Chromium for plants: photosynthesis productivity
Chromium (Cr)
Chromium also increases the chlorophyll content and productivity of photosynthesis in leaves. Treating corn seeds with a potassium chromate solution results in an increase in photosynthetic productivity by 24–40%, chlorophyll content by 16–29%, and green and dry mass weight by 34–65% in the plants grown from these seeds.
Small amounts of trivalent chromium stimulate the growth and formation of root nodules in leguminous plants.
There are three phases of chromium ion absorption. Absorption begins immediately after the roots are immersed in the solution at a high rate. This phase lasts no more than 6 minutes. During the next phase, which lasts 8–10 hours, the absorption rate gradually decreases. After 10 hours, chromium absorption ceases.
It is believed that in the first phase physical-chemical adsorption of ions occurs on the root surface. In the second phase, there is a chemical interaction of chromium ions with substances that actively bind them (proteins, amino acids, carbohydrates). In the third phase, further interaction of chromium with metabolites formed by the roots may occur at a more or less constant rate.
Chromium can enter plants not only through the root system but also through the leaves. When spraying a solution of bichromate on the leaves of ornamental plants (0.001 N), its accumulation depends on the thickness of the cuticle. Through the thin cuticle of cardamom and hibiscus, more chromium penetrates into the leaves than in the leaves of euonymus and fatshedera, which have a thicker cuticle.
In plant organs, chromium accumulates unevenly. In larger quantities, compared to other organs, chromium accumulates in the roots of plants, with the predominant part being in a soluble form in vacuoles.
The phytotoxic concentration of chromium (50% reduction in aboveground phytomass) is 100 mg/kg dry mass.
Plants that produce cardiac glycosides selectively accumulate chromium.
• Pimelea suteri Kirk., Thymelaeaceae (herb, ash content – up to 3%);
• Leptospermum scoparium J.R. et G.Forst., Myrtaceae (wood, leaves, ash content – up to 3%);
• Lobelia inflata L., Lobeliaceae (herb).
• Althaea officinalis L., Malvaceae (roots);
• Symphytum officinale L., Boraginaceae (roots);
• Rheum palmatum L., Polygonaceae (rhizome with roots);
• Helleborus L., Ranunculaceae (rhizome with roots);
• Garcinia gummi–gutta (L.) N.Robson, Clusiaceae (bark);
• Capsella bursa–pastoris (L.) Medik., Brassicaceae (herb);
• Gnaphalium uliginosum L., Asteraceae (herb);
• Adonis vernalis L., Ranunculaceae (herb);
• Convallaria majalis L., Convallariaceae (leaves, herb, flowers);
• Digitalis L., Scrophulariaceae (leaves);
• Erysimum L., Brassicaceae (herb);
• Centaurium erythraea Rafn, Gentianaceae (herb);
• Padus avium Mill., Rosaceae (leaves, content – 39.66 mg/kg dry mass);
• Lonicera xylosteum L., Caprifoliaceae (leaves, content – 29.30 mg/kg dry mass);
• Vaccinium myrtillus L., Ericaceae (leaves);
• Ginkgo biloba L., Ginkgoaceae (leaves);
• Dioscorea nipponica Makino, Dioscoreaceae (leaves);
• Plantago major L., Plantaginaceae (leaves);
• Mentha piperita L., Lamiaceae (leaves);
• Melissa officinalis L., Lamiaceae (leaves);
• Morus alba L., Moraceae (leaves, fruits);
• Strophanthus DC., Apocynaceae (seeds).