ASHS 2025 Conference

Speed breeding is a technique that utilizes controlled environments and optimal lighting (photoperiod) conditions to accelerate germination, development, and maturity of plants. One of the major constraints for its adoption and implementation in vegetable breeding programs is the high cost associated with growth chambers. The objective of this study is to develop a Speed Breeding protocol for chile peppers using an improvised, low-cost growth chamber constructed using polyvinyl chloride (PVC) plastic, greenhouse film, mylar reflective film, full-spectrum and far-red light-emitting diode (LED) growth lights. Four C. annuum L. genotypes, namely, NuMex Lotalutein (a serrano type), NuMex Odyssey (New Mexican), NuMex Las Cruces (cayenne), and Early Jalapeno (jalapeno) were planted in two randomized flat trays, using SunGro propagation soil, and watered twice daily. After reaching the 2-3 leaf stage, the treatments (control and Speed Breeding, SB) were transplanted into 8” pots, incorporating sterilized and LM-AP soil mixtures. The control group was cultivated in standard greenhouse conditions for growing chile peppers, exposed to normal daylight intensity and duration, and an average temperature of 21°C and humidity of 40%. The chamber was also constructed in the same greenhouse. From weeks 1 to 5 after planting, the SB-treatment was subjected to 20h/4h light/dark conditions daily, and 9h/15h light/dark after week 5. Light intensity was increased by ~100 photosynthetic active radiation (PAR) weekly after week 5, from ~150 PAR to ~800 PAR. Data was recorded weekly to examine the effects of treatment on germination rate, plant size, leaf number and color, number of flowers, buds, and fruits, and days to flower and fruit. There were significant differences (Tukey HSD, P < 0.05) between treatments for germination rates, number of buds, fruits, leaves, and days to flowering. The SB-treated pepper plants exhibited faster and higher germination, darker green leaves, and a higher number of buds and fruits compared to the control. For instance, SB plants started flowering, on average, about 20 ± 5 days earlier, germinated 5 ± 1 days earlier, and had, on average, 15 ± 2 more buds than the control. Notably, all genotypes under the SB-treatment had at least one fully mature fruit ~106 days after sowing. These results suggest that, at minimal costs, there is a potential to achieve increased generation times to accelerate cultivar development and genetic improvement in chile peppers.