Assessment of drought-tolerant characteristics of gamma irradiated rice variety MR263 in vitro / Imene Tatar

Fluctuating weather conditions and climate change are affecting agricultural
productions worldwide including rice yield. Combined with the increasing population
and decreasing land space for agricultural practices, biotechnological solutions are
needed to improve the livelihood of farmers and the country’s food security. Malaysian
rice variety MR263 is a popular lowland white rice which is susceptible to drought. This
study was conducted to assess the characteristics of gamma irradiated rice variety
MR263 that were tolerant to drought stress induced by polyethylene glycol 6000. The
seeds were gamma irradiated with doses 300, 350 and 350 Gy. Using in vitro tissue
culture, they were germinated on MS media, and the seedlings were introduced to
drought by the addition of 10% and 20% PEG 6000. It was found that the germination
percentage was highest in the control seeds (100%) and lowest in the 400 Gy irradiated
seeds (62.6%). Shoot lengths reduced with radiation dose, and so did the root lengths
and fresh and dry weights per treatment. The root lengths showed major increase at dose
350 Gy compared to the other treatments at 10% PEG. Fresh and dry weights generally
decreased with dosage and water stress levels. The highest fresh and dry weights
improvement was observed in seedlings irradiated with 350 Gy. The proline content
increased as the radiation doses and PEG concentrations increased with the highest
value being 11.8 ± 0.67 µM/g in the seedlings treated with 300 Gy and 20% PEG and
the lowest value being 1.3 ± 0.73 µM/g in the control seedlings. The levels of
carbohydrates in irradiated seedlings sharply increased compared to the control
seedlings at normal water levels, but did not drastically change with gamma radiation
and PEG. The least performance in terms of growth and development was observed at
300 Gy; this dose might have been too low to make substantial enhancement in the traits
of MR263. It was concluded that the seedlings which stood out amongst all were those
treated with 350 Gy, as they had the highest values of shoot and root lengths, fresh and
dry weights and proline levels. This treatment was deemed optimal to produce rice
seedlings which are tolerant to drought stress.