- P. R. Carter,
- C. C. Sheaffer and
- W. B. Voorhees2
Information is lacking on the growth response of diverse alfalfa (Medicago sativa L.) cultivars to soil moisture. Our objective was to determine the effect of soil moisture on root growth, herbage yield, and water potential of cultivars varying in winterhardiness and Phytophthora root rot (PRR) (Phytophthora megasperma Drechs. f. sp. medicaginis) resistance. ‘Agate,’ ‘Anchor,’ and ‘WL 318’ alfalfas were grown in a glasshouse and subjected to three soil moisture regimes which consisted of application of 126 (Ml), 63 (M2), and 45 (M3) cm of water during the experiment.
A moisture regime X cultivar interaction occurred for root weight as WL 318 had a greater root weight than Anchor or Agate at Ml, but at M2 and M3 cultivar root weights were similar. Cultivar root length did not change significantly as moisture level decreased, but averaged over moisture regimes, Anchor and WL 318 had greater root lengths than Agate.
Herbage yields decreased for all cultivars from Ml to M2 and M3, but Anchor and WL 318 produced significantly more herbage (averaged over moisture regimes) than Agate. Although increased root length is usually associated with increased drought avoidance, cultivars with greater root lengths (Anchor and WL 318) had lower plant water potentials under moisture stress (M3) than Agate. The relationships that occurred between cultivar herbage yields, root lengths, and plant water potentials indicate that further study of these parameters under field conditions may be useful in improvement of alfalfa forage yields under drought stress.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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