Productivity evaluation of Medicago sativa cultivars under irrigation in a semi-arid climate

Many Medicago sativa cultivars are available in South Africa, each with unique characteristics. This study evaluated 26 cultivars under irrigation on two ecotopes in terms of number of cuttings, dry matter (DM) production, seasonal DM production curve, DM production curve over lifespan and plant density, over nine growing seasons. The production per cutting decreased from 3 624 and 3 401 kg DM ha(-1) to 902 and 864 kg DM ha(-1) on soil of medium and high clay content, respectively. The production peaked during the second and third growing seasons, with respectively 22 524 and 22 640 kg DM ha(-1) on the medium-clay-content soil, and 20 442 and 20 352 kg DM ha(-1) on the high-clay-content soil. Cumulative production over nine growing seasons varied from 131 762 to 169 408 kg DM ha(-1) on the medium-clay-content soil and from 84 407 to 130 447 kg DM ha(-1) on the high-clay-content soil. The relationship between production and dormancy class was only significant after four to five growing seasons. Dormancy class six to eight seems to be more productive in this environment. The cultivars KKS 3864 and Eureka can be considered the best DM-producing cultivars under irrigation in this environment.