Wildcat Connection May 2018 - Page 12

This may be the “Charlie Brown” of wheat growing years. A nice warm weather stretch would be equivalent to Charlie confidently approaching the football, but the Mother Nature’s Lucy pulls the football away with record cold temperatures. The question that is on most wheat producers’ minds is how much damage have their plants taken.

The correct answer is it depends, which is the correct answer to almost every agricultural question. The two most important factors are how low the temperature fell and the growth stage of the plants.

Wheat yield is determined by a multitude of factors that include seed weight, seeds per head, and heads per area. While most know the growth and development of wheat, it is probably worth reviewing.

All wheat plants have a main stem that grows from the seed. This main stem is quite important (more on that later) to yield but there are additional stems that grow from the same plant called tillers. These can form in the fall, which contribute more to yield than the ones that form in the spring. Unfortunately, there was not an abundance of fall tillers formed last fall.

The main stem is always at a more advanced growth stage than the tillers throughout the growing period. Due to this, the most susceptible stalks to the recent cold are those main stems. This begs the question, just how important are the main stems to final yield?

I had hoped this would be a simple search through scientific journals to an easy answer. Unfortunately, for hard or soft red winter wheat grown in the southern plains, that is just not the case. If we consider durum wheat grown in the Mediterranean region, spring wheat grown in the northern plains, or Australian white wheat there is data available. While not a one-to-one comparison, the data should be at least somewhat applicable.

From the Mediterranean region study (Elhani, Martos, Rharrabti, et. al.), they researched wheat in ideal conditions (irrigated) verses a more stressful environment. Under ideal conditions, their research showed that the main stem contributed 68% of the yield and under a more stressful environment, it contributed 32%.

The spring wheat study (Otteson, Mergoum, Ransom, and Schatz) found that the main stem contributed approximately 55% of the main yield, the first tiller around 32%, the second tiller 11%, and all of the remaining tillers only 2%. The Australian white wheat study (Metho, Hammes, and Beyers) found that the main stem contributed 69% of the yield, the first tiller 25%, the second tiller 4%, and the remaining tillers only 2%.

Do these studies prove we have lost half or even more of our yield potential? A pessimist may say so, but we must consider the growth and development of the wheat once again. If the main stem is healthy, the plant focuses its photosynthetic product to that head. However, if it is damaged, the plant would then reprioritize its efforts into the surviving heads.

How much damage has occurred is a completely different question. There has been some yield lost, but there is still potential for at least satisfactory yield this summer. That is, at least, until Lucy (Mother Nature) pulls the football once again. For more information or if you have any questions, please call me at the office (620) 724-8233, or e-mail me at jcoltrain@ksu.edu, or visit the Wildcat Extension District website at www.wildcatdistrict.ksu.edu.

Questions on wheat damage?