Study On Blooming Date Regulation Of Ornamental Peaches Under Protected Culture And The Characteristics Of Flower Bud Differentiation

The different chilling requirement ornamental peaches are studies on bloom date regulation and flower bud differentiation.Study shows, bloom date can be regulated with forcing culture and chemical treatment. (1) The effect of treatments depends upon the varieties. We have gotten better result on Mantianhong than on Juhuatao and Yingchun. (2) The ideal treatment period is when chilling accumulation at between 200 and 250h to Yingchun; 450 or 850h to Mantianhong and between 600 and 750h to Juhuatao respectively. (3) GA3 produced the best results in all chemicals. Thiourea was nearly as effective as GA3 to Mantianhong and Juhuatao. KN03 and Calcium Cynamide were less effective than them. 6-BA and (KNOs+thiourea) were ineffective. (4) The suitable concentrations: three concentrations of GA3 (50 mg-L-1, 100 mg-L-1, 150 mg-L-1) are all fitful to ornamental peaches; To avoid damage, thiourea has to be applied at 0. 5% to 2%. The tree will be seriously injured if the concentration >4%. The best range of Calcium Cynamide is 50X?00X ; 2%~8% KN03 have the same effects. (5) The initial flower, floral initiation can be advanced significant with the chemicals. It's effect become weaker and weaker by the turn of GA3 leaf bud and flower bud expansion. The most chemicals are not effective in prolongation of the bloom period. (6) The following results are recommendable. 〧or Yingchun, bloom date can be advanced 4?6d with 50 mg.L-1 GA3 at 250h CR(chilling requirement). 〧or Mantianhong, bloom date can be advanced 6~12d with 50 mg-L-1 GA3 and 0. 5% thiourea at 450h CR. (3)For Juhuatao, bloom date can be advanced 12d with 150mg-L-1GA3 and 2% thiourea at 600h CR.Anatomic observation of flower bud differentiation shows: (1) Flower bud differentiation is centripetal development. There were 1~2 ovules on the ventral surface of unicarpellae ovary wall. Ovule were atropous,bitegminous and crassinucellar. The development of the embryo sac conformed to the Polygonum type. Meiotic division of microspore mother cell is normal. Microspore tetrad is tetrahedron type. Pollen grains have three aperturates. (2) The periods of different flower bud differentiation stages in Luohe city is as follow. Initial differentiation (in late July). Sepal priomordia appeared (from early August to early September). Petal differentiation stage(from mid-August to mid-September). Stamen differentiation stage (from late August to late September). Carpel primordia differentiation stage (from early September to early October). Ovary formaion(from early to middle October), male gametophyte formation(from early December to early March), female gametophyte formation(from early March to blooming). (3) Baishanbitao have special characteristics in the development of megagametophyte and microgametophyte. Baishanbitao form pollen grains and ovule primodium that survive the winter, but other varieties form them in the spring. (4) The pistil of Baishanbitao is normal till endodormancy. After locule has formed in mid-October, the pistil of Baishanbitao hypoevolutismus, including ovule stop development, style does not elongate and the stigmatic surface is malformation. (5)There are relationship between time of breaking endodormancy and stage of flower bud differentiation.