The application of plant growth regulator in Italian ryegrass seed crop

Abstract

In seed crops of many temperate grass species stem lodging occurs during reproductive development. Nitrogen (N) spring application maximizes grass seed production, but influence the incidence and severity of lodging. Therefore, we analyzed the effect of different N rates (0, 50 and 100 kg ha−1) in spring and growth regulator trinexapac-ethyl (TE) doses (0, 0.5 l ha−1 and 1 l ha−1; Moddus 250-EC) on morphological parameters of two commercial Italian ryegrass (Lolium multiflorum Lam) cultivars, K-13 diploid and K-29 tetraploid type. Before swathing, internodes length, stem length, spike length and the number of spikelet from 10 randomly picked tillers per plot were measured. The increase of N rate significantly increased the fifth and sixth internodes length of cv. K-29. Also, significant decrease of internodes length was achieved in cv. K-29 with 1 l ha−1 TE, while stem length in cv. K-13 was unchanged by TE and N spring application. Cv. 29 had higher spike length than cv. K-13 and TE decreases length in both cultivars, in K-13 with 1 l ha−1 TE, while in K-29 with both doses of TE. The use of higher N fertilizer rates together with TE in Italian ryegrass seed crop can be more valuable practice for tetraploid cultivars.