Key Points
- Delaying closing into late October has consistently given the highest seed yields and the best economics; late closed crops often have high seed head densities even though up to 40% of growing points may be removed.
- Frequent grazing of crops results in delayed movement of the growing point and may induce more heads to develop. Removal of main stem tillers resulted in high seed head numbers at harvest due to an increase in later tillers.
- Crops which were laxly grazed required an earlier closing date due to the growing point extending earlier in the season.
- Increasing the amount of total N available to an Italian ryegrass seed crop, above approximately 160 kg/ha, reduces seed yield and increases the amount of vegetative growth.
- Seed head density appears to be the main variant among seed yield components, while others(spikelet number, TSW, seeds/spikelet)appear relatively stable over a wide range of inputs.