Boron nutrition of rice in different production systems. A review

Abstract

Half of the world's population-more than 3.5 billion people-depend on rice for more than 20% of their daily energy requirements. Rice productivity is under threat for several reasons, particularly the deficiency of micronutrients, such as boron (B). Most rice-based cropping systems, including rice-wheat, are facing B deficiency as they are often practiced on high pH and alkaline soils with low B contents, low soil organic matter, and inadequate use of B fertilizer, which restricts the availability, uptake, and deposition of B into grains. Farmers' reluctance to fertilize rice fields with B-due to the lack of cost-effective Benriched macronutrient fertilizers-further exacerbates B deficiency in rice-based cropping systems. Here we review that, (i) while rice can tolerate excess B, its deficiency induces nutritional disorders, limits rice productivity, impairs grain quality, and affects the long-term sustainability of rice production systems. (ii) As B dynamics in the soil varies between flooded and aerobic rice systems, different B deficiency management strategies are needed in rice-based cropping systems. (iii) Correct diagnosis of B deficiency/toxicity in rice; understanding its interaction with other nutrients including nitrogen, phosphorus, potassium, and calcium; and the availability and application of B fertilizers using effective methods will help to improve the sustainability and productivity of different rice production systems. (iv) Research on rice-based systems should focus on breeding approaches, including marker-assisted selection and wide hybridization (incorporation of desirable genes), and biotechnological strategies, such as next-generation DNA and RNA sequencing, and genetic transformations to develop rice genotypes with improved B contents and abilities to acquire B from the soil. (v) Different B application strategies-seed priming and foliar and/or soil application-should be included to improve the performance of rice, particularly when grown under aerobic conditions.

Fine regulation system for distribution of boron to different tissues in rice

“…Excess B inhibits the growth of both the roots and shoots. The typical symptoms of B toxicity in rice are characterized by chlorosis, brownish leaf tips, and dark brown elliptical spots on leaves (Atique‐ur‐Rehman et al ., 2018; Wu et al ., 2019). The range between B deficiency and toxicity is extremely narrow (Eaton, 1944).…”

Gene Pyramiding for Sustainable Crop Improvement against Biotic and Abiotic Stresses

“…The green revolution has resulted in substantial progress in yield and quality improvement of important food crops globally [1]. However, the conventional crop breeding method is insufficient for advancing crop improvement at the rate that is necessary to meet the food requirement for the steadily increasing human population [2,3]. The Food and Agriculture Organization estimated that worldwide food production must be increased by 70% by 2050 in order to meet the food demand of the expanding population [4].…”

Boron Facilitates Rice Growth, Development, and Related Attributes Under Saline Soil Conditions

“…Values with different superscript characters (A, B, C) are significantly different (p < 0.05). a severe agricultural issue in more than 80 countries, for over 100 crops, in the last couple of decades (Atique-ur-Rehman et al, 2018). Deficiency of B can be readily corrected by soil applications of B fertilizers (Shorrocks, 1997).…”