Organic amendments alleviate early defoliation and increase fruit yield by altering assembly patterns and of microbial communities and enzymatic activities in sandy pear (Pyrus pyrifolia)

Yalong Kang,Caixia Dong,Yanwei Ma,Changyan Xie,Shangtao Jiang,Xiangrui An,Zhonghua Wang,Wenli Wu,Shaomin Zeng,Yangchun Xu,Qirong Shen

doi:10.1186/s13568-021-01322-5

Abstract

Severe early defoliation has become an important factor restricting the development of the pear industry in southern China. However, the assembly patterns of microbial communities and their functional activities in response to the application of bioorganic fertilizer (BIO) or humic acid (HA) in southern China’s pear orchards remain poorly understood, particularly the impact on the early defoliation of the trees. We conducted a 3-year field experiment (2017–2019) in an 18-year-old ‘Cuiguan’ pear orchard. Four fertilization schemes were tested: local custom fertilization as control (CK), CK plus HA (CK-HA), BIO, and BIO plus HA (BIO-HA). Results showed that BIO and BIO-HA application decreased the early defoliation rate by 50–60%, and increased pear yield by 40% compared with the CK and CK-HA treatments. The BIO and BIO-HA application significantly improved soil pH, available nutrient content, total enzyme activity and ecosystem multifunctionality, and also changed the structure of soil bacterial and fungal communities. The genus Acidothermus was positively correlated with the early defoliation rate, while the genus Rhodanobacter was negatively correlated. Additionally, random forest models revealed that the early defoliation rate could be best explained by soil pH, ammonium content, available phosphorus, and total enzyme activity. In conclusion, application of BIO or BIO mixed with HA could have assembled distinct microbial communities and increased total enzyme activity, leading to significant improvement of soil physicochemical traits. The increased availability of soil nutrient thus changed leaf nutrient concentrations and alleviated the early defoliation rate of pear trees in acid red soil in southern China.

Highlights

Pears are the world’s third-largest consumer fruit
Our results found that pH less than 5.0 in orchard soil treated by conventional fertilization (CK) (Table 1), indicating that the soil was troubled by acidification
In this study we found that addition of bioorganic fertilizer (BIO) and BIO-humic acid (HA) to the acid red soil of a sandy pear orchard significantly improved the soil pH to 5.3–5.5 (Table 1), which was close to the optimum condition for growth of pear trees in acid soil, Fig. 5 Network analysis revealing the co-occurrence pattern between bacterial and fungal operational taxonomic units (OTUs) in -BIO (CK and CK plus HA (CK-HA), A and C) and + BIO (BIO and BIO plus HA (BIO-HA), B and D) treated soils, 2018 and 2019

Summary

Introduction

Pears are the world’s third-largest consumer fruit. In recent years, early defoliation has become an important factor affecting the sustainable development of the pear industry in the red soil regions of southern China. That are associated with intensified application of chemical fertilizers (Dong et al 2012; Jiang et al 2020a; Ma et al 2018), such as increased soil acidification, deplete soil fertility, and inhibit soil microbial activity (Dong et al 2012; Gu et al 2019; Jiang et al 2020a; Ma et al 2018) It seriously weakens the growth and vitality of pear trees, which might be an essential factor for the early defoliation of pear trees in southern China. According to a survey by Huang et al (2010), the degree of early defoliation rate of pear trees in orchards with high soil organic matter content and soil pH above 5.0 is lower, indicating that improving soil physicochemical traits may reduce the early defoliation rate

Objectives

Methods

Results

Conclusion