Effects of foliar boron application on seed composition, cell wall boron, and seed δ15N and δ13C isotopes in water-stressed soybean plants

Abstract

Limited information is available on the effects of foliar boron (B) application on soybean seed composition. The objective of this research was to investigate the effects of foliar B on seed composition (protein, oil, fatty acids, and sugars). Our hypothesis was that since B is involved in nitrogen and carbon metabolism, it may impact seed composition. A repeated greenhouse experiment was conducted where half of the soybean plants was exposed to water stress (WS) and the other half was well-watered. Foliar boron (FB) in the form of boric acid was applied twice at a rate of 1.1 kg ha−1. The first application was during flowering stage, and the second application was during seed-fill stage. Treatments were water stressed plants with no FB (WS–B); water stressed plants with FB (WS+B); watered plants without FB (W–B), and watered plants with FB (W+B). The treatment W–B was used as a control. Comparing with WS–B plants, B concentration was the highest in leaves and seed of W+B plants (84% increase in leaves and 73% in seed). Seeds of W+B plants had higher protein (11% increase), oleic acid (27% increase), sucrose (up to 40% increase), glucose, and fructose comparing with W–B. However, seed stachyose concentrations increased by 43% in WS–B plants seed compared with W–B plants. Cell wall (structural) B concentration in leaves was higher in all plants under water stress, especially in WS–B plants where the percentage of cell wall B reached up to 90%. Water stress changed seed δ15N and δ13C values in both B applied and non-B applied plants, indicating possible effects on nitrogen and carbon metabolism. This research demonstrated that FB increased B accumulation in leaves and seed, and altered seed composition of well-watered and water stressed plants, indicating a possible involvement of B in seed protein, and oleic and linolenic fatty acids. Further research is needed to explain mechanisms of B involvement in seed protein and fatty acids.

Boron’s Importance in Plant Development and Growth: A review

“…Dordas & Brown (2001) and Stangoulis et al (2001), support this, since boron can cross membranes via passive absorption to reach boron requirements for plant. Dannel et al (2002), Dordas et al (2000) and Bellaloui et al (2013) observed that in squash roots, diffusing across plasma-membrane vesicles was slightly depressed by mercuric chloride, similar finding were reported by Trivedi (2015).…”

“…Trivedi (2015), Planchet et al (2011) and Bellaloui et al (2013) reported that the formation of esters borate through the interaction with hydroxyl groups of cell wall has been advanced as a mechanism for interacting with cell wall polymers. Casassa et al (1986) and Sarquis (1986) explained this phenomenon and sliding properties of "slime".…”

“…Boron deficiency can cause irregularly of the cell walls and a gradually decreased the formation of dimer RG-II . Noguchi et al (2003) and Bellaloui et al (2013) reported that the minimizing of grade of cross-linking particularly in cell walls of Arabidopsis bor1-1 mutant due to lower boron supply.…”

Screening of Cotton Genotypes for Protein Content, Oil and Fatty Acid Composition

“…Bellaloui and Turley (2013), observed the relationship among protein and oil contents under greenhouse conditions, and found that fuzzless cotton seeds accumulated higher oil and lower protein content compared with their equivalent fuzzy seeds, showing an inverse relationship between protein and oil contents. The inverse relationship between amount of protein and oil was previously reported in other species such as corn (Kebede et al, 2013), soybean (Burton, 1985;Ray et al, 2006;Bellaloui et al, 2013aBellaloui et al, , 2013b, and cottonseed (Pettigrew & Dowd, 2011). Only a few studies have attempted to discuss variability in cottonseed fatty acid profiles, the source of the variation, or how fatty acid percentages correlate with each other.…”

Phosphorus and Boron Application on Growth, Yield, and Quality of Soybean Seeds (Glycine max [L.] Merril)

“…Soybean plants with the application of 5 ppm B increased weight 100 grain 6.41% higher than those without B ( Table 2). The research of Bellaloui et al (2013) indicated that the application of B through the leaves could increase the seed weight (100 grain weight) of 16.1 g higher than those without B of 13.2 g of soybean on treatment given water. This is in line with Rio Tinto (2012) stated that the addition of boron in plants could increase the success of flower pollination and had a role in seed formation, and application of boron on soybean plant increased the weight of 100 grain.…”