Application of hydro time model for quantification of Malva sylvestris L. germination response to water potential

Introduction Seed germination is a complex biological process that is influenced by various environmental and genetic factors. Temperature and water potential are two primary environmental regulators of seed germination. Tall mallow (Malva sylvestris)is an important invasive weed in southwest Iran and also a medicinal plant. ). Tall mallow is native home in Western Europe, North Africa and Asia. This plant frequently found in cultivated fields, orchards, gardens, farmyards near manure piles, along roadsides, in towns, and in waste places and, can grow anywhere from 60 to 120 cm in length.Quantification of germination response to water potential is possible using hydro time model. In this study, application of hydro time model for Malva sylvestris L.   Material and methods  Experiments were conducted in 2015 at the seed laboratory of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Fruits of M. sylvestris were collected in April 2014 from Shushtar, Khuzestan (32°2'47"N, 48°50'18"E), located in southwest Iran. Seeds were separated manually from the fruits and stored in room conditions until their use. The laboratory temperature fluctuated between 30°C during day and 20°C during night. Germination response to water potential in different temperature were studied. Treatments included drought levels (0, -0.2, -0.4, -0.6, -0.8, -1, -1.2, -1.4 and -1.6 MPa) in temperatures of 15, 20 and 30 °C. The response of cumulative germination seeds to different potentials at different temperature was quantified using weibull function. All data were analysed by SAS ver 9.2. The hydro time model was fitted to cumulative germination. Goodness of fit of the hydro time models to all data was checked by constructing plots of the coefficient of determination (R2), the relationship between the observed and the predicted germination percentage and base water potential.   Results Results indicated that temperature in addition to germination percentage also on germination rate was effective. Also results showed that germination percentage and germination rate increased with increasing temperature, while germination percentage and germination rate reduced as a result of water potential increment. Also, results showed that the hydrot time model fit to data of tall mallow had high R2 values. According to the hydro time, the hydro time constant (θH) declined significantly with increasing temperatures, so that the minimum hydro time constant (10.01 MPa h) was attained at 30 °C. The increment of temperature resulted in significant reduction of base water potential, and the highest base water potential (-1.13 and -1.11 MPa) was obtained at 15 and 20 °C, and the minimum base water potential (-0.6 MPa) was attained at 30 °C. The minimum standard deviation of base water potential in population (0.31) was obtained at 30 °C. Using hydro time model for quantitation of M. sylvestris L.   Conclusion  Germination response to water potential at different temperatures, led to acceptable results. Utilizing the output of hydro time model at different temperatures can be useful in prediction of germination percentage in different water potential.