Preamble: As global temperatures increase, the conditions common vegetable plants grow in will deviate from what these crops were bred to experience, as well as the genetic experience of their ancestors. Farmers and gardeners will have to start adapting by growing varieties that are more heat tolerant; and plant breeders' sill have to start developing varieties by crossing heat tolerant strains with each other.
In previous seasons, I have grown Moskvich tomatoes, a Siberian variety that tolerates the cool temperatures of September quite well. In 2023, the season was so hot that the Moskvich varieties did poorly from August onward. However, the cherry tomatoes did exceptionally well. This gave me the idea to test a number of varieties that are considered heat tolerant for 2024.
As for beans, I typically have grown a fairly dependable and good tasting variety called Maxibel. Most season's, the beans go dormant from the heat for a period of time, making timing of the pod picking difficult to predict. This season, I wanted to try some other varieties and compare them to the Maxibel to see if they perform better by tolerating the heat and thus avoiding dormancy.
Question 1: Do different varieties of beans tolerate heat better than others, and if so, which types?
Though generally regarded as a sun loving plant that requires warm temperatures, beans will start to suffer heat stress when temperatures go beyond 29 degrees Celsius. Typically, the plants drop their blooms and cease growing until the temperatures moderate.
Prediction: Some bean types are quite heat tolerant; typically romano and dry beans. Green beans tend to do less well. There are hundreds of green bean varieties, all derived from the original dry beans of South America. Some of these varieties have retained some of the heat tolerance genes of the dry beans. I suspect that the romano beans will do better than both of my green bean varieties. I have included yellow wax beans with my green bean varieties to see if there is a difference as well.
In previous seasons, I have generally grown Maxibel. As they are a familiar variety, I will use these as my control. I have also grown Dragon Tongue romano beans, and will try another romano (Forrester) to compare their performance.
Method:
Data Gathering:
25 Row foot Dragon Tongue romano bean:
25 Row foot Forrester romano bean:
25 row foot Gold Rush yellow wax bean:
100 Row foot Maxibel green bean:
100 Row foot Jade green bean:
Data Analysis:
Conclusions:
Question 2: Do different varieties of tomatoes tolerate heat better than others, and if so, which types?
Though generally regarded as a sun and heat loving plant from the Mediterranean, tomatoes will start to suffer heat stress when temperatures go beyond certain ranges. Tomatoes grow best between 20 and 30 degrees Celsius. They become heat stressed between 30 and 40 Celsius, and cease growth altogether around 40 degrees. These temperature ranges are a generalization - some varieties will tolerate slightly higher temperatures, while others bred for northern climates may have lower tolerances.
Symptoms of heat stressed stressed tomatoes curled leaves, dropped blossoms (leading to lower yields) and generally slower growth. At higher temperatures, growth stops altogether and the plant ceases producing lycopene, the pigment that produces the color in tomatoes. The fruits may turn color on the outside, but remain undeveloped (green, poor flavor) on the inside.
Prediction: Some varieties may have a higher heat tolerance than the others, possibly due to the climate that they were bred in. Cherokee Purple and Prudens Purple (Tennessee) Cherokee Carbon (Northern California) will likely perform better than Moskvich (Siberia). Cherry tomatoes have consistently grown well during hot seasons.
In previous seasons, I have generally grown Moskvich and several cherry tomato varieties. 2023 was an exceptionally hot season and the Moskvich tomatoes did very poorly. I will use the Moskvich as a control to measure the performance of the other tomatoes against.
Method:
Data Gathering: Number of plants, variety, average Lbs. per plant
14 Sweetie Cherry tomato:
8 Moskvich tomato:
12 Prudens Purple tomato:
6 Cherokee Purple tomato:
6 Cherokee Carbon hybrid tomato:
Note: Due to uneven seed germination, I was unable to do an equal quantity (8 plants) of the non cherry types.
Other observations:
Signs of heat stress, heat induced dormancy periods, comments about season weather, etc.
Data Analysis:
Conclusions: