Date of Award

12-2018

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Renata N. Oakes

Committee Members

Gary Bates, Augustin Rius, Carl Sams

Abstract

The utilization of alfalfa (Medicago sativa) alone or in mixtures with tall fescue (Lolium arundinaceum (Schreb.) Darbyish) or bermudagrass (Cynodon dactylon (L.) Pers) in the Southeast U.S. must be assessed so better management recommendations can be given. The objective of this first study was to determine the cumulative capacity of alfalfa in monoculture (A) and mixtures with tall fescue (ATF) and bermudagrass (AB), and its indirect improvements on the nutritive (NV). Three species combinations were utilized (A, ATF and AB) and subjected to four harvest frequencies (21, 28, 35 and 42 days) throughout the 2016 and 2017 growing seasons at The University of Tennessee Plateau Research and Education Center (PREC) in Crossville, TN. Samples were collected for analysis of NV and forage mass (FM). Results indicated that on spring of 2016 and 2017, A and ATF showed highest FM values (P < 0.0001). In summer 2016, A and AB had higher FM than ATF (P < 0.0001), however, in summer of 2017 no differences were observed. The NV increased once alfalfa was incorporated into the mixtures, with higher crude protein (CP) and lower neutral detergent fiber (NDF). In conclusion, harvest frequencies above 28 days are recommended for optimum FM accumulation. Yet, harvest frequencies of 42 days tend to have increased lignification thus decreased NV. The second experiment asses the persistence of the same experiment on the third year. Based on FM, results showed that persistence of A (P = 0.0042), AB (P = 0.0002), and ATF (P = 0.0007) decreased at the third year of growth, and different harvest schedules should be followed for each species combination for increased persistence in the field. For A and AB, harvest frequencies should be 35 days and for ATF, 42 days.

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