Principles of Plant Genetics and Breeding

Figure 1 Rice panicle being prepared for crossing to produce
F 1 seed.
Figure 2 Plant height is measured in yield plots after flowering
has occurred.
BREEDING RICE 503
1992
Plant 215 F 6 panicle rows in the summer nursery.
Select 63 rows based upon field observations of
plant height, days to heading, good tillering capacity,
and good appearing grain dimensions. Harvest five
panicles per row.
1993
Project not planted due to field space limitations.
1994
Plant five F 7 panicle rows from each of 63 F 6 -derived
families in the fall planted nursery in Puerto Rico.
Select 29 rows based upon field observations of plant
height, maturity relative to check varieties, good tillering
capacity, and good appearing grain dimensions. In
each selected row harvest five panicles and bulk harvest
the row.
1995
F 8 panicle rows are planted in the summer breeding
nursery for each of the 29 families. Ten F 9 panicles are
selected from one of the five rows for each of the 29
families.
In addition, the bulk harvested F 8 seed from Puerto
Rico from each of the 29 families is planted in an
unreplicated yield trial with some 600 other entries
during the summer. In this trial, data is collected on
height (Figure 2), heading, harvest maturity, yield,
milling yield, and resistance to blast disease using
the inoculated disease screening nursery (Figure 3).
Fourteen of the 29 yield plots from the B8910 project
are selected to undergo further evaluation during the
winter for grain cooking quality traits (i.e., amylose
content and alkali spreading value) (Figure 4) and
grain chalkiness (Webb 1985). Using these data, five
lines are selected for testing in the following year.
1996
The 10 F 9 panicle rows from each of the five families
selected based upon the yield trial are planted in the
summer breeding nursery. One row is selected from
each of the five families and 10 panicles are picked.
Using the bulked yield plot seed from 1995, one of
the five families is entered into the Uniform Rice
Regional Nursery (URRN) as entry RU9603178. The URRN is an extensive replicated yield trial that includes a total of 200 entries
from four southern rice breeding programs and is planted in Texas, Arkansas, Louisiana, and Mississippi. This study has two sections:
advanced entries, which are replicated four times, and preliminary entries, which are replicated twice. RU9603178 is
entered into the preliminary trial section based upon limited availability of seed. In addition to the standard yield, agronomic,
milling, and cooking quality traits that are evaluated, several states screen all 200 entries in inoculated nurseries for resistance to
blast and sheath blight diseases as well as the physiological disorder, straighthead. Two of the states evaluate all entries for ratoon
crop yield and for reaction to nine individual races of blast using controlled greenhouse conditions. All of the entries from the
Beaumont program that are in the URRN trial also undergo additional yield testing at two to three other Texas locations which are
representative of the state’s rice growing area. The other four entries from the B8910 cross are planted only in these Texas replicated
yield trials.