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 va rious cultivars and tiller positions of wheat (Triticum aestivum L.). The f ield experiment was carried out on the experiment station of Nanjing Agricu ltural University of China, and included three sowing dates: early planting of 30 September, middle planting of 30 October and late planting of 2 Marc h 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 f or main stem and first and second tillers of middle planting plants of both cultivars. The floret development patterns on the third tillers for all tr eatments deviated from the basic models and were associated with poor flore t 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 deve lopment and explain the differences in floret development of wheat with dif ferent environments, cultivars and tiller positions. (C) 2001 Elsevier Scie nce B.V. All rights reserved.