Impact of Soil Burial Depths on Survival of Weedy Rice Seeds: Implications for Weed Management

Abstract

Weedy rice (Oryza sativa f. spontanea) is a noxious weed infesting rice fields worldwide and causes great yield losses for cultivated rice. Effective management of this weed is essential for the world’s rice production. Yet, the management of weedy rice is challenging. One of the reasons is that shattered weedy rice seeds stored in soil often trigger great weed proliferation in the succeeding crop seasons. To study the survival of weedy rice seeds in soil seedbanks, we conducted 90-day soil burial experiments at different soil depths from 0–25 cm, using weedy rice seeds from Jiangsu Province in China. Results from two independent experiments under the rice field and laboratory conditions indicated significant differences in seed death ratios (SDRs) and induced seed dormancy ratios (ISDRs) of weedy rice at different soil burial depths. Weedy rice seeds exposed to the soil surface (0 cm burial treatment) had the highest SDRs and lowest ISDRs. An evident pattern of quickly declining SDRs with increased soil burial depths was identified from this study, suggesting rapid losses of seed viability on the surface and in shallow layers of soil. Our findings provide a useful guide for designing strategies to effectively control weedy rice by maintaining shattered seeds on the surface or in shallow layers of soil. The practices can easily be achieved through adopting the no-till farming system, which can substantially minimize viable weedy rice seeds as an important component in comprehensive weed management strategies.

Keywords

• no-till farming
• rice field
• soil seed burial experiment
• seed viability
• soil seedbank
• weed management