The summer of 2020 was hot and dry in S.E. Kansas. In fact, it was so dry that normal nut development was inhibited. This past week, I was collecting nut samples when I decided to see how much nut size and shape was effected by comparing nuts harvested this year with nut samples I have saved from the high rainfall year of 2019. Since most of the nut samples I've been collecting are from my breeding project, several examples pictured below are numbered selections. However, I collected Kanza nuts to illustrate the impact of dry weather on a known cultivar. You should note that all of the nuts collected in 2020 have darker shells that 2019. That is because the 2020 samples were just pulled out of the husk (at shuck-split) and are still quite wet.
The Kanza pecans from 2020 are visibly smaller that 2019. In addition, the 2020 nuts are shorter and more rounded. The good news for Kanza this year is that we received just enough rain in late August/early September to completely fill out the kernels inside the shell.
Dry weather had minimal impact on the overall size of KT114. However, nut shape was effected. The 2020 nuts are not as blocky as the 2019 nuts. You can see the difference by looking at the base and apex of the nuts.
KT217 nuts collected in 2020 illustrate two common changes in nut appearance associated dry weather. First, overall nut size is smaller. But secondly, the 2020 nuts are more tapered toward the base. Remember, all nut development processes start at the apex and work down toward the base. In the case of KT217, water became increasingly limited during nut enlargement resulting in a nut that has a much smaller diameter base.
KT252 nuts are much smaller in 2020. The nuts are less blocky and ever show some basal taper. The overall changes in nut shape in 2020 make it hard to believe that nuts from 2019 and 2020 came from the exact same tree.
Since irrigation is not an option for my pecan grove, yearly fluctuations in nut size and shape are to be expected. Each year, I collect nut samples from each cultivar and breeding selection in my orchard. Part of the data I collect from these samples is a photographic record of nut appearance. As the years progress, I'll be able to see exactly how each clone reacts to variable weather conditions.
