MAINSTEM LEAF DEVELOPMENT AND TILLER FORMATION IN WHEAT CULTIVARS

Mainstem leaf stage and percent tiller formation are measurements utilized to evaluate the development of wheat (Triticum aestivum L.). This study was conducted to determine whether there are differences for these measurements among 11 winter wheat cultivars. Ten hard red winter wheat and one soft white winter wheat cultivars were grown in a controlled environment chamber to determine their rate of mainstem leaf stage and tiller formation percentage for coleoptile (T0), first (T1), second (T2), and third tillers (T3) when plants are grown in the absence of stress. Growth conditions were 12-h photophase at 24-degrees-C and 12-h dark at 15-degrees-C. Light intensity averages 500-mu-mol m-2s-1 photosynthetic photon flux density. Cultivars ranged from 5.3 to 6.4 in mainstem leaf stage at 700 growing degree-days (GDD) after seeding and in number of GDD required per leaf. Therefore, before attempting to model wheat development, the response of mainstem leaf appearance to GDD for specific cultivars must be determined. For percent tiller formation, T0 was quite variable, and cultivar differences were not significant. Therefore, percent tiller formation of T0 may be too variable for detection of treatment differences. Even though a significant percent tiller formation difference occurred among cultivars for T1, all but one cultivar formed 90 to 100% of T1, T2, and T3.