Effect of split application of nitrogen combined with chitooligosaccharide on lodging in rice

Aims

Lodging is one of the main factors that reduces rice yields. The application of nitrogen (N) fertilizer at an appropriate ratio and plant growth regulators (PGR) can affect the relationship between stem lodging and yield.

Methods

We conducted a 2-year field experiment with three different N fertilizer ratios (N1, decreased panicle N rate; N2, medium panicle N rate; N3, increased panicle N rate) and two PGR (P1, paclobutrazol; P2, chitooligosaccharide) and a control (water).

Results

Compared with the control, both PGR significantly improved the lodging resistance and yield of rice. The pushing resistances force (PRF) of the rice stem in the P1 and P2 treatments was increased by 3.06%–19.76% and 25.26%–58.68%, respectively, and the LI was decreased by 17.74%–39.29% and 20.62%–35.05%, respectively. Morphological analyses showed that the P2 treatment increased the internode diameter and stem wall thickness of the third and fourth internodes. The P1 treatment reduced the height of gravity center and the internode length. Chemical analyses showed that both PGR increased the weight of stems, promoted the accumulation of N, P, and K in stems, and increased the contents of lignin and cellulose. Regardless of the PGR treatment, the N2 treatment significantly improved the morphological characteristics and physiological functions of the stem, resulting in increased lodging resistance and yields.

Conclusions

Together, our results show that foliar spraying with chitooligosaccharide combined with appropriate fertilizer management can be developed as an effective agronomic strategy to increase the lodging resistance and yields of double-cropping rice.