Controlled Environment Strawberry Propagation: CO2 Light Intensity, and Daughter Plant Rooting Experiments
Samson Humphrey, MS Seminar
Monday, July 22, 2024, 9 am
(Under the direction of Dr. Ricardo Hernandez, Chair)

Location: 121 Kilgore / Hybrid
Join Zoom Meeting: https://ncsu.zoom.us/j/92069221375?pwd=cQ9QtsmsZ02lU82FqlXDcxHKtqmHq1.1
Meeting ID: 920 6922 1375
Passcode: strawberry

Humphrey.Abstr.pdf

Abstract:
The US strawberry industry has a market value of over 2 billion USD, and produces over a million tons of strawberries every year. This fruit production industry depends on strawberry nurseries to annually provide new plant material. However, the conventional strawberry nursery system is plagued with many challenges and threats, including low availability and increasing costs of labor, increasing regulations on pesticides, and the high risk of disease. Controlled environment agriculture (CEA) may be a solution to these many challenges. The environmental manipulation and optimization of CEA could produce many more strawberry daughter plants per mother plant, compared to conventional systems. But, can CEA be an economically feasible solution?

We investigated the effects of CO2 enrichment and light intensity on the mother plants, comparing overall growth rate and the number of daughter plants grown per mother. Walk-in growth chambers at the NCSU Phytotron contained three CO2 treatments: 500, 850, and 1200 μmol mol−1, and two treatments of light intensity: 250 and 500 μmol m−2 s−1. We found that a greater CO2 concentration could increase the daughter plant yield by as much as 48%, and greater light intensity could increase the yield by as much as 28%. The economic analysis indicates that it may be economical to produce daughter plants indoors, even with the ongoing costs of electricity and CO2 consumption. These results indicate that controlled environments with elevated CO2 concentration and light intensity are able to produce many more daughter plants than field conditions.

In a second experiment, we investigated the effect of daughter plant size. In greenhouses and controlled environments, strawberry mother plants produce daughter plants in a range of sizes, with a few daughters that are very large, a few that are medium sized, and many daughters that are small or very small. The objective of this study was to investigate whether the small and very small daughters can successfully root and grow, and to quantify the growth rate differences between daughters of different sizes. We collected a large number of daughter plants, and split them into size categories based on their number of “peg roots”, then rooted them in a growth chamber for 28 days. We found that the small and medium plants had the best rooting rate and survival rate, while the very small and large plants had a slightly lower rate of success by day 28. Overall, the rooting and survival rate was higher than expected, and indicated that the majority of plants of all sizes (90+% overall) can be successfully rooted and sold. Taken together, these two experiments provide evidence that CEA can produce usable strawberry daughter plants more efficiently than in the field, especially when CO2 is elevated, light intensity is increased, and daughter plants of all sizes are harvested.