Crown development of two diverse genotypes of lucerne

Abstract Crown development of ‘Moapa’ ( Medicago sativa L.) and ‘College Glutinosa’ ( M. media Per.) lucernes was examined under simulated sward conditions. The crown included all shoots originating from nodes less than 6 mm apart at the base of other stems; stubble shoots were those from nodes more than 6 mm apart. The pattern of shoot numbers and weights during crown development is described in relation to two defoliations in the establishment year and a final cut in the following spring. The crown of Moapa plants initially developed more rapidly than that of College Glutinosa, but this effect had largely disappeared by the end of the second growth cycle. After the initial growth cycle College Glutinosa had more stubble shoots than Moapa and it had developed more crown shoots than Moapa by the third growth cycle. Moapa had heavier shoots in the third growth cycle, but this did not compensate for it having fewer shoots. Because of its short stem internodes, College Glutinosa had more sites for shoot regeneration close to ground level.