Rice, generally classified as a typical glycophyte, often faces abiotic stresses such as excessive drought, high salinity, prolonged submergence, cold, and temperature, which significantly affects growth, development, and ultimately, grain yield. Among these negative impacts of abiotic factors in rice production, salinity stress is a major constraint, followed by drought. There is considerable research on the use of marker-assisted selection (MAS), genome editing techniques, and transgenic studies that have profoundly improved the present-day rice breeders’ toolboxes for developing salt-tolerant varieties. Salinity stresses significantly affect rice plants during seedling and reproductive stages. Hence, greater understanding and manipulation of genetic architecture in developing salt-tolerant rice varieties will significantly impact sustainable rice production. Rice plants’ susceptibility or tolerance to high salinity has been reported to be the result of coordinated actions of multiple stress-responsive quantitative trait loci (QTLs)/genes. This paper reviews recent literature, updating the effects of salinity stress on rice plants and germplasm collections and screening for salinity tolerance by different breeding techniques. Mapping and identification of QTLs salt tolerance genes are illuminated. The present review updates recent breeding for improvement in rice tolerance to salinity stress and how state-of-the-art tools such as MAS or genetic engineering and genome editing techniques, including mutagenesis and conventional breeding techniques, can assist in transferring salt-tolerant QTLs genes into elite rice genotypes, accelerating breeding of salt-resistant rice cultivars.

Abiotic and biotic stresses adversely affect rice growth, development and grain yield. Traditional rice breeding techniques are insufficient in modern agriculture to meet the growing population’s food needs on a long-term basis. The development of DNA markers closely linked to target genes or QTLs on rice chromosomes, and advanced molecular techniques, such as marker-assisted selection (MAS), have encouraged the evolution of contemporary techniques in rice genetics and breeding, such as gene pyramiding. Gene pyramiding refers to the act of combining two or more genes from multiple parents into a single genotype, which allows the overexpression of more than one gene for broad-spectrum abiotic and biotic stress resistance. Marker-assisted pedigree, backcrossing and pseudo-backcrossing methods can increase the conventional breeding speed by reducing the number of breeding generations in order to enhance the pyramiding process. Pyramiding is affected by several factors: the number of transferred genes; the range within gene and flanking markers; the number of chosen populations in every breeding generation; the features of genes and germplasms; and the potentiality of breeders to identify the target genes. Modern breeding methods, such as the marker-assisted backcrossing approach, have made gene pyramiding more precise and reliable for the development of stress-tolerant rice varieties in the coming decades. This review presents up-to-date knowledge on gene pyramiding schemes, marker-assisted gene pyramiding techniques, the efficiency of marker-assisted gene pyramiding and the advantages and limitations of gene pyramiding methods. This review also reports on the potential application of marker-assisted selection breeding to develop stress-tolerant rice varieties that stabilize abiotic and biotic stresses. This review will help rice breeders to improve yields by increasing rice productivity under abiotic and biotic stress conditions.

Rice is the most important staple cereal human nutrition and consumed by 75% of the global population. Rice plants need a supply of essential nutrients for their optimal growth. Rice production has increased tremendously in Malaysia insensitive irrigation and the use of inorganic fertilizers and pesticides. However, the effect of using inorganic fertilizers resulted in contamination of ground water and decreased the productivity of soil, which in turn affected the rice production in the long term. The use of organic manure may help to regain the soil health, but that is insufficient for providing the essential nutrients to achieve optimal growth. Therefore, the use of organic manure combined with inorganic fertilizers is applied to obtain optimum yields. This study aims to test the effect of organic and inorganic fertilizers on the growth and yield components of 65 rice genotypes. The pot experiment was conducted at the net house on field 10, University Putra Malaysia, UPM, Malaysia, during the period of February to June 2019 and August to December 2019 in a randomized complete block design (RCBD) with three replications. There were three treatment combinations viz. T₁: 5 t ha⁻¹ chicken manure (CM), T₂: 2.5 t ha⁻¹ CM + 50% CFRR, T₃: 100% (150 N: 60 P₂O₅: 60 K₂O kg ha⁻¹) and chemical fertilizer recommended rate (CFRR). Grain and straw samples were collected for chemical analysis, and physical parameters were measured at the harvest stage. Results showed that most of the growth and yield components were significantly influenced due to the application of organic manure with chemical fertilizer. The application of chemical fertilizer alone or in combination with organic manure resulted in a significant increase in growth, yield component traits, and nutrient content (N, P, and K) of all rice genotypes. Treatment of 2.5 t ha⁻¹ CM + 50% CFRR as well as 100% CFRR showed a better performance than the other treatments. It was observed that the yield of rice genotypes can be increased substantially with the judicious application of organic manure with chemical fertilizer. The benefits of the mixed fertilization (organic + inorganic) were not only the crop yields but also the promotion of soil health, the reduction of chemical fertilizer input, etc.

One of the most important challenges to continuously maximizing crop production on limited areas of agricultural land is maintaining or enhancing soil fertility. Organic fertilizer application is needed to replace nutrients recovered by crops from the fields in order to restore the crop production potential of the soil. The utilization of chicken manure as an organic fertilizer is essential in improving soil productivity and cop production. In Malaysia, demand for rice as a food source is rising in tandem with population growth, while paddy rice production capacity is becoming increasingly constrained. Field experiments were carried out in Sungai besar, Kuala Selangor, Malaysia during the two planting seasons in 2020 to evaluate the effects of different levels of organic fertilizer on the growth and yield of rice genotypes. A split plot layout in a randomized complete block design with three replicates was used. The twelve rice genotypes were in the main plots. The sub-plots were treatments. The experiment comprised 4 treatments, viz., T₁ = 100% NPK (N₁₅₀P₆₀K₆₀), T₂ = Chicken manure @ 5 t ha⁻¹, T₃ = Chicken manure @ 7 t ha⁻¹, and T₄ = Chicken manure @ 10 t ha⁻¹. The study indicated that different levels of chicken manure and NPK fertilizer showed significant effects on growth, yield, and yield contributing characters of all the rice genotypes. Results showed that application of chicken manure 10 t ha-¹ was the best in producing growth and yield contributing characters, grain and straw yields, and also nutrient (N, P, and K) contents in grain and straw. The maximum number of panicles (422.56 panicles m⁻¹), the maximum number of filled grains (224.49 grains panicle⁻¹), and the maximum grain yield (8.02 t ha⁻¹) and straw yield (9.88 t ha⁻¹) were recorded from T₄ treatment at the rice genotype BRRI dhan75. Although the highest biological yield was recorded from T₄ treatment, a statistically similar result was found for T₃ treatment. The highest harvest index was also recorded for T₄ treatment. Therefore, rice genotype BRRI dhan75 can be recommended under chicken manure @ 10 t ha⁻¹ for rice production in Malaysia.