Analysis of Genes for Stigma Coloration in Rice - IRRI books

Effects of genotype x
environment interaction on
late-heading Japanese rice
T. Sato
Japanese rice (Oryza sativa L.) genotypes EG1, EG2, EG3, EG4, EG5, EG6, and EG7
have the genetic constitution E 1 E 1 e 2 e 2 e 3 e 3
, e 1 e 1 E 2 E 2 e 3 e 3
, e 1 e 1 e 2 e 2 E 3 E 3
, E 1 E 1 E 2 E 2 e 3 e 3
,
e 1 e 1 E 2 E 2 E 3 E 3 , E 1 E 1 e 2 e 2 E 3 E 3
, and E 1 E 1 E 2 E 2 E 3 E 3 , respectively. The flowering responses
of the seven genotypes were analyzed under four conditions:
• short daylength (10-h photoperiod) (SD) and high temperature (28 °C) (HT)
• long daylength (14 h) (LD) and HT
• SD and low temperature (18 °C) (LT)
• LD and LT
The time to panicle initiation (PI) of these genotypes varied from 42 to 116 d under
LD, HT. Under SD, HT, however, PI occurred in 35-38 d. Furthermore, the total number
of leaves on the main culm under LD, HT appreciably differed among EG lines. Under
SD, HT, the differences were fewer (Table 1). Therefore, there were significant
differences among the seven genotypes in the photoperiod-sensitive phase, and not
in the basic vegetative phase. Low temperature increased the difference in leaf
number in EGI and EG4, which have gene E 1 , by 2.5 and 1.5, respectively, while the
difference in EG3 and EG5, which have gene E 3 , was 0.5 and 0.6, respectively. These
results indicate that genotypes having E 1 are more photoperiod sensitive under LT than
ones having E 3 .
Genotypes EG1, EG2, and EG4 (without the E 3 gene) had a critical photoperiod
between 13 and 14 h under 23 °C; the other genotypes, between 12-13 h (Fig. 1).
However, under excessive photoperiod (14 h), the panicles of EGI and EG4 developed
more than those of EG3 and EG5.
Thus, late-heading genes E 1 , E 2 , and E 3 ,control, not the basic vegetative phase but
the photoperiod-sensitive phase. Furthermore, the difference in flowering behavior of
E 1 , E 2 , and E 3 genes under optimal, critical, and excessive photoperiod may partly
explain the complex pattern of heading behavior when the seven genotypes are grown
at different latitudes in Japan.
Posters 773