Study On Flower-promoting Technology And Physiology Of Seedless Litchi

Litchi（Litchi chinensis Sonn.）is a non-infested family,litchi plants.Low temperature is an important factor in the induction of litchi flower formation.The longer the temperature time accumulation below the induced critical value is,the more it can promote the early germination of inflorescence primordium.In recent years,with the influence of the warming of the earth’s temperature and warm winter climate,is generally that the appearance of a phenomenon in Hainan Litchi,it is difficult to control、late flower formation、less fruitage and low yield.In recent years,it is frequently that Hainan comes to twarm winter years.Warm winter is easy to make litchi shoot and flower spike rush in the next year,which hinders flower bud differentiation,so that litchi tree will not blooming or less flowering,leads to decline yield and brings losses to growers,affect the development of litchi industry in hot areas seriousily.Seedless Litchi is the special Litchi variety in Hainan,which needs more stringent flower-forming conditions to flower than other varieties and it is more difficult to flower.Flower bud differentiation period is the key time to regulate flower bud formation in Litchi.The change of flower related substances during flower bud differentiation is an important factor to induce flower formation in Litchi.Nandao Seedless Litchi which is the special Litchi variety in Hainan was used to study the influence of different flower-promoting substances and their formulations on flower-forming,and to reveal the mechanism of flower-promoting substances in seedless litchi,in order to solve the problem of low flowering and low yield of seedless litchi in Hainan warm winter,so that provides technical support to make Hainan seedless litchi get yield in the warm winter,and get high yield in ordinary years.The main findings are shown as follows:1.Substance accumulation、changes of endogenous hormones and gene expression in Litchi branches and leaves with different flowering state（1）Starch、soluble sugar and ZT/GA₃of Litchi branches with different flowering state have the highest content in the threadbare period,ZT content and C/N ratio are the highest in the fresh buds period,IAA、ABA and GA₃have the highest content in the flower bud period.Soluble sugar、ZT and ABA of litchi leaves with different flowering state have the highest content in the threadbare period,the C/N ratio is the highest in the fresh buds period,starch and GA₃have the highest content in the flower bud state.（2）The expression of FT1 and FT2 in litchi branches and leaves in different flowering states has tissue specificity.The expression of FT1 and FT2 in the leaves during the threadbare period was the highest,indicating that the leaves are the organs that sense the differentiation of flower buds.2.Effects of different compounds on flower formation of“Nandao Seedless”litchiVinyl treatment can increase the flowering rate of litchi.The treatment of flower-promoting composition(chlorpyrifos 2.5 g·L^-1+naphthalene acetic acid 0.05 g·L^-1+5.0 g·L^-1compound A)can promote litchi flowering early.3.Study on the physiological mechanism of Erythromycin promoting the Flower Formation of“Nandao Seedless”litchi（1）Compared to the controls,Ethylene-lily treatment increased the rate of shoot formation and bud emergence of litchi,treatment of 0.10 g L^-1、0.15 g L^-1and 0.20 g L^-1concentrations,the branching rate of litchi can be reached respectively 50.50%、57.19%and69.45%,sprouting rate reached 71.89%、84.95%and 95.01%.（2）Ethylene-lily treatment increased the content of starch and soluble sugar in litchi branches,the content of Starch at budding stage can be reached 28.91 mg/g、28.04 mg/g、27.14 mg/g,and the content of soluble sugar can be reached 17.23 mg/g、17.10 mg/g、17.32mg/g,it provides C accumulation and promotes litchi flowering.（3）Ethylene-lily treatment increased the content of IAA and ZT of litchi branches,reduced GA₃and ABA content.At the same time,it also increased ZT/GA₃and IAA/GA₃,promoted the process of flower formation and in favor of Litchi flower.With the increase of three concentrations,the better the effect of ethephon on seedless litchi.4.Study on the Mechanism of flower-promoting combinator for early flowering of“Nandao Seedless”litchi（1）Flower-promoting composition treatment improved the number of spike per plant of litchi,it is 105.49%higher than control（2）Flower-promoting composition treatment improved the content of starch in the branches before the initiation of litchi,and before the bud of litchi,it also increased the content of soluble sugar,provides C accumulation for flowering.（3）Flower-promoting composition treatment improved the content of IAA、CTK and GA₃in litchi branches,although the content of ZT decreased during exposure,but it was still high.The ZT/ABA ratio was also increased,it is beneficial to promote the germination of litchi flower budand flowering early.