Foliar application of phosphite reduces grain weight of soybean facing postflowering phosphorus deficiency

Abstract

Background and aim: We aimed to contribute with the foundation to adopt foliar P fertilization on soybean. Methods: Treatments were a combination of contrasting postflowering root P supply versus foliar application of phosphate (Pi) or phosphite (Phi). Results: Pi improved grain yield of P-limited plants, while Phi was detrimental because of negative effects on grain weight. Conclusions: Thus, cautions should be taken with foliar application of Phi during the generative phase of soybean under low-P stress, as Phi impairs grain filling process.