The effect of high iron doses (Fe2+) on the growth of broccoli plants (Brassica oleracea var. Italica)

Abstract

Tests were carried out under greenhouse conditions in Tunja (Colombia) in order to evaluate the effect of Fe2+ toxicity on the growth of broccoli plants. 'Legacy' hybrid Brassica oleracea var. Italica plantlets were grown in glass containers with a nutritive solution. Iron sulfate was added to the substrate in order to produce excess iron at concentrations of 100 and 200 mg L-1; a control without iron sulfate applications was used. The following evaluations were made: leaf area, total dry weight of the plants, distribution of dry mass (DM) in the different organs, absolute growth rate, relative growth rate, net assimilation rate and the root:shoot ratio. The total DM decreased drastically in the plants subjected to excess Fe2+, the growth indices progressively decreased with increases in the Fe2+ concentrations in the substrate and the distribution of DM in the organs varied as a function of the needs of the plants, with 15.85 and 11.10% less DM in the roots of the plants subjected to Fe2+ than in the control plants, at 100 and 250 mg L-1, respectively.

Fe toxicity in plants: Impacts and remediation

“…Elevated Fe 2+ concentration in the substrate strongly decreases the radicle development (Rodrigues Filho et al, 2020). Moreover, Peña‐Olmos et al (2014) confirmed this decrease while working on broccoli ( Brassica oleracea var. italica ), they further documented that a higher dose of Fe 2+ (50 mg L −1 ) increases the lipid peroxidation particularly in radicle zone, which results in stunted growth and lowers dry weight production, this decrease in radical growth causes a severe effect on all the development‐related processes including loss of radicle hairs and reduction in its volume, which drastically reduce the total water content of the plant (De Dorlodot et al, 2005).…”

“…Becker and Asch (2005) reported that excess Fe 2+ concentrations in the leaves and stems results in early defoliation, and consequent decrease in growth, and in some cases complete cessation of growth in different organs of the plants. According to Peña‐Olmos et al (2014), a progressive decrease in dryness of roots, leaves, and stem supported the higher Fe 2+ flow toward the interior of plant. Nenova (2006) also opined that weight of pea ( Pisum sativum ) reduces with increasing Fe 2+ concentration up to 40 mg L −1 at 41 days after sowing (DAS).…”

“…Mehraban et al (2008) reported that total soluble protein, chl, and carbohydrate content decreases while amino acid content increases under Fe toxicity. Peña‐Olmos et al (2014) informed that higher Fe 2+ decreases the net assimilate rate, which is directly linked with photosynthetic rate. Onyango et al (2019) also observed starch reduction in Fe sensitive and tolerant varieties.…”

“…By definition, leaves are reserve organs, and Fe 2+ is immobile metal, so consistently accumulated in vacuoles of foliage cells and unable to redistribute during leaf senescence (Audebert, 2006a), so higher Fe 2+ content significantly reduces the leaf area and causes premature leaf defoliation (Peña‐Olmos et al, 2014). Becker and Asch (2005) reported that excess Fe 2+ concentrations in the leaves and stems results in early defoliation, and consequent decrease in growth, and in some cases complete cessation of growth in different organs of the plants.…”

“…Chlorophyll and carotenoid content of green grams ( V. radiata ) were also significantly decreased with an increase in the Fe content from 100 to 500 μM. Peña‐Olmos et al (2014) reported that distribution of photo‐assimilates toward leaves increased with 100 mg L −1 Fe 2+ application, while 250 mg L −1 caused higher flow of photosynthates toward stem, thereby resulting in poor/weak development of root and leaves. According to Peña‐Olmos and Casierra‐Posada (2013), electron transport chain (ETC) drastically decreases under higher Fe content, which results in lower photosynthetic activities.…”