Quantification of Cultivar Change in Double Rice Regions under a Warming Climate during 1981–2009 in China

Xiaolei Qiu,Weixing Cao,Leilei Liu,Yan Zhu,Liang Tang

doi:10.3390/agronomy9120794

Abstract

Maintaining high double rice productivity in China is very important for ensuring the food security of China. However, the double rice production system is sensitive to changes in both climate and management practices. Previous studies showed that rice production has been negatively impacted by global warming without considering the changes of cultivars and management practices. However, cultivar improvements and the impact of cultivar change must not be ignored in any assessment. In the current study, we combined data analysis with crop modeling to investigate the impacts of changes in climate and cultivars on rice productivity at three different double rice sites (Nanchang, Hengyang, and Gaoyao) in China. The results showed a warming trend at the study sites during 1981–2009, and the temperature increase rates (maximum, average, and minimum temperatures) in the late rice growing season were larger than in the early rice growing season. Global warming has led to a reduction in the length of the rice growth period. Adopting new rice cultivars may partially mitigate the declining trend of the growing duration and grain yield, but it would not completely compensate for the negative impact observed in double rice regions. In general, the changes in cultivars prolonged the growing duration by increasing the basic vegetative phase and the photoperiod formation phase. The main reasons for yield improvement were the increase in the percentage of filled grains for early rice and the increase in grain number per spike for late rice. In the face of future warming, breeding efforts are necessary for producing new cultivars that are resilient to the negative impacts of future climate change on agriculture.

Highlights

Rice is the third most widely grown cereal crop after wheat and maize and is the staple food of more than half of the world’s population [1,2,3]
Rice phenology was divided into four main phases: basic vegetative phase (BVP, from emergence to the start of the photoperiod-sensitive phase), photoperiod-sensitive phase (PSP, from the end of the basic vegetative phase to panicle initiation), panicle formation phase (PFP, from panicle initiation to flowering), and grain-filling phase (GFP, from flowering to physiological maturity)
It has been proved that the phenology and growth duration of crops have been shortened as temperatures have risen in the past decades [23], and the accelerated developmental rate caused by climate warming is often associated with a harmful effect on crop production [17,32]

Summary

Introduction

Rice is the third most widely grown cereal crop after wheat and maize and is the staple food of more than half of the world’s population [1,2,3]. China is one of the major rice-producing countries and accounts for approximately one-third of global rice production [4]. China’s 2015–2017 rice harvested area was estimated at 31.0 million ha, accounting for 18.5% of the world’s total [5], and this was dominated by double rice [6]. 66% of the total rice area in China is under a double rice cropping system [7]. It is important that the production from this system in China contributes to global food security. Over the past 60 years, rice farming practices in China have changed tremendously [8,9], and these changes have contributed significantly to the increase in production

Methods

Results

Conclusion