Weedy rice is a problematic weed that infests paddy fields worldwide. Differing populations, with varying physiological and morphological traits, characterize this weed. In particular, seed dormancy makes its control difficult. The objective of this study was to evaluate the germination behavior of five Italian weedy rice populations (two awnless, two awned, and one mucronate) after exposure of seeds to different field storage conditions (flooding, burial, and dry soil surface) during winter in two sites (Grugliasco and Vercelli, Italy). Seed samples were taken from each population, storage condition, and site, every 15 d for petri dish germinability testing. The two sites displayed slightly different germination patterns, which were probably due to the differing climatic conditions. One of the awned populations showed the highest (always exceeding 80%) and fastest germination percentage in all field conditions and sites, compared with the other four populations. Although flooding promoted germination in one awnless population, it delayed germination in two others (one awned and one awnless), attaining only 20% germination after more than 100 d. In all populations, burial delayed germination, whereas seed placement on the dry soil surface enhanced it. Our study indicated that autumn tillage that promotes weedy rice seed burial should be discouraged; spring tillage that exposes seeds to the soil surface and cause their depletion should be encouraged. The tested technique of winter flooding can also improve weedy rice control, despite its varying efficacy among populations. Cycles of flooding and drying followed by spring tillage might improve weedy rice seed control.

The effects of winter flooding on the intertidal macrobenthic assemblages in the Guadiana estuary were studied by analysing several ecological parameters (abundance, biomass, species richness, diversity, degree of dominance of annelids and deposit-feeders species and number of predator species) as well as changes in the composition of the assemblages. Significant and systematic differences were found in the values of the ecological parameters, especially between winter and summer. We found a significant interaction between the factors ‘time’ and ‘site’, attributable to changes in abundance and composition of the assemblages. The assemblages showed a predominance of some opportunist species in most of the estuary after the flooding, suggesting that these species benefited from the new environmental conditions. Conversely, the assemblages in the mouth of the estuary were severely affected as was shown by the negative changes in biomass, species richness and diversity. These converse responses of the intertidal estuarine assemblages represent effects of flooding different from both catastrophic and negative effects on macrofaunal assemblages.