Optimizing production of 'Fascination' and 'Carnivor' transplants for grafting using lower daily light integral and higher CO2

B. Huber, R. Hernández
Grafted watermelon seedlings offer several advantages for growers including resistance/tolerance to soil borne pathogens and increased yields. Consequently, the demands for grafted seedlings has increased. Precision indoor propagation (PIP) is defined as an enclosed propagation system that precisely controls environmental factors to increase plant quality and uniformity. However, PIP systems are energy intensive due to electrical lighting as the sole source light for photosynthesis. CO2 supplementation is inexpensive in systems with low air exchange rates and has shown to improve yield for many crops. The objective of this experiment is to reduce the light requirements using increased CO2 levels to maintain a high-quality seedling with reduced energy consumption. One watermelon scion ‘Fascination’ and one interspecific squash rootstock ‘Carnivor’ were subjected to three different light intensities 100±6, 150±10, and 200±11 photosynthetic photon flux (PPF: μmol m‑2 s‑1) (18 h) with a percent photon flux ratio of 42%Blue:58%Red (42B:58R). Furthermore, plants were also subjected to three different CO2 concentrations 439±23 (control), 1018±42, and 1589±10 μmol mol‑1. Seedlings were grown until the grafting stage and growth, morphology, and net photosynthetic rate were measured. Results for ‘Fascination’ and ‘Carnivor’ show that at the same light intensity (200 μmol m‑2 s‑1) plants in 1589±10 μmol mol‑1 CO2 supplementation had 24-34% greater dry mass, 11-23% greater leaf area, and 20-85% higher photosynthetic rate than plants in the control (439±23 μmol mol‑1 CO2). In addition, plants grown with 1589±10 μmol mol‑1 CO2 supplementation and 32-38% less PPF have the same plant dry mass as the control treatment (200 μmol m‑2 s‑1 PPF, 439±23 μmol mol‑1 CO2), thus reducing production costs.
Huber, B. and Hernández, R. (2021). Optimizing production of 'Fascination' and 'Carnivor' transplants for grafting using lower daily light integral and higher CO2. Acta Hortic. 1302, 103-110
DOI: 10.17660/ActaHortic.2021.1302.14
controlled environments, vegetable grafting, carbon dioxide, dli, watermelon, squash

Acta Horticulturae