The Relationship between Growth and Development of Vegetative Shoots in Genotypes of Tall Fescue (Festuca arundinacea Schreb.)

Abstract

In perennial grasses, shoot growth consists of: (a) the increase in the number of tillers (tillering), and (b) the increase in the size of tillers; while shoot development can be represented by an allometric relationship between these two components. This study examined how genetic differences in the developmental process of a shoot influence the various components of vegetative growth in 16 genotypes of a perennial grass, Festuca arundinacea Schreb. A negative correlation between the relative tillering rate (Rtil) and relative growth rate of single tillers (RGRtil) showed that the genotypes can be classified into two categories: genotypes producing few large tillers, and those producing many small tillers. The relative growth rate of the whole shoot (RGRshoot) correlated positively with RGRtil (r = 0·69**), but not with Rtil (r = 0·24). Root d. wt and the accumulation rate of nonstructural carbohydrate correlated negatively with Rtil and positively with RGRtil in spite of the absence of any apparent correlations with RGRshoot. These results demonstrate that: (1) the shoot developmental process has marked effects on various components of vegetative growth, and (2) the production of few large tillers results in higher carbon availability within a plant than the production of many small tillers.