Effect of Permissible Inhibitors from Mixing of Several Medicinal Plants on Weed Seed Bank to a Depth of 20 cm Soil

Weed seed bank in the soil is an essential source of weeds that enables them to be present in the fields. The seed bank density in a crop may reach a million seeds per square meter. Depending on the crop operation, crop rotation, and herbicide selection, the weed seed bank differs according to the location and time. Due to the economic benefits and improved crop ability, plant remains have become an attractive and acceptable way in agriculture. Allelopathic plant remnants can have a beneficial effect on weed control. The allelopathy of these plants plays a vital role in controlling the seed bank of weed soils. Therefore, this study was conducted to investigate the effect of mixing different amounts of residues of three medicinal herbs on the potential of the weed seed bank in the Malekan region.

This study was carried out at Malakan Azad University labs in 2018. Treatments included mixing different amounts of residues (0, 50, 100, and 150 g / m2), and three medicinal plants were cumin, seaweed, and marjoram. Samples had taken from a depth of 0 to 20 cm in an ocher system (7 cm radius) to measure the soil's seed bank. Weeds were isolated, and their species were identified. Laboratory studies were conducted to determine the germination strength of these seeds. This part of the experiment was carried out with three replications in a completely randomized design.

In total, 53915 weed seeds were detected per square meter. The highest seeds in the soil belonging to weed carnivorous and lambspeed were 33254 and 12457 seed per square meter of soil, respectively. The seeds of these two weeds included 95.4% of the seed bank of soil weeds. In this study, the remnants of seaweed and marigold caused a significant decrease in germination characteristics and the growth of seedlings of these weeds. Remains of cumin have little effect on the traits studied. Seed germination and seedlings growth of these weeds decreased by 44.7% and 84.9%, respectively.

By increasing the amount of application of the remains, a more significant reduction in germination and weed growth was achieved. The remnants of the two herbs had a similar effect on germination and seedling growth. Overall, this study showed that the remnants of medicinal plants could reduce the diversity and abundance of seed banks of soil weeds.