Seed loss as a result of pod shatter in spring rape and spring turnip rape in Finland

Abstract

The aims of this study were to evaluate seed shedding in spring turnip rape (Brassica rapa L.) and spring rape (B. napus L.) and to assess the effect of delayed harvesting on seed yield loss. Experiments on spring turnip rape (cv. Emma) were conducted in 1988-1990 and on spring rape (cv. Topas) in 1989-1990 in Jokioinen (60o49'N, 23o28'E). Rimmed tin boxes were used to collect seed from shattered pods. They were placed between the continuous rows before pods started to shatter. The shed seeds were collected two to three times a week. Susceptibility and timing of pod shattering varies between spring turnip rape and rape. However, before optimal harvest date spring rape does not shatter significantly more than spring turnip rape. Spring rape starts to shatter more compared with spring turnip rape after its optimal harvest date. It is also more sensitive to weather conditions than spring turnip rape. Furthermore, pod shattering after optimal harvest time differs among years. Weather conditions are discussed as one possible cause of pod shattering