Dose-response effects of EMS treatments on germination and early seedling traits in Moroccan paprika (Capsicum annuum L.)

Abstract

Abstract Ethyl methanesulfonate (EMS) is one of the most widely used chemical mutagens in plant breeding for inducing point mutations; however, its success is strongly dependent on the genotype, concentration, and exposure time. The present study aimed to evaluate the effects of different EMS concentrations and exposure times on germination and early seedling traits in paprika ( Capsicum annuum L.) in order to identify suitable preliminary treatment ranges for EMS applications. In this sense, seeds from two local genotypes of paprika from Morocco, ‘Lukus’ and ‘Beldia’, were tested under seven EMS concentrations (T0:0; T1:0.01; T2:0.02; T3:0.04: T4:0.08; T5:0.10; T6:0.50% v/v) for five different exposure times (0.5, 1, 4, 24, and 48 h) in addition to a control. The measurements included the germination percentage, mean germination time, time to 50% germination, germination speed index, and radicle length. Results showed that the effects of EMS treatments on the germination traits of both genotypes tested depended on EMS concentration and exposure time. The germination percentage and germination speed were significantly affected by the higher EMS concentrations (T5 and T6), with a reduction exceeding 70% in both genotypes. This effect was accompanied by a longer average time to germination and a slower rate of reaching 50% germination. Regarding the genotype factor, the ‘Beldia’ genotype exhibited greater tolerance to EMS-induced stress compared with ‘Lukus’. Multivariate analysis revealed that the first two principal components explained more than 79% of the total variability. Hierarchical clustering grouped EMS treatments into three distinct clusters corresponding to low-, intermediate-, and high-stress EMS conditions. Overall, the integration of germination kinetics and multivariate analyses allowed the identification of EMS treatment ranges associated with moderate physiological stress and acceptable germination performance. These findings provide preliminary insights into EMS dose-response behavior in Moroccan paprika genotypes and may serve as a basis for future mutation-breeding studies that require validation in subsequent generations.