Potential determinants of salinity tolerance in rice (Oryza sativa L.) and modulation of tolerance by exogenous ascorbic acid application

Md Musfiqur Rahman,Abdullah Al Mamun Sohag,Mirza Moffazzal Islam,Mst Fatema Tuzzohora,Israt Jahan,David J Burritt,Mohammad Anwar Hossain,Md Mahmud Al Noor,Sharif-Ar Raffi

doi:10.25081/jp.2020.v12.6535

Md Musfiqur Rahman, Abdullah Al Mamun Sohag + Show 7 more

Open Access

https://doi.org/10.25081/jp.2020.v12.6535

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Abstract

Rice is a relatively salt-sensitive crop with the reproductive and seedling stages being the most sensitive. Two separate experiments were conducted to isolate potential determinants of salinity tolerance and to investigate the possibility of modulating salt tolerance by exogenous ascorbic acid (AsA) application. Rice plants were imposed to salinity (EC= 10.0 dS m-1) both at the seedling and reproductive phases of growth. Salinity at the seedling stage resulted a sharp decline in shoot and root growth related traits including leaf chlorophyll content, while hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels increased. Plants experienced with salinity at the reproductive phases of growth showed a significant reduction in yield attributing traits while the tissue levels of H2O2 increased. Exogenous AsA application reversed the negative impact of salt stress, modulating the root and shoots growth and yield related traits and lowering H2O2 and MDA levels. FL-478 was identified as the most tolerant genotype at the seedling stage, with Binadhan-10 being the most tolerant at the reproductive stage. Grain yield panicle-1 significantly and positively corrected with number of filled grains panicle-1, panicle length, plant height, and spikelet fertility, and negatively correlated with H2O2 levels. Stress tolerance indices clearly separated the tolerant and susceptible genotypes. A principal component analysis revealed that the first two components explained 87% of the total variation among the genotypes. Breeding efforts could therefore to undertake for developing salinity tolerance by manipulating endogenous AsA content in rice.

Highlights

Saline soils are one of the most severe constraints to crop productivity worldwide and are a major concern for global food security [1].It has been projected that more than 20% of the world’s arable land and 50% of irrigated areas, which include around 30% of rice growing areas, already suffer from salinity problems [2]
In response to exogenous ascorbic acid (AsA) pre-treatment, the salt susceptible variety Binadhan-6 showed the greatest increase in root length (14.70%), followed by BRRI dhan28, BRRI dhan67, BRRI dhan78, Binadhan-10, Binadhan-8 and FL-478 (10.53, 5.96, 5.55, 2.82, 1.08 and 0.42%, respectively), in comparison with the seedlings imposed to salinity without AsA pretreatment
The current study showed that the imposition of salt stress significantly reduced the shoot growth and root characteristics and as well as leaf chlorophyll content (Table 1)

Summary

Introduction

Saline soils are one of the most severe constraints to crop productivity worldwide and are a major concern for global food security [1].It has been projected that more than 20% of the world’s arable land and 50% of irrigated areas, which include around 30% of rice growing areas, already suffer from salinity problems [2]. To feed an increasing global population, it will be essential to utilize these saline soils either by using reclamation to reduce salinity or by growing salt tolerant crop plant [3]. Conventional plant breeding to increase crop yields in saline environments is often slow, due to our poor understanding of the molecular and genetic mechanisms of salt stress tolerance as well as lack of suitable phenotyping and genotyping techniques [4]. Rice (Oryza sativa L.) is an essential crop that provides food for more than half of the world population.

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