Paper No. 8 



MORPHOGENESIS AND MANAGEMENT OF PERENNIAL GRASSES IN 



AUSTRALIA 



By D. M. Calder 1 



Abstract 



The essence of rangeland management must 

 be to promote plant welfare. This can be done 

 more effectively if we understand the genetic and 

 environmental control of plant growth and devel- 

 opment and the effect of utilization by the graz- 

 ing animal. Perennial grasses play an important 

 role in the rangelands of Australia. This paper 

 discusses the main morphogenetic events in the 

 life of a perennial grass, viz, germination and 

 establishment; quantity and quality of vegetative 

 growth; perennation; and flowering and seed 

 production. 



Additional key words : Arid zone grasses ; growth 

 and development ; mitchell grasses ; review ; phys- 

 iological ecology 



Introduction 



In 1969, C. Wayne Cook (3) said "It is rec- 

 ognized that the biological efficiency of the ecosys- 

 tem is measured by responses of both plants and 

 animals to management. However, once the nu- 

 tritional requirements of the grazing animal have 

 been provided by varying vegetation types, man- 

 agement becomes largely a matter of plant wel- 

 fare." 



You will find in this generalization, as in most, 

 some points of debate, but the significant phrase 

 in the present context is the last, viz, that man- 

 agement becomes largely a matter of plant wel- 

 fare. I would go further and say that, because 

 productivity of the ecosystem is largely a matter 

 of the welfare of the primary producers, mcm- 

 agement must promote plant welfare — the condi- 



1 Senior Lecturer in Botany, University of Melbourne, 

 Melbourne, Victoria, Australia. 



tion of the range depends almost entirely on the 

 condition of the plants which grow on it. 



There are, obviously, many different kinds of 

 range environments, but they are all characterized 

 by extended periods which are unfavorable to 

 plant growth. Consequently, plant recovery from 

 heavy grazing is naturally slow ; it is, indeed, un- 

 predictable because of the variable nature o*f the 

 climate. These points draw attention to the vul- 

 nerability and the sensitivity of range vegetation 

 and to the basis for their slow recovery. From 

 this it is clear that in the management of range- 

 lands we need to be primarily concerned with 

 plant welfare. 



Enlightened management is attainable only if 

 we have a thorough understanding of the ways in 

 which the component species react under the 

 particular conditions of climate, soil, and man- 

 agement to which they are exposed. Unlike the 

 situation in areas of high production, manage- 

 ment of rangelands is largely determined by and 

 dependent upon the natural environment. In Aus- 

 tralia, at present, it is impractical to change this 

 by irrigation, fertilization, or other similar activ- 

 ities aimed at improving the environment. Since 

 it is not possible to modify the environment to 

 suit the plant, the plant must be adapted to the 

 environment of which grazing is a part. We must, 

 therefore, understand the morphological and 

 physiological basis of plant adaptation as well 

 as the biological limitations to the continued sur- 

 vival of species. 



In this discussion, we consider how plant wel- 

 fare is influenced by environmental conditions of 

 climate, soil, and management in rangeland areas 

 with very different floras and with very different 

 histories. At the outset, I should confess to the 

 paucity of information of Australian origin on 

 this subject, and hence, my contribution will be 

 more general in character and will include state- 



81 



