Anna Myers McClung, U.S. Department of Agriculture—Agricultural Research Service, Rice Research Unit, Beaumont, Texas
RICE: Chemistry and Technology, Third Edition
From seeding to harvest, the growth and development of the rice plant occurs over a span of approximately four months under typical growing conditions in the United States. The primary developmental phases of the rice plant include germination, vegetative, reproductive, and grainfill stages. A detailed description of the morphological changes that occur within each of these phases has been given by Counce et al (2000). Weather, field conditions, cultural management methods, and genetics of the crop influence the physiological processes that occur within the plant and thus affect the duration of each phase as well as the composition and dimensions of the grain that ultimately develops. For example, in the southern rice-growing region of the United States, planting rice at a relatively early date (e.g., February) under cool conditions can result in slow seedling emergence and initial vegetative growth, with grainfill occurring under very warm conditions (e.g., July). Planting in this same region at a later date (e.g., April) and under warmer field conditions generally results in rapid seedling emergence and vegetative growth, with grainfill occurring in relatively cool temperatures. Because of this, breeders test new genetic materials over multiple years and locations to get a better indication of the general performance of a cultivar in response to a wide range of environments.