Model analysis of the determination of leaf, spikelet and floret primordium number on main stem of Japanese spring type wheat [Triticum aestivum] in the southwestern part of Japan
2003
Toyota, M. (Kagawa Univ., Miki (Japan). Faculty of Agriculture) | Kusutani, A. | Asanuma, K.
Abstract : Primordium initiation on the main stem of field-grown Japanese spring type wheat was studied with a scanning electron microscope to quantify the process determining the number of leaves, spikelets and florets. The number of leaves and spikelets was related to growing degree-days (GDD) with a three-piece linear-spline model. The rate of primordium initiation was 0.0181 [leaf (square C d) -l] and 0.0995 [spikelet (square C d)sup(-l)], and the duration of leaf and spikelet initiation was 374 square C d and 149 square C d, respectively. The relationship between the number of floret per spike and GDD was described with the Gompertz model and a linear regression model. The initiation of florets commenced at 494 square C d, and the number of florets reached the maximum (116 florets per spike) at 821 square C d. The number of florets per spike let was closely correlated with GDD in all spike let Positions except the 15th spike let. These significant linear equations made it possible to estimate the start of floret initiation, the rate of floret initiation and the time of initiation of the most distal floret per spikelet that formed grain at maturity (ISF). The number of grains per spikelet was maximum at the central spikelet and declined both toward the basal and distal spikelets. There were close relationships between the number of grains per spikelets and the start of floret initiation. The variations in the rate of floret initiation and ISF with the spikelet position were demonstrated and the significance of those traits to the distribution pattern of grain number per spikelet was discussed.
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