Thinning effect of Calcium-formic Acid Compound on the apple flowers of Gala

【Objective】 The research was conducted to select the optimum spraying time and concentration of Calcium-formic Acid Compound by studying its thinning effect on the Gala Apple Flowers in Loess Plateau.【Method】 With mid-maturing variety Gala as test material,the experiment was carried out by using the method of Experimental design orthogonal rotation which set 5 different concentration and spraying time treatments with blank,solvent and manual control.The optimum concentration and spraing time were established by investigating the center flower fruit set,lateral flower fruit set,inflorescence fruit set and total flower fruit set,and the fruit quality was also compared between the treatments and controls.【Result】 The effects of the Calcium-formic Acid Compound Concentration and spraying time on the flower setting rate such as center flower fruit set,lateral flower fruit set,inflorescence fruit set,total flowers fruit set were researched and mathematical regression models were established.The models were effective after examing.Single-factor analysis showed the significance of thinning effect on center flower fruit set was spraying timespraying concentration,but for the inflorescence fruit set it was spraying concentrationspraying time.The overall effect of Marginal utility was spraying timespraying concentration.In combination of the fruit set analysis and fruit quality,the thinning effect was significant when the concentration of Calcium-formic Acid Compound was 9.74-10.41 g/L at the time of 2.71-4.37 days after 5% of the central flower in full bloom.【Conclusion】 Thinning can achieve significant results without excessive risk at an optimum spraying time and concentration.