干湿交替灌溉是水稻高产节水栽培的重要措施之一，但干湿交替灌溉条件下水稻根系形态生理和土壤生物学性状的变化及其相互作用机制尚不清楚。本项目拟以对水分反应敏感性有明显差异的水稻品种(籼稻和粳稻各两个)为材料，设置轻度干湿交替灌溉和重度干湿交替灌溉，并以常规高产灌溉方式为对照，研究 ：(1) 主要生育期(分蘖盛期、穗分化期、抽穗期和成熟期)和稻田复水前后水稻根系形态和生理的变化特点。(2) 主要生育期和稻田复水前后土壤生物学性状（微生物量和土壤主要酶类活性等）的变化特征。(3) 养分管理(含麦秸秆还田)和土壤类型(沙土、壤土和粘土)对水稻根系形态生理和土壤生物学性状的调控。以期明确干湿交替灌溉对水稻根系形态生理和土壤生物学性状的影响，阐明根系生长与土壤生物学性状的互作机制，提出调控水稻根系生长和土壤生物学性状提高水稻产量的栽培技术途径，为水稻高产节水栽培提供理论和实践依据。

Alternate wetting and soil drying irrigation (AWD) is an important method for increasing grain yield and saving water in rice production. However, the changes of morphological and physiological traits in rice root and biological traits in paddy soil under AWD and their interaction mechanisms have not been very clearly understood. Four rice cultivars (two indica and two japonica cultivars) with different responses to soil moisture will be used as materials, three types of irrigation regimes, including wetting and moderate soil drying irrigation, wetting and severe soil drying irrigation, and conventional irrigation (CK) are designed to investigate:.(1) The changes of morphological (root number, root length, root density, root diameter, root weight, root surface area and ultrastructure of root tip cells) and physiological (the root oxidation activity, total and active absorption area, hormones contents in root and the contents of hormones, organic acids, amino acids in root bleedings and the concentrations of ions and organic acids exuded from roots) traits in rice root at main growth stages (mid-tillering stage, panicle initiation, heading stage and maturity) and before and after rewetting stage..(2) The dynamic changes of biological traits (microbial biomass and main enzymes activities) in paddy soil at main growth stages and before and after rewetting stage..(3) The regulating effects of nutrient management (including wheat straw returning to the paddy field) and soil types (sandy soil, loam soil and clay soil) on morphological and physiological traits in rice roots and biological traits in paddy soil..This study is expected to elucidate the effect of AWD on morphological and physiological traits in rice root and biological traits in paddy soil and their interaction mechanisms, and put forward the cultivating approaches to regulating root growth and yield formation through the regulation of morphological and physiological traits in rice roots and biological traits in paddy soil.