Optimized nitrogen management enhances lodging resistance of rice and its morpho-anatomical, mechanical, and molecular mechanisms

Junfeng Pan,Yanzhuo Liu,Xuhua Zhong,Nongrong Huang,Ka Tian,Junliang Zhao,Farooq Shah,Bin Liu,Kaiming Liang

doi:10.1038/s41598-019-56620-7

Abstract

Increasing evidence shows that improved nitrogen management can enhance lodging resistance and lower internodes play a key role in the lodging resistance of rice. However, little is known about the cellular and molecular mechanisms underlying the enhanced lodging resistance under improved nitrogen management. In the present study, two rice varieties, with contrasting lodging resistance, were grown under optimized N management (OPT) and farmers’ fertilizer practices. Under OPT, the lower internodes of both cultivars were shorter but the upper internodes were longer, while both culm diameter and wall thickness of lower internodes were dramatically increased. Microscopic examination showed that the culm wall of lower internodes under OPT contained more sclerenchyma cells beneath epidermis and vascular bundle sheath. The genome-wide gene expression profiling revealed that transcription of genes encoding cell wall loosening factors was down-regulated while transcription of genes participating in lignin and starch synthesis was up-regulated under OPT, resulting in inhibition of longitudinal growth, promotion in transverse growth of lower internodes and enhancement of lodging resistance. This is the first comprehensive report on the morpho-anatomical, mechanical, and molecular mechanisms of lodging resistance of rice under optimized N management.

Highlights

Increasing evidence shows that improved nitrogen management can enhance lodging resistance and lower internodes play a key role in the lodging resistance of rice
The main difference between optimized N management (OPT) and fertilizer practices of N application (FFP) was that N application at tillering stage was reduced by more than a half in contrast to FFP (Table 1)
Our results showed that increase in the culm weight, culm diameter and culm wall thickness of lower internodes under OPT was caused by the enhanced expression level of genes participating in the starch synthesis pathways

Summary

Introduction

Increasing evidence shows that improved nitrogen management can enhance lodging resistance and lower internodes play a key role in the lodging resistance of rice. Compared to that of conventional farmers’ fertilizer practices of N application (FFP), fertilizer N input for ‘three controls’ technology is cut off by 50% during tillering, while N input after panicle initiation is more than doubled, resulting in a 20% reduction in total N input[14] This technology is very famous due to its superiority in lodging resistance in China[15,16,17,18,19,20], especially in coastal areas where typhoon usually prevails during the rice-growing season. Farmers can typically save 20% nitrogen fertilizer and obtain 10% more grain yield compared to their conventional practice[14,21] It was officially released in 2007 and was on the recommendation list of the Ministry of Agriculture of China in 2012 It is widely adopted in more than ten rice-growing provinces in China

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