Breeding Temperate Japonica Rice Varieties Adaptable to Tropical Regions: Progress and Prospects

Myrish Pacleb,Il-Ryong Choi,Lenie Pautin,Dong-Soo Park,Sung-Ryul Kim,Woong-Jo Hyun,Jesson Y Del-Amen,Sumin Jo,Joum-Ho Lee,Sais-Beul Lee,Hyun-Su Park,Elbert E Sana,Jong-Cheol Ko,Gideon Torollo,Rustum Braceros,Jeong-Heui Lee,Nese Sreenivasulu,Jun-Hyeon Cho,Jong‐Min Jeong ,Ki‐Young Kim ,Thelma Padolina ,Jiyoun Lee ,Jeom‐Sig Lee ,O‐Young Jeong ,Man‐Kee Baek ,Byeong-Ju Kim ,Jae-Sung Lee

doi:10.3390/agronomy11112253

Abstract

Temperate japonica rice is mainly cultivated in temperate regions. Many temperate japonica varieties have a superior grain quality that is preferred in Northeast Asian countries such as Japan, Korea, and China. The changes in consumers’ preferences in Southeast Asia and Western countries has contributed to increasing the demand for temperate japonica. Most temperate japonica varieties developed in temperate regions typically exhibit extra-early flowering under the short-day conditions in the tropics, which usually results in severely reduced yields. Since 1992, we have been developing temperate japonica varieties that can adapt to tropical environments to meet the increasing demand for temperate japonica rice, having released six varieties in the Philippines. Especially, the yield of one of the temperate japonica varieties, Japonica 7, was comparable to the yields of leading indica varieties in the Philippines. Here, we discuss the current breeding initiatives and future plans for the development of tropical-region-bred temperate japonica rice.

Highlights

Japonica rice, a subspecies of Oryza sativa L., can thrive in tropical and temperate zones; it can be divided into two subgroups: temperate japonica and tropical japonica [1].Tropical japonica is cultivated in Southeast Asian countries such as the Philippines and Indonesia, while temperate japonica is mostly grown in North-East Asian countries such asJapan, Korea, and China, where the seasonal changes in climate temperature are distinct.Globally, temperate japonica is more produced and consumed than tropical japonica [2]
The frequencies of the resistance allele types for xa5 and brown planthopper (BPH) 32 in temperate japonica and indica were similar to those for Pita (Table 7). These results suggest that many temperate japonica rice plants, which have been mostly cultivated in the temperate region, do not harbor important genes necessary to adapt to the tropical region
The goal of our endeavor described here is to develop temperate japonica varieties adapted to the tropical environment

Summary

Introduction

A subspecies of Oryza sativa L., can thrive in tropical and temperate zones; it can be divided into two subgroups: temperate japonica and tropical japonica [1]. Due to the unique attributes of temperate japonica varieties such as their sticky texture, they are often classified as special-purpose rice in the regions where indica rice is predominantly consumed or rice is not the primary staple food [3]. Many temperate japonica rice varieties are valued for their sticky texture and high grain quality that are distinct from those of indica. Due to the poor adaptability of many temperate japonica rice plants to tropical environments, the production of temperate japonica rice has been very limited in the Southeast Asian countries. Temperate japonica rice has small and very specialized markets in Southeast Asia, the demand for temperate japonica varieties is increasing and it has great potential for realizing higher income returns to farmers in the region

Progress of Temperate Japonica Rice Adaptable to Tropical Regions

13 September 2021

Challenges anddate

Findings

Conclusions and Future Work