Study On Cutting Propagation Technology Optimization And Rooting Mechanism Of Feijoa (Acca Sellowiana Berg)

Acca sellowiana Berg is the evergreen woody plant of Magnoliopsida Rosaceae（Myrtaceae）Feijoa Berg or Acca Berg,it?s an emerging fruit with ornamental,edible and medicinal values.Cuttage propagation has the advantages of simple operation,low cost of raising seedlings,and maintaining the characters of excellent varieties of the parents,but there are also some problems in Feijoa cutting propagation,such as difficult rooting,long seedling raising time and so on.In order to speed up the cutting propagation process of Feijoa fruit and improve the breeding quality of seedlings.The effects of different degrees of shading yellowing（non-yellowing,40%shading yellowing and 70%shading yellowing）on the rooting and growth of cuttings in different growing parts（upper,middle and lower parts of the tree body）and different maturity（shoots,semi-lignified shoots and lignified shoots）were investigated by orthogonal experimental design.The rooting growth of semi-lignefied cuttings was promoted by spraying biological stimulants（6-BA,KH₂PO₄,amino acid fertilizer）on the leaf surface and soaking different rooting inhibitor eluents（silver nitrate,potassium permanganate,ethanol,acetic acid,water）at the base of cuttings.Container cultivation was further carried out for surviving cuttings,and the effects of container material,container size,matrix volume ratio and compound fertilizer ratio on the growth of container seedlings were explored.Since IBA was used as the basic hormone treatment in cutting optimization,it is necessary to explore the influence of the change of endogenous hormone level in cortex,rooting oxidase activity and nutrient content on cuttings morphogenesis under IBA treatment.The results show that:（1）The yellowing treatment was the main factor affecting the rooting rate and the new shoot rate of the cuttings.The principal component analysis showed that the best rooting effect could be obtained by cutting the semi-lignified cuttings from the upper part of the tree after 40%shading yellowed.The rooting rate of cuttings was 73.17%and the incidence of new shoots was 50.33%.Compared with the lowest score group,the rooting rate increased by 39.41%.（2）The concentration of 6-BA was the main factor affecting the rooting characteristics and the growth characteristics of new shoots.The most suitable treatments selected by principal component analysis are 20 mg/L 6-BA,40 mg/L KH₂PO₄,and 400 mg/L amino acid fertilizer.Compared with CK,the rooting rate and the incidence of new shoots were increased by 39.43%and 23.34%respectively.（3）After soaking the base of cuttings with different eluents,the average rooting rate of cuttings was in the order of potassium permanganate>acetic acid>silver nitrate>clear water>Ethanol.The 0.1%potassium permanganate treatment achieved the highest comprehensive score.The rooting rate of cuttings was 82.39%and the incidence of new shoots was 66.67%.Compared with CK without elution,the rooting rate increased by 48.06%and the incidence of new shoots increased by 18.24%.（4）The container size was the main factor affecting seedling height increment,number of new leaves,new stem diameter and number of branches.new stem diameter and number of branches.The optimal treatment was white non-woven fabric planting bag with a volume of25×17cm,matrix peat:coconut bran:perite（3:1:1）,and compound fertilizer ratio of N∶P₂O₅∶K₂O（15∶5∶25）.Under this treatment,the seedling height increment reached24.00cm in 10-190 days,and the number of new leaves reached 16.60.Compared with CK,the seedling height increment increased by 10.02cm,and the number of new leaves increased by 6.60.（5）The effect of IBA on the rooting mechanism of Feijoa cuttings showed that IBA treatment promoted the rooting of Feijoa,and the rooting rate of Feijoa was 69.13%under1000mg/L IBA treatment,which was better than other treatments.The rooting stage was callus stage（0-20 days）,root primordium induction stage（20-40 days）,adventitious root expression stage（40-60 days）and adventitious root elongation stage（after 60 days）.High concentration of IAA,IAA/ABA,IAA/ZR and low concentration of ABA and ZR were beneficial to root formation.IBA stimulates cuttings to synthesize more endogenous hormone IAA,promotes the consumption of ABA and ZR,and increases the ratio of IAA/ABA and IAA/ZR.Low IAAO activity and high POD,PPO activities jointly regulate the IAA level of cuttings to promote rooting.IBA can accelerate the speed and intensity of nutrient metabolism in cuttings.High concentration of soluble protein facilitates the induction of root primordium,starch is hydrolyzed into soluble sugar in time,and soluble sugar provides energy for the entire rooting process.The rooting rate of the cuttings was significantly increased after yellowing,but the incidence of new shoots was lower than that of the unyellowing branches.The combination of yellowing treatment and leaf spraying with biological stimulant could improve the rooting rate of the fayot fruits and supplement the nutrition of the branches.0.1%potassium permanganate treatment can be used before cutting to sterilize and elute rooting inhibitors.Growth regulator IBA treatment is necessary to promote rooting.