Abstract:

To explore the feasibility of using rice straw mulching instead of plastic film and study the effects of different rice straw mulching amounts on pepper growth and soil environment, two mulching methods of plastic film (DM) and rice straw were conducted in this study, and three rice straw mulching amounts were set, including 3000 kg/hm² (JG3), 6000 kg/hm² (JG6), and 9000 kg/hm² (JG9), with no mulching as control (CK). The changes of pepper yield and quality, soil physicochemical properties, soil enzyme activities, and soil bacterial community diversity in different treatments were analyzed and compared. The results showed that the rice straw decomposition rate was decreased with the increase of their mulching amount; the plant height, stem diameter, and yield were significantly increased in rice straw mulching treatments, and the highest yield was exhibited in treatment JG6 of 20627.90 kg/hm². Rice straw mulching was also beneficial for reducing the crude fiber content of peppers, increasing the capsaicin content, fruit length, fresh fruit weight, fruit diameter, and flesh thickness. The highest capsaicin content, fresh fruit weight, fruit diameter, and flesh thickness were observed in JG6 treatment by 36.7 mg/kg, 37.2 g, 26.5 mm, and 3.56 mm, respectively. Compared with plastic film mulching treatment, the activities of soil acid phosphatase, sucrase, dehydrogenase, soil pH, total organic carbon, and available phosphorus content was significantly increased in rice straw mulching treatment, while in treatment DM, soil pH was significantly decreased. The urease activity, total organic carbon, alkaline hydrolyzable nitrogen, and available potassium content were all lower than those in CK. The high-throughput sequencing results showed that the OTU, Shannon diversity index, Chao1 index, and ACE index in DM treatment were all lower than CK, while those in straw mulching treatment were all higher than CK. The dominant bacteria in all five treatments were Proteobacteria, Acidobacteria, and Actinobacteria, with relative abundance ranges of 30.49% to 34.13%, 17.19% to 22.11%, and 10.26% to 12.28%, respectively. Relative abundance of Chloroflexi in DM treatment was 12.95%, which was significantly higher than all other treatments. Correlation analysis showed that pepper yield was significantly positive correlated with OTU, Chao1, ACE, and Bacteroidota, while pepper stem thickness was significantly negative correlated with Chloroflexi and Firmicutes. Soil pH, total organic carbon content, enzyme activity, and available potassium content were positively correlated with Bacteroidota. Consequently, higher pepper yield and better quality were observed than other treatments when the rice straw mulching amount was 6000 kg/hm². Compared with plastic film mulching, rice straw mulching improved the pepper yield, pepper quality, and soil environment.

Key words: pepper, rice straw, mulching amount, soil enzyme activity, soil bacterial community