Six varieties of rice, representative of those cultivated in California and other southern regions of the United States were grown in a series of nine experiments. In a greenhouse, seeds were sown into pots placed in a constant temperature water bath possessing compartments maintained at water temperatures of 60°, 75°, 60° and 90°F. Many characteristics of plant growth and development were influenced by water temperature. Generally shoot lengths and weights, root lengths and weights, leaf lamina, leaf sheath lengths and stomata number were greater at the higher, than at the lower, temperatures. The type and intensity of silica crystal formation in the leaves increased with increase in temperature. Stomata sizes were larger at lower, than at higher, temperatures. Irrespective of plants being submerged or non-submerged, at continuous or changed temperatures, the higher temperatures produced the greatest response. Californian varieties were found to be more sensitive than other southern varieties in their response to both low and high temperature treatments, indicating a greater range of adaptability. / Land and Food Systems, Faculty of / Graduate