A COMPARISON OF LEAF APPEARANCE RATES AMONG TEOSINTE, MAIZE LANDRACES AND MODERN MAIZE

摘要

The rate at which successive new leaves emerge at the stein apex in gramineae (phyllochron) is largely controlled by temperature. Utilizing genetic variation for the phyllochron may be a way to alter plants' responses to the environment or to manipulate time to maturity. Little is known about possible genetic variation in the phyllochron among maize landraces, its ancestor teosinte and modern maize. Controlled environment (phytotron) and field studies were conducted to investigate possible genetic variation for the phyllochron among seven maize (Zea mays) landraces (Apachito, Chapalote, Conico, Tabloncillo, Tehua, Tuxpeno, and Zapalote Chico) sampled from the center of maize diversity in Mexico, a modern US maize hybrid (B73 x Mo17, and two teosintes (Zea diploperennis and Z. mays ssp. parviglumis). In the phytotron the phyllochron was determined for three dayight temperature regimes (22/18, 27/21 and 33/25 degrees C under a 12 h photoperiod. Genetic variation for the phyllochron among the genotypes was observed in the phytotron and field, however, it was small with extreme Values Of about +/-15% of the mean. A generally similar phyllochron for modern maize and its wild relatives suggested that this trait has been conserved despite thousands of years of human and natural selection. A similar leaf development rate among genotypes which varied widely for final leaf numbers (14-24) indicated that early flowering in some landraces was almost exclusively due to earlier floral initiation.