Dynamic characteristics of floret primordium development in wheat

This study was undertaken to determine the time-course of floret primordium initiation and degeneration in relation to thermal time after sowing in various cultivars and tiller positions of wheat (Triticum aestivum L.). The field experiment was carried out on the experiment station of Nanjing Agricultural University of China, and included three sowing dates: early planting of 30 September, middle planting of 30 October and late planting of 2 March and two wheat cultivars: winter type 'Jing 411' and spring type 'Yangmai 158'. Quadratic and linear relationships could describe floret initiation, degeneration and abortion in response to growing-degree-days after sowing for main stem and first and second tillers of middle planting plants of both cultivars. The floret development patterns on the third tillers for all treatments deviated from the basic models and were associated with poor floret fertility. The growing-degree-days from sowing to floret initiation were significantly different between the three sowing dates and between the two cultivars. These results help quantify the dynamic processes of apical development and explain the differences in floret development of wheat with different environments, cultivars and tiller positions. (C) 2001 Elsevier Science B.V. All rights reserved.