Study On The Heredity Of The Traits Relative With The Sensitivity To Photoperiod Of Temperate×Tropical Crosses In Maize

Using 2 temperate inbred lines and 2 tropical subtropicalinbred lines as parents, according to Hayman model and by means of thegeneration mean analysis, we studied the gene effects, gene x environmentaleffects of 3 temperate x tropical subtropical crosses' basic vegetative growth stage, plant height and ear height that are relative with the sensitivity to photoperiod. The main results were as followed:(l)The qualitative effects for earlier days to anther, days to shed, days to silk because of the different temperate genetic component ratio in 6 generations were found. (2) Fl vegetative stage was close to the breeding aim in temperate area, but Fl ear height, plant height can not be used directly. BC1 vegetative stage, ear height, plant height accorded with the breeding aim in temperate area. Therefore, the sensitivity to photoperiod of vegetative growth stage of tropical germplasm can be decreased significantly by crossing the temperate inbred lines with the tropical inbred lines. Inbred lines whose sensitivity to photoperiod of all traits were decreased significantly can be selected from the populations that were formed by backcrossing with the temperategermplasm.(3)The heredity of tassel length of 478 x CML312 andHUANGZAO4 x CML312 under spring sowing conformed to the genetic model of additive-dominance. The heredity of plant height, ear height, days to anther, days to shed and days to silk conformed to the genetic model of additive梔ominance梕pistatic. When the crosses were planted under summer sowing, the heredity of all the traits conformed to the genetic model of additive梔ominance梕pistatic. In the genetic variation of the traits relative with the sensitivity to photoperiod among generations, the main components were additive effects and dominance effects. Additive effects were superior to dominance effects in days to anther, days to shed, days to silk. Dominance effects were superior to additive effects in plant height, ear height and tassel length. (4) In all the traits of all the crosses, enviromentaleffect is remarkable. In the genetic variation of the traits connected with the sensitivity to photoperiod among generations, enviromental effect can notbe neglected. (5)When progeny selection was done from the temperate x tropical crosses under spring sowing, more plants can be selected whose weak sensitivity to photoperiod can be hereditied steadily. Therefore, it is better for the progeny selection to be done under spring sowing than summer sowing.