Effect of Cold Stress on the Anatomy and Morphology of the Tolerant and Sensitive Cultivars of Rice During Germination

Plants face many stresses in nature and have different defense mechanisms against stress. Rice is a cold sensitive plant and its product considerably decreases under cold stress. Since rice is an important crop, recognizing the tolerant cultivar and their defense mechanism against low temperature seems necessary. In the present study anatomic and morphological features of tolerant (Onda) and sensitive (Nemat) rice varieties were studied at the germination phase under low (10, 15°C) and room temperature (25°C) for a period of of 8 days. Results show that dry weight, length of the hypocotyl and radicle of both Onda and Nemat cultivars under stress were decreased. The decrease was greater in the Nemat cultivar than the Onda cultivar. In addition, anatomic features of both cultivars under cold stress underwent some changes including increase of thickness of suberin layers and decrease of the amount of aeranchyma tissues. Changes observed in the two varieties of rice were towards increasing resistance to low temperature stress. The Onda variety had a more suitable defense mechanism compared to the Nemat variety.