| Gazania, originating in Africa, is a perennial plant and belonging to Gazania genus,Compositae. The capitulum with colorful petals opens in the morning and closes at night,for each capitulum it can live up to10days or so. It has many good characteristics such as:evergreen, flowering in three seasons, good resistance, once planted the landscape can bekept for many years and so on. Both gazania leaf and flower are good ornamental aspects.Besides, gazania can be planted in pots and open fields, which makes it a perfect candidateas groundcover plant used for dress up urban landscape, enriching groundcover plantdiversity and building low carbon gardens.This study investigated gazania main agronomic ornamental traits, superior individualbreeding, physiological indicators index and photosynthetic characteristics of hybridizationparents and their hybrid under artificial environmental (temperature and drought) stress,rapid propagation and low carbon cultivation techniques were also researched. The mainresults were as flows:(1)By investigating agronomic ornamental traits conserved in horticultural practicebase, hybrid seeds were planted in plugs and an excellent plant (‘Xingbai’×’Hongwen’hybrid)--‘XH’, compared with its parents ‘XH’ has a higher ornamental value.(2)After low temperature (6℃,3℃,0℃,-3℃and-6℃) treatment for24h,relative conductivity (REC) of three cultivars increased with increasing stress intensity;malondialdehyde (MDA) content showed a decreasing trend; both REC and MDA contentshowed a significant correlation with temperature; Pn, Tr, WUE and LUE value showed thetrend of decreasing gradually with increasing stress intensity. After-3℃treatment for24h, leaves of the three cultivar became soft, dropping and water-soaked, a small amount ofgreen leaves still left in ‘XH’. Under-6℃treatment, three cultivars were dead. Overall,‘XH’ had a better cold resistance than ‘Hongwen’.(3) After high temperature (35℃,40℃,45℃,50℃and55℃) treatment for24h, relative conductivity (REC) and MDA content of three cultivars decreased first and increased then; free proline (Pro) content increased with increasing stress intensity; Pn andLUE value increased with increasing temperature stress intensity; Gs, Tr and WUE valueincreased first and decreased. Under50℃treatment, leaf edges of three cultivarsturned anti-roll and dry and a small amount of burning spots showed in young leaf edges,‘XH’ damage degree was lower than ‘Hongwen’ while higher than ‘Xingbai’. Under55℃treatment, three cultivars were dead. In general,‘XH’ physiological indexes were betweenits parents and it had a medium resistance.(4)Under drought treatments(1d,4d,7d,10d,13d and16d), REC and Pro contentincreased first, decreased then and increased again; MDA content decreased; there was asignificantly positive correlation between Pro content and drought days; Pn, Gs, Tr, WUEand LUE showed significant negative correlation with drought stress. After16d treatment,most leaves of ‘Hongwen’ turned dry while ‘Xingbai’ and ‘XH’ had nearly half leavesturned dry.(5)By using improved capacity method and gravimetric method to determine gazaniatranspiration rate, the results showed that both branches and whole plant transpiration ratedecreased over time; for each cultivar, whole plant transpiration rate was bigger thanbranch’s; this method could better reflect plant water consumption.(6)As for cutting propagation, rooting rate, root number, length and soil into groupsituation were considered,100%garden soil or garden soil: plant ash=1:2(V:V) were moresuitable for gazania cutting. Both ‘Xingbai’ and ‘Hongwen’ had a good cutting effect withrooting rate more than80%.(7)In Suzhou area,‘XH’ could be propagated by cutting in winter without heatingconditions, which made it possible for gazania propagation by cutting all the year around;by using large hole plugs (54cm×48cm×8.5cm) for gazania propagation by cutting, itcould not only shorten breeding time but also reduce middle process from transplanting innutritious bowl to be planted in garden. |
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