The development of winter wheat in the field. 1. Relation between apical development and plant morphology within and between seasons

Abstract

SUMMARY Main-stem apical development and its inter-relations with other aspects of plant morphology were studied in seven field crops of winter wheat ( Triticum aestivum L., cv. Maris Huntsman). Apical primordia were produced slowly in autumn and winter, then faster in spring as the weather became warmer. Spikelets were initiated about three times as fast as leaves. Leaf initiation ended at around the time that tiller bud initiation stopped. Apical dome length and diameter both increased during leaf initiation, reached a maximum at double ridges and then decreased. Double ridges appeared when very nearly 50% (range 49–52%) of the final number of spikelets was present. Spikelet initiation ended a few days after the first florets were initiated and when stem extension began, but usually before the stem apex rose above the soil. Floret initiation finished at about the time that the flag leaf appeared. Throughout tillering there was a strong association between tiller emergence and leaf appearance. There were considerable differences between seasons in the timing of developmental events on the apices of main stems, but a difference in sowing date of 5 months was reduced to little more than 1 month in the timing of anthesis and the maximum numbers of organs varied only slightly with sowing date.