N. Mariappan · P. Srimathi · L. Sundaramoorthi · K. Sudhakar

Effect of growing media on seed germination and vigor in biofuel tree species

N. Mariappan · P. Srimathi · L. Sundaramoorthi · K. Sudhakar

Received: 2013-6-19 Accepted: 2013-9-3

? Northeast Forestry University and Springer-VerlagBerlin Heidelberg 2014

To evaluate laboratory germination media, seed germination rates and methodology for both Jatropha curcas and Pongamia pinnata were counted in different germination medium, such as river sand, quartz sand and vermiculite. The seeds of both species were sown at 2-cm depth of river sand, quartz sand and vermiculite. We evaluated methodologies of seeds of J. curcas and P. pinnata by ISTA (International Seed Testing Association). The results showed that river sand is the best medium for tree seeds planted at 2-cm depth of River sand. Vermiculite was second best. On paper media, there were many abnormal seedlings and this media were unsuitable for germination of the larger seeds.

Jatropha curcas, Pongamia pinnata, germination media, normal seedlings

Introduction

Jatropha (Jatropha curcas) and Pungam (Pongamia pinnata) are trees in backyards of households in India based on their multipurpose utility. These species are becoming more important in plantation forestry because of their utility as crops for productionof fossil fuel, and they are typically propagated from seeds (Daniel and Hegde 2007). Among many seed quality characters, germination is most important. It should be evaluated in appropriate media to give accurate and reproducible results. Germination of seed in a laboratory test is essential structures, which indicates whether or not it is able to develop further into a satisfactory plant under favorable conditions in soil (ISTA 2007). Laboratory environmental conditions (moisture, temperature, aeration and light) must not only facilitate seed germination but also be favorable for the development of seedlings. Differences in characteristics of germination media such as river sand, paper, and vermiculite influence germination testing because seeds have speciesspecific germination requirements for moisture and oxygen. Generally, sand is most suitable medium for germination of large seeds and paper medium for small seeds (Bahar 2008). Our study objective was to evaluate laboratory germination media and methodologies for seeds of J.curcas and P. pinnata.

Materials and methods

Seed sources

The study was carried out at the Department of Seed Science and Technology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India during 2009 and 2010. Seeds of J. curcas and P. pinnata were collected from two separate sites in Tamil Nadu, viz., J. curcas from Mettupalayam (11.3000° N, 76.9500° E), and P. pinnata from Cuddalore (11.75° N, 79.75° E).

Germination testing

Seeds of J. curcas and P. pinnata were germinated in a temperature-controlled cabinet (at 30°C). Six types of germination media were used, viz. top of paper (TP), and rolled paper towel (RT), river sand (SS), top of sand (TS) (ISTA 1976), detoxified white quartz sand (QS), and vermiculite (VT). In river sand, quartz sand and vermiculite, seeds of both species were sown at 2-cm depth. In the top-of-sand method, seeds were pressed into thesurface of the sand. For each germination medium, 100 seeds were evaluated in four replicates.

Data recording

Seeds germination rate was evaluated at 16 and 25 days after sowing for J. curcas and P. pinnata, respectively. The methodology of seed germination was categorized as normal, abnormal, hard or dead seeds (ISTA 1999). We randomly selected ten normal seedlings to measure root and shoot lengths and fresh weight and dry weight in grams (Gupta 1993). Rate of germination was calculated based on the following formula of Maguire (1962):

where, S is rate of germination, X1, X2and Xnare number of seeds germinated on first, second and nth day, respectively and Y1, Y2and Ynare number of days from sowing to first, second and nth day, respectively.

Vigor index values were computed (Abdul Baki and Anderson 1973) adopting the following formulae:

where, V is Vigour index; G is Germination (%); T is Total seedling length (cm).

Statistical analysis

Data were analyzed using analysis of variance (Panse and Sukhathme 1985). Significance level was set at 5%.

Results and discussion

Seed germination rate varied significantly by germination medium for both J. curcas and P. pinnata (Table 1 and 2). Seed germination began on the 5th and 16th days after sowing on quartz sand and on the 5th and 17th days after sowing on river sand for J. curcas and P. pinnata, respectively. The rate of seed germination was highest on vermiculite for J. curcas and quartz sand for P. pinnata. Germination rate was slowest on paper media for both species. Seed germination on top of paper was delayed by five and four days, compared to quartz and sand germination media for J. curcas and P. pinnata, respectively. The highest germination percentages were recorded in river sand for J. curcas (82%) and P. pinnata (88%), while vermiculite yielded slightly lower germination percentages (Figs. 1 and 2). Zhe et al. (2009) reported that seeds germinated in quartz sand were seemed to grow faster but in a few days after germination, seedlings died. We recorded no seedling mortality in quartz sand but seed germination was faster in river sand than in quartz sand. Seed germination rate of P. pinnata on sand media (2-cm depth) was higher by 6%, compared with vermiculite.

Table 1: Effect of media on germination behaviour of Jatropha curcas seeds

Frequency of normal seedlings was higher in sand (SS and QS) and vermiculite than in other media. Moreover, abnormal seedlings with the decayed and deformed seedlings and dead seeds were higher in paper media. We conclude that paper medium is not a suitable medium for germination of J. curcas and P. pinnata seeds. Based on easy availability and economic utility for J. curcas and P. pinnata, the river sand could be used as the testing media, but in that too, in sand media (SS) method should be adopted for obtaining reproducible results in the germination test. It was followed by quartz sand (QS) and vermiculite (VT) germination medium.

Table 2: Effect of media on germination behaviour of Pongamia pinnata seeds

Fig. 1: Evaluation of Jatropha curcas seed germination in different media and methods

Frequency of normal seedlings was higher in sand (SS and QS) and vermiculite than in other media. Moreover, abnormal seedlings with the decayed and deformed seedlings and dead seeds were higher in paper media. We conclude that paper medium is not a suitable medium for germination of J. curcas and P. pinnata seeds. Based on easy availability and economic utility for J. curcas and P. pinnata, the river sand could be used as the testing media, but in that too, in sand media (SS) method should beadopted for obtaining reproducible results in the germination test. It was followed by quartz sand (QS) and vermiculite (VT) germination medium.

Fig. 2: Evaluation of Pongamia pinnata seed germination in different media and methods

Bahar (2008) reported that the choice of germination medium depends on the species being tested. Minute seeds are best germinated on top of paper while large seeds are best germinated in sand or on paper towel. Paper towel is more commonly used for germination of medium-sized seed because. Large seeds can also be rolled in paper towel when seed quantities are small but it is an inconvenient method to test a large number of seeds at one time. Sand is not suitable for very small seeds but is widely used for large seeds especially for tree seeds that require longer periods of time for germination. Sand can be sterilized easily and fungal development on sterilized sand is easier to be controlled. Sand also provides good contact between the seed and moisture because seeds can be pressed into the medium. Sand has often proven to be the best medium for germination of forest tree seeds (Bahar 2010; Hassanein 2010; Bahar and Singh 2007; Sagta and Nautiyal 2001).

Our findings are supported by the research of Egharevba et al. (2005, 1987a, b; Vilela and Ravette 2001; Docker and Hubble 2008; Thapliyal and Rawat 1991). Each of these authors recommends use of sand and in-sand planting for production of highest percentages of normal seedlings from irrespective the source seeds.

Conclusions

River sand is the best medium for evaluating the germination of normal seedlings in Jatropha curcas and Pongamia pinnata. Paper media (RT and TP) produced many abnormal seedlings, showing that these media are unsuitable for larger seeds.

Acknowledgements

We thank the National Oil seeds and Vegetable Oils Development (NOVOD) board for funding and supporting this project. We also thank the editors at Journal of Forestry Research for improving the quality of this manuscript.

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DOI 10.1007/s11676-014-0484-8

Project funding: This study is supported by National Oil seeds and Vegetable Oils Development (NOVOD), Board (Ministry of Agriculture, Department of Agriculture and Co-operation) and Government of India, Gurgaon (Haryana).

The online version is available at http:// www.springerlink.com

Department of Forestry, Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi -642103, Tamil Nadu, India.

E-mail: mariappann21@gmail.com

P. Srimathi, L. Sundaramoorthi, K. Sudhakar

Department of Seed Science and Technology, Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi -642103, Tamil Nadu, India.

Corresponding editor: Zhu Hong