Corn plants develop through growth stages that are well defined and easy to identify. Crop managers can adjust some environmental conditions to increase yield. Knowing how a corn plant develops is crucial to promoting and applying management practices in the field to make a crop more sustainable and profitable.

Plant growth is divided into vegetative and reproductive stages, each with morphological characteristics and physiological processes. Corn growth and development are measured by the amount of dry weight accumulation in the plant that happens through photosynthesis, a physiological process in which plants manufacture carbohydrates, proteins, and oils, and which is directly related to environmental conditions. Thus, corn growth and yield are the result of interactions between genetics and the environment during the plant life cycle.

Farmers can manage some environmental factors to maximize yield, such as seeding at the right time, using adequate plant density, fertilizing the soil, and optimizing weed, insect, and disease control. Other factors, such as air temperature and solar radiation, cannot be controlled but do affect the way plants develop. Understanding how corn plants grow helps producers identify management practices to obtain higher yields.

Corn plant development is divided into vegetative (V) and reproductive (R) stages as shown in table 1. Vegetative emergence (VE) occurs when the coleoptile, or spike, emerges through the soil, and the vegetative stages are numbered V1 through Vn, where n is the number of leaves with visible leaf collar until the tassel emerges (VT). The collar is the point where the leaf blade visually separates from the sheath and the stalk of the plant, and V stages refer to the number of visible leaf collars. Each V or R stage is defined only when 50 percent or more of the plants in the field are in or beyond that stage.

See table 2 for more detailed information on corn growth stages and management practices.

The vegetative and reproductive stages comprise the development of an individual plant; however, determining the specific stage of an entire cornfield requires that at least 50 percent of all the plants be at that stage or beyond. To adequately and accurately determine the average stage of development, collect plants from different places in the field, including at least one 10-plant sample for every 10 acres. Select plants randomly at each inspection site, but avoid selecting only the largest or most vigorous ones. To ensure random selection of plants within a row, try to evaluate consecutive plants that have an undamaged main stalk.

Appropriately and accurately identifying growth stages helps guarantee that those involved in corn production use the same terminology when discussing corn development, thus reducing the risk of damaging a field with a poor management practice decision. If, for example, herbicide treatment is recommended before corn reaches the V4 stage or if a fertilizer application at the right time provides a greater response, identifying which leaves are included to properly identify the stage makes for a more informed decision.

Reference

Ritchie, S. W., Hanway, J. J., Benson, G.O., and Herman, J. C. How a corn plant develops. 1993. Special Report 48.

Eros Francisco, Extension Specialist, Assistant Professor, Crop, Soil, and Environmental Sciences, Auburn University.

New February 2022, How a Corn Plant Develops, ANR-2863