Different Fertilization Treatments On The Growth And Fruit Quality Of Carya Illinoinensis ’Pownee’ And The Impact Of Soil

Pecan（Carya illinoinensis）is a high-quality nut and oil crop species with high economic value.This experiment aimed to address the problems of soil nutrient deficiency,tree growth and development damage,reduced fruit quality and sustainable production caused by the unreasonable fertilizer ratio in the production process of pecans.The variety"Pony"was used as the research object,and different types of fertilization treatments[single application of chemical fertilizer（CF）,chemical fertilizer combined with rapeseed dregs application（CF+CC）,chemical fertilizer combined with manure application（CF+M）,and chemical fertilizer combined with manure and rapeseed dregs application（CF+CC+M）]were set up to analyze and study the soil quality,leaf characteristics,and fruit quality of pecan samples.The main results are as follows:（1）Compared with single application of chemical fertilizer,the addition of organic fertilizer can increase the content of total nutrients,available nutrients,and trace elements in the soil.Regarding total nutrients（TN,TP,K,Ga,Mg）,the best effect was achieved with the application of the three fertilizers mixed together（CF+CC+M）except for Mg,with their content reaching 69.01 mg·kg^-1,5.38 mg·kg^-1,9.08 mg·kg^-1,and 4.21 mg·kg^-1,respectively.The Mg content was highest in the chemical fertilizer mixed with manure treatment（CF+M）,but there was no significant difference（P<0.05）compared to the three-fertilizer mixed treatment.Regarding available nutrients（AP,NH₄⁺-N,NO₃^--N）,the three-fertilizer mixed treatment was also the best,with their content being 4.69 mg·kg^-1,1.93 mg·kg^-1,and 23.23 mg·kg^-1,respectively.Among trace elements（Zn,Mn,Fe,and Cu）,the content of Zn and Mn elements was highest in the three-fertilizer mixed treatment,and their content increased significantly after the three fertilizers were mixed.The Fe content was highest in the treatment with mixed rapeseed dregs fertilizer（CF+CC）,and the Cu content was highest in the treatment with mixed manure（CF+M）.（2）The addition of organic fertilizer increased the organic matter and soil enzyme activity in varying degrees.The effect of rapeseed dregs fertilizer（CF+CC）on improving soil organic matter,peroxidase,and sucrase activity was the most significant（P<0.05）,with its organic matter content reaching 28.13 g·kg^-1,and the soil sucrase and peroxidase activities reaching 2922.2 U·g^-1and 2575.8 U·g^-1,respectively.Urease activity was the highest in the three-fertilizer mixed treatment,and there was a significant difference compared to the other three fertilizers（P<0.05）,reaching 7.06 U·g^-1.Acid phosphatase activity was highest in the mixed manure treatment（P<0.05）,reaching 49.74 U·g^-1.（3）The addition of organic fertilizer enhanced plant photosynthesis rate,and promoted vegetation growth.The best effect was achieved with the application of the three fertilizers mixed together（CF+CC+M）,with the net photosynthetic rate reaching 24.42μmol·m^-2·s^-1,and the chlorophyll content reaching 2.36 mg·g^-1.Other indicators reflecting the physiological growth status of plants（except transpiration rate）were also the best with the three-fertilizer mixed treatment.（4）The organic fertilizer applications can increase the yield of Pecan.Although the initial increase in yield was not significant,soil nutrients gradually improved with the application time,and the yield increase rate far exceeds that of single chemical fertilizer,with the highest yield increase reaching up to twice.In summary,the best effect was achieved by mixing three kinds of fertilizers （CF+CC+M）,which can be widely applied during the production process of pecan.