The Difference And Mechanism Of Chilling Requirement And Heat Requirement Of Lforal Buds In Red Fuji Apple On Different Dwarfing Interstocks And In Different Apple Cultivars

This experiment was carried out during2011-2013at College of Horticulture inAgricultural University of Hebei with floral buds in apple variety Hongqian,Gala,Dounan and in Red Fuji apple grafted on interstock78-48, M26, CG-24, CX-3, B9and Mark. The differences and mechanism of chilling and heat requirements indifferent test materials were studied, and the physiological and biochemical changesin the buds of different test materials during dormant and sprouting period wereanalyzed. The main results were as follows:1.Chilling and heat requirements of Red Fuji apple floral buds on differentdwarfing interstocks were significantly different. Chilling requirement of floral budsof Red Fuji apple grafted on interstock CX-3, estimated by≤7.2℃model,0-7.2℃model and Utah model, was the highest, which was significantly higher than that onother rootstocks, while that grafted on interstock78-48and M26was the lowest. Heatrequirement of floral buds of Red Fuji apple, estimated by Growing degree hoursmodel and effective accumulative temperature model, was highest on interstock Mark.That grafted on interstock78-48, CX-3, B9, CG-24and M26were followed.2. Chilling and heat requirements of the floral buds were significantly differentbetween different apple varieties. Chilling requirement, estimated by≤7.2℃model,0-7.2℃model Utah model, wasthe highest in Hongqian, and lowest in Dounan. Heatrequirement, estimated by Growing degree hours model and effective accumulativetemperature model, was highest in Gala, and lowest in Dounan.3.During the dormancy, contents of soluble sugar, starch, and soluble proteinreached a low point in dormancy-broken, and then recovered. The date, when thecontents of soluble sugar, starch, and soluble protein reached a low point, wasconsistent with their dormancy-broken moments respectively.4.During the dormancy, GA, ABA, and ZR contents of apple floral buds reacheda peak near the period of dormancy, and then decreased sharply afterdormancy-broken. However, IAA content showed an opposite trend. The date, whencontents of GA, ABA, and ZR reached the peak and IAA in low point, was consistentwith their dormancy breaking moments respectively. 5.During the sprouting process of apple floral buds in Red Fuji apple on differentdwarfing interstocks and in different apple cultivars, contents of soluble sugar andstarch showed a declining trend, while protein content showed a trend of rising untilthe alabastrums began to separate in the inflorescence, and then fell down till fullbloom. Contents of IAA, GA, and ZR in apple floral buds reached a peak respectivelynear the inflorescence elongation stage, and then decreased rapidly. However, ABAcontent showed an opposite trend.6.During the sprouting process of apple floral buds in different apple, most of theamino acid contents reduced slightly as the floral buds swelled, then they rose. Afterthe inflorescence elongation stage or alabastrum separation stage in the inflorescence,they reduced again. In addition, acidic amino acid contents were significantly higherthan other amino acids’.