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Bulletin of the National Institute of Ecology 15: 201-205, 2005 Gupta et al. (Editors): Ecology and Environmental Management: Issues and Research Needs © NATIONAL INSTITUTE OF ECOLOGY, NEW DELHI & JAIPUR

Germination Behaviour of Some Trees and Grasses of Arid Lands

PRACHI JAISWAL* AND SMITA CHAUDHARY Department of Bioscience and Biotechnology, Banasthali Vidyapith, Banasthali 304022, Rajasthan, India (Email: [email protected]); *Dept. Of Environmental Science, Gurukul Kangri Vishwavidyalaya, Hardwar. Email: [email protected]

ABSTRACT

The present study deals with analyzing the effect of substrate quality on seed germination of some medicinal and multipurpose tree and grass species of arid lands. Morphological characters of seeds (seed size, seed weight, texture of seed coat and water imbibition by seeds) were studied in relation to seed germination and substrate characteristics. Optimum germination of seeds was recorded on Whatman filter paper (WFP) and Ordinary filter paper (OFP). Seeds of B. monosperma, C. siamea, P. cineraria and C. ciliaris exhibited maximum germination on WFP while seeds of A. lebbeck, C. angustifolia, S. hamatha and Capsicum exhibited maximum germination on OFP. The species showed differential response to different substrates according to the specific requirements of their seeds as governed by their morphological attributes. Key Words: Seed Germination, Substrate, Morphological Characters, Imbibition.

INTRODUCTION The seeds of many multipurpose tree and grass species have potential for establishment in arid lands but exhibit seed dormancy due to the presence of hard seed coats. Besides seed dormancy, the microclimatic conditions of the soil in arid areas also inhibit seed germination. The most important requirements for normal germination are substrate, moisture, temperature and light (Chalam et al. 1967). The morphological features of the seeds play an important role in seed germination. Substrate holds a key to the successful germination and establishment of the seedlings. Therefore, an important factor influencing the seed germination and consequent seedling growth is the right choice of substrate. The essential feature of a substratum is that it contains numerous cellular spaces which are not filled with water so as to provide access of air to the seeds (Thomson 1992). The substrate used for seed germination must be non-toxic and free from moulds and microorganisms besides providing adequate aeration and moisture to the germinating seeds. The substrate must be easy to use and handle as well as cost effective. It should also make a good contrast for judging the sprout of seedlings (Agrawal 1997).The present study was planned with the primary objective to study the germination behaviour of some

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multipurpose forestry tree species and forage grass species having potential for establishment in the arid areas.

MATERIALS AND METHODS Nine important multipurposes tree and grass species of different life forms viz.,Acacia tortilis, Albizzia lebbeck, Butea monosperma, Cassia angustifolia, Cassia siamea, Cenchrus ciliaris, Prosopis cineraria, Stylosanthus hamatha and Tecomella undulata having potential for establishment in arid lands were selected and checked for germination performance using different substrates.The morphological features of the seeds of each species viz.,colour,shape, texture of seed coat, length, width, seed weight and imbibition characters were studied. Five different substrates viz. Whattman filter paper no. 1 (WFP), ordinary filter paper (OFP), tissue paper (TP), cotton wool and soil were tested for the suitability of substrates for seed for germination based on moisture holding capacity, capillary rise of water, moisture retention, drying period, phytotoxicity, cost effectiveness and individual germination performance of all the selected species on different substrates. Seeds of Capsicum sp were germinated using all the substrates to check the phytotoxicity. Hundred seeds of each species were germinated over each of the five substrates in replicates of 5 each, using distilled water, in growth chamber at 28 ± 20C temperature, 9 hr photoperiod and 80% relative humidity.

RESULTS AND DISCUSSION Germination is a complicated phenomenon in which besides the qualities of substrate, the morphological features of seeds like texture of seed coat, seed size, seed weight, imbibition of water by seeds, etc. holds a great significance. The morphological characters of seeds of different species showed significant variability. The seed coat of Acacia tortilis was very hard and smooth, where as that of Butea monosperma, Cenchrus ciliaris and Stylosanthus hamata were soft (Table 1). The seed coat of other five species were moderately hard. The length and width of seeds also varied among different species. The seeds of B. monosperma were the largest with length and width raging from 34-44mm and 22-30mm, respectively (Table 1). The seeds of C. ciliaris were the smallest with length ranges of 4-5 mm and width ranges of 3-5 mm. Seed weight of S. hamatha varied from 0.0014 to 0.0044 gram per seed, where as that of B. monosperma was 0.53 to 1.77gram per seed (Table 1). Seeds of B. monosperma showed the maximum imbibition of water per 100 seeds (10.27g) during 30 minutes. The seeds of T. undulata exhibited minimum imbibition of only 0.009g of water per 100g seeds in 30 minutes, (Table 1). Individually different species showed varying performances over different substrates. A. tortilis exhibited maximum germination in soil. Seed coat of A. tortilis was very hard with very poor imbibition. This species exhibited best germination in

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soil as it needed more water and due to little embedding in soil it got more water from various directions rather than only from bottom surface as in blotters.

Table 1. Morphological features and imbibition by seeds of different species.

Species Acacia tortilis Abizzia lebbeck Butea monosperma Cassia siamea Prosopis cineraria Tecomella undulata Cassia angustifolia Colour Blackish brown Brown Wine red Dark brown Dull brown Shape Ovoid Spindle shaped Flat, bean Shaped Flat Compressed Ovate Seeds winged Texture of seed coat Very hard stiff and Smooth Moderately hard Soft Smooth, stiff, hard Smooth hard Length * Width* (mm) (mm) 6-7 4-5 6-10 34-44 7-9 6-7 5-8 22-30 5-7 4-5 Seed weight* (g) 0.047-0.081 0.06-0.15 0.53-1.77 0.02-0.04 0.029-0.055 **Water Imbibition 0.023± 0.0021 0.219± 0.0151 10.276± 0.143 0.048± 0.0022 0.053± 0.0026 0.009± 0.0015 0.063± 0.0079 0.0087± 0.0097 0.0643± 0.0029

Blackish Feathery soft 7-8 5-7 0.003-0.143 brown Greenish Gram like Rough, moderately 6-7 3-5 0.02-0.04 brown to Obovate Hard brown Cenchrus ciliaris Blackish Prickly, spindle Rough, prickly soft 4-5 3-5 0.023-0.138 brown Shaped Stylosanthes Brown Elongated Leathery soft. 6 2 0.014-0.0044 hamata Hooked * Length, width and weight of seeds are minimum to maximum measures among 50 seeds of each species. ** Imbibition is the amount of water (g) absorbed by 100 seeds in 30 minutes.

120

100

Cumulative Percent Germination

80 capsicum A.tortilis A.lebbeck B.frondosa C.siamea P.cineraria T.undulata C.angustifolia C.ciliaris S.hamatha

60

40

20

0 0 10 20 30 Time (Days) 40 50 60

Fig. 1 Cumulative Percent Germination of Selected Multipurpose Species on the Best Substrates

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A. lebbeck exhibited maximum germination on OFP (58 %, Figure 1). Its seed coat was moderately hard but the imbibition was fairly good, therefore it showed best germination on OFP, ie., the substrate having moderate water saturation requirements. Germination performance of B. monosperma was best on WFP (100%, Figure 1). B. monosperma with very thin and papery seed coat needed moderate amount of water, hence showed best germination over WFP. Seeds of C. siamea, P. cineraria and C. ciliaris exhibited maximum germination over WFP, total germination percentage is 66%, 18.3% and 11% respectively (Figure 1). Seed coats of these three species are moderately hard and have very similar seed weight ranges and interestingly all these showed best germination over those substrates which need moderate amount of water for saturation i.e. over OFP and WFP. T. undulata showed best germination on cotton (28.3%). Seeds of C. angustifolia and S. hamatha exhibited maximum germination on OFP 17% and 13% respectively. Seeds of two drought resistant grass species C. ciliaris and S. hamatha are soft with very low seed weight and poor imbibition. These species germinate better on WFP and OFP as these substrates have moderate water requirements and better capillary rise of water. Among all the species tested for germination (including Capsicum), over the five substrates, four species showed best germination over WFP, four over OFP, one in soil and one in cotton. But none of the species favoured TP. Thus 80% species have favoured WFP and OFP for germination. Capillary rise is also a very important attribute, as it is the capacity of the substrate to circulate water throughout the surface. Filter paper is especially good for small size seeds because seeds can be easily found and checked for germination. However, filter paper can be expensive (Baskin and Baskin 1998). OFP and WFP not only hold a fairly good amount of water but also dissipate the water evenly all over the surface very quickly. The typical pattern of moisture uptake by seeds has three phases, i.e., a rapid initial uptake, a short lag period of extremely low uptake and another rapid period of uptake just before germination (Vertucci 1989). Among five substrates considered for the study, WFP and OFP showed moderate moisture holding capacity and moderate saturation requirements. Germination may be inhibited if the amount of water is too low, but it can also be inhibited if too much water is present (Botha et al. 1984). Thus the substrate having moderate water holding capacities (viz. OFP and WFP) was considered to be best for germination. Phytotoxicity is very important to recognize in a substrate. The substrate must be free from any toxic substance which negatively affects the quality of germinating seeds and delicate seedlings. When tested for phytotoxic symptoms for germination the Capsicum seeds showed maximum germination (96.7%) on ordinary filter papers, which could be attributed to optimum water holding capacity. On the tissue paper and cotton wool, the root tips got softened. Among the five substrates, WFP was found to be most expensive, and the cost of using the OFP was lowest for the seed germination study under laboratory conditions. Thus, the selection of substrates are species specific which must be given due consideration for seed germination while developing nursery practices for raising the seedlings.

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REFERENCES

Agrawal, R.L. (Editor). 1997. Seed Technology. Oxford and IBH Publishing, New Delhi. 829 pages. Baskin, C.C. and Baskin J.M. (Editors). 1998. Seeds: Ecology, Biogeography and Evolution of Dormancy and Germination, Academic Press, London. Botha, F.C., Grobellaar,N. and Small, J.G.C. 1984. The effect of water stress on the germination of Citrullus lanatus Seeds. South African Journal of Botany 3: 111-114. Chalam, G.V., Douglas, J.C. and Singh A. 1967. Seed testing procedures in brief. Pages 48-50, In: Seed Testing Mannual. Indian Council of Agricultural Research, New Delhi. Thomson, J.R. 1992. Testing for germination capacity and vigour. Pages 198-221, In: Thomson, J.R. (Editor) An Introduction to Seed Technology. Leonard Hill Publisger, London. Vertucci, C.W. 1989. The kinetics of seed imbibition: controlling factors and relevance to seedling vigor. Pages 93-115, In: Stanwood, P.C. and McDonald, M.B. (Editors) Seed Moisture. Special Publication 14, Crop Science Society of America, Washington, D.C.

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