Adaptability of High-Yielding Rice Cultivars in Relation to Biomass Productivity under Moderately Water Stressed Upland Conditions

Tomohiro Hyoda,Takeshi Horie,Keisuke Katsura,Tatsuhiko Shiraiwa,Koki Homma

doi:10.4236/as.2015.63036

Abstract

Recent studies have focused on the improvement of rice productivity under aerobic conditions for times when water resources and food production are limited. This study aimed to evaluate the adaptability of high-yielding rice cultivars to moderately water-stressed upland conditions in order to contribute breeding. A three-year field experiment in the temperate climate of Kyoto, Japan, indicated that the decrease in yield was mainly derived from a decrease in above-ground total dry matter (TDM) rather than a decrease in harvest index (HI). Although the decrease in TDM was mostly caused by a decrease in radiation use efficiency (RUE), we determined that the key to adapting high-yielding cultivars to upland conditions is intercepted radiation per day (IRPD), governed by leaf area index (LAI). Although the effect was not robust, LAI growth under upland conditions was associated with root length density. RUE was dependent on leaf water potential (LWP), indicating that a plant’s ability to maintain LWP under water-stressed conditions is important. The results also suggest the necessity of a canopy analyzer to evaluate LAI, as well as an infrared radiation thermometer to evaluate RUE. Performing such measurements during breeding efforts allows us to select for genotypes that are suitable for less stressed aerobic conditions.

Highlights

Rice is a staple food for about 50% of people in the world, most of whom live in Asia
Since precipitation was infrequent and limited after the rainy season, SMC0-30 sometimes decreased below 0.1 m3∙m−3
The analysis in this study indicated that decreases in total dry matter (TDM) under upland conditions were closely correlated with decreases in radiation use efficiency (RUE)

Summary

Introduction

Rice is a staple food for about 50% of people in the world, most of whom live in Asia. The production of rice increased double from 1960 to 2010 depending on yield increase, which was caused by improvement of cultivar, cropping and resource management [1]. Together with the aspects of world population increase, we are recommended to improve rice productivity. Recent research indicates that the water available for irrigation has been reduced by limited water resources, as well as increased industrial and city water use [3]. Previous studies indicated the greatest potential for increasing rice production in the face of certain population expansion will involve rainfed and upland rice ecosystems [4] [5]. While the level of rice yield in irrigated conditions has plateaued, yields in rainfed and upland conditions demonstrate room for growth. High-yield production under limited water conditions will be the key to increasing future rice productivity

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