Yield of Five Alfalfa Varieties (Medicago sativa L.) Under Two Cutting Frequencies

Objective: To determine the yield and morphological composition of five alfalfa varieties under two defoliation frequencies during the spring-summer period. Design/Methodology/Approach: A randomized block design was employed, following a 5×2×2 factorial arrangements. The factors considered were five alfalfa varieties, two cutting frequencies (CF), and two seasons of the year, resulting in a total of 20 treatments with three replicates. The evaluated variables included dry matter yield (DMY), plant height, leaf-to-stem ratio (L:S), leaf area index (LAI), and morphological composition (MC). A factorial analysis was conducted using the FACTORIAL ANOVA and PROC GLM procedures, along with a mean sensitivity test via Tukey (α=0.05), utilizing the SAS statistical software. Results: The San Miguel variety exhibited the highest DMY (2,150 kg DM ha⁻¹) and plant height (31 cm). A light CF (35 days) resulted in higher yield (1,256 kg DM ha⁻¹), greater height (29 cm), and a higher LAI (3.3), while also favoring the L:S ratio (1.07). Summer yielded higher production (2,280 kg DM ha⁻¹), whereas spring showed a higher leaf proportion (1.05). Regardless of variety and season, MC displayed a greater percentage of leaves and stems under a light cutting frequency. Study Limitations/Implications: No limitations were identified; however, further evaluations are needed during the autumn-winter period. Findings/Conclusions: Cutting frequency was the determining factor influencing the evaluated variables. Its interaction with the season largely defined the proportion of morphological components and overall pasture quality.