The impact of nitrogen fertilizer application on lodging resistance for rice plants has emerged as a significant factor influencing rice yield and structural stability. A recent study conducted at Jilin Agricultural University has illuminated how different levels of nitrogen fertilizers affect the integrity of rice stems, which is particularly relevant for addressing challenges associated with excessive lodging—a phenomenon detrimental to both yield and post-harvest management.
Rice (Oryza sativa L.) is one of the world's most important crops, with soaring global demand necessitating increased production. Agricultural practices have turned to fertilizers, especially nitrogen, to boost yields. While nitrogen is pivotal for plant growth—promoting photosynthesis and biomass accumulation—its overuse can weaken stem structures, leading to lodging.
The study explored the morphological structure, mechanical properties, and chemical composition of four japonica rice varieties under different nitrogen application levels. The researchers set up controlled plots with nitrogen levels ranging from none (N0) to 300 kg hm−2 (N5) to assess the corresponding effects on lodging resistance at various growth stages.
The results revealed complex dynamics for nitrogen applications: among the tested varieties, WYD4 demonstrated peak yields under N1 treatment, whereas JYJ, JJ 525, and JND 667 thrived best under N2 treatment. Notably, the lodging index—a measure of the plant's susceptibility to lodging—was at its highest under N5, which indicates excessive nitrogen levels significantly increase lodging risk.
“Excessive nitrogen fertilizer can have negative effects on the carbohydrate content of the second internode at the base, leading to reduced stem plumpness and bending moment, as well as increased risk of lodging,” the authors noted. They found increments of up to 1.21 times the lodging index with rising nitrogen applications, which correlated with diminished mechanical properties like the bending moment and fracture strength of rice stems.
At key growth intervals, particularly 30 days after heading, the lodging index peaked, underscoring the importance of managing nitrogen levels during this sensitive period. An analysis of morphological traits revealed significant increases in plant height, internode length, and the center of gravity with elevated nitrogen rates, highlighting how these changes impact physical stability.
Interestingly, chemical analyses showed decreases in cellulose and lignin as nitrogen levels rose. “This suggests the use of nitrogen fertilizer reduces stem strength and increases the risk of rice lodging by diminishing the content of stem lignin and cellulose,” the researchers concluded. These insights shed light on the delicate balance necessary for optimal fertilizer application—while nitrogen boosts yields, it must be employed judiciously to safeguard against lodging.
Overall, the findings point to the pressing need for refined nitrogen management practices aimed at maximizing both yield potential and crop structural integrity. With the global rice yield expected to increase by 20% by 2030, strategies incorporating these insights will be pivotal for meeting future food demands effectively.