Control Of Vegetative Growth And Changes Of Nitrogen Nutrient And Starch During Flowering Formation Of Wax Apple

Wax apple（Syzygium samarangense Merr.et Perry.）,an evergreen fruit tree originated from tropical Southeast Asia region with colored and delicious fruits.It is popular with consumers.It is also called’fruit emperor’.Among them,’Heizhenzhu’and’Yinduhong’are the main cultivars for production.With the regulation of off-seasonal production,its market competitiveness can be enhanced.And the key technology of the production is controlling the vegetative growth with shading.The effects of shading on the growth and flower development in wax apple are still to be studied.In the present study,’Heizhenzhu’and ’Yinduhong’were shaded or sprayed with chemicals during August 2015 and 2016.The effect of the treatments on shoot growth and the SPAD value of leaves were studied.The changes of morp hology of the apical bud and the starch were observed by microscope.The activities of GS and NR,the contents of NO₃^-and NH₄⁺were measured.The results are as follow:1.Shaded with 90%shading net reduced the number,length and ratio of the new shoots as well as the SPAD value of the leaves.The effects of shading on the shoots for 40 days were better than that for 20 days.2.Sprayed with 100 mg·L^-1 PP₃₃₃ and 1/300 Amisar-top,the average of shoot number,length and ratio of the new shoots of the treated trees were significantly decreased,and the SPAD value were significantly increased for two weeks treatment.3.Compared to the control trees,starch granules were found in buds after shading for 45days.When the flower bud differentiation was finished,starch granules could be found in all spikes.Its distribution changes over time,suggesting that starch granules were needed during the flower bud differentiation.4.Spraying with 100 mg·L^-1 ABA and 100 mg·L^-1 ALA reduced the conductivity of leaves,and the drop rate of leaves in wax apple,suggesting that ABA and ALA could increase the stress resistance.