As a rice plant grows and develops, it progresses through a number of different growth stages until it reaches harvest maturity and is ready for the combine. Most of our currently grown rice varieties need approximately 120 days from seed germination until the grain is ready for harvest. However, rice growth and development are temperature-dependent. So, June-planted rice requires fewer days to complete its life cycle than March-planted rice because the average daily temperature is higher in June.

After planting, the rice seed germinates and develops into a seedling (seedling stage). For the first two to three weeks of its life, that seedling is living mainly from the stored reserves in that seed while the root and leaf systems develop to the point that they can provide for the growth and development of the plant.

Under good growing conditions, after about 30 days, the rice plants begin to develop tillers or stools (tillering stage). Tillers are secondary shoots that originate at the crown (base) of the rice plant. Each of these tillers will produce a panicle or seedhead on which the rice grains are later formed. The number of tillers produced is dependent on plant population, nutrient availability, plant health or stress level, etc. Rice farmers try to keep the rice plants in ideal growing conditions to optimize the number of tillers because this is an important component that will later help determine yield.

At approximately the midpoint of the 120-day cycle, rice plants slowly shift from solely vegetative growth to a combination of vegetative and reproductive growth. The onset of reproductive growth means that the plant starts the process that eventually will lead to grain formation. Because this occurs at about the midpoint of the plant’s growth cycle, this stage is often referred to as midseason. The shift to reproductive growth is also often referred to as the green ring stage because if the base of the rice stem is properly dissected, a green band is visible encircling the stem at this stage. This green band occurs from the accumulation of chlorophyll below the stem node (joint). Chlorophyll is the substance that gives plants the green color and is necessary for photosynthesis. Photosynthesis is the process in which carbohydrates are synthesized from carbon dioxide and water using light as an energy source. It’s the process that makes plants grow.

The green ring stage is critical for rice producers. If a rice field is to be drained and dried to prevent the physiological disorder straighthead, this should be done before this green ring stage. Also, if a rice farmer plans to use the herbicide 2,4-D, this material can only be used safely within a 5- to 7-day window around this green ring stage. Using this herbicide before or after this window can often cause injury to the rice plants. This stage is also the latest that several other rice herbicides can be used. As with any pesticide, application timing information is always provided on the label.

The green ring stage is important to the timing of nitrogen fertilization. This is when most fields will receive the final application of nitrogen-containing fertilizer. It is especially important that the rice plants have adequate available nitrogen as the grains begin to form within the stems. This also will help ensure maximum yields later.

Other later growth stages for rice are booting and heading. In the booting stage, the panicle (seedhead) forms and enlarges within the stem. This causes a noticeable bulge in the upper portion of the stem. As the panicle becomes more developed, it pushes its way out of the stem and becomes visible. This signals the initiation of the heading stage. The late-booting/early-heading stages are typically the proper timeframe for applying foliar fungicides to minimize the damage from fungal diseases, which are often prevalent in Louisiana rice production.

After the panicle has emerged, rice farmers need to start scouting for infestations of the rice stink bug. This is a piercing-sucking insect that causes yield and quality damage by feeding on the developing grains after heading. If populations are high enough, this will warrant an insecticide application to control this damaging pest.

As always, for the latest information on rice production, consult your county agent or the LSU AgCenter Web site. To watch and learn how rice goes, go to the Rice Station’s blog.

Permission granted from B. Leonards (LA. Farm & Ranch) on June 2, 2008 to republish article on the LSU AgCenter Website.