Achieving Potential Herbage Seed Yields in Species of Temperate Regions

The potential seed yield (PSY) of a crop is represented by the total number of ovules present at anthesis in a unit area and is very high for nil forage species. However, seed yield or the agricultural realised seed potential (ARSP) is very low especially if compared with major grain crops (e.g., 15% vs 40% of PSY, respectively). The need for obtaining primarily high yield of high quality forage indicates that seed yield should be increased by improving the efficiency of the reproductive system rather than increasing its size. Seed setting and development and seed shattering are the characters to be primarily considered in breeding programmes for seed yield increase, A deeper knowledge about the physiology of the forage plants grown for seed is believed important to improve the utilisation of ovule sites. Induction and initiation of flowering are critical stages to obtain high PSY; they depend mostly on environmental and nutritional conditions. Control of lodging and pests, improving leaf area duration and photosynthetic efficiency, are very important; breeding work has to play a key role in this context owing to strong limitations imposed on the use of chemicals for economic reasons and pollution concern. The choice of suitable environments for seed production and the management practices (how to obtain the optimal density of inflorescences per m2, use of fertiliser, chemical control of plant growth, control of weeds and pests, pollination, harvest) contribute highly to ARSP.