INSIGHTS
Ear flex is achieved through increases in kernel number (rows and length) and weight.
Hybrids differ in their ability to recover yield potential when planted at suboptimal seeding rates
Identifying hybrids with high ear flex potential can help overcome a suboptimal seeding rate when conditions are favorable for elevated yield potential.
Introduction
The ability to provide stable yields is an important selection factor when choosing hybrids for dryland environments. Hybrid selection strategies in these environments typically places less emphasis on high-end yield potential, and more on consistency under moisture deficit stress. This strategy limits yield potential when favorable environmental conditions align for elevated yield. Golden Harvest continues to research and identify hybrids that are both highly adaptable to moisture-limited dryland environments and able to provide yield upside when conditions are favorable.
Trials to Characterize Hybrid Adaptability
Table 1. Response of nineteen Golden Harvest hybrids to suboptimal planting populations.Agronomy in Action research trials are conducted annually to understand how Golden Harvest® hybrids perform under “defensive” dryland seeding rates when sufficient water is present. Trials are established at irrigated sites and individual hybrids are planted at 32,000 seeds/A and 17,000 seeds/A to illustrate dryland yield potential in an above-average rainfall year (Table 1). The optimal seeding rate (32,000 seeds/A) identifies the overall yield potential of each hybrid under optimum dryland conditions. The 17,000 seeds/A seeding rate allows us to identify hybrids that are better able to maximize yield when planted at a seeding rate that is suboptimal for the above average growing conditions by comparing yields to the more optimal seeding rate yields.
While raw yields in Table 1 do indicate the ability of each hybrid to maximize yield potential under optimal dryland conditions, it is still a scenario that rarely occurs naturally. Calculating yield recovery of each hybrid is a more useful indicator, as it identifies which hybrids are more effective at recapturing overall yield potential when plant population is suboptimal. 2024 trials tested nineteen Golden Harvest hybrids at sites in Nebraska and Kansas and found that, on average, they yielded 77% of their genetic yield potential when planted at the suboptimal population. As expected, a wide gradient in yield recovery existed among hybrids, ranging from 71% (G15J91 brand) to 90% (G09B15 brand) (Table 1). These responses indicate that there is significant variability in the ability of a hybrid to adapt to conditions that support high yield when it is planted at a suboptimal population.
Figure 1. Ear comparisons of two hybrids at 29,000 and 17,000 seeding rates where kernel number (G16Q82 brand) and kernel weight (G16K01 brand) were the primary contributor to overall ear flex.Ear Flex is Critical for Yield Recovery
Graph 1. Recovery efficiency off eight Golden Harvest hybrid brands tested in 2023-24. By ensuring that sufficient water is available through the use of irrigation at these sites, the observed hybrid responses are likely a result of phenotypic characteristic differences (i.e., ear flex) rather than how well they withstand drought stress. Ear flex occurs either through an individual increase in kernel number, kernel weight, or a combination of the two (Table 1). The timing of favorable or unfavorable growing conditions influences the type and degree of ear flex, especially in dryland environments. For example, total kernel number (through row number and ear length) is determined during vegetative growth stages. The maximum number of kernels is maintained when favorable conditions persist throughout vegetative stages. In comparison, maximizing kernel weight (via depth or density) through starch accumulation during grain fill stages can further increase yield potential after kernel number has been determined.
Identifying Adaptable Hybrids with Yield Upside
Table 2. Flex type and drought tolerance ratings of eight Golden Harvest hybrids tested in 2023-24. Multi-year testing is critical for confidently characterizing the ability of a hybrid to adapt to favorable environmental changes through ear flex. Eight hybrids ranging from 109-116 day relative maturity (RM) were tested within this trial in both 2023 and 2024. The multi-year results identified several hybrids such as G09B15, G09Y24, G10L16, and G16K01 brands as hybrids that are highly capable of recovering overall yield potential under optimum growing conditions when planted at suboptimal populations (Graph 1). Understanding which hybrids can maximize yields at normal dryland seeding rates when rainfall is adequate (Graph 1) and pairing these learnings with locally adapted hybrids that have agronomic characteristics suitable for dryland, such as drought tolerance (Table 2), can be great tools for dryland hybrid selection.
Summary
Planting dryland-adapted hybrids with high ear flex potential provides yield stability while also offering an opportunity to capitalize on potential yield when conditions allow. While these results do indicate potential hybrid candidates that can offer this upside, contact your local Golden Harvest seed advisor, sales representative, or agronomist to help select the best hybrids for your dryland strategy.
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