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Faculty Mentor

Lan Xu

Abstract

Alfalfa (Medicago sativa L.) is a valuable crop worldwide. In addition to its use as forage, the nitrogen fixation capabilities of root nodules make it a valuable component for improving soil health. Unfortunately, the semi-arid region of the Northern Great Plains introduces a number of environmental stresses that are detrimental to stand establishment and persistence. The ability to produce adventitious shoots from roots is generally considered a favorable trait for increasing stress resistance. This study aimed to identify alfalfa populations possessing the ability to produce adventitious shoot from root segments. Seven Plant Introductions (PIs), selected from the National Plant Germplasm System, and one commercial cultivar (Persist II) were evaluated. Two 6cm root segments originated at 1cm and 7cm below the cotyledonary node from 1-year-old plants. Root segments were planted in Miracle-Gro® potting soil for 16 weeks. Adventitious shoot emergence was recorded throughout the experimental period. At the end of the experimental period, a number of root segments that produced adventitious shoots, shoot survival, status of flowering and non-shoot-bearing root segment decay were determined. Six of the seven PIs produced adventitious shoots. No shoots produced on Persist II and PI 494662 roots. Among the six populations, frequency of generating adventitious shoots from roots ranged from 3.8% to 57% and frequency of shoot survival varied from 33% to 100%. Speed of regeneration from roots and viability of root segments in soil varied among populations. PI 631678 had the greatest frequency and speed of regeneration from roots, high survival and flowering frequencies. Little difference in adventitious shoot regeneration and survival related to distance below the cotyledonary node within the same populations.

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