Response Of Red Fuji Apple Grafted On Different Interstock To Iron-stress

Red Fuji apple is the major cultivar at present, but the young trees grow excessively and are difficult in forming flower bud. Appliance of dwarfing inter-stock could not only promote its formation of flower bud and reach the purpose of setting earlier, but also exert the adaptability of the rootstock. However, the result of observation for several years in the field indicated that Red Fuji apple grafted on different interstocks showed different iron deficiency chlorosis phenomena in calcareous soil .The reason of the difference of chlorosis phenomena is a problem that was worth to study and hasn抰 been reported till now. In order to reveal this reason and provide theoretical base for remedying iron deficiency chlorosis, this paper was made with Red Fuji apple grafted on five sorts of inter-stocks by the method of water culture (iron-deficiency and iron-abundance), iron-stress response and chlorosis mechanism were studied. The main results were as follows: I Under iron-stress, the original chlorosis period of Red Fuji apple with different inter-stocks is different. The leaves?original chlorosis period of Red Fuji apple with SH33 SH40 stocks were the earliest and showed chlorosis in 5d and 8d after iron-stress; The leaves?original chlorosis period of Red Fuji apple with 77-34, Mark stocks were the latest and were 21st d after iron stress; Red Fuji apple grafted on M26 stocks was the middle one and were 17th d. Research result for new shoot growth, chlorophyll content and net photosynthesis rate showed that Red Fuji apple grafted on SH33 and SH40 are affected deepest; however Red Fuji apple grafted on Mark were affected less. 2 Under iron-stress, compared with abundant iron, Rhizosphere acidification phenomenon showed difference in time and that sensitive to iron stress showed earlier, but that resisting iron stress showed later, Root system Fe3~ reducing ability of Red Fuji apple with different interstock were promoted, and Red Fuji apple sensitive to iron stress were promoted bigger range and Red Fuji apple resisting iron stress were promoted less range. 3 The studies of iron content indicated that under iron stress condition ,compared with control, iron content of the upper and middle leaves of Red Fuji apple grafted on different interstocks were reduced, especially the Red Fuji apples with SH3S,SH4O were reduced big range. Iron content of root system was also reduced, and the reduced percentage of iron content of root was correlated negatively with that of leaves. Under iron stress, iron content of interstock part of the Red Fuji apple was higher than that of control. That grafted on SH38,SH4O were the most significant; that grafted on Mark was the lowest. However, leaves?iron content of Red Fuji apple with SH3, interstock was the highest under iron-stress. Total iron content couldn抰 reflect chlorosis degree. 4 The study of ratio of total iron and active iron indicated that upper and middle leaves?ratio of total iron and active iron content of Red Fuji apple with five interstocks were correlated with chlorosis degree positively, and correlation coefficient was respectively 0.9267* 0.9935**. This indicated that the ratio of total iron and active iron could reflect chlorosis degree better.