Assessment of perennial ryegrass (Lolium perenne L.) genotypes under Latvia agro-ecological conditions

Within the frame of the Nordic/Baltic public-private partnership ’PPP for pre-breeding in perennial ryegrass’ various activities were performed, including assessment of L. perenne (Lp) genotypes under agro-ecological conditions of Latvia. This article summarizes the data obtained in two harvest years for 19 intermediate tetraploid (4x) Lp genotypes. In order to compare the results obtained in ryegrass with performance of grass interspecies hybrids (Fl), which become especially relevant in the recent years, two varieties, developed in Latvia – Lolium × boucheanum Kunth. ‘Saikava’ and × Festulolium ‘Vizule’ were included in the experiment. Various scores were performed, including evaluation of regrowth, intensity of culm development, sward cover, crown rust (Puccinia coronata) susceptibility, etc. The dry matter yield (DMY) and fodder quality were also determined. It can be concluded that the genotypes showed relatively good results in the first two harvest years. Wintering conditions were favourable. Despite the intensified drought and heat in the 1st ley year, relatively high DMY, which ranged from 9.30 to 12.15 t ha-1, for Lp were harvested in three cuts. In the 2nd ley year, under more favourable humidity conditions, Lp in four cuts provided similar DMY, which ranged from 8.81 to 11.50 t ha-1. If we compare the average DMY of Lp and Fl genotypes, it can be concluded that in the first two harvest years no significant differences were found, the average DMY was 10.30 and 10.64 t ha-1, respectively. No significant differences were found between Lp and Fl in terms of forage quality.

Evaluarea calităţii biomasei de Lolium perenne L. Ca furaj și substrat pentru obținerea biometanului

We studied the biochemical composition, nutritive value of the green mass and prepared hay from Ro-manian cultivars of perennial ryegrass, Lolium perenne L. „Mara” and „Măgura” grown in monoculture on the experimental plot of the National Botanical Garden (Institute) “Alexandru Ciubotaru”, Chisinau, R. Mol-dova. Results revealed that dry matter of harvested green mass contained 98-116 g/kg CP, 299-326 g/kg CF, 71-77 g/kg ash, 329-353 g/kg ADF, 546-593 g/kg NDF, 38-40 g/kg ADL, 291-313 g/kg Cel, 217-240 g/kg HC, with nutritive and energy value 60.9-65.3 % DMD, 60.1-64.8 % ODM, RFV=96-108, 12.12-12.45 MJ/kg DE, 9.95- 10.23 MJ/kg ME and 5.97-6.25 MJ/kg NEl. The biochemical composition, nutritive and energy va-lue of prepared hay: 94-110 g/kg CP, 351-385 g/kg CF, 79-82 g/kg ash, 390-423 g/kg ADF, 631-689 g/kg NDF, 46-50 g/kg ADL, 344-373g/kg Cel, 241-266 g/kg HC, RFV=76-86, 11.13-11.61 MJ/kg DE, 9.14- 9.53 MJ/kg ME and 5.17-5.55 MJ/kg NEl. The biochemical methane potential of green mass substrates reached 338-344 L/kg organic matter. The studied cultivars of Lolium perennec could be used in the Republic of Mol-dova for the restoration of degraded permanent grasslands, as a component of the mix of grasses and legumes for the creation of temporary grasslands, the harvested biomass can be used as feed for farm animals or as substrate in biogas generator for renewable energy production.

Management options to recover perennial ryegrass populations and productivity in run-out pastures

In parts of the upper North Island, farmers frequently report perennial ryegrass (Lolium perenne L.) pastures failing within 3 or 4 years post-sowing. This appears to be related to interactions between several factors: climatic (drier, hotter summers), biotic (insect pest), soil (texture, water-holding capacity) and grazing management factors that vary spatially and temporally. The efficacy of three management interventions for recovering ryegrass populations and production in runout pasture was assessed in an experiment initiated in 2018/19 in central Waikato. Treatments were a long-spring rotation (LSR), a longer grazing deferral during late spring and summer (pasture deferral, PD) and under-sowing with perennial ryegrass (US), each applied to pastures of four ryegrass cultivars. In the year after the treatments were implemented, the yield of ryegrass in PD was 2.4 t DM/ha greater than for the control (7-year-old pasture), and ryegrass tiller populations initially doubled but later declined. Yields in US and LSR were intermediate but not significantly different from the control. Ground score changes responded more positively to PD compared with the other treatments. Relative to the baseline prior to initiation of the study, tiller populations increased for PD and US but declined for control and LSR. There were no interactions between management treatment and cultivar for any of the variables measured. Pasture deferral shows promise as an intervention for recovering failing ryegrass pastures through natural reseeding. However, the longevity of the benefits observed here has yet to be determined.