Abstract:
The diagnosis and evaluation of salt tolerance about crop during germination is the basic research of modern agriculture, and it has very important significance to ensure global food security.Currently, there are many reports on evaluation of salt tolerance during crop germination, and mostly based on morphological index such as the germination rate, germination energy, germ length, root length and seed fresh quality.These traditional evaluation methods have many defects such as a lot of work, very complex calculations, long measurement period, more amount of seeds to use, and not suitable for rare species.Ultraweak photon emission, including spontaneous photon emission and delayed photon emission induced by external light, is a kind of life information in the form of living cells.According to the changes of ultraweak photon emission, the noninvasive detection about the changes of metabolism and functional state of living cell can be achieved and may be applied to evaluate crops salt tolerance.In order to explore the noninvasive detection and evaluation method about the salt tolerance of corn during germination based on the ultraweak photon emission from germinating crop seed, NaCl with 100 mmol/L was used to form the salt stress, and this paper studied the differences of two corn varieties Wanrui No.168 and Zhengdan No.958 in salt tolerance during germination period based on the conventional seed germination salt tolerance index.At the same time, we also studied the differences of the spontaneous photon emission and delayed photon emission induced by blue LED about corn varieties Wanrui No.168 and Zhengdan No.958 during germination under the 100 mmol/L NaCl stress.The results showed that the seed fresh quality, spontaneous photon emission intensity and delayed photon emission integral intensity of two corns varieties Wanrui No.168 and Zhengdan No.958 gradually increased in the normal germination process, there was positive correlation between the changes of seed fresh quality and spontaneous photon emission(the correlation coefficient was 0.982 27 and 0.962 51 respectively).Under the 100 mmol/L NaCl stress, there was also a positive correlation between the seed fresh quality and spontaneous photon emission of two varieties of corn (the correlation coefficient was 0.983 57 and 0.991 06, respectively).The study also found that the NaCl stress inhibited the increase of seed fresh quality and spontaneous photon emission of the two corn varieties in different degrees, inhibitory effect of the NaCl stress on Zhengdan No.958 was greater than Wanrui No.168.According to the relative inhibition rate of NaCl stress on the spontaneous photon emission and delayed photon emission during germination could distinguish and evaluate the strength of salt tolerance about corn varieties Wanrui No.168 and Zhengdan No.958 during germination.Compared the evaluation result based on the relative inhibition rate on spontaneous photon emission and delayed photon emission from germinating seeds under the NaCl stress with the conventional seed germination salt tolerance index and storage material transport rate, the evaluation results were the same, and it showed that the evaluation methods based on the relative inhibition rate of spontaneous photon emission and delayed photon emission under the NaCl stress were reliable.The relative inhibition rate of spontaneous photon emission and delayed photon emission respectively reflected the impact of NaCl stress on cell metabolism and cell damage.Since the evaluation method about salt tolerance based on the spontaneous photon emission and delayed photon emission from germinating seeds cells has many advantages, such as sensitive, rapid, non destructive and so on, this method can reflect the response of cellular metabolism, adaptation and harm process under NaCl stress, and it is expected to become a kind of practical, wide applicability and reliable new method of evaluation salt tolerance on germinating crops seeds.