Seedbank Dynamics and Vertical Distribution of Portulaca oleracea Seeds in Vegetable Fields Under Different Tillage Systems

Abstract

Portulaca oleracea (common purslane) is a widespread and highly adaptable annual weed that poses a significant challenge in vegetable production systems due to its prolific seed production, rapid growth, and persistence in the soil seedbank. The longevity and vertical distribution of its seeds are strongly influenced by tillage practices, which affect seed burial, dormancy, and subsequent weed emergence. Understanding seedbank dynamics is essential for developing effective and sustainable weed management strategies. The present study was conducted to investigate the seedbank dynamics and vertical distribution of P. oleracea seeds in vegetable fields under different tillage systems. Field experiments were carried out using conventional tillage, reduced tillage, and no-tillage systems to evaluate their effects on seed distribution across soil depths, seed persistence, and seasonal emergence patterns. Soil samples were collected from different depth intervals and analyzed for seed density and viability, while weed emergence and population dynamics were monitored throughout the cropping season. The results demonstrated significant differences in seed distribution and persistence among tillage systems. Conventional tillage redistributed seeds to deeper soil layers, resulting in a more uniform vertical distribution profile, whereas reduced and no-tillage systems retained a greater proportion of seeds near the soil surface. Surface-concentrated seeds in conservation tillage systems exhibited higher germination and emergence rates due to favorable environmental conditions such as light exposure and temperature fluctuations. In contrast, deeply buried seeds showed prolonged persistence and delayed emergence, contributing to long-term seedbank maintenance. Seasonal fluctuations in seedbank density indicated continuous replenishment through seed production in unmanaged plots. The findings highlight the strong influence of tillage practices on the ecology and persistence of P. oleracea in vegetable agroecosystems. Understanding seedbank dynamics and vertical seed distribution provides valuable insights for designing integrated weed management programs aimed at reducing seedbank replenishment, minimizing weed emergence, and improving sustainable vegetable crop production.