Study on the relation between mineral nutrition levels and creasing peel in mature orange

The relation between mineral nutrition levels and creasing peel in mature sweet orange were studies by analysing the contents of nitrogen, phosphorus, potassium, calcium, magnesium in the 'Hong yiqi' sweet orange (Citrus sinensis Osbeck, cv. Hong yiqi) and 'Hong jiang' sweet orange (Citrus sinensis Osbeck, cv. Hong jiang) including normal fruits and creasing, shaded fruits and exposed halves of fruits. There was fewer creasing fruits, only 7.34%, in 'Hong yiqi' and severe creasing fruits, 28.06%, in 'Hong jiang' sweet orange. A significant difference in creasing fruit rates was observed between shaded halves of fruits and exposed halves of fruits. Major creasing peel, above 86%, occurred in shaded halves of fruits. There was not a significant correlation between N or P contents and creasing fruit rates. K contents in peel of creasing fruits exposed halves of fruits were higher than that of normal fruits and shaded halves of fruits. Mg ontents in cell wall or peel of creasing fruits and shaded halves of fruits were fewer lower than that of normal fruits and exposed halved of fruits, but there was a no significant negative correlation between Mg contents and rates of creasing fruit. Ca contents in cell wall or peel of normal fruits and exposed halves of fruits were higher than that of creasing fruit and shaded of fruits. There was a significant negative correlation between Ca contents in peel and creasing fruit rate.