Shoot numbers, shoot size, and yield of regrowth in three lucerne cultivars

Abstract

Three lucerne cultivars were grown out of doors and cut at two intensities. In the lenient intensity all shoots were cut at 5 cm from the crown, and in the severe intensity all shoots greater than 5 cm length were cut at the crown. Some plants were shaded for the 3 days prior to cutting. The change in the number and size of the regrowth shoots, and the total yield of dry matter were observed for 4 weeks after cutting.Shading the plants before cutting produced a large and uniform decrease in the weight of tops, stubble, and roots. The weights of shoots at the base of the plant, which were very small, were not consistently affected by shading. The total yield of shoots 2 and 4 weeks after cutting was not affected by the shading, although there was evidence that shoots labelled at the time of cutting did not grow so large on the shaded plants. The number of shoots remaining after cutting, the number produced during regrowth, and the size to which they grew all varied between cultivars and between cutting treatments. Shoot size depended mainly on the length of its growing period, but on plants cut severely the few shoots remaining immediately after cutting grew larger than those of the same age on leniently cut plants. The previous conclusion from work on cv. Hunter River that the yield of regrowth within lucerne cultivars depends primarily on the number of shoots and the time when each resumes growth can be extended to the additional cultivars included in the present study.