appear, and as a consequence of a few such attacks, which may last 3 to 6 weeks, the plants perish. The seedlings emerging early during JulyAugust also fall prey to these pests. A new rust infecting the leaves and belonging to Pucciniaceae (RoY & GuPTA 1959; W AKHLOO 1962) and Synchytriurn sp. infecting and causing moderately large galls in the roots (W AKHLOO 1962) have been reported, for the first time, during the course of the present studies. These fungi are, however, infrequent and they can scarcely be of any significance to the species. In addition, nematodes causing tumours in the roots have been observed. Mineral content of the shoot and its relation to soils: The foliar ash analysis data for the three phases of growth viz. pre-flowering, flowering and fruiting (Table 3) shows that potassium increases upto flowering and then falls as fruits set, nevertheless remaining at a higher level than at pre-flowering. Calcium and phosphate fall continuously with growth, being at their maximum at pre-flowering. Magnesium increases till flowering after which it falls, remaining at a higher level than at preflowering. Potassium is the largest single element in the plant, constituting on an average 27 per cent of the foliar ash. The major elements in the foliar ash show a quantitative relation to the exchangeable ions in the soils. Foliar Ca bears a direct quantitative relation to the soil Ca at pH levels higher than 6.5. Foliar K is directly proportional to soil K under moderate soil Ca levels. Where soil Ca is relatively high (13.8 m. e.%) foliar K is low for its quantity in the soil. And, where soil Ca is low (4.2 m. e %) foliar K is high even at its low values in the soil. Foliar Mg directly increases with its quantity in the soil. Higher Cain the soil does not seem to effect the quantity of Mg in the shoot, but where soil Ca and Mg both are low, foliar Mg is high. The sum of foliar Mg and Ca is, more or less the same in all cases. Foliar phosphate content is directly proportional to its values in the soil upto a pH of 6.3. High amounts of exchangeable Ca in the soil favours foliar P content. Performance of the species: Observations on the performance of the species in different situations and the corresponding soil analysis data are recorded in Table 4. The performance of the species shows a direct relation to the quantities of exchangeable Ca and K in the soils. The species is very susceptible to excess soil and atmospheric moisture content. The number of sterile flowers produced is correlated with the quantity of foliar potassium. With increasing foliar potassium content their
490
J. L. WAKHLOO
42.4
0.483 1.78
3.52 0.07 1.58 30.7 21.8 0.89 0.32 0.34
1.918 2.296 1.823 1.417 2.201 2.2B8 2.283 2.832 2.305
1.410 1.980 1.620 1.345 1.583 1.542 1.731 2.071 2.120
1.135 1544 1.946 1.025 1.311 1.126 1.4GB 1.730 1.633
c 2.950 3.104 2.930 3.017 3.25 2.68 3.321 4.107 3.123
2.797 3.598 3.025 2.837 3.201 2.54 2.952 3.771 2.87 3.214 4.304 2.468 3.208 3.436 2.83 3.531 4.241 3.219
c
0.713 0.452 0.549 0.532 0.455 0.425 0.464 0.342 0.487
0.820 0.749 0.504 0.756 0.467 0.453 0.473 0.329 0.458
7.8
0.295 0.312 0.229 0.214 0.223 0.254 0.310 0.314 0.238
0.259 0.269 0.214 0.172 0.218 0.231 0.282 0.110 0.203
Phosphorus A B
silty loam
0.614 0.552 0.812 0.551 0.452 0.381 0.441 0.655 0.422
20.6
pH
silty loam 9.2 sand 8.6 sandy loam 6.5 sand 6.0 sandy loam 6.3 sandy loam 7.1 sand 7.5 sandy loam 7.7
Textural type
c
42.2
43.75 17.5 7.5 15.5 :!0.0 13.7 13.12 6.1 25.7 15.0 35.6 11.2 15.5 12.8 38.9 17.8
clay
Magnesium A B
37.1
32.6 75.7 63.0 44.0 33.7 50.5 70.6 41.84
Mechanical analysis Coarse F-ine silt sand sand
Potassium A B
LA-Preflowering; B-Flowering; C-Fruiting stages
1. 2. 3. 4. 5. 6. 7. 8. 9.
35.2 34.4 34.2 32.3 37.5 41.9 37.5 39.1
0.295 0.342 0.315 0.985 0.610 0.583 0.315 0.444
Water retaining rapacity
Foliar analysis of 8. xanthocarpum (%dry wt.)
Calcium A+ B
Table 3
1. University campus Varanasi 2. Ganges Bank, Varanasi 3. Embankment, Saarnath 4. Roadside, Ranchi 5. Roadside, Daltonganj 6. Pond bank, Saarnath 7. Cultivated field, Tandia 8. Sultanjang, Bhangalpur 9. Cultivated field Bhagalpur
Organic carbon gm.%
Soil analysis for S. xanthocarpum (dry wt. basis)
Locality of Collection
Table 2
1.28 8.31 2.28 4.56 9.21 1.67 7.63 3.37
17.40 15.50 16.28 15.40 14.23 16.63 16.39 17.74 17.30
Ash A
11.39 6.53
s.oo
4.21 12.34 6.66 6.00 13.88 9.79 8.46
0.203 0.212 0.116 0.126 0.219 0.202 0.105 0.092 0.127
c
0.32
0.13 1.0 0.02 0.03 0.01 0.02 0.04 0.87
12.78 14.43 15.13 13.27 11.01 15.92 14.25 17.15 13.59
B
0.98
0.44 2.44 2.15 1.49 1.50 0.74 4.93 1.25
11.39 11.30 12.16 11.59. 10.02 12.31 11.01 16.23 9.87
c
0.007
0.021 0.31 0.003 0.01tl 0.013 0.015 0.108 0.017
Carbo- Exchangeable ions Acid sol.P nate rn. eq.% Mg K gm.% Ca gm.% t;rJ
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492
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WAKHLOO
percentage falls continuously (Fig. 3). This observation was supported by the culture experiments. An increase in foliar K affected by supplying K 2 SO 4 to the soils resulted in decrease in the percentage of sterile flowers and consequently the fruit and the seed output increased. The increased K had, however, no apparent effect on the vegetative growth of the treated plants. In the region covering the present study 320 seeds, on an average, are produced from a berry. The number of seeds produced per berry shows a direct relation to its size. A plant, on an average, produces 20,995 seeds and the average germination being 80 per cent (W AKHLOO 1964 b), the reproductive capacity works out at 16,796. The aggressive capacity could not be calculated as in nature the germination is discontinuous and spread over a long period. Besides, a very large percentage of seedlings are devoured by biotic agencies. In any case it appears to be low. <:::>
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Fig. 3. Relation between foliar potassium, sterile flowers and the seed out-put.
Conclusions
S. xanthocarpum starts its development towards the later part of monsoon and thrives during winter and summer. The arrival of monsoon, in the following July, marks the end of its vigorous activity. In comparatively low lying areas the plants perish because of water logging, while those on the uplands, on ridges and slopes, have their foliage destroyed with fatal consequencies, by the biotic agencies which thrive under conditions of high atmospheric humidity. In regions with an annual rainfall of about 120 em. and over, S. xanthocarpum appears to be an annual due to these exigencies. It follows, therefore, that in regions with less rainfall, and that too
.... '" o•
!"'
t:C
F
5'
."'
Il. G.
2. 3. 4.
1.
27.2 31.9 37.G G0.7 75.3
35.G 46.9 51.3 74.5 76.8
13.14 32.34 21.98 45.73 50.62 -
43.2 51.6 53.0 91.0 90.9
-
v
Fresh wt. of shoot gm.
2.58 4.88 4.04 8.91 10.4
26 20 72 95 92 45
216 215 391 390 405 302
Dry wt. No. of No. of of berries seeds shoot per plant per gm. berry
5616 4,300 28,154 37,050 37,260 13,590
Seed out put per plant
1.11 1.10 1.32 1.48 1.52 1.14
wt. of one seed mg.
Performance of S ..wnthocarpurn in relation to soils and foliar potassium
Leaf Product sq. em. III IV leaves
Ta hie 4
51.3 53.0 39.0 31.3 21.3 44.3
per cent sterile flowers
2.9ii 2.93 3.10 3.25 3.32 3.017 1.12 2.28 8.31 9.21 7.63 4.56
4.21 6.66 12.34 13.88 8.46 6.00
0.02 0.003 0.31 0.013 0.108 0.018
per cent K in fruiting shoot
Soil nutrients exchangeable m.eq. gm. m.eq. 0/ o;, ,o % '" p Ca K
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494
.J. L.
WAKHLOO
scattered over long periods, the species should survive this monsoonic onslought. This is practically true and in regions such as Rasjashthan, areas around Delhi including western Utter Pradesh, the species is "perennial". A stomatal frequency gradient has not been observed in fully developed leaves from different nodes of the stem. The absence of this well recognised gradient (SALISBURY 1927; WEAVER & CLEMENTS 1938) is attributed to the prosterate habit of the species whereby all the leaves are at almost the same height from the ground and hence exposed to practically the same environment. It follows, therefore, that atmospheric moisture relations have a decisive role in determining stomatal frequencies. A correlation between the quantities of the major soil exchangeable ions and their amounts in the shoot has been established. The level of foliar K is considerably effected by soil Ca. At low K levels associated with low to moderate Ca levels in the soils, the accumulation of K in the shoot is favoured. And, at higher soil Ca levels the quantity of foliar K is adversely effected at all soil K values. This is in accordance with the "single carrier compound" concept (OvERSTREET 1952; F AWZY 1954; TANADA 1955). The sum of foliar Mg and Ca are almost the same under different soil conditions pointing to their complementary role and the preferrential absorption of Mg (DROSDORFF et al1955). Correlations between the quantities of soil exchangeable ions and the mineral constituents of the foliar or shoot ash have been established by many workers (PANDEYA 1953; SHARMA 1955; MALL 1955). JosHI (1959) working with Anogeissus latifolia observed an increase in soil exchangeable Ca upto 0.17 per cent, and at higher values of soil Ca, a decrease in foliar Ca. To the authors knowledge no such work on autecology has considered the inter-action of soil ions and their consequent influence upon the mineral composition of the shoot and the species behaviour. From the present study is has emerged out that S. xanthocarpum requires higher quantities of K for its development. Ca in itself may not be injurious, and any adverse effect due to its excess may be attributed to its adverse effect upon K absorption- an indirect harmful effect no doubt. It may be no wonder if at least some of our established calcifuges behave similarly. The seed output shows a remarkable increase with increasing foliar K at the fruiting stage, as a result of decrease in the number of sterile flowers. The reproductive capacity is 16.796 potential offsprings per plant. Inspite of this, relatively high value, the species is not gregarious in distribution. The adverse effects of shading and high soil moisture on germination (WAKHLOO 1964 b) and growth, and the fatal damage by the biotic agencies that thrive under conditions of high humidity seem to be the factors responsible for its relatively sparse distribution.
Ecological and Physiological Studies on Two Species of Solanum
495
Summary Solamtm xanthocarpum is an annual or perennial, flowering and fruiting throughout the year. The habit of the species seems to be governed by an interaction of the biotic agencies and moisture relations. The absence of a stomatal gradient has been reported and its possible significance has been suggested. The environmental factors operating upon the species have been described and a correlation between the major soil exchangeable ions and their content in the shoot has been established. The a.ntagonism between K+, Ca ++and l\fg+ · has been discussed The influence of K on the performance, especially the seed output has been discussed. Th0 ecological distribution of the species has been described.
Acknowledgement I express my deep gratitude to Professor Dr. R. 1\hsR.\, Head of the Department of Botany, Banaras Hindu University, where a part of this work was conducted, for his counsel and encouragement.
Literature DRosooRH, ?11., et al, 195i'J. Interrelations of source of nitrogen with levels of nitrogen. calcium and magnesium in tung nutrition. Proc. Amer. Soc. Hort. Sci., 65, 32-40. FAwzv, II., QvgRSTREET, R., & JACOBSON, L., 1954. The influence of hydrogen ion concentration on cation absorption by barley root. Plant Physiol., 29, 234-237. HooKER, J. D., 1885. The Flora of British India. 3, Reeve & Co. Kent. JosHI, S. R., 1959. Foliar calcium in Anogeissus latifolia. J. Indian Bot. Soc., 38, 93-102 . .VIALL, L. P., 1!l5ii. Ecology of Dry Ponds and some common weeds. Doctoral Thesis, Saugar University. OVERSTREET, R., JAcOBSON, L., & HANNDLEY, R., 1952. The effect of calcium on the absorption of potassium by barley roots. Plant Physiol., 27, 583-590. P.DmEY.\, S.C., 1953. Studies on the morphology and ecology of three species of Dichanthium Willemet. J. Indian Bot. Soc., 32, 86-100. Rov, R. Y., & GuPTA, S. K., 1959. A new species of Puccinia (P. xanthocarpi Sp. nov.). Proc. Indian Sci. Congr. Assoc. 3, 339. S.\LISBURY, E ..J., 1927. On the causes and ecological significanee of stomatal frequency, with special reference to the woodland flora. Phil. Trans. Roy. Soc. London. B. 216, 1--65. SHARMA, V. B., 19:Ji). An autecological study of Boswellia sen·ata Roxb. Doctoral Thesis, Saugar University. Tc\S.\DA, T., 1955. Effects of ultraviolet radiation and calcium and their interaction on salt absorption by excised mung bean roots. Plant Physiol., 30, 221-22i1. W.ui:!ILOO, J. L., 1962. Rust on Solanum xanlhocarpurn. J. Indian Bot. Soc., 41, 217-219. 19G2. A new host for Synchytriurn., Comrn. Phytopath. News, 8, 61-62. 1963. Variations in the total Alkaloid content of Rauvolfia serpentin'! roots: A consideration from Ecologi.;al point of view. J. Indian Bot. Soc., 42, 214-221. 1964a. Autecology of Rauvolfia serpentina BENT H.: I. Dispersal and Germination of Seeds. J. Indian Bot. Soc. 43, 96-101. 1964 b. Ecological and Physiological studies of two species of Solanum.: I. Germination and development of 8. xanthocarpum and 8. nigrum. Flora 155, 237-249. 34*
496
J. L. WAKHLOO
WAKHLOO J. L. 1964c. Autecology of RaU'uo!fia serpentina BENTH.: II. Ecology and Anatomy. J. Indian Bot. Soc. 43, 374-390 WEAYER, J. E., & CLEMENTS, F. E., 1938. Plant Ecology. Me Graw Hill Book Co., New York. pp. 601. Authors Address: Dr. J. L. WAKIILOO, Dept. of Botany, Bhagalpur University, Bhagalpur-7. Bihar (India).
Ecological and Physiological Studies on Two Species of Solanum II. Factors Controlling the Ecological Distribution of S. Xanthocarpum ScHRAD & WENDL
By J. L. WAKHLOO With 3 figures in the text (Received August 6, 1964)
The report covers a part of the investigations on the ecological distribution and physiology of some Indian medicinal plants carried out at Benaras and Bhagalpur during the last few years (WAKHLOO 1963; 1964a, b, c). S. xanthocarpum is almost confined to the southern hemisphere, having been reported from Ceylon, Malaya, tropical Australia and Polynesia. Indian sub- continent, including Pakistan and Burma, happen to be the only regions in the northern hemisphere where the species is found (HooKER 1885). In In.dia it has been reported from practically all the places, except the higher altitudes in Himalayas, as its altitudinal limit is 2000 meters. Methods employed in these investigations, including the green-house experiments, have been described in an earlier report (WAKHLOO 1963; 1964 c). Field observations were mainly recorded in the state of Utter Pradesh and Bihar during 1957-1961. Observations recorded elsewhere have been cited wherever relevant.
Observations
Habit and Habitat: The species is found usually in waste, open situations, such as dry sandy river banks, occasionally in cultivated fields, as a winter-summer weed, where less irrigation is practiced. The plant is very prickly, diffuse, procumbent herb, both annual and perennial, reaching a spread of 2 to 3 meters, under favourable conditions of growth, and has an extensive tap root. The young branches, and the leaves on both surfaces, are clothed with deciduous stellate hairs. Later the upper leaf surface becomes glabrous and shiny, remaining, however, armed with a myraid of prickles on both the surfaces. Phenology: S. xanthocarpum seedlings begin to appear during the rains in July and continue to appear in large numbers till the later part of monsoon, when the heavy showers are few and far between and the temperatures remain around 30 °C.
Ecological and Physiological Studies on Two Species of Solanum.
487
During the light winter rains stray seedlings have been observed following occasional short rise in temperatures, but the plants produced are feebly developed which usually perish upon exposure to the desiccative westerlies which start in March. However, seedlings appearing during this season in cultivated fields which are lightly irrigated may thrive. The roots develop faster than the shoot and soon reach deeper layers of soil. An adult plant may have a straight tap root 2 meters or more in length. Flowering begins when the plants are 8 to 10 weeks old and continues all the year round, except during the heavy and prolonged rains. A considerable number of flowers have been observed to be sterile, falling off soon after opening. Such flowers are morphologically distinguishable from the fertile ones by their relatively smaller diameter, smaller ovaries and shorter styles (Fig. 1). In summer, from March to June, the species thrives and is at its best, attaining a considerable spread, In regions where the rains are heavy and prolonged and in low lying areas, such as North Bihar and Bengal, the species behaves as an annual, disappearing completely in JulyAugust. In regions where rainfall is less and long intervals elapse between showers, the species behaves as a perennial attaining a spread of 3 meters or more and flowers throughout the year. In areas where winter is severe, such as Kashmir valley and Simla, the plant is small beginning its life in May-June and ending by November.
Fig. 1. Top: A fertile flower and the gynoecia of fertile flowers. Bottom: A sterile flower and the gynoecia of sterile flowers.
488
J. L.
WAKHLOO
Stomatal Frequency and Index: Stomata, mostly of the anisocytic, occasionally of the diacytic type, are found on both the leaf surfaces, being about 24 and 34 per sq. mm. on the upper and the lower surfaces respectively. The stomatal index shows a similar relation, being 21 and 28 in the upper and the lower surfaces respectively. A stomatal frequency gradient is observed from the mid-rib to the margin of a single leaf, but no such gradient is observed in the stomatal frequencies of fully developed leaves from different nodes of the stem even though great care was taken to get the epidermal peelings from precisely corresponding portions of the leaf surfaces (Table 1) Environmental Factors
Edaphic: The species grows on silty and sandy loams and on sand, thriving in soils with low water retaining capacities. The nutrient status, textural and other analytic data regarding the soils are given in Table 2. pH varies from moderately acidic (6.05) to considerably alkaline (9.2). Organic carbon ranges from 0.295 to 0.985 per cent, which also indicates that the plants grow in soils relatively poor in nitrogen. Carbonate content is very low varying from 0.01 to 1.0 per cent. Exchangeable calcium ranges from 4.2 to 13.88 m. e. (milliequivalent) per cent, potassium from 1.12 to 9.21 m. e. per cent and magnesium from 0.448 to 4.936 m. e. per cent. Acid soluble phosphorus ranges from 0.017 to 0.310 per cent of the dry weight. A noteworthy feature of the soils, supporting the species, is their relatively high potassium content, a wide range of hydrogen ion concentration and the very low carbonate content. Table 1
No. of Stomata per unit area of leaf surface of S. xanthocarpurn. (Mean of 100 readings from 50 plants) Position of the leaf; node no.
Leaf surface
III
Upper Lower Upper Lower Upper Lower Upper Lower
IV
v VI
Stomata per unit area
28 34
27 35
27 33
26 35
Biotic: The species is subjected to considerable biotic influences. Goat and the buffalo browse at the young shoots rarely, only when there is nothing else around to feed upon. In cultivated fields it is often weeded out. The real menace to the species is from two insect pests viz. a beetle, Epilachria dodecastigma (Coccinellidae), and a
Ecological and Physiological Studies on Two Species of Solanum
489
larva (which could not be identified). The latter is exclusively restricted to this species while the former is found on many other species. These two pests are responsible for complete annihilation of large healthy plants in a matter of hours (Fig. 2.) They thrive in warm humid weather during monsoon. What one day is a luxuriant growth is reduced to a mere mass of prickly stems in a day or two. The egg~ being laid on the stems and leaves, the nymphs and grubs developing, feed on the foliage and flowers. The attack is repeated on the same plant several times, devouring any new growth that may appear, and as a consequence of a few such attacks, which may last 3 to 6 weeks, the plants perish. The seedlings emerging early during JulyAugust also fall prey to these pests. A new rust infecting the leaves and belonging to Pucciniaceae (RoY & GuPTA 1959; W AKHLOO 1962) and Synchytriurn sp. infecting and causing moderately large galls in the roots (W AKHLOO 1962) have been reported, for the first time, during the course of the present studies. These fungi are, however, infrequent and they can scarcely be of any significance to the species. In addition, nematodes causing tumours in the roots have been observed. Mineral content of the shoot and its relation to soils: The foliar ash analysis data for the three phases of growth viz. pre-flowering, flowering and fruiting (Table 3) shows that potassium increases upto flowering and then falls as fruits set, nevertheless remaining at a higher level than at pre-flowering. Calcium and phosphate fall continuously with growth, being at their maximum at pre-flowering. Magnesium increases till flowering after which it falls, remaining at a higher level than at preflowering. Potassium is the largest single element in the plant, constituting on an average 27 per cent of the foliar ash. The major elements in the foliar ash show a quantitative relation to the exchangeable ions in the soils. Foliar Ca bears a direct quantitative relation to the soil Ca at pH levels higher than 6.5. Foliar K is directly proportional to soil K under moderate soil Ca levels. Where soil Ca is relatively high (13.8 m. e.%) foliar K is low for its quantity in the soil. And, where soil Ca is low (4.2 m. e %) foliar K is high even at its low values in the soil. Foliar Mg directly increases with its quantity in the soil. Higher Cain the soil does not seem to effect the quantity of Mg in the shoot, but where soil Ca and Mg both are low, foliar Mg is high. The sum of foliar Mg and Ca is, more or less the same in all cases. Foliar phosphate content is directly proportional to its values in the soil upto a pH of 6.3. High amounts of exchangeable Ca in the soil favours foliar P content. Performance of the species: Observations on the performance of the species in different situations and the corresponding soil analysis data are recorded in Table 4. The performance of the species shows a direct relation to the quantities of exchangeable Ca and K in the soils. The species is very susceptible to excess soil and atmospheric moisture content. The number of sterile flowers produced is correlated with the quantity of foliar potassium. With increasing foliar potassium content their
490
J. L. WAKHLOO
42.4
0.483 1.78
3.52 0.07 1.58 30.7 21.8 0.89 0.32 0.34
1.918 2.296 1.823 1.417 2.201 2.2B8 2.283 2.832 2.305
1.410 1.980 1.620 1.345 1.583 1.542 1.731 2.071 2.120
1.135 1544 1.946 1.025 1.311 1.126 1.4GB 1.730 1.633
c 2.950 3.104 2.930 3.017 3.25 2.68 3.321 4.107 3.123
2.797 3.598 3.025 2.837 3.201 2.54 2.952 3.771 2.87 3.214 4.304 2.468 3.208 3.436 2.83 3.531 4.241 3.219
c
0.713 0.452 0.549 0.532 0.455 0.425 0.464 0.342 0.487
0.820 0.749 0.504 0.756 0.467 0.453 0.473 0.329 0.458
7.8
0.295 0.312 0.229 0.214 0.223 0.254 0.310 0.314 0.238
0.259 0.269 0.214 0.172 0.218 0.231 0.282 0.110 0.203
Phosphorus A B
silty loam
0.614 0.552 0.812 0.551 0.452 0.381 0.441 0.655 0.422
20.6
pH
silty loam 9.2 sand 8.6 sandy loam 6.5 sand 6.0 sandy loam 6.3 sandy loam 7.1 sand 7.5 sandy loam 7.7
Textural type
c
42.2
43.75 17.5 7.5 15.5 :!0.0 13.7 13.12 6.1 25.7 15.0 35.6 11.2 15.5 12.8 38.9 17.8
clay
Magnesium A B
37.1
32.6 75.7 63.0 44.0 33.7 50.5 70.6 41.84
Mechanical analysis Coarse F-ine silt sand sand
Potassium A B
LA-Preflowering; B-Flowering; C-Fruiting stages
1. 2. 3. 4. 5. 6. 7. 8. 9.
35.2 34.4 34.2 32.3 37.5 41.9 37.5 39.1
0.295 0.342 0.315 0.985 0.610 0.583 0.315 0.444
Water retaining rapacity
Foliar analysis of 8. xanthocarpum (%dry wt.)
Calcium A+ B
Table 3
1. University campus Varanasi 2. Ganges Bank, Varanasi 3. Embankment, Saarnath 4. Roadside, Ranchi 5. Roadside, Daltonganj 6. Pond bank, Saarnath 7. Cultivated field, Tandia 8. Sultanjang, Bhangalpur 9. Cultivated field Bhagalpur
Organic carbon gm.%
Soil analysis for S. xanthocarpum (dry wt. basis)
Locality of Collection
Table 2
1.28 8.31 2.28 4.56 9.21 1.67 7.63 3.37
17.40 15.50 16.28 15.40 14.23 16.63 16.39 17.74 17.30
Ash A
11.39 6.53
s.oo
4.21 12.34 6.66 6.00 13.88 9.79 8.46
0.203 0.212 0.116 0.126 0.219 0.202 0.105 0.092 0.127
c
0.32
0.13 1.0 0.02 0.03 0.01 0.02 0.04 0.87
12.78 14.43 15.13 13.27 11.01 15.92 14.25 17.15 13.59
B
0.98
0.44 2.44 2.15 1.49 1.50 0.74 4.93 1.25
11.39 11.30 12.16 11.59. 10.02 12.31 11.01 16.23 9.87
c
0.007
0.021 0.31 0.003 0.01tl 0.013 0.015 0.108 0.017
Carbo- Exchangeable ions Acid sol.P nate rn. eq.% Mg K gm.% Ca gm.% t;rJ
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percentage falls continuously (Fig. 3). This observation was supported by the culture experiments. An increase in foliar K affected by supplying K 2 SO 4 to the soils resulted in decrease in the percentage of sterile flowers and consequently the fruit and the seed output increased. The increased K had, however, no apparent effect on the vegetative growth of the treated plants. In the region covering the present study 320 seeds, on an average, are produced from a berry. The number of seeds produced per berry shows a direct relation to its size. A plant, on an average, produces 20,995 seeds and the average germination being 80 per cent (W AKHLOO 1964 b), the reproductive capacity works out at 16,796. The aggressive capacity could not be calculated as in nature the germination is discontinuous and spread over a long period. Besides, a very large percentage of seedlings are devoured by biotic agencies. In any case it appears to be low. <:::>
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Conclusions
S. xanthocarpum starts its development towards the later part of monsoon and thrives during winter and summer. The arrival of monsoon, in the following July, marks the end of its vigorous activity. In comparatively low lying areas the plants perish because of water logging, while those on the uplands, on ridges and slopes, have their foliage destroyed with fatal consequencies, by the biotic agencies which thrive under conditions of high atmospheric humidity. In regions with an annual rainfall of about 120 em. and over, S. xanthocarpum appears to be an annual due to these exigencies. It follows, therefore, that in regions with less rainfall, and that too
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2. 3. 4.
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27.2 31.9 37.G G0.7 75.3
35.G 46.9 51.3 74.5 76.8
13.14 32.34 21.98 45.73 50.62 -
43.2 51.6 53.0 91.0 90.9
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Fresh wt. of shoot gm.
2.58 4.88 4.04 8.91 10.4
26 20 72 95 92 45
216 215 391 390 405 302
Dry wt. No. of No. of of berries seeds shoot per plant per gm. berry
5616 4,300 28,154 37,050 37,260 13,590
Seed out put per plant
1.11 1.10 1.32 1.48 1.52 1.14
wt. of one seed mg.
Performance of S ..wnthocarpurn in relation to soils and foliar potassium
Leaf Product sq. em. III IV leaves
Ta hie 4
51.3 53.0 39.0 31.3 21.3 44.3
per cent sterile flowers
2.9ii 2.93 3.10 3.25 3.32 3.017 1.12 2.28 8.31 9.21 7.63 4.56
4.21 6.66 12.34 13.88 8.46 6.00
0.02 0.003 0.31 0.013 0.108 0.018
per cent K in fruiting shoot
Soil nutrients exchangeable m.eq. gm. m.eq. 0/ o;, ,o % '" p Ca K
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WAKHLOO
scattered over long periods, the species should survive this monsoonic onslought. This is practically true and in regions such as Rasjashthan, areas around Delhi including western Utter Pradesh, the species is "perennial". A stomatal frequency gradient has not been observed in fully developed leaves from different nodes of the stem. The absence of this well recognised gradient (SALISBURY 1927; WEAVER & CLEMENTS 1938) is attributed to the prosterate habit of the species whereby all the leaves are at almost the same height from the ground and hence exposed to practically the same environment. It follows, therefore, that atmospheric moisture relations have a decisive role in determining stomatal frequencies. A correlation between the quantities of the major soil exchangeable ions and their amounts in the shoot has been established. The level of foliar K is considerably effected by soil Ca. At low K levels associated with low to moderate Ca levels in the soils, the accumulation of K in the shoot is favoured. And, at higher soil Ca levels the quantity of foliar K is adversely effected at all soil K values. This is in accordance with the "single carrier compound" concept (OvERSTREET 1952; F AWZY 1954; TANADA 1955). The sum of foliar Mg and Ca are almost the same under different soil conditions pointing to their complementary role and the preferrential absorption of Mg (DROSDORFF et al1955). Correlations between the quantities of soil exchangeable ions and the mineral constituents of the foliar or shoot ash have been established by many workers (PANDEYA 1953; SHARMA 1955; MALL 1955). JosHI (1959) working with Anogeissus latifolia observed an increase in soil exchangeable Ca upto 0.17 per cent, and at higher values of soil Ca, a decrease in foliar Ca. To the authors knowledge no such work on autecology has considered the inter-action of soil ions and their consequent influence upon the mineral composition of the shoot and the species behaviour. From the present study is has emerged out that S. xanthocarpum requires higher quantities of K for its development. Ca in itself may not be injurious, and any adverse effect due to its excess may be attributed to its adverse effect upon K absorption- an indirect harmful effect no doubt. It may be no wonder if at least some of our established calcifuges behave similarly. The seed output shows a remarkable increase with increasing foliar K at the fruiting stage, as a result of decrease in the number of sterile flowers. The reproductive capacity is 16.796 potential offsprings per plant. Inspite of this, relatively high value, the species is not gregarious in distribution. The adverse effects of shading and high soil moisture on germination (WAKHLOO 1964 b) and growth, and the fatal damage by the biotic agencies that thrive under conditions of high humidity seem to be the factors responsible for its relatively sparse distribution.
Ecological and Physiological Studies on Two Species of Solanum
495
Summary Solamtm xanthocarpum is an annual or perennial, flowering and fruiting throughout the year. The habit of the species seems to be governed by an interaction of the biotic agencies and moisture relations. The absence of a stomatal gradient has been reported and its possible significance has been suggested. The environmental factors operating upon the species have been described and a correlation between the major soil exchangeable ions and their content in the shoot has been established. The a.ntagonism between K+, Ca ++and l\fg+ · has been discussed The influence of K on the performance, especially the seed output has been discussed. Th0 ecological distribution of the species has been described.
Acknowledgement I express my deep gratitude to Professor Dr. R. 1\hsR.\, Head of the Department of Botany, Banaras Hindu University, where a part of this work was conducted, for his counsel and encouragement.
Literature DRosooRH, ?11., et al, 195i'J. Interrelations of source of nitrogen with levels of nitrogen. calcium and magnesium in tung nutrition. Proc. Amer. Soc. Hort. Sci., 65, 32-40. FAwzv, II., QvgRSTREET, R., & JACOBSON, L., 1954. The influence of hydrogen ion concentration on cation absorption by barley root. Plant Physiol., 29, 234-237. HooKER, J. D., 1885. The Flora of British India. 3, Reeve & Co. Kent. JosHI, S. R., 1959. Foliar calcium in Anogeissus latifolia. J. Indian Bot. Soc., 38, 93-102 . .VIALL, L. P., 1!l5ii. Ecology of Dry Ponds and some common weeds. Doctoral Thesis, Saugar University. OVERSTREET, R., JAcOBSON, L., & HANNDLEY, R., 1952. The effect of calcium on the absorption of potassium by barley roots. Plant Physiol., 27, 583-590. P.DmEY.\, S.C., 1953. Studies on the morphology and ecology of three species of Dichanthium Willemet. J. Indian Bot. Soc., 32, 86-100. Rov, R. Y., & GuPTA, S. K., 1959. A new species of Puccinia (P. xanthocarpi Sp. nov.). Proc. Indian Sci. Congr. Assoc. 3, 339. S.\LISBURY, E ..J., 1927. On the causes and ecological significanee of stomatal frequency, with special reference to the woodland flora. Phil. Trans. Roy. Soc. London. B. 216, 1--65. SHARMA, V. B., 19:Ji). An autecological study of Boswellia sen·ata Roxb. Doctoral Thesis, Saugar University. Tc\S.\DA, T., 1955. Effects of ultraviolet radiation and calcium and their interaction on salt absorption by excised mung bean roots. Plant Physiol., 30, 221-22i1. W.ui:!ILOO, J. L., 1962. Rust on Solanum xanlhocarpurn. J. Indian Bot. Soc., 41, 217-219. 19G2. A new host for Synchytriurn., Comrn. Phytopath. News, 8, 61-62. 1963. Variations in the total Alkaloid content of Rauvolfia serpentin'! roots: A consideration from Ecologi.;al point of view. J. Indian Bot. Soc., 42, 214-221. 1964a. Autecology of Rauvolfia serpentina BENT H.: I. Dispersal and Germination of Seeds. J. Indian Bot. Soc. 43, 96-101. 1964 b. Ecological and Physiological studies of two species of Solanum.: I. Germination and development of 8. xanthocarpum and 8. nigrum. Flora 155, 237-249. 34*
496
J. L. WAKHLOO
WAKHLOO J. L. 1964c. Autecology of RaU'uo!fia serpentina BENTH.: II. Ecology and Anatomy. J. Indian Bot. Soc. 43, 374-390 WEAYER, J. E., & CLEMENTS, F. E., 1938. Plant Ecology. Me Graw Hill Book Co., New York. pp. 601. Authors Address: Dr. J. L. WAKIILOO, Dept. of Botany, Bhagalpur University, Bhagalpur-7. Bihar (India).