EFFECTS OF ARTIFICIAL REDUCTION IN PANICLE SIZE ON WEIGHT OF SECONDARY SEEDS IN OATS (Avena sativa L.)

Intra-plant variation for progress of cell division in developing oat grains: a preliminary study

“…Dissecting out primary grains and at various stages secondary grains, caused a marked increase in weights of the remaining secondary grains. However, the potential grain weight of remaining secondary grains appeared restricted as they constantly failed to reach the weight of primary grains recorded from intact control panicles (Tibelius and Klinck 1987). This limited capacity of secondary grains to fill -even when improved assimilate availability is likely to follow from absence of the primary grain -may result from limitations in grain expansion due to restricting hulls, lemma and palea (Tibelius and Klinck 1987), and/or limitations in assimilate transport capacity as for wheat (Hanif and Langer 1972).…”

“…Within each spikelet, the primary floret that develops into a primary grain is at more advanced development stage compared to that of secondary florets (Youngs andShands 1974, Tibelius andKlinck 1987). Similarly, growth of primary grain exceeds growth of secondary and tertiary grains (Youngs and Shands 1974, Tibelius and Klinck 1987, Doehlert et al 2002.…”

“…Similarly, growth of primary grain exceeds growth of secondary and tertiary grains (Youngs and Shands 1974, Tibelius and Klinck 1987, Doehlert et al 2002. In fact, the single kernel weight of primary grain seems to be dependent on number of florets in spikelet.…”

“…There are several, possibly interacting, factors contributing to the variation in grain weight. It may result from intra-panicle and intra-spikelet differences in development rate and time of pollination that are reflected in duration of grain-filling period (Bonnett 1961a, Tibelius andKlinck 1987), vascular transport capacity (Hanif and Langer 1972, shown in wheat;Housley and Peterson 1982), cell division rate and duration of developing grains as shown for wheat (Brocklehurst 1977, Radley 1978, and/or hormonal balance as shown for barley and maize (Michael and Seiler-Kelbitch 1972, Mounler et al 1980, Myers et al 1990, Ober et al 1991.…”

“…The position of the spikelet in the panicle and the floret in the spikelet contributes to sink capacity of the grain and determine thereby its potential grain weight (Bonnett 1961a, Youngs and Shands 1974, Housley and Peterson 1982, Tibelius and Klinck 1987Doehlert et al 2002), which is realised at varying degree depending (strongly) on growing conditions at grain-filling period. There are several, possibly interacting, factors contributing to the variation in grain weight.…”