Describing the growth of pepper plants is essential for efficient management and the selection of superior genotypes. The objective of this study was to fit nonlinear growth models for the height and crown diameter of ornamental pepper accessions under heat stress. Height and crown diameter were evaluated every four days in two environments: (i) a greenhouse with humidity and temperature control and (ii) a greenhouse without control of these factors. The Logistic, Exponential, Gompertz, Richards, and Von Bertalanffy models were fitted. The results indicate that the choice of model depends on the characteristic measured and on the environment. The Gompertz, Richards, and Logistic models satisfactorily described plant height, while the Von Bertalanffy ( R²= 0.99) model better represented the behavior of crown diameter under heat stress, characterizing a gradual deceleration of growth. These models should be used to estimate parameters that assist in the selection and management of ornamental pepper plants.

Water stress compromises morphological and physiological aspects of pepper plants (Capsicum spp.), affecting their development. Polyethylene glycol (PEG) is widely used to simulate drought conditions in vitro, making it possible to assess crop tolerance to water restriction and assist in the selection of more resilient varieties. This study aimed to evaluate the in vitro germination, initial growth, and stomatal characteristics of ornamental pepper accessions subjected to different levels of water stress induced by PEG 6000. The study assessed seven pepper accessions and five concentrations of PEG 6000 (0%, 5%, 10%, 15%, and 20%) in Murashigue and Skoog media. Under PEG-induced water deficit conditions, no germination occurred at concentrations above 5%, unlike other studies observed with Capsicum. This result highlights the effect of genotype on tolerance to PEG levels. Water deficit resulted in a 13.1% reduction in germination compared to the control (p<0.05), in addition to significantly affecting the percentage of dry matter in the shoot and roots. A decrease in stomatal density (51.6 to 35.4 stomata mm⁻²) and in the width of the stomatal midpoint (from 14.16 µm to 12.62 µm) was also observed. Among the genotypes evaluated, accessions CPCE 020, CPCE 018, and CPCE 011 showed better performance under stress, demonstrating greater tolerance to water deficit.