Research On Difference On Physiological And Biochemical Characteristics Among Different Capsicum Frutescens Cultivars Under Salt Stress

The menace of land salinization to agriculture is a global problem. Raising salt-toleranceof crop has been an important subject in agriculture research. Chilli pepper is a kind ofimportant vegetable.1/4of pepper’s cultivation area is occupied by Capsicum frutescens.There is a lack of systematic research on salt-tolerance of pepper.20Capsicum frutescenscultivars were taken as material in this research. Their difference on salt-tolerance atgermination and growing time were studied and salt-tolerant cultivars were screened. Thedifference on physiological and biochemical characteristics in seedlings among cultivars withdifferent salt-tolerance was also explored. The results showed as follows:1. NaCl treatment had apparent effects on pepper at germination which was differentamong different cultivars. Some of them had higher germination rate than check treatmentunder treatment of0.5%concentration. All cultivars had lower germination than control whentreated with concentration higher than2.0%. There were more obvious effects on germinationpotentiality with NaCl treatment. Germination was delayed when concentration was higherthan1.0%.14#,15#,18#had got higher salt-tolerance at germination, and2#,16#,17#,21#had lower salt-tolerance in this stage. NaCl treatment with lower concentration couldaccelerate plant growth of some cultivars. Symptoms of salt damage revealed gradually withthe increasing of NaCl stress which had different extent on different cultivars.2#,7-1#,14#,15#,18#,19#had got smaller index of salt stress under higher concentration.2. Classification of salt-tolerance of20cultivars had been obtained with comprehensiveanalysis of indicators of germination and growing time:14#,15#,18#were cultivars withhigher salt-tolerance and7#,9#,10#,12#,17#,20#,22#,23#were cultivars with lowersalt-tolerance. Others cultivars had got medium salt-tolerance.3. Protective enzymes SOD, POD, CAT activities of3cultivars with different salttolerance rose under NaCl stress. Protective enzymes activities reduced when the stress got toa certain degree.18#with higher salt tolerance maintained high levels in POD and CATactivities under serious salt stress. The effects of NaCl stress on soluble protein, proline andsoluble sugar content in seedlings of pepper showed decline trend after initial ascent. Thesoluble protein content rose with aggravation of NaCl stress, but there were not many differences on situation among3cultivars.10#with lower had poorer capacity ofaccumulation of proline meanwhile18#had stronger capacity.18#had lower soluble sugarcontent than2#and10#under salt stress. MDA content and plasma membrane of3cultivarswith different salt tolerance showed upward tendency with aggravation of NaCl stress whichindicated the more serious the salt stress was, the more serious damage the plasma membranegot.10#with lower salt-tolerance accumulated more MDA and got a higher permeability.4. Cultivars with higher salt-tolerance were not necessarily better than those with lowersalt tolerance on every indicator. Different cultivars showed superior or inferior situation ondifferent indicators. Differences on plant salt tolerance are the result of together action ofmany substances and mechanisms.