Non-Structural Carbohydrates Accumulation in Contrasting Rice Genotypes Subjected to High Night Temperatures

Diogo S Moura,Fábio Schreiber,Paulo R R Fagundes,Fabiane G S Porto,Sidnei Deuner,Ítalo L Moraes,Ângela D Campos,Sheila B Teixeira,Giovani G Brito,André Andres

doi:10.5539/jas.v9n12p302

Abstract

Non-structural carbohydrates (NSC) accumulation and photosynthesis traits were studied in two rice (Oryza sativa L.) genotypes maintained under control (22/30 °C - night/day) and at high night temperatures (HNT) (28/30 °C) conditions from heading to milk stage. Rice cultivars were Nagina22 - N22 and BRS Querência - Quer, which are tolerant and sensitive to high temperatures, respectively. The source-sink flow related attributes were tested to understand the nature of NSC accumulation and translocation. Compared to N22, Quer maintained higher stem starch in glucose on seventh day after heading and at milk stage independently of imposed temperatures. However, the levels of starch in glucose were lower for N22 meanwhile their total sugar concentration (TSC) were higher at control and at HNT at milk stage as compared to Quer. N22 maintained unaltered the spikelet sterility and 1000-grain weight across environments showing a consistent trend with its stem NSC translocation. Both genotypes showed similarity in some gas exchange and chlorophyll fluorescence performance suggesting unaffected photosystem II photochemistry, linear electron flux, and CO2 assimilation. Beyond indicating that source functioning was not the limiting factor for low TSC and starch in glucose levels found in N22 on seventh day after heading stage. Moreover, our data suggest that the higher translocation capacity shown by N22 can be involved in their lower spikelet sterility and 1000-grain weight stability across the environments. These results indicate that selecting genotypes with higher capacity to stem NSC translocation at HNT could lead to more grain yield stability in future climate scenarios.

Highlights

Rice (Oryza sativa L.) is one of the most relevant staple foods for more than half of the world’s population (Fan et al, 2016)
Evaluation of the chlorophyll fluorescence were used to complement those shown by gas exchange analysis
Our results indicate that N22 maintain unaltered yield components such as spikelet sterility rate, grain per panicle and 1000-grain weight when submitted to high night temperature

Summary

Introduction

Rice (Oryza sativa L.) is one of the most relevant staple foods for more than half of the world’s population (Fan et al, 2016). There is a consensus that in the future the climate changes will become a bottleneck for crop yield and its stability (Brito et al, 2010, 2011, 2016; Diola et al, 2011, 2013; Guimarães et al, 2017; Weber et al, 2014). In this way, projected climate changes could reduce crop yields in the future (Fan et al, 2016; Tian et al, 2015). Projected impact of climate change on crop yield has been extensively published in the last decade, comparatively, there is still a lack of studies that highlight the role of high nighttime temperatures on rice physiological response and, changes in the rice yield performance

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Conclusion