Phenotypic Variation and Selection for Cold-Tolerant Rice (Oryza sativa L.) at Germination and Seedling Stages

Doan Cong Dien,Takeo Yamakawa

doi:10.3390/agriculture9080162

Abstract

Owing to its origin in tropical and subtropical areas, rice is susceptible to cold stress. Low temperatures at the germination and seedling stages can result in seed loss, a delayed transplanting period, and lower final yield. In this study, 181 rice varieties from around the world were investigated for cold tolerance at the germination and seedling stages. At the germination stage, the responses of different rice varieties were examined based on the germination index, coleoptile length, and radicle length at low (13 °C) and control temperatures (25 °C). Significant variations in the germination index, coleoptile length, and radicle length were observed among varieties. Low temperature significantly decreased germination ability, and coleoptile and radicle growth in the studied varieties. At the seedling stage, cold tolerance of the rice varieties was evaluated based on the leaf color score under natural low temperature. Similar to the germination stage, at the seedling stage, significant variation in root and shoot growth was observed in the response of rice varieties to low temperature conditions. Based on the results from both the germination and seedling stages, two varieties (Hei-Chiao-Chui-Li-Hsiang and Ta-Mao-Tao) were selected as the best cold-tolerant varieties. Our results also indicate the benefits of warming treatments to protect rice seedlings from low temperature conditions.

Highlights

Rice (Oryza sativa L.) is one of the most important staple food crops globally and the most important one in Vietnam [1,2]
In the northern regions of Vietnam, rice cultivation in the spring season (February to June) is usually affected by low temperatures at the germination and seedling stages [6], which results in seed loss and delay in the transplanting period
Our results indicated the beneficial effects of warming treatment on the growth of rice seedlings under cold stress conditions

Summary

Introduction

Rice (Oryza sativa L.) is one of the most important staple food crops globally and the most important one in Vietnam [1,2]. Vietnam is one of the world’s major rice exporters, in some mountainous areas, the northwest provinces, it is difficult to maintain food security due to low rice productivity caused by unfavorable environmental conditions. Owing to its origin in tropical and subtropical regions, rice is sensitive to cold stress [3], at the germination and seedling stages [4,5]. In the northern regions of Vietnam, rice cultivation in the spring season (February to June) is usually affected by low temperatures at the germination and seedling stages [6], which results in seed loss and delay in the transplanting period. Cold tolerance in rice is a complex trait [7]

Results

Discussion

Conclusion