Growth of lucerne following defoliation

In a simulated sward of Wairau lucerne cut at an immature stage of growth to leave a stubble of 10-11 cm, removal of all or one-half the residual leaf area resulted in an initial decline of root weight and low or negative crop growth rates. After 4 weeks, top dry weights showed no significant differences. Calculation of net assimilation rates suggested that previously shaded foliage may initially have had low photosynthetic efficiency following exposure to full light after cutting. Since, in addition, the major part of the regrowth ,came from the crown shoots, it is concluded that few advantages accrue from leaving a tall stubble