Study On Mechanism Of Respiration During Dormancy Induction And Release

Respiration inhibitors and oxygen electrode were used to investigate respiration rate, the changesof respiratory pathway, the effects of photoperiod and temperature on dormancy induction and effects ofleaves and breaking dormancy chemicals on dormancy release in grape buds (high chilling requirementgrape cultivar Summer Black and low chilling requirement grape cultivar Jingmi). The main resultswere as follow:1. Dormancy induction:(1) TCA and EMP-TCA partly turned to PPP and fat protein-TCA, andalternative pathway temporarily increased during dormancy induction. Activation of PPP and shift fromcarbohydrate to fat and protein in respiratory substrate were the symbolic physiological change duringdormancy induction and the key for buds dormancy induction. Alternative pathway played an importantrole in inducing buds dormancy.(2) Grape buds dormancy could be induced by natural low temperatureor short sunlight. Low temperature was the main factor, which induced respiration rate and changes ofsubstrate respiratory pathway, and short sunlight was the secondary one. Alternative pathway could beactivated by low temperature and short sunlight. Shorter sunlight had more effect on dormancyinduction.(3) The date when low chilling requirement grape cultivar went into dormancy induction waslater and depth of dormancy was shallower.2. Dormancy release:(1) The variation in total respiratory rate showed single peak curves.EMP-TCA increased and alternative pathway and residual pathway were activated during dormancyrelease. EMP-TCA was the key of dormancy release. Alternative pathway and residual pathway mightbe an important role in dormancy release.(2) Soluble and reducing sugar content of dormancy withleaves was higher than defoliation and respiration rate, EMP-TCA, alternative pathway and residualpathway of dormancy with leaves were more activate than defoliation during dormancy release.Dormancy with leaves may promote changes of respiratory metabolism by increasing soluble andreducing sugar content to release dormancy earlier.(3) GA3and ABA content changed obviously duringdormancy release, GA3and ABA played an important role in dormancy release. GA3/ABA, ZT/ABA,IAA/ABA increased during dormancy release, and GA3/ABA was higer than others. Antagonism of GA3and ABA was the main factor to release dormancy, and antagonism of ZT, IAA and ABA was thesecondary one.(4) Activation of TCA, attenuation of PPP, increase of CP and decrease of AP werepromoted by dormancy breaking agent, while deficient chilling exposure blocked it. Dormancy breakingagent may activate following step of dormancy release instead of part of chilling hours by inhibition ofmitochondrial respiration.(5) We Partitioned based on changes of respiratory metabolism into twophase: First,0to2/3chilling requirement, environmental adaptation phase; Second,2/3chillingrequirement to fulfill, growth recovery phase.