Developing drought-tolerant corn hybrids
If drought is often a challenge in your farming operation, you may be interested in new advances in drought tolerant corn and whether to include these hybrids in your crop rotation. This article describes
- the process currently used to create drought tolerant corn;
- why drought tolerance is a trait which is difficult to improve in comparison to herbicide resistance or insect resistance traits; and
- the limitations and benefits of drought tolerant hybrids.
Why Do Crops Need Water?
Crops need water to carry out processes necessary for survival. Water helps cool plants and transports dissolved nutrients throughout the plant and supports photosynthesis and plant growth.
The Nature of Drought Tolerant Traits and How They Affect Plant Processes
Why would you want multiple genes to improve drought tolerance in a corn variety? Drought tolerance is called a quantitative trait. Quantitative traits are heavily influenced by the environment and are controlled by large numbers of genes. Other traits, which are not influenced as much by environmental conditions and are controlled by only a few genes, are called qualitative traits. Examples of these are herbicide resistance and insect resistance. Quantitative traits are more difficult for breeders to improve due to the number of environmental factors influencing how the trait is expressed, coupled with needing to work with a larger number of genes.
Some of the environmental and genetic factors affecting drought tolerance include the timing and duration of water stress, soil type, heat, and humidity. All of these influence plant processes, such as closing of the stomata (openings in the plant leaf surface). The stomata allow carbon dioxide in to make sugars for plant growth and release water, increasing transpiration and protein production.
Genes related to drought stress can affect these and other plant processes differently. For example, one hybrid contains a trait which increases root depth and another which increases silking vigor. In the Corn Belt deeper roots mean the plant will find more available moisture deep in the soil profile. Improving silk vigor is important because prolific silk growth increases the likelihood of good pollination. Silks are 98% water by weight, which explains why drought can be so detrimental to silk development. More traits related to drought tolerance will offer multiple modes of action, such as these, in response to drought stress conditions.