关键词: 优标体系, 稻米产量与质量, 土壤肥力, 土壤酶活性, 土壤微生物多样性

Abstract:

【Objective】 In view of the fertilizer-pesticide reduction approaches in rice production, the rice good quality standard system (GQS) was developed independently in the early stage. The objective of this study is to analyze the rice yield, rice contaminant content and soil quality characteristics under GQS application, evaluate the effect of applying GQS in agricultural practices, and to provide scientific basis for the reasonable design and timely adjustment of GQS.【Method】 The fixed-point rice growing areas with continuous application of GQS for 1-5 years in Jiangsu and Shanghai were selected. The adjacent areas with conventional rice cultivation system (CCS) were taken as control. The rice samples and soil samples were collected at harvest stage for analysis. The rice yield was measured. The contents of pesticide residues and toxic heavy metals were determined by SGS. Soil fertility was evaluated by using Nemerow index method. The activity of dehydrogenase, urease, and sucrase in soil was determined by using TTC reduction method, indophenol blue colorimetric method, and 3,5-dinitrosalicylic acid colorimetric method, respectively. Soil microbial diversity was analyzed using 16S rDNA high-throughput sequencing.【Result】 Compared with the CCS, the application of nitrogen fertilizer was reduced by 46.8% in GQS with organic fertilizer, EM bacteria agent, foliar fertilizer, and zinc fertilizer as alternatives. The high safety standard of rice in GQS was ensured by using biological agents and chemical pesticides with low toxicity and low residues. Applying GQS significantly increased soil total nitrogen and organic matter content without compromised rice yield and quality. The comprehensive score of soil fertility of the GQS was higher than that of the CCS after 1-4 years of continuous implementation, but the comprehensive score of soil fertility of the GQS was lower than that of the CCS at the fifth year. Applying GQS for two consecutive years resulted in the increase of urease, dehydrogenase and sucrase activity in rice paddy soil than CCS, and it was also found that the diversity and abundance of bacterial community increased in rice paddy soil with the application of GQS. Bacteroidetes and Chloroflexi showed repeated changes in the increasing ratio of soil bacterial richness after the one-year and the five consecutive years application of GQS. Terrimonas and Flavobacterium were the dominant genera. Correlation analysis showed that the abundances of Bacteroidetes and Chloroflexi were positively correlated with soil pH fertility index and total P fertility index after one-year implementation of GQS. Soil pH fertility index was positively correlated with the abundance of Bacteroidetes and Chloroflexi, respectively, after five consecutive years implementation of GQS. In addition, soil dehydrogenase activity was positively correlated with the abundance of Bacteroidetes and Chloroflexi, respectively.【Conclusion】 The application of GQS was helpful for the restoration of rice soil fertility by effectively improving the soil quality and the diversity of soil bacterial community without compromised rice yield and safety.

Key words: good quality standard system, rice yield and quality, soil fertility, soil enzyme activity, soil microbial diversity