Growth/temperature relationships of tropical grasses and legumes.

Abstract

The response of plant species to the climatic environment is considered a necessary prerequisite for sound grazing management strategies of pastures in the dry tropical region of North Queensland. Information on introduced pasture growth during the dry winter months is limited. This work presents quantitative information on the response of a grass and a legume to temperature and winter field conditions. Previous studies undertaken indicate that the two introduced study species, Urochloa mosambicensis Hack and S tylos anthes hamata (L) Taub cv Verano, are suitable species for the dry tropics. Three experiments were undertaken. The first was carried out under environmentally controlled conditions, and growth rates of the two species were compared at 20°C and 30°C. Maximum relative growth rates of the two species were similar at the respective temperatures, with values for both species greater at the higher temperature. Growth responses of U, mosambieensis and 5, hamata cv Verano to nitrogen and phosphorus under winter field conditions at Townsville were observed in Experiment 2. A positive growth response of U, mosambieensis to nitrogen was observed, while fertilizer applications did not significantly effect the aboveground growth of S, hamata cv Verano. The third experiment observed the growth response of S. hamat cv Verano to applications of water and phosphorus in winter. A slight response to the treatments occurred. The conclusion that water and nutrients are not the major factors limiting growth in winter are discussed in relation to growth of the species in summer months. Show more