Effects of nitrogen regulation on fruit quality of long\|term sand\|covered apple orchard in Jingning, Gansu Province
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DOI:10.7606/j.issn.1000-7601.2022.04.14
Key Words: nitrogen level  apple quality  fruit surface color  sand mulching for a long time
Author NameAffiliation
LIU Xiaoyong Institute of Fruit and Floriculture of Gansu Academy of Agricultural Sciences, Lanzhou, Gansu 730070, China 
REN Jing Institute of Fruit and Floriculture of Gansu Academy of Agricultural Sciences, Lanzhou, Gansu 730070, China 
KONG Fen Institute of Fruit and Floriculture of Gansu Academy of Agricultural Sciences, Lanzhou, Gansu 730070, China 
HAN Fujun Institute of Fruit and Floriculture of Gansu Academy of Agricultural Sciences, Lanzhou, Gansu 730070, China 
PENG Hai Institute of Fruit and Floriculture of Gansu Academy of Agricultural Sciences, Lanzhou, Gansu 730070, China 
LI Jianming Fruit Tree Institute of Jingning County, Jingning, Gansu 743400, China 
LI Qiang Fruit Tree Institute of Jingning County, Jingning, Gansu 743400, China 
JIA Junping Jingning County Fruit Industry Service Center, Jingning, Gansu 743400 
WEN Youfu Jingning County Fruit Industry Service Center, Jingning, Gansu 743400 
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Abstract:
      The objectives of this experiment were to explore the appropriate amount of nitrogen application under different tillage methods for apples in dry land and to study the effects of different nitrogen levels on fruit quality in order to provide the basis for accurate nitrogen application. The split\|plot experiment design method was adopted in the long\|term sand\|covered apple orchard on the Loess Plateau. The main test area was sand\|covered (SM) and clear tillage (CT), and five nitrogen levels were applied in the test secondary area. The nitrogen application rates of each apple trees were 0 (N1), 109 g (N2), 218 g (N3), 327 g (N4) and 436 g (N5) respectively while the equal amounts of phosphorus (P2O5, 145 g), potassium (K2O, 87 g) and commercial organic fertilizer 6.5 kg were applied. (1) The fruit weight, vertical and horizontal diameter, firmness and soluble solid content were significantly increased in the sand\|covered orchard. Compared with clear tillage, the average increase was 15.3%, 4.1%, 5.6%, 3.5% and 1.8%, respectively. The fruit coloration was improved with brighter and redder fruits. The values of A *, C* and FCI on the shady side of fruit were increased by 55.1%, 18.5% and 15.1% more than that of clear tillage, respectively. (2) With the increase of nitrogen application rate, the fruit weight and vertical and horizontal diameter were increased. The fruit shape index, soluble solids, total sugar and Vc contents showed a change trend of rising first and then falling. The hardness in the fruit sunny side was decreased. An appropriate supply of nitrogen promoted the fruit shape index increased and the improvement of contents of the total sugar, organic acid and Vc and the soluble solids in the sunny side of apple. According to the comprehensive analysis, the fruit quality was the best when N application rate was N3(179.85 kg·hm-2). (3) Sand covering maintained the fruit hardness and soluble solid content at the storage stage. It also maintained the chroma of fruit shady side, and increased FCI index. The degree and change regularity of fruit quality in storage were different with different tillage methods and nitrogen application rates. After 90 days of cold storage, the total sugar content of the fruit was significantly increased by 2.47~3.29 times while the contents of Vc and organic acids were significantly decreased by 55.7%~82.7% and 18.2%~50.3%, respectively as comparing with the clean orchard. Low temperature storage weakened the effects of nitrogen application rate and tillage method on organic acid, Vc content and shade hardness of fruits. Sand mulching in orchard significantly improved fruit quality. The appropriate nitrogen application was beneficial to fruit quality. The optimal N application rate of a tree was 218 g·plant-1 in the dry area of Loess Plateau.