Seed storage affects the competitive advantage of weeds: The case of Portulaca oleracea L.

Crop-weed competition causes major damage to land productivity because of its competitive edge over farm crops. The presence of weeds has been reported to reduce growth of a wide range of commercially grown crops. It is certainly true for UAE farmers who suffer from the competitive abilities of weeds, such as Portulaca oleracea L., in their farms. Hence, the effect of storage (stored vs fresh), seed burial depth, solarization duration (using Polyethylene plastic sheeting) of P. oleracea, a major weed in UAE farms, was investigated. Percent germination of P. oleracea seeds was lowest for stored seeds (33.9 and 36.9% for stored and fresh seeds; respectively at P < 0.05). The results of the germination rate followed the same trend as percent germination. Seeds buried at 2.5 cm had a significantly lower germination percent than those buried at 15 cm (P < 0.05). The analysis of variance also showed a significant storage by depth and depth by duration interactions (P < 0.05). Germination percent was consistently lower for seeds buried at 2.5 cm. This highlights the efficacy of soil solarization in ridding crops of unwanted weeds, such as P. oleracea. Moreover, seed germination percent, for both burial depths, declined as the solarization duration increased, which highlights that the duration of application of Polyethylene plastic sheeting plays an important role in the success of minimizing the impact of weeds. For germination rate, there was a significant depth by duration interaction (P < 0.05). Germination rate of both fresh and stored seeds was consistently lower for 2.5 cm burial depth than for 15 cm depth. In short, seeds of P. oleracea underwent detrimental effects from storage, burial depth and solarization duration. We posit that competition from P. oleracea may be greatly diminished if soil solarization becomes an integral part of weed control that is practiced early enough while P. oleracea seeds are still at the top soil. Solarization durations for as much as 30 days may significantly lessen the impact of P. oleracea competition of crops. Accumulating P. oleracea seeds over many seasons would make it harder for UAE farmers to minimize its competition with their crop species.