Hydrotime model analysis of lemon balm (Melissa officinalis L.) using different distribution functions

Abstract

Water potential is an important factor for a successful germination. The hydrotime model can help quantify the seed germination response to water potential (ψ). This present study aimed to investigate the response of lemon balm (Melissa officinalis L.) seed emergence rate to water deficit with six levels (−0.165, −0.35, −0.45, −0.85, −1.25, and Field Capacity (FC) with -0.03 MPa) as a pot experiment. In addition, the germination behavior was studied in six water potentials in PEG solution (0, −0.2, −0.4, −0.6, −0.8 and −1 MPa) as the completely randomized design in 2018. The data were analyzed through the hydrotime model and five distribution functions (Normal, Gumbel, Weibull, Logistic and Loglogistic) were fitted to data for lemon balm. According to the model criteria, the Logistic distribution gave the best fit by the highest adjusted R2 of 0.921 and 0.989, and the lowest Akaike index (AICc) of −1677.855 and −471.777 in the germination and emergence experiments, respectively. According to the results, hydrotime constant (θH) in the two experiments were estimated to be 49.891 and 83.991 MPa h, respectively, which were significantly different (P < .001). However, there was no significant difference between the mean base water potential (ψb(50)), which were estimated as −0.340 and −0.439 MPa in the germination and emergence experiments respectively. The suggested hydrotime modeling in the present study may help predict lemon balm seed germination and emergence in soil under water deficit conditions.