Morpho-Physiological Characterization of Diverse Rice Genotypes for Seedling Stage High- and Low-Temperature Tolerance

Kambham Raja Reddy,Chathurika Wijewardana,Akanksha Seghal,Daryl Chastain,Shasthree Taduri,Ajaz A Lone,Firas Ahmed Alsajri,Salah Jumaa,Wei Gao,Edilberto D Redoña,Naqeebullah Kakar,Raju Bheemanahalli

doi:10.3390/agronomy11010112

Abstract

Extreme temperatures are considered one of the main constraints that limit the growth and development of rice. We elucidated the root and shoot developmental plasticity of 64 rice genotypes during early seedling establishment, using the sunlit plant growth chambers at 22/14 (low), 30/22 (optimum), and 38/30 °C (high) day/night temperatures. Low temperature severely inhibited 23 traits, such as shoot (68%), root (57%), and physiological (35%) attributes. On the contrary, the high temperature positively affected most of the shoot (48%) and root (31%) traits, except root diameter and root/shoot ratio, compared with the optimum. Alternatively, leaf chlorophyll fluorescence-associated parameters declined under low (34%) and high (8%) temperatures. A weak correlation between cumulative high-temperature response index (CHTRI) and cumulative low-temperature response index (CLTRI) indicates the operation of different low- and high-temperature tolerance mechanisms at the early seedling stage. Groups of distinct rice genotypes associated with low or high-temperature tolerance were selected based on CHTRI and CLTRI. The genotypes that commonly performed well under low and high temperatures (IR65600-81-5-2-3, CT18593-1-7-2-2-5, RU1504114, RU1504122, Bowman, and INIA Tacuari) will be valuable genetic resources for breeders in developing early-season high- and low-temperature-tolerant genotypes for a broad range of both tropical and temperate rice-growing environments.

Highlights

Rice (Oryza sativa L.) is one of the major cereal crops grown under different agroecosystems
The 64 rice genotypes examined in this study exhibited substantial variability in their responses for root and shoot traits
Cold stress caused significant reductions in all root, shoot, and physiological traits, whereas a significant increase in all traits was observed under high temperatures among genotypes, compared with optimum temperatures

Summary

Introduction

Rice (Oryza sativa L.) is one of the major cereal crops grown under different agroecosystems. The harvested rice area had increased from 120.1 million ha in 1960 to. During this time, the average rice yield doubled from 1.84 to. Rice is grown in different climatic regions (temperate, tropical, and subtropical), it is challenging to maintain rice productivity at a high level due to its higher sensitivity to unfavorable environmental conditions [3,4]. Rice productivity in most rice-growing areas suffers from one or two extreme production challenges at the same or different periods of any growing season [6]. With the increasing demand for food production, unfavorable environmental conditions such as extreme temperatures (low and high), drought, submergence, and salinity, are becoming threats to sustaining yield [5,6,7]

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