The response of roots and rhizosphere environment to integrative cultivation practices in paddy rice

Abstract

Integrative cultivation practices (ICPs) are essential in enhancing cereal yield and resource use efficiency. Although, the ICP effects on the rhizosphere environment of paddy rice and roots remain to be poorly understood. In this study, four rice varieties were produced in field. The investigation was performed with six cultivation techniques, includes zero nitrogen application (0 N), local farmers’ practice (LFP), nitrogen reduction (NR), and three progressive ICP 1–3 comprised of enhanced fertilizer N practice and increased plant density (ICP1), Similar to ICP1 but with alternate wetting and moderate drying instead of continuous flooding (ICP2), in addition to the same practices as ICP2 application of organic fertilizer (ICP3). ICPs had greater grain production and nitrogen use efficiency. Root length, dry weight, root diameter, activity of root oxidation, root bleeding rate, zeatin and zeatin riboside compositions, and total organic acids in root exudates elevated with the introduction of successive cultivation practices. ICPs enhanced nitrate nitrogen, activities of urease and invertase, and diversity of microbes (bacteria) in rhizosphere and non-rhizosphere soil, while decreasing ammonium nitrogen content. The nutrient content (ammonium nitrogen, total nitrogen, total potassium, total phosphorus, nitrate, and available phosphorus) and urease activity in rhizosphere soil were decreased in all treatments in comparison with non-rhizosphere soil, but opposing outcomes were reported for invertase activity and bacterial -diversity. The main root morphology, physiology and ammonium nitrogen contents in rhizosphere soil at the primary stages were closely correlated with grain yield and internal nitrogen use efficiency. These findings suggest that the coordinated enhancement of the root system and the environment of rhizosphere under integrative cultivation approaches may participate in a higher rice production.