I didnt take all the pictures that I wanted yesterday, so I came back out this morning. And wouldnt you know it. It is too windy and I cant take any pictures in the field (I should have finished yesterday--theres probably a moral here!). So, I picked five stems that are in different stages of heading and tried to get out of the wind.
This stem is in full boot stage. You can see the awns poking out of the flag leaf whorl or collar. The leaf sheath is just starting to split. Lets see how big the head is now.
It sure is a lot bigger than the last time we saw it at the second node stage. It doesnt have a dark green color yet. You are probably asking, "where are the kernels?" They havent developed yet, but you can see where they will be. Notice the "rows" on each side of the head (Farmers like to call them "meshes"). Those are called spikelets. Inside each spikelet there are florets or flowers. When a floret is pollinated it will produce a kernel or seed.
|Part of this head can be seen, now that the leaf sheath is splitting open. This head is just a day or two ahead of the previous stem in the boot stage. Lets look at this head.|
|This head may be a little bigger than the first one, dont you think?. The stem or peduncle is getting bigger. It still has a lime green color.|
|The leaf sheath continues to open and the tip of the head is slightly above the flag leaf collar. Have you wondered how the head is moving above the flag leaf? The stem or peduncle, between the last node and the head is elongating and that pushes the head upward. Its the same way the growing point moves up within the stem like we saw several weeks ago. This head is a day older than the previous head. This one looks even bigger than the last one. Lets look at it.|
|This head is longer, but it also is getting bigger in diameter. The spikelets are enlarging. It is getting a little darker green.|
|This head looks like it is about 1/4 emerged. So, it probably has at least 2 days before it is completely emerged. You are probably thinking the head is at least Ĺ emerged, but Im looking at how much of the head is above the leaf collar.|
|This head is definitely darker green than the previous ones.|
|Now this head is about Ĺ emerged and it will be completely headed (Thats farmer talk that means the head is fully out of the boot.) probably tomorrow. During the boot stage and through heading wheat is very susceptible to freezing temperatures. If you want to see freeze damage during this stage click here. Lets look at the head.|
|This head is about as big as it is going to get. If thatís the case, you are probably wondering how many kernels it will produce. The total number of florets, where the kernels will develop, has been determined. But we donít know yet how many florets will develop kernels. Usually, a normal wheat head will have about 25 kernels (give or take a few). Heads from late tillers or younger tillers wonít produce as many kernels because the growing conditions become harsher later in the season, thatís to say, it gets hotter and drier. And they are generally smaller and they wonít have as many spikelets either.|
|Now, letís compare all five heads. Thereís quite a difference among the heads from boot stage to 50 percent headed. One of the big differences is the number of spikelets or rows. The head on the left (boot stage) has fewer spikelets (count them) than the others. Therefore, it is not as long. Heads will grow a little larger from the early boot stage to fully headed, but I donít want to give you the idea the heads will develop more spikelets. The number of spikelets a head will have was determined more than a month ago before the hollow stem stage. At the bottom of the heads on either side you can see spikelets that formed but didnít develop. These wonít produce any kernels.|