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Studies on Physiological and Biochemical Characteristics of Salt-Tolerance Difference among Different Spinach Varieties (Spinacia Oleracea L.)

Author: WangJunWei
Tutor: WeiYouYing
School: Shandong Agricultural University
Course: Olericulture
Keywords: spinach salt stress osmotica and ions antioxidant enzymes Endogenous hormones biochemical characteristics
CLC: S636.1
Type: Master's thesis
Year: 2008
Downloads: 100
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Abstract

This topic based on the existing research, using five conventional varieties andfour hybrids, the effect of sodium chloride stress on germination characteristics andphysiological and biochemical characteristics at seedling stage were studied in thisarticle to provide theoretical basis for selecting and breeding dalt-tolerance varietiesof spinach and cultivating spinach in saline land.The main results were as follows:1. The spinach seeds germination was stimulated at low salt concentration(50mmol/L). The inhibition to seed germination was significantly strengthened withthe sodium chloride concentrations increase. Germination rate and germinationenergy of salt-resistant varieties were both more than common varieties. Salt-resistantvarieties had higher germination rate and the capability of salt-resistant than commonones. These nine cultivars had different levels of salt endurance. In the NaCl stress of300mmol/L, the relative germination rate of 48# was still more than 50%. From thethree indices of germination index, germination percentage and germination energy,we can see that 48# showed perfect salt tolerance, and had many fine traits in manyrespects, can be used as a good salt-tolerance variety.2. There were differences in osmotic adjustment ability of salt-stressed spinachseeding with different salt endurance. With the stress concentrations increase, theproline and soluble protein content increased and salt-resistant varieties had largeincreasing range than common varieties. From the changes we can see thatsalt-resistant varieties could accumulate more proline, soluble protein and sugar toresist osmotic stress, to keep higher water content of spinach seedings and maintainnormal cell physiological metabolism.3. The MDA content of spinach seedings increased with the increase ofconcentrations and duration of sodium chloride stress. 39# variety had the mostquickly increase of MDA and its increase range of MDA was larger than 48#’s, whichcan show that cell membrane of 39# had greater damage. There were diffrences ofantioxidant enzyme activities among different varieties. With the increase of saltconcentration, POD and SOD activities increased, salt-resistant varieties had higheractivities. The results showed that POD and SOD activity of salt-resistant varietiesreached its maximum at the concentration of 150mmol/L, Medium salt-resistant onesreached its maximum at l00mmol/L, with the increase of salt concentration both PODand SOD activity of leaves first increased but later went down slowly with thepassage of time.4. Chlorophyll content among three salt-stressed spinach varieties all increased firstand then decreased which can change leaves ability of capture and utilization lightenergy. Both photosynthetic and transpiration rate decreased with the prolongation oftime and increase of sodium chloride stress. The result showed that the chlorophyllcontent of salt-resistant varieties reached its maximum at the concentration oflOOmmol/L, Medium ones reached its maximum at 50 mmol/L, withthe salt concentration increasing, the chlorophyll content first increasedbut later went down slowly . 5. With the prolongation of time and increase of sodium chloride stressrelative permeability of cell membrane and MDA content increased gradually. With the prolongation of sodium chloride stress time, metabolic enzyme activities enhance and degradation rate of protein speeds up. The result showed that soluble protein began to decrease and proline content increased gradully in the same condition in different spinach varieties.There were some differences in the change range of test physiological indices in different salt-tolerance varieties during the period of sodium chloride stress. Compared with salt-intolerance spinach varieties, Salt-tolerance varieties had a more rapidly increase of proline content in seeding leaves and a more slowly degradation rate of protein which maintained in a higher level, and had a more slow production and accumulation of MDA.

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