| The stone cell, a characteristic construction in fruit of pears, is one of pivotal factors affecting the quality of pear fruit. Dangshan pear is the main variety planted in northern and Northwest China, ancient channel of Yellow River. Because of nice shape, good flavor, high nutrition value and durable store, Dangshan pear is not only favored extensively, but it is one of the chief pear kinds exported in China. Recently years, due to species degeneration or poor management of cultivation, Dangshan pear stone cell content was becoming more and more, pulp became crude and poor edible quality, which affected seriously the quality of Dangshan pear. Dangshan pears of forty years old planted in Dangshan fruit garden of Anhui province were used as experiment material. Stone cell developing process, changes of endogenous hormone (ZR, IAA, ABA), enzymes (POD, PPO, PAL) and mineral elements etc during growth and development of Dangshan pear under four kinds of light intensities were studied. The purpose is to illuminate the base of physiological metabolism of Dangshan pears' stone cell formation and to reveal the factors affecting the formation of the stone cell, which would provide the theoretical gist in adopting reasonable planting technology in order to decrease the stone cell content of Dangshan pear and improve the quality of Dangshan pear during planting management. Main results were as follows:1.The increase of fruit fresh weight, vertical and horizontal size represent slowing-fasting-slowing model like "s" curve. The two proceeding phase of the growth of Dangshan pear were the primary period of the formation of its yield and quality.2.The research on the stone cell growing indicated that the stone cell was formed through the thin cell wall thickening and lignifying. The period of Dangshan pear fruits cell abruption is the pivotal period of the stone cell forming. The peak of the stone cell formation of Dangshan pear is the seventh weeks after flowering and the longest diameter of stone cell appears at the eleventh weeks after flowering. Termination of the stone cell development is the eleventh weeks after flowering. Suitable agriculture measures before stone cell abruption could control and decrease the formation of stone cell and improve quality of Dangshan pear. 3.During growth and development of Dangshan pear, endogenous hormone (ZR, IAA and ABA) content had two peaks. The highest content time of ZR,IAA and ABA appeared at the first week after blooming. Another peak of ZR and IAA appeared at the seventh week after blooming. But the other peak of ABA content appeared at the twenty weeks after blooming. These results showed that ZR and IAA took part in the pear fruit cell abruption and expanding, when, ABA promoted Dangshan pear absorbed assimilative substance in early period, and stimulated the fruit ripe in late period. The result of comparative study on endogenous hormone content under different light intensity indicated that the content was the highest under high light intensity, the middle light intensity was higher, the thin light intensity was followed, and the thinnest light intensity was worst, which showed light intensity was favor to synthesize endogenous hormone of Dangshan pear. Light intensity may stimulate synthesis of endogenous hormone to reduce the stone cell forming.4.The character of mineral elements (Ca2+, Zn2+) changing of fruit during Dangshan pear growth and development was that the two peak of Ca2+ and Zn2+ content appeared at the first and seventh week after pear flowering. This showed Ca2+ and Zn2+ have important function on the unripe growing, and they can restrain the form of the stone cell. The result of comparative study on Ca2+ and Zn2+ content under different light intensity indicated that light intensity was higher, Ca2+ and Zn2+ content was higher.5.During growing of Dangshan pear, enzyme (POD, PPO, PAL) activity of fruit at the prophase is higher than anaphase. The result showed POD and PPO and PAL promoted the form of the stone cell of Dangshan pear.6.The...
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