Rice grain yield is more sensitive to irrigation withholding imposed from the beginning of grain filling than from the panicle exsertion
A more detailed look at another collection of flowers showed nectar contents of 0.20 [+ or -] 0.15 [[micro]liter] before the stigma was exserted, 0.35 [+ or -] 0.18 [[micro]liter] after exsertion
but before the corolla began to open, and 0.88 [+ or -] 0.17 [[micro]liter] in pink flowers that had begun to open (mean [+ or -] 1 SE, n = 9, 11, and 4, respectively), indicating that the onset of nectar production occurs at about the time of stigma exsertion
A specific hypothesis of selection on stigma exsertion
was advanced by Conner and Via (1993).
Finally, pollen shed and silk exsertion
on physically separated plants increases the probability that floral asynchrony can lead to poor kernel set.
Measurements of selection were conducted in three years, and included measurements of directional and stabilizing selection on anther exsertion
and flower size, and directional selection on pollen production per flower and total lifetime flower production.
The associated directional phenotypic selection has the potential, in the absence of counteracting selection through other components of fitness, to increase mean stigma exsertion
by 0.23 SD per generation (Campbell 1989).
Separate male and female flowers require that the timing of pollen shed coincide closely with silk exsertion
and that tassels produce an overabundance of pollen to ensure pollination of exposed silks.
Yet, these population dynamics provide no direct quantitative information about the intensity of pollen shed, or the actual dynamics of silk exsertion
for the population.
Stigma size, style length, stigma exsertion
, stigma receptivity, anther size, filament size, and pollen grain number are important floral characters that influence gene flow in wheat.
Final leaf number, time of panicle emergence, time of complete panicle exsertion
(node of the lowermost panicle branch visible above the collar), and final panicle length (tip to node of lowermost panicle branch) were recorded on the first tiller (of the original five) in each pot that produced a panicle.
of RTx437 ranged from 0 to 17 cm (Table 1).
Once stigma exsertion
occurred, the date was recorded and each stigma was examined with a 16x hand lens to determine if pollen was present.