Study On The Thining Effects Of Two Chemical Thinning Agents To Apple Flowers

The management of Apple fruits and flowers is one of the key techniques to produce apples with high quality, flower and fruit thinning is an important technique of them. Under the new situation of labor shortages and production cost increase, the blossom and post-blossom thinning of apple is an appropriate alternative method to thin by hands. Thus, based on the ecological conditions of the Loess Plateau of apple production, two kinds of organic chemical thinning agents calcium-formic acid compound and lime sulphur were chosen, the thinning effect on'Fuji'and'Gala'apple were studied. According to the binary quadratic regression orthogonal rotary design, two factors of spraying time and concentration are setting five levels respectively, setting thinning by hand, spraying water and natural method as controls, and center flower fruit set, lateral flower fruit set, inflorescence flower fruit set and total flowers fruit set as evaluation indexes, by data processing and analysis software, the appropriate spraying concentration and time are established. The main results are as follows:Using four fruit set rates as Objective variables and two factors of spraying concentration and time as dependent variable , the poisson regression models are resulted, and the thinning effect can be figure out after analyzing further. For the thinning effect of CFA on'gala'apple, the best spraying time is 3-4 days after 5% flowers are blossom, the best concentration is 9.74～10.41 g/L, center flower fruit set, lateral flower fruit set, inflorescence flower fruit set and total flowers fruit set are 66.96%,47.10%,96.97% and 77.6% respectively. For the effect on'Fuji'apple, the best spraying time is 2-4 days after 5% flowers are blossom, the best concentration is 6.91-8.49g/L, center flower fruit set, lateral flower fruit set, inflorescence flower fruit set and total flowers fruit set are 67.75%, 50.16%, 85.20% and 57.11% respectively. After comparing fruit quality with controls the result shows some indicators of fruit quality like fruit weight, soluble solids contents, titrable acidity are increased but not significant, other indicators like fruit rest index shows spraying CFA could make the degree of fruit rest serious.Using four fruit set rates as objective variables and two factors of spraying concentration and time as dependent variables , the poisson regression models are resulted, and the thinning effect can be figure out after analyzing further. For the thinning effect of LS on'gala'apple, the best spraying time is 4-6 days after 5% flowers are blossom, the best concentration is1.22-2.43 degree, center flower fruit set, lateral flower fruit set, inflorescence flower fruit set and total flowers fruit set are 46.61%,11.58%,61.23% and 64.32% respectively. For the effect on'Fuji'apple, the best spraying time is1-4 days after 5% flowers are blossom, the best concentration is0.44-1.35 degree,center flower fruit set, lateral flower fruit set, inflorescence flower fruit set and total flowers fruit set are 84.59%,58.36%,88.03% and 73.31%.After comparing fruit quality with controls the results show some indexes like soluble solid contents titrable acidity are increased but not significant. For'gala'apple, the other fruit quality indicators like fruit weight and fruit rest indicators increased, and for'Fuji'apple the fruit hardness is reducing after treatment with LS and the fruit rest is increased, thus, spraying LS could make the degree of fruit rest serious on both'Fuji'and'Gala'apples.