Comparative performance of ‘Grasslands Ruanui’ and ‘Grasslands Nui’ perennial ryegrass cultivars in hill country

Abstract

Persistence and production of ‘Grasslands Ruanui’ and ‘Grasslands Nui’ perennial ryegrass (Lolium perenne L.) cultivars were evaluated under sheep grazing on 2 sites (sunny or shady aspect) and at 3 nitrogen fertiliser levels (0, 50, 100 kg N/ha per year) in summer-moist hill country for 5 years. The Ruanui seed sown was endophyte-free, whereas a small percentage (4%) of the Nui seed was endophyte-infected. Nui produced as much or more herbage than Ruanui in all situations. Nui was superior to Ruanui on the sunny site (52% higher production), and in summer and autumn, confirming its reputation as a drought-tolerant cultivar. Nui was markedly superior to Ruanui at the highest N input (63% higher production), but not at the zero N level (9% higher production). There was more white clover in Nui-based swards than Ruanui-based swards at the zero N input, but not at the intermediate or highest N input. Total production of Ruanui and Nui swards was greater than resident swards on the sunny site (17 and 34% higher production for Ruanui and Nui respectively) and shady site (12 and 10% respectively). Nui swards produced more than Ruanui swards on the sunny site (1630 kg dry matter/ha per year, or 15%), but not on the shady site. Endophyte levels may in part have been a reason for Nui's superior performance, but the major reason was Nui's greater growth potential. The results of this trial suggest that Nui should be sown in preference to Ruanui in summermoist hill country.

Keywords:

• hill country
• perennial ryegrass
• Lolium perenne
• cultivars
• pasture production
• aspect
• nitrogen fertiliser
• Grasslands Nui
• Grasslands Ruanui