PRODUCTION OF TEN VARIETIES OF ALFALFA (Medicago sativa L.) AFTER FOUR YEARS OF BEING ESTABLISHED

Abstract

Alfalfa (Medicago sativa L.) is the forage species most commonly used to feed dairy cattle in Mexico. The objective of this study was to evaluate the production of ten varieties of alfalfa, harvested at cutting intervals defined seasonally. The varieties were distributed in 40 plots (9 x 7 m), and the experimental design was completely randomized with four repetitions. The study was performed at the Colegio de Postgraduados, Campus Montecillo, Texcoco, Mexico, from September 2011 to September 2012. The variables evaluated were forage yield (FY), botanical and morphological composition (BMC), leaf:stem ratio (R:L/S), population density of stems (SD) and plant density (PD). The Júpiter variety showed the higher values for FY (14 510 kg DM ha1 ), R:L/S (1.8), SD (578 stems m-2 ) and PD (18 plants m-2 ), and San Miguelito the lower values for FY (7890 kg DM ha1 ), SD (282 stems m-2 ) and PD (8 plants m-2 ). The average FY was (3508 kg DM ha-1 ) higher in summer and fall, and lower in winter (2214 kg DM ha-1 average). In fall and winter they presented higher R:L/S, SD and PD (1.5, 546 stems m-2 and 20 plants m-2 in average). In contrast, in springsummer, R:L/S, SD and PD were lower (1.0, 371 stems m-2 and 12 plants m-2 in average). The annual FY was 56 %. The undergrowth had the highest contribution (43 %) and the dead material (9 %), the lowest. Júpiter was the most productive variety and summer contributed most to the annual FY. The age of the grassland caused a higher invasion of undergrowth and a lower presence of alfalfa.