Introduction: Floodging is a stress that disrupts many physiological and biochemical processes in plants. Among these processes, we can mention photosynthetic capacity, root and stem growth rate, plant biomass production, water relations, carbohydrate metabolism, nutrition, and hormonal balance, which have been observed in corn and bean plants. Seed germination is one of the crucial and decisive stages in the growth cycle of plant species because it guarantees the successful establishment of the plant and its final performance. Heterotrophic growth of seedlings can be divided into two components: the weight of transferred or activated seed reserves and the efficiency of converting transferred seed reserves into seedling tissue. The reduction in the amount of seed reserve utilization and the reduction in the fraction of transferred seed reserves to seedlings can be due to the reduction of the hormone gibberellin and the reduction in the synthesis of hydrolytic enzymes in the germination process.
Materials and methods: This study was conducted on watermelon cultivar seeds in the Agronomy Laboratory of Gonbad Kavous College of Agriculture and Natural Resources in a factorial experiment with a completely randomized design in four replications in 2014. The treatments studied included: duration of the flooding period of 0, 24, 48, 72 and 96 hours and four cultivars (Charleston Gray, Crimson Sweet, Sugar Baby, and Sugar King). To conduct the experiment, all equipment was first soaked with plain water and dishwashing liquid and vitex and finally with plain water again, and then paper towels, vacuum containers and all equipment were placed in an autoclave at 120 degrees and a pressure of 30 atmospheres for 15 minutes for disinfection. Then, all seeds were disinfected with the fungicide difenoconazole at a dose of 2 per thousand. To investigate the effect of flooding on germination characteristics and seedling growth in each cultivar, two experiments were conducted.
Results: The effect of flooding stress, cultivar and the interaction between the two had a significant effect on all traits studied in the germination test. Also, after 24 hours of waterlogging, there was an increase in the speed, uniformity and percentage of germination, as well as the interaction effects of cultivar × flooding on all traits tested were significant at the 1% probability level. The fraction of seed reserves consumed also increased in all cultivars except for the Crimson Sweet cultivar at the 24-hour treatment level, but with increasing flooding stress after 24 hours, the fraction of seed reserves consumed in all seeds decreased. Also, the dry weight of the seedling generally decreased in all cultivars with increasing stress, which was significant after 72 hours.
Conclusion: In general, increasing the duration of waterlogging stress will have an adverse effect on all studied traits. It is suggested that this experiment for watermelon be conducted at different times and under natural field conditions to determine the duration that causes a decrease in traits in the varieties under evaluation. |
