Precipitation during anthesis reduces seed set in perennial ryegrass

Abstract

In perennial ryegrass seed production, the establishment of seed yield potential occurs until the point of anthesis. However, utilizing potential seed yield is predominately focused on processes after anthesis, namely seed set (%) and seed filling. In practice, seed yield is the product of the number of harvested seeds remaining after cleaning and average seed weight. For this study, the anthesis patterns and seed set were recorded in a diploid variety grown in seed production fields in three different Danish regions with contrasting weather conditions and investigated in 2013 and 2014. Increases in the total precipitation during anthesis reduced the anthesis synchrony and the seed set, which ranged from 50% to 66%. Under semi-controlled environmental conditions in which the influence of precipitation was excluded, the seed set was found to be influenced by the floret position in the spikelet and ranged from 73% in the florets in basal positions to 25% in the distal florets. It is suggested that a lower number of florets per spikelet will reduce the anthesis period. These results may provide insights for breeding programmes focused on increasing seed yield.