CHARACTERIZATION OF ROOT AND SHOOT DEVELOPMENT OF JOINTED GOATGRASS (AEGILOPS-CYLINDRICA)

Greenhouse and field studies were conducted to compare root development of jointed goatgrass to winter wheat. Time of seminal root development in jointed goatgrass was similar to that of winter wheat and to root development predicted by a model. The only exception was the epiblast node roots (-1A and -1B), which developed approximately 1 phyllochron later in jointed goatgrass than in winter wheat. At crown nodes, A and B roots developed later in jointed goatgrass than in winter wheat, but development of X and Y roots at these nodes was similar for both species. First-order branching at a given root axis in jointed goatgrass roots began approximately 1 phyllochron after development of that axis, compared to 2.5 phyllochrons for winter wheat and the model. Second- and third-order branching of jointed goatgrass roots began 1 and 0.5 phyllochrons earlier than the respective branching of winter wheat roots. Leaf and tiller development followed the same pattern with time for both species. Maximum distance between crown roots was 1.5 to 3 times greater in winter wheat than in jointed goatgrass. Root length density at the 0- to 10-cm depth was less for jointed goatgrass than for winter wheat, but there were no differences at greater depths. The frequency of branching of first-order laterals was greater for jointed goatgrass than for winter wheat. In the field, the relationship of jointed goatgrass shoot development to accumulated growing degree-days was linear (R2 = 0.97), with a slope and y-intercept similar to winter wheat (R2 = 0.95). These data, showing slight differences in root growth and development between jointed goatgrass and winter wheat, may be used in predictive modeling to better understand the biology and ecology of each species, and may be used in conjunction with other models to establish weed threshold levels and improve selective placement of fertilizers and herbicides to benefit crop development.