| The browning spot of Huangguan pear and blossom-end rot of Korla fragrant pear were considered as fruit physiological diseases caused by calcium deficiency in fruit. In recent years, there appeared a kind of phenomenon that the skin of pear was spottedly brown during the mature stage or storage, commonly known as "chicken feet", in the province of Hebei, Gansu and other places, where the Huangguan pear was cultivated in a large area. It seriously influences the appearance and quality of the fruit, leading to great economic losses. On the other hands, the calyx end of Korla fragrant pear was black spot, commonly known as blossom-end rot, is another calcium related disease. Thus, two field experiments were conducted on12-year-old Huangguan pear orchard and14-year-Korla fragrant pear orchard to study the effects of spraying different kinds of calium fertilizers at different stages on the reduction of the two calcium related diseases. The main results were as follows:The use of fruit-expander effectively improved the fruit weight of Huangguan pear and advanced the time of maturity20days. It also changed daily growth rates, the daily growth rates of fruit without fruit-expander arrived maximum at100-120days after flowering(DAF), while the daily growth rates of fruit with fruit-expander arrived maximum at85～100DAF, among which, the treatment of Compo calcium(CPC) with fruit-expander was the highest, the daily growth gradually declined at100～120DAF.With the growth of Huangguan pear, the content of calcium, potassium and phosphorus decreased gradually, among which, calcium content reduced rapidly after85DAF, potassium and phosphorus content changed similarly. Generally, these three essential elements content in the fruit with fruit-expander treatment were lower than without fruit-expander treatment in the same period. In the growth period, without using fruit-expander, the calcium accumulation content gradually increased until85DAF and then decreased, of which, spraying sugar alcohol calcium(SAC) was the best; whereas, the calcium accumulation content with fruit-expander increased all the time, the effect of CPC and SAC was the best; the potassium and phosphorus accumulation content of Huangguan pear both gradually increased, at the same time, their accumulation content of which treated with fruit-expander also had a higher level than those not treated. Spraying CPC and SAC can effectively improve calcium content both in the flesh and peel of mature Huangguan pear. Spraying four times calcium fertilizers reduced the content of potassium and phosphorus.In different period, spraying SAC and CPC improved the fruit firmness, soluble solids, soluble sugar and reduced the content of titratable acid; The use of fruit-expander reduced the fruit firmness and titratable acid content, but improved the content of soluble sugar and soluble solids. Increasing the times of calcium spraying effectively reduced the incidence of browning spot of Huangguan pear, among which, spraying SAC had the most obviously effect; Improving the quality and calcium content, reducing potassium and phosphorus contents in the peel may have a better prevention to the browning spot of Huangguan pear.Spraying calcium improved calcium content of Korla Fragrant pear to some degree, and it’s preferable when spraying at the young fruit stage; Spraying calcium reduced potassium and phosphorus contents, but had little influence on magnesium and boron contents. Spraying Fruit calcium and CPC at the expanding stage prevented the occurrence of blossom-end rot in Korla Fragrant pear during storage, improving the calcium content of the calyx-end had a good effect to the reduction of blossom-end rot. |
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