Rice Science

Hydrogen Sulfide Improves Rice Seed Germination by Regulating Absorption of Al, Internal Antioxidant Enzyme System and Osmotic Balance Under Al Toxicity Conditions

WEI Qianqian, KONG Yali, XIANG Xingjia, ZHU Lianfeng, LIU Jia, TIAN Wenhao, JIN Qianyu, YU Yijun, ZHANG Junhua, ZHU Chunquan

2023, 30(4): 1.

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Germplasm Resources, Genes and Perspective for Aromatic Rice

Prafulla Kumar BEHERA, Debabrata PANDA

2023, 30(4): 3.

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Aromatic rice is considered an important commodity in the global market because of its strong aroma and eating and cooking quality. Asian countries, such as India and Pakistan, are the leading traders of Basmati rice, whereas Thailand is the major supplier of Jasmine rice in the international market. The strong aroma of rice is associated with more than 300 volatile compounds, among which 2-acetyl-1-pyrroline (2-AP) is the principal component. 2-AP is a phenotypic expression of spontaneous mutations in the recessive gene OsBadh2 or Badh2. The present review focuses on the origin, evolution and diversity of genetic resources of aromatic rice available worldwide. A brief discussion is presented on the genes responsible for quality traits along with details of their molecular genetics. This compilation and discussion will be useful for future breeding programs and the biofortification of quality traits of aromatic rice to ensure food and nutritional security.

Assessment of Climate Change Impact on Water Requirements and Rice Productivity

Konan Jean-Yves N’GUESSAN, Botou ADAHI, Arthur-Brice KONAN-WAIDHET, Satoh MASAYOSHI, Nogbou Emmanuel ASSIDJO

2023, 30(4): 4.

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Assessing the impact of climate change (CC) on agricultural production systems is mainly done using crop models associated with climate model outputs. This re-view is one of the few, with the main objective of providing a recent compendium of CC impact studies on irrigation needs and rice yields for a better understanding and use of climate and crop models. While opening perspectives, this manuscript discusses the strengths and weaknesses of climate impact studies on agricultural production systems, with a particular focus on uncertainty and sensitivity analyses of crop models. The work reviewed reveals that, although the new generation GCMs are more robust than previous ones, there is still a need to consider the effect of climate uncertainty on estimates when using them. Current GCMs cannot directly simulate the agro-climatic variables of interest for future irrigation assessment, hence the use of climate smart tools. Therefore, sensitivity and uncertainty analyses must necessarily be applied to crop models, especially for their calibration under different conditions. The impacts of CC on irrigation needs and rice yields vary across regions, seasons, varieties, and crop models. Finally, integrated assessments, the use of remote sensing data, climate smart tools, CO₂ enrichment experiments, consideration of changing crop management practices and multi-scale crop modeling, seem to be the approaches to be pursued for future climate impact assessments for agricultural systems.

Diversity of Arbuscular Mycorrhizal Fungi Associated with Six Rice Cultivars in Italian Agricultural Ecosystem Managed with Alternate Wetting and Drying

Veronica VOLPE, Franco MAGURNO, Paola BONFANTE, Stefano GHIGNONE, Erica LUMINI

2023, 30(4): 5.

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Rice cultivation systems require large amounts of irrigation water, and in the last few years， the need to find alternative cultivation methods has emerged. Different practices of rice cultivation, which are more sustainable in terms of utilization of water and nutrients, have been proposed, limiting the risk of soil and water pollution. One of these is the ‘alternate wetting and drying’ (AWD) system, in which water has been reduced by approximately 35% with an increased occurrence of beneficial arbuscular mycorrhizal (AM) symbiosis and no negative impact on rice yield. In this study, we selected six rice cultivars (Centauro, Loto, Selenio, Vialone nano, JSendra and Puntal) grown under AWD conditions. We investigated their responsiveness to AM colonization, and how they select diverse AM taxa. In order to investigate the root-associated AMF communities, molecular cloning-Sanger sequencing on small subunit rDNA data were obtained from five out of six rice cultivars and compared with Next Generation Sequencing (NGS) data, which were previously obtained in Vialone nano cultivar. The results showed that all cultivars were responsive to AM colonization with the development of AM symbiotic structures, even if with differences in the colonization and arbuscule abundance in the root systems. We identified 16 virtual taxa (VT) in the soil compartment and 7 VT in the root apparatus. We emphasized that the NGS analysis gives additional value to the results thanks to a more in-depth reading of the less represented AMF taxa.

Iron Toxicity Tolerance of Rice Genotypes in Relation to Growth, Yield and Physiochemical Characters

Sheikh Faruk AHMED, Hayat ULLAH, May Zun AUNG, Rujira TISARUM, Suriyan CHA-UM, Avishek DATTA

2023, 30(4): 8.

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Iron (Fe) toxicity, generated from excess reduced ferrous Fe (Fe²⁺) ion formation within the soil under submerged condition, is a potent environmental stress that limits lowland rice production. Total 11 diverse Thai rice genotypes, including a recognized tolerant (Azucena) and a susceptible (IR64) genotype, were evaluated against five Fe²⁺ levels (0 [control], 150, 300, 600 and 900 mg/L) with the objective to screen the tested genotypes for their Fe-toxicity tolerance and to classify them as a sensitive/tolerant category. The evaluation was conducted by a germination study, followed by a polyhouse study on growth, yield and physiochemical performance. Results showed significant variations in Fe²⁺-tolerance across genotypes. Increasing Fe²⁺ level beyond 300 mg/L was detrimental for germination and growth of all tested genotypes, although germination responses were negatively affected at Fe²⁺ ³ 300 mg/L. Physiochemical responses in the form of leaf greenness, net photosynthetic rate, membrane stability index, and leaf and root Fe content were the most representative of Fe²⁺-toxicity-mediated impairments on overall growth and yield. Difference in physiochemical responses was effectively correlated with the contrasting ability of the genotypes on lowering excess Fe²⁺ in tissues. Analysis of average tolerance and stress tolerance index unveiled that the genotypes RD85 and RD31 were the closest to the tolerant-check Azucena and the sensitive-check IR64, respectively. The UPGMA clustering revealed three major clusters, with cluster II (four genotypes) being Fe²⁺ tolerant and cluster I (four genotypes) being Fe²⁺ sensitive. Principal component (PC) analysis and genotype by trait-biplot analysis showed that the first two components explained 90.5% of the total variation, with PC1 accounting for 56.6% and PC2 for 33.9% of the total variation. The findings contribute to the present understanding on Fe²⁺-toxicity response and provide a basis for future genotype selection or rice crop improvement programs against Fe²⁺-toxicity. The selected tolerant rice genotypes show potentials for cultivation in Fe²⁺-toxic lowlands for better productivity.

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