|Abstract or Summary
- Seventeen parental clones were selected, from 9,000 plants,
on the basis of self-sterility, seed and forage yield potential using
phenotypic ratings, crude protein and chromogen content. The parental
clones were divided into two populations based on date of maturity.
Group I was intermediate in maturity and had nine parental
clones, while group E was early maturing and had eight parental
Six progeny testing methods (vegetative cuttings of parental
clones, first generation selfed-seed (S₁ progeny), open-pollinated
progeny, polycross progeny, seed from all possible single crosses,
and selfed seed from the single-crosses or F₂ progeny) were compared
using simple correlation coefficients between the progeny
test and by comparing the rankings of the clones on the basis of each progeny test. The actual polycross performance was compared
with the theoretical polycross performance or average of all
possible single crosses, to see if equal and random fertilization
occurred in the actual polycross.
The results from the comparison of the six progeny testing
methods indicated the vegetative cuttings of the parental clones and
the single-cross progeny tests are the two most effective progeny
testing methods when considering all four traits and both populations
The open pollinated and polycross progeny tests were generally
undesirable, because frequently there was no significant difference
among their progeny.
The S₁ progeny test was generally not desirable in group I;
however, it appeared to be the most satisfactory test for seed yield
when both populations of plants were considered.
The results illustrate why there are inconsistencies in the
literature concerning the effectiveness of the progeny testing methods.
The effectiveness of the six progeny tests varied, to some
extent, from trait to trait and for the two populations. For all four
traits there was much less agreement among the six progeny tests
in group E than in group I.
In all four traits the F₂ generation showed a great inbreeding
depression. The average of the single crosses was lower than the parents for tiller number, plant height, and 100 seed weight, but
equalled the parents in yield per plant. The S₁ progeny were usually
approximately equal to the average of the single cross progeny.
The open-pollinated and polycross progeny were generally the
highest for all four traits.
The results from the comparison of the actual polycross with
the theoretical polycross indicated that equal and random fertilization
did not occur in the actual polycross. The more desirable
clones appeared to contribute the majority of the pollen, since the
actual polycross performance was usually greater than the theoretical