Screening Of Salt Tolerance And Resistance Of Iron Deficiency From Hybrid Progenies Of Several Apple Rootstocks

The apple rootstock is a decisive factor of apple adaptation to salinity and alkali. It can improve apple salt tolerance ability to screen and breed salt tolerance and iron tolerance on rootstocks. Evaluation on salt tolerance and iron tolerance ability of different rootstocks is one of the most important procedure.For studying its salt tolerance and iron tolerance, this experiment studied the characteristic of physiology and biochemistry in apple rootstocks under salt-stress and iron stress by tissue culture and hydroponic plant. The results are summarized as below:1 Under NaCl-stress, the ablity of salt tolerance with different apple rootstocks is different. With NaCl content increasing and stress time prolonging,the growth was restrained, salt injury index and stress susceptibility index increased, moreover the regeneration coefficient and the accumulation of biomass decreased rapidly. it was found that the sequence of salt-tolerance is C2-0.4-11,C1-0.4-11>Malus Zumi>C6-0.35-1.2 Studies on physiological and biochemical characteristics of apple rootstock to NaCl stress. Under NaCl-stress, the SOD and POD activity decreased after increasing with NaCl stress time prolonging, and the salt tolerance was the best while the activity maintains high level in a long time. The content of MDA decreased after increasing with NaCl-stress time prolonging, and the smaller the salt tolerance was, the bigger increased extent was. The content of free proline increased in the first instance, then decreased rapidly. The salt tolerance was the best, the higher the content of free proline was. Plasma membrane permeability increased with NaCl-stress time prolonging, and the smaller the salt tolerance was, the bigger increased extent was. According to analysis of indexes concerned with salt tolerance, the activity of SOD, the content of MDA, cell membrane permeability in apple rootstock leaves can be used as evaluation indexes of salt tolerance of strawberry varieties. the activity of POD, The content of free proline can be used as reference indexes.3 Under iron stress, the ablity of iron tolerance with different apple rootstocks is different. Under iron stress by tissue culture, the leaves original chlorosis period with C6-0.35-1 was the earliest and C1-0.4-11 and C2-0.3-3 were the latest. Research result for the chlorisis index, regeneration coefficient, chlorophyll content showed that C6-0.35-1 was affected deepest; however C1-0.4-11 and C2-0.3-3 were affected less. Under iron stress by hydroponic plant, the leaves original chlorosis period with C6-0.35-1 and C6-0.35-6 were the earliest and C1-0.4-11 and C1-0.4-14 were the latest.Research result for new shoot growth,chlorophyll content and photosynthesis rate showed that C2-0.35-9 and C6-0.35-6 were affected deepest;however C1-0.4-11 and C1-0.4-14 were affected less.4 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.5 According to synthesis comparison to the growth and physiological and biochemical reaction of apple rootstocks under NaCl stress and iron stress, it was found that the sequence of salt tolerance and iron tolerance is C1-0.4-11>Malus Zumi>C6-0.35-1.