Floret Initiation and Development in Spring Wheat (Triticum aestivum L.)

Initiation and Development of Spikelets and Florets in Wheat as Influenced by Shading and Nitrogen Supply at the Spikelet Phase

“…3, Table 3). This is in agreement with the results of other studies (Langer and Hanif, 1973;Sibony and Pinthus, 1988;Whingwiri and Stern, 1982). However, the effect of N supply on the initiation and the increase in the number of floret primordia varies from report to report.…”

“…In good agreement with the results of Sibony and Pinthus (1988), the initiation of floret primordia commenced at approximately 10 days (67"C d) prior to the TS stage (Fig. 2).…”

“…Whingwiri and Stern ( 1982) concluded that the florets that initiated before the TS stage formed grains and those initiated later did not. Sibony and Pinthus (1988) showed that 7 to 8 florets initiated before the TS stage, among which up to 4 florets finally formed grain, and that no florets initiated after the TS stage formed grains. In the present study, about 3 floret primordia initiated on lower-middle spikelets at the TS stage, and among the florets that finally set grains, 62 to 74% were initiated by the TS stage, and 26 to 38% of florets were initiated after the TS stage.…”

“…The number of florets initiated before the TS stage varies considerably with the report. For instance, Kirby (1974) observed that 2 to 3 florets initiated on the lower-middle spikelet, Whingwiri and Stern (1982) observed that up to 4 florets initiated, and Sibony and Pinthus (1988) showed that 7 florets initiated on each of the 7th to the 12th spikelets. Moreover, there are some arguments about which florets survive to form grains, and when those florets initiate relative to TS formation.…”

“…Despite the result that supplemental N promoted the initiation and development of floret primordia, the weight and number of grains per spike at maturity was slightly decreased though not significantly (Table 4, Table 5). However, N application up to ear emergence generally increases the number of grains, due to its effect on the ability of florets to set grain (Darwinkel, 1983;Langer and Liew, 1973;Peltonen, 1993;Sibony and Pinthus, 1988;Whingwiri and Kemp, 1980;Whingwiri and Stern, 1982). The cause of this inconsistency was not elucidated by the present study, but it was assumed that N supply at the DR stage induces the competition for N between the main culm and tillers or induces mutual shading between plants, as was speculated by Whingwiri and Kemp (1980), who obtained a result similar to that in the present study.…”