Effects Of Plant Growth Regulators On Flower Bud Differentiation And Yield Of Juglans Regia L.

Walnut(Juglans regia L.)is an important edible nut and woody oil tree species.In recent years,the rapid development of the walnut industry has been accompanied by many problems,such as low yield and poor quality,which directly affect the economic benefits of walnuts.Plant growth regulators have an important effect on walnut growth and fruiting,but the specific effect is still unclear.In this experiment,‘Qingxiang’ walnut was used as the test material,and three plant growth regulators:Paclobutrazol(PP333),Brassinolide(BR)and Benzylaminopurine(BA)were used to treat the walnuts when the new shoots were about15 cm long.Brassinolide and benzylaminopurine were sprayed by foliar spray,and paclobutrazol was sprayed by foliar spray,soil watering and trunk injection.Investigate and record the indicators of tree growth(Dry week,New Shoot Growth,Leaf Area),flower bud differentiation(Male and Female Flowers),fruit development(Fruit Number,Fruit Setting Rate,Single Fruit Weight)and other indicators.The content of five endogenous hormones Auxin(IAA),Gibberellin(GA3),Zeatin(ZT),Abscisic acid(ABA)and Salicylic acid(SA)in leaves at different fruit development stages were determined by liquid chromatography.The effects of three plant growth regulators and their different application methods on walnut tree growth,flower bud differentiation,fruit development and endogenous hormone content provide theoretical and practical basis for walnut flowering regulation.The results are as follows:(1)The growth of new shoots and internodes was inhibited after paclobutrazol treatment.The foliar spraying of 20 mg/L brassinolide and 40 mg/L benzylaminopurine can significantly promote the growth of new shoots and leaf area.Spraying brassinolide 10mg/L and benzylaminopurine 40mg/L increased the number of female flowers and fruits.When paclobutrazol was sprayed three times and the trunk was injected with 1.2 g/plant,the number of female and male flowers decreased.When benzylaminopurine is 40 mg/L,the number of male flowers increases.Plant growth regulators had no significant effect on dry week,three diameters of fruit,green peel,nucleolus weight and kernel yield.Principal component analysis results show that the order of principal component scores from high to low is BA3>Y2>BR1>C3>BA2> BAck>Y3> BRck>Yck> C2 > Y1> Cck > BR2 >BR3> Tck>Zck>BA1> C1 >Z3>T3>Z1>Z2>T2>T1.The best treatments were BA3(spraying benzylaminopurine 50mg/L)and Y2(spraying paclobutrazol 1000mg/L),and the main component scores reached 46.06 and 32.83.(2)The content of endogenous ZT in walnut plants showed a trend of “Rising first,then Falling and then Steady”,the content of GA3 showed a trend of “Rising first,then Falling and then Rising”,the content of IAA roughly showed a trend of “Decreasing”,and the changes of SA content and IAA content were basically the same,ABA content presents a "Gradual Increase" trend.After paclobutrazol treatment of walnut plants,in addition to soil watering,foliar spraying and trunk injection paclobutrazol can reduce the content of endogenous ZT,GA3,IAA,SA and increase the content of ABA in "Fragrant" walnuts to varying degrees.Spraying benzylaminopurine can reduce the content of endogenous IAA and ABA,and increase the content of ZT and GA3,with no obvious changes in SA.However,spraying brassinolide can increase the content of endogenous ZT,GA3,IAA,SA,and decrease the content of ABA.