Preliminary Study On Sexual Reproduction And Asexual Reproduction Of Water Spinach

Water spinach is a kind of Ipomoea aquatic Forsk,which is cultivated in southern China.In recent years,it began to introduce cultivation in the north.In production practice,water spinach is difficult to keep seed.In this dissertation,Changsha water spinach was used as material to study the cutting propagation,tissue culture and propagation,photoperiodic characteristics,flower organ development and intraspecific hybridization of Fujisawa.The main results are as follows:1 Study on cutting propagation of Water spinachAccording to the cutting research of Changsha water spinach,it is concluded that peat is the best substrate for cutting propagation of water spinach.The rooting rate of cuttings is60%,and the average number of rooting is 8.2,which is significantly better than other combinations.Different types of hormones have good effects on water spinach cuttings.The promotion effect was the most significant with the NAA promotion effect;the NAA of1000 mg·kg^-1 was the best hormone and the best concentration for water spinach cutting propagation,the rooting rate was as high as 93.3%,and the average rooting number was22.6.The best cutting position of water spinach was the lower part of the branches,the rooting rate was 73.3%,and the average number of rooting was 9.6.2 Study on Tissue Culture and Rapid Propagation of Water spinachThrough the study of tissue culture of Changshan water spinach,it was concluded that the stems of water spinach had direct rooting and sprouting,and then grew into plants.The best medium for tissue culture with stems of water spinach was MS+NAA 0.1 mg·L-1;the best number of tissue cultures for young stems of water spinach was 5¹0;after inoculation with water spinach,3 d can germinate and take root,sprouting faster than rooting,20 days can be practiced seedling transplanting,the survival rate of transplanting reached more than80%.3 Study on the Photoperiod of Flowering of Water spinachThrough the study of the photoperiod of Changsha water spinach,we characterized the critical photoperiod（Pc）,limited inductive photoperiod（LIP）and juvenile phase inChangsha water spinach（Ipomoea aquatica）,a shy-flowering vegetable（i.e.it does not flower in the wild）.By transferring the plants between short days（SD）and long days（LD）,the results show that the Pc of Changsha water spinach is 12 h light/12 h dark,the LIP is 16days,and the juvenile phase of Changsha water spinach will terminate at4-leaf stage.Additionally,the results also show an up 13-hours dark period can be more conducive to the flower bud differentiation in Changsha water spinach,while the differentiated flower bud would be reversed if the induced photoperiod is less than LIP.These results thus demonstrate that Changsha water spinach is an obligate short day plant.3 Study on the Photoperiod of Flowering of Water spinachThrough the study of the photoperiod of Changsha water spinach,we characterized the critical photoperiod（Pc）,limited inductive photoperiod（LIP）and juvenile phase in Changsha water spinach（Ipomoea aquatica）,a shy-flowering vegetable（i.e.it does not flower in the wild）.By transferring the plants between short days（SD）and long days（LD）,the results show that the Pc of Changsha water spinach is 12 h light/12 h dark,the LIP is 16days,and the juvenile phase of Changsha water spinach will terminate at4-leaf stage.Additionally,the results also show an up 13-hours dark period can be more conducive to the flower bud differentiation in Changsha water spinach,while the differentiated flower bud would be reversed if the induced photoperiod is less than LIP.These results thus demonstrate that Changsha water spinach is an obligate short day plant.4 Study on the Pollination Biological Characteristics of Water spinachBy measuring the pollen viability,stigma receptivity,self-compatibility,and combining field flower traits,it was observed that the flowering duration of water spinach was shorter and could be maintained for about 12 hours.The loose powder started 1 h after flowering,but the pollen was thick and not easy to spread.The pollen viability increased first and then decreased with the extension of time.The activity was the strongest at 1 h after flowering and almost no activity after 4 h.Regardless of the storage method of water spinach pollen,the pollen viability of water spinach decreased significantly with the prolongation of storage time.The stigma receptivity was highly reproducible during the flowering period,and it was the strongest at 4 hours after flowering,and the receptivity was lost after the stigma wilting.The self-incompatibility index of Changsha water spinachmushroom is 0.144,which is less than 1,so the Changshan water spinach is preliminarily judged to be self-incompatible.