This experiment sought to examine the effects of prolonged photoperiod and modified temperature and humidity in chile peppers, aiming to develop a protocol to accelerate their growth and enhance breeding efficiency. Four genotypes from three Capsicum species (C. annuum - Chimayo, Early Jalapeno; C. chinense - Orange Habanero; Chiltepin - C. annuum var. glabriusculum) were planted in two randomized flat trays per entry using SunGro propagation soil. After reaching the 2-3 leaf stage, they were transplanted into 8” pots, incorporating sterilized and LM-AP soil mixtures. The experimental population was grown in an improvised growth chamber with an average temperature of 25°C and humidity of 60% and exposed to a 20-hour daily cycle of 450 nm full spectrum LED grow lights and 730 nm Far Red LED grow lights and 4 hours of darkness. The control group grew in normal greenhouse conditions, exposed to normal daylight intensity and duration and an average temperature of 21°C and humidity of 40%. Weekly data recordings included plant growth measurements of plant height and leaf count. Basal branches were counted approximately 12 weeks after planting, and leaf widths were recorded 14 weeks after transplanting. Number of flowers and fruits were also recorded at 14 weeks after transplanting. Data were analyzed using RStudio, and Tukey HSD was used to detect differences between treatments and among genotypes. In terms of plant height, all experimental plants demonstrated a significant increase compared to the control group, both in absolute amounts and in rates, especially later in the growth stage. The leaf numbers in experimental plants were significantly lower than the control group, except for Orange Habanero, which showed no significant difference. Early Jalapeno, in both treatments, exhibited no significant difference in basal branches. In contrast, the remaining experimental plants displayed fewer or no basal branches compared to the control group. All experimental plants exhibited significantly wider leaves in comparison with the control group. While most experimental plants started flowering earlier, no significant differences were observed between numbers of flowers and fruits. The faster growth rates observed hold the promise of accelerated progress and improved efficiency in breeding initiatives, offering a fundamental shift in the way we approach crop development. Additionally, fewer number of basal branches may have implications for machine harvestability, as fewer basal branches is considered a desirable trait for machine harvesting.
