Inter- and intra-population genetic variation for leaf:stem ratio in landraces and varieties of lucerne

Abstract

A comparison was made of landrace vs. variety inter- and intra-population genetic variation for leaf:stem ratio in lucerne and investigated its relationship with forage yield and other characters. Very early-flowering genotypes were excluded from the assessment to limit the impact of maturity stage on the variation in leaf:stem ratio. The evaluation was performed on a summer harvest of 390 genotypes belonging to ten landraces from northern Italy and to six well-performing varieties, and on nineteen clones of a single genotype which were used to estimate the environmental variance. Landrace and variety groups did not differ in mean leaf:stem ratio. Variation for this trait was significant among varieties (P < 0.05) but not among landraces. Within-population variation was significant for both germplasm groups (P < 0.01), being somewhat larger in landraces. The estimated within-population variance component largely exceeded the among-population variance component within varieties. Higher leaf:stem ratios were mainly associated with shorter and thinner main stems in genotypes and populations, and showed a modest inverse correlation with forage yield. The results highlight the importance of landrace germplasm and the paramount importance of selection within populations to identify parent material with a high leaf:stem ratio. © 2007 The Author Journal compilation 2007 Blackwell Publishing Ltd.