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Paper ID: 91

Effects of Acute Gamma Irradiation on the Morphology of Stevia rebaudiana

Aida Khalida Hamdan1, Azhar Mohamad3, Nor Azma Yusuf1,2 and Shamsiah Abdullah1,2*

1Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA, Cawangan Melaka Kampus Jasin, 77300 Merlimau, Melaka, Malaysia

2Agriculture Biotechnology Research Group, Universiti Teknologi MARA Malaysia

3Agrotechnology & Bioscience Division, Agensi Nuklear Malaysia, Bangi 43000 Kajang, Selangor Darul Ehsan, Malaysia

Email: shamsiah3938@uitm.edu.my

Stevia rebaudiana Bertoni is cultivated in many regions across the world and famous for its sweetness. Stevia is a short-day plant therefore, with almost a constant day length less than 12 hours in Malaysia cause to generate flower early. The plants have very short vegetative period, resulting in low leaves yield and as a result low content of steviol glycosides compound. Cultivation of stevia in Malaysia is a challenge due to lack of suitable variety. Gamma irradiation can generate genetic variability to improve the plant. The response to gamma irradiation varies among plant species and varieties and affected by the total irradiation dose and dose rate. The method applied was acute gamma irradiation. Seeds of stevia were irradiated with six doses of gamma rays (50, 100, 250, 300, 400 and 500 Gy) to investigate the effect of radiation on germination ability, survival rate, plant height and other morphological variations. From the observation, irradiation treatment affects the plant growth. The radio sensitivity test indicated that LD50 was approximately 182 Gy. The number of days for seed to germinate was varied in all treatments and none of the seedlings survived at 400 Gy and 500 Gy of irradiation. The plant height recorded the highest in treatment 50 Gy (142.0±1.98). Meanwhile, compared to non-irradiated controls, the number of leaves and the number of branches were decreased as the doses increase. However, the width and the length of leaves recorded was highest in treatment 0 Gy (control) with 3.55±0.32 and 8.23±0.61 respectively. Overall, our findings suggest that low doses of radiation (below 100 Gy) is the optimum doses to study the improvement of stevia by acute gamma irradiation.

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