Performance of dry matter yield and its components in germoplasm of alfalfa (Medicago sativa L.)

The present research work was carried on to study the productive performance of a group of 100 half-sib families (HSF) derived from each of Oaxaca and San Miguel commercial varieties, and San Miguel x Oaxaca and Oaxaca x San Miguel populations, in pots placed outdoors at Colegio de Postgraduados, Montecillo, Texcoco, State of Mexico. Harvests of aerial biomass were made every 5 wk during the fall-winter growing season 2013-2014 and 4 wk during the spring growing season 2014. The HSF derived from San Miguel x Oaxaca and Oaxaca x San Miguel had 10 % higher dry matter yield (DMY), absolute crop growth rate (ACGR) and leaf: stem ratio (L:S) per plant than the HSF derived from San Miguel and Oaxaca in every growing season and harvest. On the other hand, the HSF derived from San Miguel had greater number of tillers (NS) per plant in the winter and spring seasons, and lower plant height (PH) in the spring season than the HSF derived from Oaxaca, San Miguel x Oaxaca and Oaxaca x San Miguel. The DMY and ACGR were 57 % and 33 % higher in spring than in fall and winter. The L: S was 5 % higher in fall than in winter and 30 % higher than in spring; the greatest values for NS and PH were measured in spring. The radiation use efficiency (RUE) had higher values in spring than in fall and winter with the highest values in April. The observed variability among the HSF derived from San Miguel x Oaxaca and Oaxaca x San Miguel, suggests the possibility of selecting families with higher dry matter yield.