Down and Dirty with Rachel

Jan 15, 2023 | Experiences, Information

When my brother and I were younger, my parents would give us each eight cents on the first night of Hanukkah and double the amount they gave us each night. By the eighth night, we had received a total of $20.40 and a better understanding of exponential growth. (Even holidays were educational in my house.) My parents knew enough about exponential growth to know that this present was safe for eight days but not much longer.

8th night of Hanukkah fell on Christmas in 2022

8th night of Hanukkah fell on Christmas in 2022

They also told us the story of the man who made a chessboard for a king and as payment asked for one grain of rice on the first square, two grains on the second square, four on the third, and so on for all sixty-four squares. The king accepted before realizing the impossible deal he had made. He was to owe the chessboard maker 9,223,372,036,854,775,808 grains of rice on the 64th square and 18,446,744,073,709,551,615 grains total. That’s approximately 9 and 18 quintillion grains, respectively.

The farmer-mathematician in me wondered how long it would take the king to amass this amount of rice if he saved seeds. If we assume that each grain of rice planted germinates and grows into a healthy plant, then 270 grains per plant is reasonable. By replanting each grain that is produced, the king could pay off his debt on the eighth year, from a purely mathematical point of view. However, if we consider that one rice grain is approximately .025 milligrams and consider global rice production, we are looking at anywhere from 860 to 1370 years, depending on how productive our rice cultivation is. (You can get in touch with me if you want the nitty-gritty of my calculations.)

The king may, however, breed a new variety of rice that produces lots and lots of tiny grains in a small area in order to pay his debt quickly. Humans have been saving seeds and breeding plants for around 10,000 years. You, too, can save seeds from your garden and select for plant traits that you like. Master Gardener Sam Thompson has been saving seeds for years and now grows plump, tasty tomatoes that thrive in our climate (see picture).

Saving seeds is a great way to ensure an adequate seed supply, contribute to a greater diversity of cultivars, grow plants to your taste, and have fun, among others. New Mexico State University has a few resources on saving seeds. Check out this Southwest Yard & Garden post and this Extension publication. I also recommend the book The Seed Garden: The Art and Practice of Seed Saving, by Lee Buttala, Micaela Colley, Shanyn Siegel, Jared Zystro. It is an interesting read even if you aren’t into seed saving. For instance, did you know that acorn squash and summer squash are the same species (Cucurbita pepo), but butternut squash is a different species (Cucurbita moschata)?

Happy New Year and may you grow some royally delicious veggies this year.

Note: I realized I made a typo in last month’s puzzler.​
The correct puzzler and answer are below.

Last month’s puzzler:

If  1 = 5
2 = 6,
3 = 7
4 = 8
Then 5 = ?

Last month’s answer: 1, because 1 = 5.

This Month’s Puzzler:

A man was looking at a picture and says, “Brothers or sisters, I have none, but this man’s father is my father’s son.” Who is the man in the picture?


Rachel Zweig is our Sandoval County Agriculture and Extension Agent

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