Effects of Boron Omission and Foliar Fertilization on Nutrition Efficiency and Production of Cowpea

Abstract

Additional index words. Vigna unguiculata, plant nutrition, crop quality, nutrient management, sorbitolAbstract. This study aimed to evaluate the effects of boron (B) omission on cowpea nutrition and to compare the impact of foliar B fertilization with and without sorbitol on cowpea growth, nutritional status, and B uptake. Two trials using a completely randomized experimental design were conducted. During the first experiment, nutrient solution was provided without B (LB) and with B (+B) in 10 replicates. During the second experiment, a 5 3 2 factorial treatment scheme was used. Five B concentrations (0, 1.25, 2.5, 3.75, and 5.0 g · L L1 ) were administered foliarly in the form of boric acid with or without sorbitol (500 mmol · L L1 ) in four replicates. B omission symptoms, root growth, plant organ dry mass and B content, and grain yield were evaluated. B omission induced greater losses in reproductive organ and root growth than in leaf and stem production. It also caused deformation of the middle lamella and accumulation of starch in the chloroplasts. Foliar applications of 2.6 to 2.9 g · L L1 B improved cowpea production. The addition of sorbitol did not enhance plant growth. However, it increased B absorption in the vegetative parts of the plant but did not enhance seed production.

10Boron Is Mobile in Cowpea Plants

“…Therefore, the foliar application of B resulted in a residual effect that benefited new leaves, corroborating the study of Wu et al (2019) with citrange. It was also observed that these treatments increased the total B concentration of new leaves (Table 1), reaching an adequate range for this species (21 to 35 mg kg −1 ) (Silva et al, 2018).…”

“…Boron must be optimally absorbed in order to generate a significant response to its application in cowpea plants (Silva et al, 2018). In this sense, our study indicated that applying B via foliar spraying in association with growth media fertilization ( 10 B-L + B-S) resulted in a greater accumulation of this nutrient in plant organs compared with the control treatment without B supply (Figure 2).…”

“…In relation to the foliar fertilization, newly formed leaves that were completely expanded received 1.4 ml (4.76 mg of B per plant) of a solution containing B at a concentration of 3.4 g L −1 (Silva et al, 2018) at 25, 30, and 35 days after transplanting (DAT). The applications of B were carried out at 17 h, with the use of a 5-cm plastic rod with cotton fixed in its tip, enabling the distribution of the solution on the leaf surface.…”

“…Cowpea [Vigna unguiculata (L.) Walp] is a crop of high nutritional value because of its dietary proteins and all essential amino acids, carbohydrates, vitamins, minerals, and fibers (Devi et al, 2015). One of the most important micronutrients known to increase its productivity is boron (B) (Silva et al, 2018). B deficiency in plants is a result of the low concentration of this element in the soil and is widely disseminated in the most diverse areas of cultivation in the world (Wimmer and Eichert, 2013), distributed in South and Southeast Asia, Eastern Australia, New Zealand, Africa, North and South America, and Northern Europe (Lehto et al, 2010).…”