| The short stem is the commonality of most fresh peach varieties currently produced.The material in this research is a nectarine variety ’Manyuan Hong’,which is a typical short stem variety.The short peach stem will cause the peach fruit on the thick branch to squeeze with the fructify branch after the second expansion.The fruit drop,up to 30%,is serious.Farmers mostly use the middle branch,the short fruit branch and the weak branch to fructify in production,which affecting the peach production and fruit quality.Short peach stems also affect the application of mechanized harvesting in their production.In this experiment,four kinds of GA3 smears were applied to the peach stems(Pedunical stems)in the full bloom stage,1 week after the flowering,and 2 weeks after the flowering.The experiment mainly studied the effects of different concentrations of GA3 treatment on peach stems and their anatomical characteristics during these three periods to explore the effect of GA3 on the length of peach stems.Then we screened out the appropriate period and corresponding concentration to promote the length of peach stems.These results will provide a practical basis and theoretical support for the application of medium-strong branches and appropriate external hormones on fruit stems in future production.Also,these lay a foundation for exploring the mechanization application on picking of peach fruit.The test results are as follows:1.Effects of different concentrations of GA3 on peach traits:During the full bloom stage,GA3 from 100 mg/L to 250 mg/L can promote the increase of peach stem length.There is no significant difference between 100 mg/L treatment and control.The effect which in the 200 mg/L treatment was the best;It have no significantly difference between the four concentrations of GA3 treatment and the control when treated at 1 week after the flowering;The treatment with 250 mg/L GA3 inhibited the growth of the fruit stem significantly when treated at 2 weeks after flowering.During the same period,it has no significant effect on the diameter of peach fruit stems treated with different concentrations of GA3.but the diameter of fruit stems treated with GA3 at full bloom stage was larger than that stem diameter of treated at 1 week after full bloom and 2 weeks after full bloom.The GA3 treatment made the peach fruit stem start the rapid growth earlier than the control.The GA3 with 100 mg/L,150 mg/L and 200 mg/L allowed the peach stem to grow slowly before the fruit matured.2.Effects of different concentrations of GA3 on the anatomical structure of peach fruit stems:GA3 treatment had different effects on xylem of peach fruit stems in different periods.In the full-bloom stage,GA3 treatment,which the concentrations from 200 mg/L and 250 mg/L,can significantly increase the thickness of xylem compared with the control.In one week after full bloom stage,the GA3 at each concentration significantly increased of xylem thickness of peach stems,and the concentration of 150 mg/L had the most significantly affect.The GA3 treatment,which the concentration as 100 mg/L and 150mg/L,did not have significant effect on the xylem of peach fruit stems that treated at two weeks after full bloom.The treatment of GA3 with 200 mg/L and 250 mg/L significantly inhibited the xylem thickness of peach fruit.In contrast,the GA3 treatment with 200 mg/L and 250mg/L did not inhibited the thickness of phloem.3.The effect of exogenous GA3 on peach fruit in different periods.During the three treatment periods,high concentration of GA3(250 mg/L)treatment had an bad effect on peach fruit and fruit stems,including inhibiting the growth of fruit size or fruit stems,and increasing the number of fruit on stout branch drop before harvest.In the three treatment periods,compared with stage of the one week and two week after full bloom,the application of GA3 used in full bloom stage(flower pedicels)had the better fruit quality and the lower fruit drop rate.The four treatment concentrations could reduce the fruit drop rate before harvesting.The effects of GA3 treatment on the length and fruit drop rate showed the basically same trend.Treated with 200 mg/L of GA3 during the full bloom stage,the number of fruit on stout branch was inhibited,and did not reduce the weight of the peach. |
