Root morphological traits and distribution indirect-seededrice underdenseplanting with reducednitrogen.

Jun Deng,Xiaohai Tian,Ke Liu,Liying Huang,Haotian Chong,Jian Lu,Cheng Shang,Yunbo Zhang,Xiangqian Feng,Danying Wang,Meixue Zhou

doi:10.1371/journal.pone.0238362

Jun Deng, Xiaohai Tian + Show 9 more

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https://doi.org/10.1371/journal.pone.0238362

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Abstract

Water and nutrient absorption from soil by crops mainly depend on the morphological traits and distribution of the crop roots. Dense planting with reduced nitrogen is a sustainable strategy for improving grain yield and nitrogen use efficiency. However, there is little information on the effects of dense planting with reduced nitrogen on direct-seeded inbred rice. Two-year field experiments were conducted with minirhizotron techniques to characterize the root morphological traits and distributions under different nitrogen application rates and sowing densities in two representative inbred rice varieties, Huanghuazhan (HHZ) and Yuenongsimiao (YNSM), grown under three nitrogen application rates (N0: 0 kg ha–1, LN: 135 kg ha-1, HN: 180 kg ha–1) and two sowing densities (LD: 18.75 kg ha−1, HD: 22.5 kg ha−1). Our study showed that dense planting with low nitrogen improved grain yield partly due to the increased panicle number. The higher sowing density with low nitrogen significantly affected the total root number (TRN), total root length (TRL), total root surface area (TRSA), and total root volume (TRV). There was a significant positive correlation between grain yield and TRL in the 10–20-cm soil layer (P < 0.05). The root morphological indexes were positively correlated with dry matter accumulation (P < 0.05) and negatively correlated with nitrogen content (P < 0.05) at the maturity stage. This study showed that a high sowing density with low nitrogen application can improve root morphology and distribution and increase grain yield and nitrogen use efficiency in direct-seeded inbred rice.

Highlights

Rice is one of the major cereal crops in the world, and more than 60% of the world’s population consumes rice as their staple food
The grain yield of HHZ showed a positive correlation with the N application rate and sowing density in 2018
The N application rate had no significant effect on the number of spikelets per panicle of either variety under the LN × HD treatment, and there was no significant difference in the grain-filling percentage or grain weight among N application rates

Summary

Introduction

Rice is one of the major cereal crops in the world, and more than 60% of the world’s population consumes rice as their staple food. It is, of great importance to increase rice yield to ensure food security in China and worldwide [1]. The main mode of rice planting in China is manual transplanting. Root traits and distribution of rice under dense planting with reducing nitrogen

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