Bagheri-Novair Sepideh, Mirseyed Hosseini Hossein, Etesami Hassan, Razavipour Teimour, Asgari Lajayer Behnam, Astatkie Tess
Department of Soil Science, College of Agriculture and Natural Resources, University of Tehran, Tehran, Iran.
Rice Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran.
3 Biotech. 2020 Nov;10(11):492. doi: 10.1007/s13205-020-02486-w. Epub 2020 Oct 27.
Paddy soils represent the largest anthropogenic wetlands on earth. Soil drying and rewetting that occurs annually inflict significant stress on soil microbial activities in paddy soils. An incubation experiment of 60 years of paddy soil was conducted to simulate the conditions of paddy fields (25 °C and 75% air humidity) during a 16-day incubation time. The effect of drying-rewetting [DRW, with 4 levels: (1) constant soil moisture (CSM), (2) one-stage drought stress (DRW1), (3) two-stage drought stress (DRW2), and (4) three-stage drought stress (DRW3)] and how it evolves over 0, 4, 8. 12, and 16 days after incubation on the concentration of available phosphorus (AP), microbial biomass P (MBP) and microbial biomass C (MBC), and respiration rate (RES) was determined using repeated measures analysis (RMA). The results revealed that an increase in the number of drying-rewetting increases MBC and RES. Compared to CSM, frequent drying and rewetting caused an increase in RES, MBC and MBP by 88%, 38%, and 11%, respectively. Drying-rewetting increased microbial biomass C (MBC) and P (MBP) by 24-38% and 11-54%, respectively, during 8-16 days of incubation. Increasing the number of DRW cycles reduced AP concentration (except in DRW1). The decrease in available phosphorus is due to the increase in the intensity of immobilization under these conditions. Positive correlations were also observed between AP and MBP ( = 0.52), and between RES and MBC ( = 0.91). In general, the frequency of moisture in the paddy soil is favorable for increasing microbial activity.
稻田土是地球上最大的人工湿地。每年发生的土壤干湿交替对稻田土壤微生物活动造成显著压力。进行了一项为期60年的稻田土培养实验，以模拟稻田在16天培养期内的条件（25°C和75%空气湿度）。采用重复测量分析（RMA）确定了干湿交替[DRW，有4个水平：（1）恒定土壤湿度（CSM），（2）一阶段干旱胁迫（DRW1），（3）两阶段干旱胁迫（DRW2），和（4）三阶段干旱胁迫（DRW3）]及其在培养0、4、8、12和16天后对有效磷（AP）、微生物生物量磷（MBP）、微生物生物量碳（MBC）浓度和呼吸速率（RES）的影响。结果表明，干湿交替次数增加会使MBC和RES升高。与CSM相比，频繁的干湿交替使RES、MBC和MBP分别增加了88%、38%和11%。在培养8 - 16天期间，干湿交替使微生物生物量碳（MBC）和磷（MBP）分别增加了24 - 38%和11 - 54%。增加DRW循环次数会降低AP浓度（DRW1除外）。有效磷的减少是由于在这些条件下固定化强度增加所致。在AP和MBP之间（r = 0.52）以及RES和MBC之间（r = 0.91）也观察到正相关。总体而言，稻田土壤水分频率有利于提高微生物活性。
