| Citrus is not only a kind of significant fruit to economic development,but also a pillar industry for poverty alleviation and rural revitalization in most rural areas of southern China.The maintenance of high yield of citrus needs a large amount of fertilizers,especially chemical fertilizer.However,unreasonable or even excessive application of chemical fertilizer can not effectively improve and enhance the yield and quality of fruit,but will bring about multiple environmental problems,such as reducing the competitiveness of fruit,hurting the enthusiasm of orchardman in citrus,and hindering the healthy development of Chinese citrus industry.There are abundant organic fertilizer resources in China.Hence,reducing the application of chemical fertilizer and supplementing organic fertilizer meets the requirements of Chinese agricultural green development.At present,the research about reduction of chemical fertilizer and supplement of organic fertilizer is mainly concentrated on the effects of decreasing nitrogen fertilizer.Nevertheless,there are few studies on the effects of equal N,P and K nutrient about reducing chemical fertilizer and supplying organic fertilizer on the growth and physiology of citrus,nutrient accumulation,soil properties,yield and quality.Apart from that,the study of primary fruit tree is rarely reported.Taking the wide acreage of citrus reticulate variety “Ponkan” and representative citrus of hybrid varieties “Ehime 28” as the experiment object,under the equal amounts of N,P and K nutrient,this paper set the replacing part of the chemical fertilizer by organic fertilizer and different kinds of organic fertilizer combined with chemical fertilizer,and investigated their effects on the growth and physiology of Ponkan(fruiting peak period)and Ehime(early fruiting period),yield and quality,and soil properties.In order to provide theoretical basis and technical support for scientific reduction of chemical fertilizer and rational increase of organic fertilizer,the optimal replacement ratio and types of organic fertilizer for citrus(fruiting peak period and early fruiting period)were explored.The main results can be listed as follows:(1)The research about effects of organic fertilizer replacing chemical fertilizer on the growth,physiology and soil properties of Ponkan showed the following results.Compared with the treatment of only chemical fertilizer,replacement of chemical fertilizer by organic fertilizer promoted the growth of branches and roots,improved photosynthetic physiology of Ponkan leaves,and enhanced dry matter as well as nutrient accumulation of various tissues of Ponkan.In 2019 and 2020,the treatment of organic fertilizer replacing chemical fertilizer increased yield by 7.2%～26.4% and2.0%～36.9%,respectively,and fertilizer contribution rate increased by 5.2%～45.4%and 3.3%～54.9%.To some extent,the internal and external quality of Ponkan fruit was also improved and enhanced.In addition,the treatments of organic fertilizer replacing chemical fertilizer increased TSS/TA and Vc by 12.1%～29.4% and1.8%～8.0% in 2020.Treatments of organic fertilizer replacing chemical fertilizer improved soil physical and chemical properties,enhanced soil fertility,increased the activities of soil urease,sucrase,phosphatase,catalase and the number of culturable bacteria,actinomycetes,fungi,and reduced the risk of nitrate nitrogen migration to deep soil layer.Meanwhile,the treatments of organic fertilizer replacing chemical fertilizer significantly increased p H and organic matter of soil by 4.6%～12.6% and10.2%～15.3% in 2020.However,with the increase of organic replacement ratio,soil carbon emission had the potential risk of increasing.For Ponkan in the fruiting peak period,organic replacement of 15%～20% nitrogen fertilizer,38%～51% phosphorus fertilizer and 27%～36% potassium fertilizer had a better effect.(2)The research about effects of different organic fertilizer combined chemical fertilizer application on the growth,physiology and soil properties in Ponkan showed the following results.Compared with the single application of chemical fertilizer(FP),the treatment of five organic and inorganic fertilizers including M1(ordinary organic fertilizer),M2(biological organic fertilizer),M3(tobacco stem biological organic fertilizer),M4(compound microbial fertilizer),and M5(rapeseed cake fertilizer)promoted the growth of branches and roots,improved photosynthetic physiology of Ponkan leaves,and enhanced the dry matter and nutrient accumulation of various tissues of Ponkan.In 2019 and 2020,each treatment of organic fertilizer increased yield by 19.4%～26.9% and 23.1%～34.0%,respectively.Meanwhile,the internal and external quality of Ponkan fruit was also improved and enhanced to some extent.Besides,each treatment of organic fertilizer increased a/b and TSS/TA by11.9%～19.4% and 13.8%～32.7% in 2020.Different kinds of organic fertilizer combined with chemical fertilizer enhanced soil physicochemical properties,and each treatment of organic fertilizer improved organic matter of soil by 5.3%～17.0% and12.5%～24.7% in 2019 and 2020,raised the activities of soil enzymes and the number of culturable microorganisms,decreased nitrate nitrogen on each soil layer and its migration to deep soil layer,but increased soil carbon emission flux.The comprehensive score of principal components was in the order of M3>M2>M5>M1>M4>FP,indicating that various organic fertilizers combined with chemical fertilizer of this research had a good overall effect on Ponkan growth and physiology,soil characteristics,and fruit yield and quality,especially M3 treatment.(3)The research about effects of organic fertilizer replacing chemical fertilizer on the growth,physiology,and soil properties in Ehime primary fruit trees showed the following results.Compared with single application of chemical fertilizer,organic fertilizer replacing chemical fertilizer improved the growth of branches to a certain extent,which was beneficial to the dry matter and nutrient accumulation of each tissue.Besides,the treatment of organic fertilizer replacing chemical fertilizer increased yield by 7.4%～26.2% and the internal and external quality of fruit was also improved.Additionally,the treatments of organic fertilizer replacing chemical fertilizer increased the rate of juice and TSS/TA by 1.7%～3.5% and 2.2%～23.5%.The replacement of chemical fertilizers by bioorganic fertilizers improved soil p H value and organic matter by 3.4%～16.5% and 5.8%～22.7% respectively,and also improved the content of alkali-hydrolyzable nitrogen,available phosphorus and available potassium of soil.The effect of bioorganic fertilizer replacing 20%～30% nitrogen fertilizer,40%～60% phosphorus fertilizer,and 30%～45% potassium fertilizer was the best for Ehime primary fruit trees.(4)The research about effects of different organic fertilizer application on growth,physiology,and soil properties in Ehime primary fruit trees showed the following results.Compared with the single application of chemical fertilizer(CF),organic and inorganic fertilizer including K1(biological organic fertilizer),K2(ordinary organic fertilizer),K3(tobacco stem biological organic fertilizer)and K4(compound microbial fertilizer)promoted the growth and development of branches to a certain extent,and enhanced the accumulation of dry matter and nutrient absorption and utilization of Ehime tissues.In addition,each treatment of organic fertilizer increased yield by 1.9%～40.6%.Meanwhile,internal and external quality of fruit on Ehima was also improved and enhanced to some extent.Besides,each treatment of organic fertilizer increased a/b and Vc by 17.6%～52.9% and 10.9%～26.4%,respectively.Each treatment of organic fertilizer improved and increased soil p H value and organic matter by 2.3%～16.0% and 2.9%～16.4% respectively,and increased the soil nutrients.The order of comprehensive score of principal component analysis was K3>K1>K2>K4>CF,suggesting that tobacco stem biological organic fertilizer(K3)on growth and physiology of Ehime,soil characteristics as well as fruit yield and quality was good.In conclusion,the tobacco stem biological organic fertilizer is favorable for the growth and physiology of citrus.For Ponkan in the fruiting peak period,organic replacement of 15%～20% nitrogen fertilizer,38%～51% phosphorus fertilizer and27%～36% potassium fertilizer showed a better effect.Beyond that,the effect of organic fertilizer replacing 20%～30% nitrogen fertilizer,40%～60% phosphorus fertilizer and 30%～45% potassium fertilizer was the best for Ehime primary fruit trees. |
PDF Full Text Request