by Jourdan M. Bell, Texas A&M AgriLife Extension and Research Agronomist, Amarillo

Corn hybrid selection can be an overwhelming decision; however, knowledge of hybrid characteristics can help producers correctly position hybrids to their production environment as well as minimize some in-season production risks. When selecting a hybrid, a few key characteristics producers need to consider are maturity class, drought tolerance, heat tolerance, ear flex, and staygreen expression. Selection of the correct hybrid maturity class allows the producer to match the hybrid to the available water; however, it is always important to remember that total water use changes with maturity length not the daily water use. This is an important consideration during peak water use periods. In addition to irrigation capacity, producers should consider pre-plant soil moisture profiles to at least three feet in addition to well capacities. In regions with limited water, it is essential to have sufficient stored soil water reserves to carry the crop through periods of high daily water demands; especially, if irrigation is insufficient and precipitation is not timely in order to avoid yield reductions. In areas with limited water, many producers are incorporating newer drought tolerant hybrids. While drought tolerant hybrids are able to use water more efficiently under water stress, cumulative seasonal water use is not necessarily less when trying to maximize yield. There are three drought tolerant hybrids currently on the market:

Droughtgard (Monsanto)

• Combination of native traits and transgenic
• Temporal pattern of water use varies not necessarily seasonal water use – ensures plant reaches flowering under favorable soil moisture

Artesian (Syngenta)

• Native Traits
• Enhanced stay green for deeper kernel set
• Aggressive silking
• Robust root system

AQUAmax (Pioneer)

• Native Traits
• Enhanced stay green for deeper kernel set
• Aggressive silking
• Improved Stomatal regulation

Heat tolerance, while often associated with drought tolerance, is a distinctive characteristic. Elevated temperatures can damage exposed silks and pollen, and at increased temperatures, less assimilate is produced per growth stage. Pollen shed occurs mid-morning when temperatures are lower, but we often see 10 to 20ᵒF differences in morning temperatures between different corn producing regions. Heat can also be managed with maturity class and planting dates in order to avoid high afternoon and morning temperatures.

There are three primary ear types: fixed ear, semi-flex ear and flex ear. Fixed ears do not change size. Fixed ear corn hybrids can be planted at lower populations, but in order to optimize yield, fixed-ear hybrids are best positioned in fully irrigated, high population environments. Semi-flex ear maintains size with high populations and optimal inputs while flexing to preserve yield at lower populations and inputs. Full flex ear hybrids will increase with optimal inputs and population in addition to provide producers the flexibility to maximize yields at lower populations. However, if full flex ear hybrids are under high populations with low fertility and water, there is often a yield reduction as the hybrids flexes backwards. Producers often recognize this with small ears. While ear flex truly provides a producer flexibility in management, it is important that the hybrids are positioned correctly to the available inputs.

Lastly, the presences of Staygreen can further enhance yield and drought tolerance. Rather than allowing senescence, Staygreen maintains transpiration and photosynthesis, which lengthens the duration of the grainfill period, kernel set and test weight. While variety trials are very helpful in demonstrating a hybrids yield potential in relation to other hybrid, hybrids should be positioned based on specific characteristics. It is recommended that producers consult with their Extension personnel and seedsman concerning hybrid characteristics and positioning.

Jourdan Bell
Assistant Professor and Extension Agronomist
Dept. of Soil&Crop Sciences
jourdan.bell@ag.tamu.edu