Effect of sowing rate, grass competition and cutting frequency on persistence and productivity of two lucerne (Medicago sativa) cultivars at Biloela, Queensland

Abstract

Persistence and production of lucerne (Medicago sativa) cvv. Hunter River and Siro Peruvian were studied on alluvial soil under raingrown conditions in a factorial experiment examining effects of lucerne sowing rates (1.1 and 4.4 kg ha-1), competition from buffel grass (Cenchrus ciliaris cv. Biloela) and 3,6 and 9-weekly cutting frequencies. Lucerne populations at establishment from 1.1 and 4.4 kg ha-1seed averaged 18 and 60 plants m-2, which reduced to 4 and 7 plants m-2 respectively after three years. Population initially declined rapidly at the higher sowing rate and the presence of buffel grass accentuated this decline. Persistence of Siro Peruvian was inferior to that of Hunter River. Cutting frequency did not affect lucerne persistence. Sowing pure lucerne and cutting every six weeks produced highest lucerne yield, but total yield was greatest from the lucerne/buffel grass mixture cut either 6- or 9-weekly. Increasing lucerne sowing rate increased lucerne yield only slightly and lucerne cultivar had no effect on total lucerne yield.

Above–Belowground Herbivore Interactions in Mixed Plant Communities Are Influenced by Altered Precipitation Patterns

“…Using a model grass–legume mixture of Harding grass ( Phalaris aquatica L.) and lucerne (otherwise known as alfalfa, Medicago sativa L.), this study addressed the effects of water stress (simulated drought and elevated precipitation) and root nodule herbivory by S. discoideus on both the plant–plant interactions between lucerne and Harding grass and on foliar-feeding pea aphids ( A. pisum ), one of the most damaging pests of lucerne [see Ryalls et al ( 2013a ) for review]. The long-term co-existence of lucerne and grass can be perilous, with one often failing to persist under competition with the other (Bishop and Gramshaw, 1977 ; Dear et al, 1999 ). Harding grass, one of the most persistent sown temperate perennial grasses in south-eastern Australia, is one species that complements lucerne and achieves a dynamic balance in a mixture with lucerne (Sherrell, 1984 ; McKenzie et al, 1990 ; Culvenor et al, 2007 ).…”