Effects of seedling age and cultivation density on agronomic characteristics and grain yield of mechanically transplanted rice

Jingling Li,Xuebiao Zhou,Caiyun Xin,Qihua Liu

doi:10.1038/s41598-017-14672-7

Jingling Li, Xuebiao Zhou + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-14672-7

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Abstract

Delayed transplantation frequently occurs in mechanically transplanted rice in China, leading to a significant reduction in grain yield. Thus, determining how to compensate grain yield loss is crucial for improving rice cultivation technology. A field experiment was conducted to investigate the effects of cultivation density and seedling age on agronomic traits and grain yield of mechanically transplanted rice. With increasing seedling age, rice tiller number, pre-anthesis dry matter accumulation, remobilization efficiency and contribution to grain yield, as well as post-anthesis photosynthesis amount decreased, causing reductions in the number of effective panicles, the total number of grains per panicle, the sink capacity per tiller, and grain yield. In rice transplanted at 30- and 35-day seedling ages, increasing cultivation density significantly enhanced the number of effective panicles and grain yield. Additionally, there existed strong, positive correlations between sink capacity per tiller and pre-anthesis dry matter remobilization efficiency and pre-anthesis dry matter contribution to grain yield. We conclude that in addition to cultivation density, enhancing the amount of pre-anthesis dry matter and the remobilization efficiency could be feasible for mitigating grain yield loss caused by delayed transplantation.

Highlights

With the increasing scarcity of the rural labour force, mechanical transplantation has become a prevalent and simplified cultivation method to replace hand transplantation in Chinese rice production
The objectives of this research were (1) to determine the effect of cultivation density on tiller occurrence, pre-anthesis dry matter remobilization and utilization efficiencies, post-anthesis photosynthetic products use efficiency, sink capacity per tiller, and the grain yield component of rice with optimal and old seedling ages; (2) to ascertain whether increasing the cultivation density could significantly compensate for the grain yield loss of mechanically transplanted rice incurred by delaying transplantation; and (3) to clarify the relationship between the utilization efficiency of photoassimilates and sink capacity
Previous reports showed that rice jointing, heading, and maturity stages under mechanical transplantation were delayed compared with those under hand transplantation, with this difference increasing with the delay of mechanical transplantation[6]

Summary

Introduction

With the increasing scarcity of the rural labour force, mechanical transplantation has become a prevalent and simplified cultivation method to replace hand transplantation in Chinese rice production. Hu et al reported that an optimum nitrogen application pattern (a split application ration of 4:3:3 before transplantation, at tillering and at panicle initiation stages) could significantly enhance the nitrogen utilization efficiency and grain yield of delayed mechanically transplanted rice[9]. The objectives of this research were (1) to determine the effect of cultivation density on tiller occurrence, pre-anthesis dry matter remobilization and utilization efficiencies, post-anthesis photosynthetic products use efficiency, sink capacity per tiller, and the grain yield component of rice with optimal and old seedling ages; (2) to ascertain whether increasing the cultivation density could significantly compensate for the grain yield loss of mechanically transplanted rice incurred by delaying transplantation; and (3) to clarify the relationship between the utilization efficiency of photoassimilates and sink capacity

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