Influence of feral Raphanus sativus seed attributes and burial depth in seedling emergence dynamics

Abstract

Understanding the emergence patterns of agricultural weeds is paramount for effective management practices. This study investigates the emergence dynamics of feral radish (Raphanus sativus L.), a widespread weed in the Americas, unravelling the intri- cate interplay of seed attributes—low or no dormancy, darkness requirement, and indehiscent siliques—on seedling emergence. To explore this, we (1) buried isolated seeds and intact siliques at six increasing depths (0–16 cm) under controlled condi- tions, and (2) evaluated seedling emergence from both isolated seeds and intact siliques placed on the soil surface and buried at 10 cm under field conditions over 3 years. Our findings reveal that seedlings emergence was about five-fold higher from shallow buried than from surficial isolated seeds, and from isolated seeds than from seeds inside siliques, suggesting strong effects of burial depth and the pericarp. Even isolated seeds buried at 12 cm depth outperformed surface isolated seeds. The burial depth influenced emergence patterns; isolated seeds exhibited rapid emergence, with rates five times higher at 10 cm deep compared to those on the soil surface, showing no emergence after year 1. Conversely, the pericarp delayed and staggered seedlings emergence, contributing to the formation of a persistent seed bank for at least 3 years in both burial depths. Seedlings emergence from seeds inside siliques buried at 10 cm begins in year 1 and in those placed on the soil surface year 2, with emergence peaks predominantly in autumn. These findings enrich our under- standing of feral radish seedling emergence, providing valuable insights for the devel- opment of sustainable and efficient management practices.