Study On Dormancy And Growth Characteristics Of Narcissus

Narcissus （Narcissus pseudonarcissus L.） is a kind of perennialherbaceous plant belongs to Amaryllidaceae in Narcissus L., as a worldfamous bulb flowers, it is widely cultivated in the world. Nowadays, therewere not much too study on dormancy and growth characteristics ofnarcissus, also there was no report about the relationship between narcissusdormancy release and its phenolic acids mechanisms. In this article, phenolicacids mechanisms during dormancy release and growth and photosyntheticcharacteristics of narcissus were investigated. The main results were showedas below:1、Changes of Carbohydrates content in narcissus bulbs stored atdifferent temperature for dormancy release were studied. The resultsindicated that: The content of starch declined46.3%during the periods of thebulbs treated by7℃,compared to the21.3%declined treated by roomtemperature; The content of soluble sugar had a tendency of increase, and theincrease extent of bulbs treated by7℃was higher than it treated by roomtemperature. at the same time, in8th week, the content had a decrease; Thesoluble protein had the same increase tendency as the soluble sugar; The SDS-PAGE of soluble protein showed that there were17feature bands, andthe protein bands of54kD、40kD areas were appeared by a method of“sisters” which means isoenzyme proteins.18kD and below areas proteinbands may be the storage proteins of the bulb of narcissus; There were no oldprevious disappeared or new previous appeared during the periods treated bydifferent temperatures.2、Changes of phenolic acids content and activities of polyphenoloxidase （PPO） and phenylalanin ammonialyase （PAL） were studied in thebulbs of Narcissus pseudonarcissus. var.‘Shangnong Zaochun’bulbs storedat7℃. Results indicated that total phenolic content decreased dramaticallyduring the low temperature storage. Five phenolic acids （gallic acid,chlorogenic acid,4-dihydroxyphenylacetic acid,3,4-dihydroxycinnamic acid,4-hydroxy-3-methoxybenzoic acid） were identified in narcissus bulbs. Thecontent of4-dihydroxyphenylacetic acid was the highest during thedormancy release. Negative correlation existed between total phenolic acidcontent and PPO activity, while positive correlation was observed betweentotal phenolic content and PAL activity. The decrease of phenolic acids maybe one of the mechanisms of narcissus dormancy release.3、Studied the correlate relationship between changes in carbohydratecontent and enzymes （POD, PAL, PPO） activitivies related to phenolic acidsmetabolism with changes of total phenolic content and the five phenolicacids contents in narcissus bulbs treated by low temperature for dormancy release.The results showed that the changes in the starch content, POD andPPO activities may be the major factors in changes of total phenolic content.Soluble sugar, soluble protein content and POD activity changes may beinvolved in three phenolic acids （gallic acid, chlorogenic acid,4-hydroxybenzoic） metabolism during the dormancy release of narcissus bulbs treatedby low temperature. The stepwise regression analysis between activities ofenzymes related phenolic acids metabolism and the five phenolic acidsshowed that: POD and PAL were mainly related with4-hydroxybenzoic acidmetabolism while PPO was mainly related with gallic acid metabolismduring dormancy release of narcisuss bulds treated by low temperature.4、The breeding and photosynthetic characteristics of two new narcissuscultivars （‘Shangnong Zaochun’ and ‘Shangnong Dieying’） were studied.The results showed that the average diameter of ‘Shangnong Zaochun’ and‘Shangnong Dieying’ were13.6cm and12.8cm, respectively. Themultiplication coefficients were1.04and1.32, respectively. The diurnalvariation of Net photosynthetic rate （Pn） of two cultivars was “double-peak”curve and an obvious phenomenon of‘mid-day depression’occurred in thethree periods （early April、early May and middle May）. The PFD-Pnresponse curves showed that no significant difference existed in Pn of thetwo cultivars when the photon flux density （PFD） was under300μmol·m^-2·s^-1. Pn of two cultivars both increased rapidly with increasing PFDwhen PFD was between300μmol·m^-2·s^-11200μmol·m^-2·s^-1. Pn of ‘Shangnong Zaochun’ was always higher than that of ‘Shangnong Dieying’.The apparent quantum yield （AQY） of ‘Shangnong Zaochun’ was also higherthan that of ‘Shangnong Dieying’. The CO₂-Pn curves showed that the CO₂saturation points of ‘Shangnong Zaochun’ and ‘Shangnong Dieying’were1463μmol·mol-1and1641μmol·mol-1, respectively. Air temperature-Pnresponse curves showed that the most suitable air temperature of ‘ShangnongZaochun’ and ‘Shangnong Dieying’ were22.6℃and22.4℃, respectively.