Boron bioavailability enhanced by foliar applied fulvic acid to improve grain yield and quality of fine basmati rice

Boron is a critical yet poorly understood micronutrient, especially regarding its transport within plant leaves. Little research has been done to enhance the bioavailability of Boron in rice using organic compounds like fulvic acid for better nutrient quality and yield. While fulvic acid (FA) is well-known for enhancing the mobility of metallic nutrients like iron (Fe) and zinc (Zn), however, its role in facilitating Boron, a metalloid, remains unclear. Therefore, this study aimed to evaluate the potential of FA in mediating Boron transport to improve grain quality and yield in Basmati rice. A field trial was conducted using a randomized complete block design (13 × 24 ft²), applying foliar treatments of Boron alone and Boron combined with FA at critical growth stages (tillering and panicle formation). The study assessed the impact of these treatments on rice morpho-physiological parameters, grain yield and leaf Boron content. The results revealed that both foliar treatments significantly improved yield and leaf Boron content over control. However, the promising results were obtained in response to boron's only application. Boron application (T2) significantly increased number of tillers (41%), chlorophyll content (55%), 1000 grain weight (32%), Boron content (131%) and yield per plot (43) as compared to control (T1). While combined application Boron + FA (T3) substantially enhanced number of tillers (34%), fertile florets per panicle (23%), Boron content (46%) and yield per plot (33%) over control (T1). The present findings suggest that Boron foliar application enhances grain weight, yield, and rice quality while reducing panicle sterility. However, FA did not significantly mediate Boron uptake in rice, indicating limited interaction between FA and this non-metallic micronutrient.