Fertilization is an important practical measure in agricultural production. As an important nutrient element of plants, nitrogen (N) has a significant impact on the plant productivity and microbial function. Rhizosphere microorganisms affect plant growth and development, nitrogen uptake and utilization, and ecological adaptability. The interaction mechanism between plant and rhizosphere microorganisms is one of the hotspots in life science research and the key program of agricultural microorganism utilization. In this article, the relationship among plant root morphology and physiology, rhizosphere microorganisms, and nitrogen is reviewed, summarized, and prospected.

The biological characteristics of crop roots are closely related to the efficient utilization of nitrogen and have become a research hotspot in agricultural cultivation and breeding in recent years. The root system and root microbiota play a crucial role in both the basic and the plastic growth and development of plants in response to external environmental changes. Nitrogen is an indispensable nutrient element for crop growth, and the efficient utilization of nitrogen is the key to achieving the high yield and quality of crops and establishing environmentally friendly agricultural production. The nitrogen absorbed and utilized by rice mainly enters the aboveground part of the plant through the root system from within the soil. This process is explored from the perspective of root biology (root morphology, physiological and biochemical characteristics, root growth and development process and regulation, rhizosphere microorganisms, and their symbiotic systems), which is in line with the directions of “less investment, increased production, environmental protection, and sustainable development” in China. Based on the research status in this field at present, this article explored the interaction mechanism between crop root biology and nitrogen absorption and utilization, and looks forward to the future research directions for root biology. This study provides a theoretical basis for reducing nitrogen fertilizer application, optimizing nitrogen-efficient cultivation management techniques, and selecting nitrogen-efficient varieties.

Colored rice is richer in nutrients and contains more nutrients and bioactive substances than ordinary white rice. Moderate consumption of black (purple) rice has a variety of physiological effects, such as antioxidant effects, blood lipid regulation, and blood sugar control. Therefore, we utilized nontargeted metabolomics, quantitative assays for flavonoid and phenolic compounds, and physiological and biochemical data to explore the correlations between metabolites and the development of antioxidant characteristics in pigmented rice seeds. The findings indicated that, among Yangjinnuo 818 (YJN818), Hongnuo (HN), Yangchannuo 1 hao (YCN1H), and Yangzi 6 hao (YZ6H), YZ6H exhibited the highest PAL activity, which was 2.13, 3.08, and 3.25 times greater than those of YJN818, HN, and YCN1H, respectively. YZ6H likewise exhibited the highest flavonoid content, which was 3.8, 7.06, and 35.54 times greater than those of YJN818, HN, and YCN1H, respectively. YZ6H also had the highest total antioxidant capacity, which was 2.42, 3.76, and 3.77 times greater than those of YJN818, HN, and YCN1H, respectively. Thus, purple rice grains have stronger antioxidant properties than other colored rice grains. Receiver operating characteristic (ROC) curve analysis revealed that trans-3,3′,4′,5,5′,7-hexahydroxyflavanone, phorizin, and trilobatin in the YZ6H, HN, and YCN1H comparison groups all had area under the curve (AUC) values of 1. Phlorizin, trans-3,3′,4′,5,5′,7-hexahydroxyflavanone, and trilobatin were recognized as indices of antioxidant capability in colored rice in this research. This research adds to the understanding of antioxidant compounds in pigmented rice, which can increase the nutritional value of rice and promote the overall well-being of individuals. This type of information is of immense importance in maintaining a balanced and healthy diet.