FACTORS AFFECTING ESTABLISHMENT AND SPREAD OF "GRASSLAND MAKU" LOTUS IN TUSSOCK GRASSLANDS

Abstract

Observations of blocks oversown with Maku lotus in the Otago tussock grasslands have indicated that the potential yields are not being obtained as a result of low seedling establishment and limited spread of established plants. Satisfactory establishment is dependent on correct aerial oversowing techniques and suitable site preparation. Inoculation with rhizobia is essential for nodulation on most areas of the tussock grasslands and the present recommendation is to slurry-inoculate seed at up to 5times the normal manufacturers rate. The incorporation of 10% (w:v) gum arabic in the slurry improves viability of rhizobia and allows seed to be stored for 1-2 weeks before sowing. Vegetative spread of established plants depend on growth of rhizomes during the summer/autumn period. This rhizome growth is sensitive to time of defoliation of the sward. Defoliation as early as the start of January reduced the amount of rhizome present in April while early-February or early-March defoliation virtually eliminated rhizome growth. In sparse swards of Maku lotus where maximum spread of existing plants is required it is recommended that grazing be avoided over this critical period. Where adequate plant density has been obtained either through the use of correct seedling establishment techniques or earlier management for rhizome spread, it is not necessary to adhere to this recommendation and swards can be rotationally grazed over the summer/autumn period. Seed production of Maku lotus is limited, particularly at higher altitudes and on shady aspects, and the technique of natural reseeding has limited application in these tussock grasslands. Keywords: grazing management, inoculation, Maku lotus, rhizome, seed production