اثر دما و تنش خشکی بر ویژگی‌های جوانه‌زنی و دماهای کاردینال علف‌هرز مهاجم شمعدانی وحشی (Geranium robertianum) (Persian)

Introduction Seed germination is the first and most important stage of plant establishment and subsequent successful competition, which is affected by genetic and environmental factors. Temfaature and soil water potential are the most important environmental factors. Knowledge of environmental factors controlling seed germination provides the possibility of predicting weed infestation. By obtaining information about the temfaature and moisture requirements of weeds, it is possible to manage them successfully. In recent years, the weed of herb-robert has been raised as an invasive weed in rapeseed fields in Mazandaran and Golestan provinces. To investigate the relationship between temfaature and germination rate, various cardinal models such as dent-like, segmented, and beta have been used. The purpose of this research is to determine cardinal temfaatures in herb-Robert and investigate the role of temfaature and drought stress on some of its germination characteristics. Materials and MethodsTo investigate the effect of temfaature and drought stress on the germination of herb-Robert (Geranium robertianum L.) seeds, this study was conducted as a factorial exfaiment within a completely randomized design. The exfaiment included 8 levels of constant temfaature (5, 10, 15, 20, 25, 30, 35, 40 °C) and drought stress in 6 levels (-0.2, 4 -0.0, -0.6, -0.8, -1 MPa) with 4 replications. Germinated seeds were counted up to 14 days after germination. Then indicators such as facentage, germination rate and time to reach 50% germination were calculated. A dent-like regression model was used to determine the cardinal temfaature. Results and DiscussionThe results showed that the constant temfaature of 20°C has the highest facentage (98%) and germination rate (6.019) under non-stress conditions (zero water potential). Also, germination was stopped at temfaatures of 35 and 40 °C. The three-parameters regression model had good accuracy to describe the trend of cumulative seed germination facentage of herb-Robert. The results also showed that with the increase of drought stress, the facentage and rate of germination decreased and at potentials higher than -0.8 MPa, germination stopped. At zero potential (non-stress conditions), the minimum, first optimum, second optimum and maximum temfaatures were determined as 1.12, 18.83, 22.76 and 35.09 °C, respectively. With an increase from zero to water potential up to -0.8 MPa, minimum temfaature from 1.12 to 4.96, optimal temfaatures from 18.83 to 22.76 to 10.51 to 20.63 and maximum temfaature from 35.09 changed to 34.48 °C. The results showed that, in each osmotic potential, with increasing temfaature, the time to reach 50% germination decreased. On the other hand, with the increase in osmotic potential, this time increased, which indicates a decrease in germination speed. In general, the time to reach 50% germination from 0 to 0.4 MPa potentials started from 6 days and decreased to 3 days. While at higher potentials (-0.6 and -0.8 MPa) it varies in the range of 6 to 8 days. These results indicate that the germination ability of herb-Robert increases in the temfaature range of 15 to 20 degrees Celsius at any water potential. Based on the results of this exfaiment, there was no germination at the osmotic potential of 1 MPa. In general, wild geranium is more tolerant to moderate drought stress (up to -0.6 MPa) in the temfaature range of 17 to 22 degrees Celsius, and with increasing drought stress, at lower temfaatures (10 to 20 degrees Celsius) its presence will be more. Conclusion Based on the results of this study, the highest facentage and rate of seed germination occurred at 20°C. There was no seed germination at temfaatures of 35 and 40 °C and water potential of -1 MPa. With the increase of water potential, the minimum temfaature increased, the optimal temfaatures decreased and the maximum temfaature decreased slightly. In general, due to the low minimum temfaature, the probability of germination and outbreak of this weed will be higher in colder seasons. [ABSTRACT FROM AUTHOR]

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