"Revolution" was introduced into the U.S. because of its tolerance to the African maize streak virus. The original collection was made on the island of Reunion by Dr. K. Bock, who was a virologist for the Overseas Development Ministry of the U.K., then assigned to the East African Agriculture and Forestry Research Organization in Muguga, Kenya. Some tolerance to MDMV was noted during the quarantine greenhouse growout required for importation. Revolution flowered after all other nursery material when grown in Missouri; selection for earliness was done as part of the seed increase procedure.
"Tennessee early low ear" (TELE) was developed by Dr. L. M. Josephson at the University of Tennessee. When grown in Missouri, TELE is relatively early flowering and has a very desirable ear height.
Crosses were initially made between Revolution and Mo940, BS13, and a mixture of white lines with the gametophyte factor. Selection currently continues in material advanced from the first two crosses. Significant F1 plant heterosis was noted with plant heights near 300 cm. In an attempt to "tame down" the F1 response, crosses were made to TELE and, for contrast, to "Tennessee late low ear" (TLLE). Crosses were made both ways to increase seed production and to ensure retention of any cytoplasmic benefit from Revolution in subsequent virus selection. On growout, the F1's of Revolution and TLLE appeared similar, but a noticeable difference in flowering date and ear placement was observed between the F1 crosses of Revolution and TELE.
The F1 crosses were selfed and reciprocal backcrosses to both parents produced for evaluation to clarify the unusual behavior. Revolution, TELE, the F1's and F2's, the backcrosses to both parents, and B73 x Mo17 were grown at Rollins' Bottom, Columbia, MO; the Agronomy Research Center (ARC), east of Columbia, MO; and Ames, IA, in 1984.
Significant differences between TELE x Revolution and Revolution x TELE for stand percent (89.2 vs. 80.2%,), plant height (231.5 vs. 259.3 cm), ear height (101.7 vs. 133.8 cm), yield (61.3 vs. 46.6 qha-1), and days-to-flower (74.9 vs. 80.6) were observed (Table 1). Similar significant differences occurred in the F2 generation for the same characters with plant and ear height being reduced and days-to-flower being increased. No differences among entries were found for root and stalk lodging. The greatest expression of differences was at Ames, IA, where the test material was most unadapted.
Differences among the backcross progenies of the form 1(1x2) vs. (1x2)1 and 2(1x2) vs. (1x2)2, as well as backcrosses of the (2x1) F1 cross, were inconsistently significant. The ear height response is depicted graphically in Fig. 1. Ear height was measured at all sites and usually is thought of as being highly repeatable. Stands of Revolution per se were very poor. Yield measurements were not done on the full number of plots for Revolution because some plots were judged missing.
Seed of the crosses and parents is available in limited quantity from the University of Missouri.
Table 1. Revolution-TELE maternal effect evaluation. combined data from three sites.
Fig. 1. Ear height responses of TELE, Revolution, their F1, F2, and backcross generations.
L. L. Darrah, M. S. Zuber, and L. M. Pollak
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