Study On Effect Of Photoperiod On Dormancy Induction And Respiratory Metabolism Of Nectarine Peach Buds During Dormancy Induction Period

The research had been carried out in fruit experiment station and protected fruit trees lab, Shandong Agricultural University from 2006 to 2007 with nectarine peach (Prunus persica var. nectariana cv. Shuguang). It was mainly studied the effects of photoperiod on dormancy induction and related physiological metabolism, the changes of respiration metabolism, carbohydrate content, water status, properties of membrane. The main results were as follows:1. The dormancy induction period was a transition period from growth to dormancy for plant. Shuguang nectariana buds dormancy induction period was 60d, that started from early september to early November under natural conditions, and then the plant transferred to dormancy period.2. Photoperiod had greatly induction effects on dormancy induction process. Short day could induce the growth stop of peach shoots ahead, promote the development of dormancy, and induce buds into dormancy with 21d previous to control. Long day treatment postponed the growth stop and induction and development of dormancy for 7d.3. Changes of bud respiration rate and pathways were closely related with the stage of dormancy induction. Bud respiration rate changed as an asymmetry"W"during the dormancy induction period, and the first respiration rate minimum appeared 7d after start of dormancy induction period while the second corresponded with the end of dormancy induction.The TCA ratio in nectarine was stable and at dominant position; the EMP ratio tend to decrease; and the PPP ratio tend to increase in dormancy induction period.At the same time, MDH activity changed little and decreased at the end of dormancy induction; PGI activity decreased continuously; G-6-DPH activity increased during this period.4. Starch content increased rapidly from the first 10 days of September and decreased slowly after the middle of October. Soluble sugar content increased continuously from the last 10 days of September. Soluble protein deceased until the end of dormancy induction(November). All these trends were consistent with change of respiration . 5. The changes of water state was correlated with the process of dormancy induction.During the dormancyt induction period, total water content declined slightly, freee water content decreased rapidly from the start of dormancy induction and maintained at the low level from the last of September. Bound water content increased rapidly associated with dormancy state, until the end of dormancy induction(November).The ratio of free water/bound water declined rapidly when nectarine transferring to dormancy induction.Membrane permeability declined at the dormacy induction period ,proline content first increased then decreased at middle of October, Content of lipid peroxidation products(Molondialdehyde, MDA) showed decreasing trend during this period.6. Photoperiod also influenced on dormancy related physiological indexes, with the influence on dormancy induction. Long day treatment improved respiratory rate, contents of carbohydrate, proline and MDA, restrained transformation of free water to bound watert. Short day treatment increased soluble protein content and effected ratios of each respiron pathway slightly.