Morphological and physiological change of rice (Oryza sativa L.) under water stress at early season

Water stress is a major factor affecting rice production. Water stress causes changes in physiology and morphology for plant tolerance to water stress. In this study, six varieties were examined for their tolerance to water stress. The check varieties for comparisons of tolerant, moderate tolerant and sensitivity to water stress, namely Situ Patenggang, Towuti and IR 64; while the test varieties in this study are three Aceh rice traditional varieties. Water stress significantly influences the number of tillers, length of internode, proline, chlorophyll a, b and the total content, leaf rolling, drying score and leaf recovery, in which the changes occur varies among varieties, in vegetative stages. Chlorophyll is the main indicator of rice tolerance to drought in the early season of the rice growing season. Varieties that have good adaptation to water stress are able to maintain their chlorophyll content. Leaf rolling, drying score and recovering from water stress show a small difference between three comparative varieties and three rice traditional varieties of Aceh in vegetative stage. To overcome water stress, it is necessary to change rice cultivation by adjusting planting time, planting season, using water stress tolerant varieties, traditional varieties and national superior varieties; changes in irrigation and fertilization management.