Identification of Promising Genotypes Through Systematic Evaluation for Arsenic Tolerance and Exclusion in Rice (Oryza sativa L.)

Abstract

Rice remains a major staple food source for the rapidly growing world population. However, regular occurrences of carcinogenic arsenic (As) minerals in waterlogged paddy topsoil pose a great threat to rice production and consumers across the globe. Although As contamination in rice has been well recognized over the past two decades, no suitable rice germplasm had been identified to exploit in adaptive breeding programs. Therefore, this current study identified suitable rice germplasm for As tolerance and exclusion based on a variety of traits and investigated the interlinkages of favorable traits during different growth stages. Fifty-three different genotypes were systematically evaluated for As tolerance and accumulation. A germination screening assay was carried out to identify the ability of individual germplasm to germinate under varying As stress. Seedling-stage screening was conducted in hydroponics under varying As stress to identify tolerant and excluder genotypes, and a field experiment was carried out to identify genotypes accumulating less As in grain. Irrespective of the rice genotypes, plant health declined significantly with increasing As in the treatment. However, genotype-dependent variation in germination, tolerance, and As accumulation was observed among the genotypes. Some genotypes (WTR1-BRRI dhan69, NPT-IR68552-55-3-2, OM997, and GSR IR1-5-Y4-S1-Y1) showed high tolerance by excluding As in the shoot system. Arsenic content in grain ranged from 0.12 mg kg−1 in Huang-Hua-Zhan (indica) from China to 0.48 mg kg−1 in IRAT 109 (japonica) from Brazil. This current study provides novel insights into the performance of rice genotypes under varying As stress during different growth stages for further use in ongoing breeding programs for the development of As-excluding rice varieties for As-polluted environments.

Differential effects of arsenite and arsenate on rice (Oryza sativa) plants differing in glutathione S-transferase gene expression

“…Two stress types, acute (10 mg L −1 As for ten days) and chronic (2 mg L −1 As for 20 days), were established. These stress intensities correspond to As concentrations commonly prevailing in the pore water of affected rice fields (Abedin et al 2002 ; Cao et al 2017 ; Murugaiyan et al 2021 , 2019 ; Yu et al 2012 ; Zhang et al 2008 ). Screening experiments were conducted in hydroponic systems without aeration to simulate anaerobic conditions in paddy fields.…”

Do Rice Farmers Have Knowledge of Greenhouse Gas (GHG) Emission Mitigation Strategies? New Evidence from Nigeria

“…Rice is traditionally produced in soggy paddy soils. Scientific communities have been quite concerned about rice paddies because they create dangerous and persistent GHGs, primarily CH 4 and N 2 O [9]. Rice fields release around 30% and 11% of the world's agricultural emissions of CH 4 and N 2 O, respectively [10].…”

“…Some of the GHG emission mitigation strategies in rice field includes; alternate wetting and drying (AWD); system of rice intensification (SRI); changing tillage operations (CTO); Nitrogen Fertilizer Management (NFM); residue management (RM) and aerobic rice varieties (ARV) [12,13,14]. Substantial empirical evidence [9,11,13] exists on measuring and mitigating GHG emissions in rice fields in developed and developing countries and different researchers have analyzed the likely effects on rice production with various parameters. Reducing GHG emissions and water use in rice fields is critical for combating climate change, and increasing the yield, income and standard of living of the farmers.…”