A PROFILE OF THE POTENTIAL FLORA IN MAIZE FIELDS OF THE PO VALLEY

Qualitative and quantitative surveys (biological and ecophysiological spectrum, structural organization, seed bank size) of the potential flora (PF) in maize (Zea mays L.) fields of the Po Valley are reported. Data were collected from 45 sites and two sampling depths (0–20 cm and 21–40 cm). Soil seed content was highly variable, ranging from 1660 to 53371 seeds m−2, with an average value of 10391 seeds m−2 and a median of 5500 seeds m−2. Seed stock was lower than 2000 seeds m−2 in 6.6% of the sites and over 10000 in 26.6%. Six species were found in more than 50% of the sites, representing 27.7% of the total stock: Anagallis arvensis L., Chenopodium album L., Stellaria media (L.) Vill., Echinochloa crus‐galli (L.) P. Beauv., Amaranthus spp., Polygonum persicaria L. + P. lapathifolium > L. Overall, 63 species were recorded, the species number per site ranging from 4 to 25, with a median value of 11. Therophytes accounted for 90.6% of the species and 94.3% of individuals. Of the species, ...