Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Plant, Soil and Environmental Sciences

Major Professor

John H. Reynolds

Committee Members

Charles R. Graves, William D. Barber


Eleven cultivars of alfalfa (Medicago sativa L.) were seeded in 1971 at the Plant Science Farm in Knoxville, Tennessee to determine the relationship of yield in 1972 to various parameters thought to be related to productivity. The parameters measured included specific leaf weight (SLW), plant density, and concentrations of N, P, K, Ca, and Mg in the forage. The cultivars were 'Bonanza', 'Buffalo', 'Caliverde 65', 'Cherokee', 'Delta', 'Europa', 'Mesilla', 'Saranac', 'Team', 'Vernal', and 'Weevlchek', which were selected as representatives of various degrees of winter-hardiness ranging from very hardy to slightly hardy.

Dry matter yield was positively correlated with plant density but was not correlated with SLW or with concentration in the forage of any of the individual elements: N, P, K, Ca, Mg. Winter-hardy cultivars had greater plant densities and produced higher yields than did slightly hardy cultivars. Total dry matter yield ranged from 8.27 t/ha for Caliverde 65, a slightly hardy cultivar, to 11.60 t/ha for Weevlchek, a hardy cultivar. Plant density, averaged over five counts during the harvest season, ranged from 85 plants/m2 for Bonanza, a slightly hardy cultivar, to 112 plants/m2 for Weevlchek.

Specific leaf weight varied among cultivars and dates of sampling. When averaged over all sampling dates, SLW ranged from 3.72 mg/cm2 for Team to 4.34 mg/cm2 for Delta. The SLW generally increased at the later sampling dates. Averaged over all cultivars, SLW was lowest with 3.22 mg/cm2 on May 10 and highest with 4.71 mg/cm2 on August 29.

Chemical composition of the forage varied among cultivars within each of the five harvests and among harvests. Generally, N and Ca contents were lowest at the third harvest and highest at the last harvest; K content was highest at the first harvest and lowest at the last harvest; P and Mg contents were nearly constant across all harvests. When averaged over all harvests, the ranges in percent composition were: N, 3.22 for Europa to 3.47 for Team; P, 0.29 for Delta and Mesilla to 0.32 for Vernal; K, 2.52 for Vernal to 2.77 for Caliverde 65; Ca, 1.11 for Europa to 1.31 for Delta; and Mg, 0.21 for Caliverde 65 and Buffalo to 0.23 for Europa, Mesilla, and Saranac.

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