Forage rapeseed yield and nutrition following carpet-seedling transplantation on different planting dates

A field experiment on carpet-seedling planting techniques of forage rapeseed was conducted from 2016 to 2017 on five different transplanting dates (from 10 to 30 October at 5-day intervals), in the Yangtze river delta. Growth parameters, biomass yield, and nutritional content were analysed to clarify the optimal planting and harvest dates of forage rapeseed in rice fields. The results showed that the biomass of forage rapeseed increased rapidly from the seedling to final flowering stages, which was stable until the podding stage. The crude protein content was decreased at the podding stage. A delay in transplanting inhibited leaf growth and rhizome width at the seedling stage and plant height at the flowering stage. Compared to late transplantation (25 and 30 October), the biomass yield and crude protein content were improved when transplantation was conducted from 10 to 20 October. Whereas, in the plants transplanted on 10 October, the neutral detergent fibre content was significantly increased compared to the other treatments (P < 0.05). Furthermore, a significantly positive correlation was observed between forage yield and secondary branch number, rhizome width, first branch number, and effective leaf number pre-winter. Considering yield, nutrition, and storage, it is optimal to transplant seedlings from 15 to 20 October and harvest at the final flowering until the podding stage for forage rapeseed using the carpet-seedling planting technique in the Yangtze river delta .