ecological requirements of germination

White morning glory (Ipomoea lacunose L.) is one of the weeds that have recently spread in the fields of Golestan province and has become a serious challenge for farmers. In this study, the effect of different environmental conditions, including constant temperature, alternating temperature, water stress, salinity, high temperature, and burial depth on the germination and emergence of three seed populations of this plant collected in 2018, 2019, and 2020 (at the time of the experiment, these seeds were after-ripped 15, 3, and 0 months, respectively) were investigated. All experiments were conducted based on a completely randomized design with three replications. The results showed that the response of germination to the studied environmental factors was different in seed populations. Germination percentage started at 10°C and increased with increasing temperature. Although the germination percentage was significant at 40°C, it was completely stopped at 45°C. Alternating temperature compared to constant temperature increased the germination in the range of low temperatures; however, there was no difference with the constant temperature in the high-temperature range. The water potential required to reduce 50% of germination in the seeds of 2018, 2019, and 2020 was -0.83, -0.82, and -0.43 MPa, respectively. The tolerance of this species to salt stress was much higher than to water stress, and the increase of salinity up to the potential of -1.1 to -1.4 MPa reduced its maximum germination by 50%. Increasing the high temperature to 80 and 100 °C stimulated the germination, and no seeds survived at 120°C. In the populations of 2018 and 2020, the emergence percentage of seeds increased with the increase of burial depth; so that it reached its maximum value at a depth of 3 cm. By increasing the burial depth, the percentage of seedlings emergence of these populations decreased and stopped at a depth of 9 cm. The seedlings emergence of 2019 population also happened with the same process (but in smaller numbers), but no seedlings emergence occurred at a depth of 5 cm. In general, the results of this study showed that the reaction of white morning glory germination to environmental factors is different. Knowing the germination response of this species against the mentioned factors can help predict the germination and emergence of this plant to design suitable management strategies.