Effect Of Iron-deficiency Stress On Physiological Characters And Screening Out Iron Tolerance Of Pyrus Betulifolia Bge.

This experiment was to study the selection of iron high-efficiency resources and the physiological and biochemical indexes of different areas of Pyrus beulaefolia Bge. seedlings under the iron-deficiency stress by using the method of hydroponics and by using the five different sources of seedlings from seed propagation, which were GS(Gansu), SX(Shanxi), XK(Xingjiang Ku’erle), XA(Xinjiang Ala’er) and XT(Xinjiang Tiemenguan), and to provide some basic date for screening and using the rootstocks with excellent complex characters and iron efficiency. The main research results were as follows:1. Leaves of different sources of seedlings show the chlorisis symptoms first under iron-deficiency stress. With the extend of the treatment period, the chlorisis started to become severe. XT, XK and GS sources of seedlings showed later chlorisis, which was the fifth day of the treatment, and their chlorisis percentage was the lowest, followed by XA sources of seedlings. The SX sources of seedlings was least resistant to iron-deficiency, the chlorisis symptoms showed up early at the third day of treatment and with a higher amount.2. Different seedlings showed noticeable acidification in different times under iron-deficiency stress in their rhizosphere. The SX and XA sources of seedlings with earlier chlorisis showed earlier noticeable acidification. Besides, the later the chlorisis time, the later the noticeable acidification time.3. Iron-deficiency leads to the increase of SODase and PODase enzyme activity and proline amount. XK, XT and GS sources of seedlings showed higher SODase and PODase enzyme activity and higher proline amount, while XA and SX sources showed lower enzyme activity and proline amount, which was in accordance with the chlorisis phenomenon.4. Iron-deficiency induces the activity of Fe3+ reductase in the seedling of seedlings, which was XT>XK>GS>SX>XA. At the same time, iron-deficiency increases the root activity while decreases the chlorophyll content in the leaves. Depends on different sources of seedlings, the effect was different.5. Morphological indexes were influenced by iron-deficiency in different sources of seedlings. The seedling height, leaf number, stem diameter, leaf area, and the increase of dry and fresh weight tend to decrease. At the same time, iron-efficiency increased the root length and the number of side roots.6. In the root system of seedlings, there were higher amount of active iron and total iron than that in leaves. No matter in the root system or leaves, the total iron content was more than the active iron content. The active iron was the indication of the iron circumstances of seedlings, which can be the index of iron-deficiency resistance, while the total iron cannot.7. Based on high-efficiency of iron, iron-deficiency resistant seedlings were selected. There were 5 XT seedlings, followed by XK and GS(3 seedlings each), and XA had only 2 seedlings. A rough estimation was made according to the resistance on iron-deficiency stress: XT>XK≥GS>XA>SX. XT sources had the highest resistance, while SX had the lowest.8. The total amount of iron absorption in different sources of seedlings increased with the iron concentration in hydroponics. At the same iron concentration, the order on total amount of iron absorption was XT>GS≥XK>XA≥SX. With the same treatment time, the order of absorption rate was XT>XK>GS>XA>SX.