A positive response of rice rhizosphere to alternate moderate wetting and drying irrigation at grain filling stage

作者：Li, Zhou; Li, Zhong; Letuma, Puleng; Zhao, Hong; Zhang, Zhixing; Lin, Weiwei; Chen, Hongfei^*; Lin, Wenxiong^*

来源：Agricultural Water Management, 2018, 207: 26-36.

DOI：10.1016/j.agwat.2018.05.022

• Alternate wetting and drying
• Grain filling
• Photosynthesis
• Root activity
• Soil redox potential (Eh)
• T-RFLP

Paddy fields are drained and irrigated several times during the whole rice growth period. Although studies have acknowledged the sensitivity of flooding and drainage in rice rhizosphere, current knowledge regarding how moderate drying at grain filling stage affects ecological characteristics of rice rhizosphere is limited. A field experiment with two irrigation regimes [alternate moderate wetting and drying irrigation (AMWD) and continuous irrigation (CI)] was conducted to investigate the changes in soil physical and chemical properties and microbial communities. Results from this investigation demonstrated that soil pH under AMWD was decreased, while Eh was increased. Moreover, soil electrical conductivity increased and decreased with a decline in soil water potential, interestingly all studied variables quickly recovered after re-watering.
The terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the diversity indices of bacterial communities were higher in drying phase as compared to the initial treatment of AMWD regime, but the evenness index decreased. Remarkably, AMWD process increased the proportion of aerobic bacteria, such as Azotobacter, nitrifying bacteria, phosphate and potassium solubilizing bacteria (which participate in the nutrient cycling). In addition, the increase of enzyme activity under AMWD regime promoted the release of nutrients, thereby enhancing the amounts of NO3--N, available phosphorus (P) and potassium (K) in soils, which met rice nutrient demands at late grain filling stage. This led to a promotion in plant physiological activities and grain filling, and hence increased grain yield. From these results we infer that there was a positive response of rice rhizosphere to AMWD irrigation at grain filling stage, which laid the groundwork to set up a sound irrigation system in rice fields without reducing its yield.

• 出版日期2018-8-30
• 单位福建农林大学