Lanthanum Affects Bell Pepper Seedling Quality Depending on the Genotype and Time of Exposure by Differentially Modifying Plant Height, Stem Diameter and Concentrations of Chlorophylls, Sugars, Amino Acids, and Proteins

Abstract

Lanthanum (La) is considered a beneficial element, capable of inducing hormesis. Hormesis is a dose-response relationship phenomenon characterized by low-dose stimulation and high-dose inhibition. Herein we tested the effect of 0 and 10 μM La on growth and biomolecule concentrations of seedlings of four sweet bell pepper (Capsicum annuum L.) varieties, namely Sven, Sympathy, Yolo Wonder, and Zidenka. Seedling evaluations were performed 15 and 30 days after treatment applications (dat) under hydroponic greenhouse conditions. Seedling height was significantly increased by La, growing 20% taller in Yolo Wonder plants, in comparison to the control. Similarly, La significantly enhanced shoot diameter, with increases of 9 and 9.8% in measurements performed 15 and 30 dat, respectively, as compared to the control. Likewise, La-treated seedlings had a higher number of flower buds than the control. An increase in the number of leaves because of La application was observed in Yolo Wonder seedlings, both 15 and 30 dat, while leaf area was augmented in this variety only 30 dat. Nevertheless, La did not affect dry biomass accumulation. La effects on biomolecule concentration were differential over time. In all varieties, La stimulated the biosynthesis of chlorophyll a, b and total 15 dat, though 30 dat only the varieties Sympathy and Yolo Wonder showed enhanced concentrations of these molecules because of La. Total soluble sugars increased in La-treated seedlings 30 dat. Interestingly, while most varieties exposed to La showed a reduction in amino acid concentration 15 dat, the opposite trend was observed 30 dat. Importantly, in all varieties evaluated, La stimulated soluble protein concentration 30 dat. It is important to note that while chlorophyll concentrations increased in all varieties exposed to La, both 15 and 30 dat, those of soluble sugars and proteins consistently increased only 30 dat, but not 15 dat. Our results confirm that La may improve seedling quality by enhancing some growth parameters and biomolecule concentrations, depending on the genotype, and time of exposure.

Lanthanum Prolongs Vase Life of Cut Tulip Flowers by Increasing Water Consumption and Concentrations of Sugars, Proteins and Chlorophylls

“…In Chinese cabbage (Brassica chinensis), applications of La increased soluble sugar and vitamin C contents 72 . Similarly, a positive response to La was observed in all four pepper varieties evaluated (Sven, Sympathy, Yolo Wonder, and Zidenka) 30 dat, with increases in sugar concentrations superior to 25% as compared to the corresponding controls 11 . Likewise, increases in the contents of soluble sugars and proteins, as well as the relative water content in cut Easter lily flowers, were reported in response to the application of 60 µM La 22 .…”

“…In rice seedlings established in two types of soil and treated with La 3+ (0, 30, 150, 300, 600, 900 and 1200 mg/kg LaCl 3 ), the total chlorophyll concentration increased with high La doses, while the chlorophyll a/b ratio decreased by increasing the La concentration 65 . In cowpea (Vigna unguiculata), low La doses (0.1 to 2.5 µg/g) also increased the content of chlorophylls (a, b and total) 66 , which was also observed in pepper plants with the application of 10 µM LaCl 3 11 and in soybean with 0.2 mM La 3+ 67 . Plant senescence is usually accompanied by an overall depletion of sugar contents.…”

“…In agriculture, it has been successfully applied in various crops 29,30 . Importantly, La has been proven to induce hormesis in various plant species including Himalayan yew 27 , desert broomrape 28 , horseradish 25 , eucalyptus (Eucalyptus grandis x E. uroplylla) 31 , cotton (Gossypium hirsutum) 32 , maize 32,33 , rice (Oryza sativa) 34 , common bean (Phaseolus vulgaris) 33 , faba bean (Vicia faba) 35 , soybean 15,16 , tomato (Solanum lycopersicum) 36 , pepper 11 , www.nature.com/scientificreports www.nature.com/scientificreports/ and spinach (Spinacea oleracea) 37,38 , among others. In ornamental plants, the effect of La has been tested in snapdragon, tulip, rose and lily [18][19][20][21][22] .…”

“…When La is applied at low concentrations, the mean of 142% of the control is reached at 56 μM La, while the average concentration of the no-observed-adverse-effect-level (NOAEL) is 249 μM La. Importantly, factors such as intra and interspecific variations among plants tested, the pH value in the growth substrate, the concentrations of the NOAEL, and the period of time considered in the measurements may affect hormetic responses induced by La and other REEs [10][11][12] .…”

“…The beneficial effects of La on plants are diverse. In sweet bell pepper (Capsicum annuum), La improved seedling quality by enhancing some growth parameters and biomolecule concentrations, depending on the genotype and time of exposure 11 . In adzuki bean (Vigna angularis) seedlings, the application of lanthanum nitrate [150 mg/L La(NO 3 ) 3 ] improved phosphorus (P) use efficiency and tolerance to P-deficiency stress 13 .…”