Investigations on seed retention strength in spikelets of Lolium multiflorum

Investigations were carried out in 2008–2009 to assess the seed retention strength in spikelets of various Lolium multiflorum genotypes depending on their growth stages. The cultivars (Turtetra and Mitos), breeding strains (SZD 1021, SZD 1022, SZD 1023, SZD 216 and SZD 228) and ecotypes were used. With the aid of a special testing machine, retention strength of successive flowers/kernels in spikelets as well as strength required to rachilla breaking of selected spikelets were determined. It was found that the examined Lolium multiflorum genotypes were characterised by specificity regarding seed retention strength in spikelets. This biological feature was smaller for top flowers/kernels and increased with the movement down the spikelet. It was found that in the examined genotypes of Italian ryegrass the seed retention strength in spikelets in the analysed consecutive growth stages was smallest in spikelets situated in the upper part of the inflorescence and the highest in the lower part