Abstract
Mimosine content was studied in F2, F3 and F4 generations resulting from hybridizing Leucaena pulverulenta with L. leucocephala cv. 'Cunningham' and backcrossing twice with 'Cunningham'. High mimosine contents resulted from tropical conditions, fertile soils and sampling method. Mimosine in the 'Cunningham' controls varied little within and between years and averaged 11.3%. Within the F2, F3 and F4 generations the ranges in mimosine levels of vigorous trees were 4.6-14.4, 4.5-15.8, 5.8—11.6 respectively. The number of vigorous, low-mimosine trees was reduced to only two in the F4 generation. Among lines of L. diversifolia, L. esculenta. L. pulverulenta and L. shannoni, only L. pulverulenta, appeared to have low-mimosine potential. The self-incompatibility of L. pulverulenta was not retained in F3 of the backcross. Chromosome changes in the F2 –F4 segregates showed an alteration in L. pulverulenta chromosomes and a progression towards the somatic number of 'Cunningham'. This was apparently accompanied by a reduction in the number of vigorous, low-mimosine segregates.
