Leaf anatomy and gas exchange of ornamental sunflower in response to silicon application

Abstract

Silicon applied to substrate for greenhouse cultivation of ornamental pot plants can improve the yield and quality of the ornamental product; however, the possible anatomical and physiological changes caused by Si have to be assessed. Therefore, the objective of this study was to evaluate gas exchange rates and leaf anatomy of ornamental sunflower 'Sunbright' grown on a substrate amended with Si. The experiment was conducted in a greenhouse, and the treatments consisted of sunflower plants cultivated in pots containing 600 g substrate fertilized with Si at rates of 0, 0.25, 0.50, 0.75, and 1.00 g kg -1 . The treatments were arranged in randomized complete block design and four replications. Samples from the middle region of leaf blades in the sixth pair from the apex were collected and analyzed morphometrically. Epidermal trichomes were analyzed using diaphanization and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The following traits were determined: leaf blade thickness, palisade and spongy parenchyma thickness, mesophyll thickness, and abaxial and adaxial epidermis thickness. Net photosynthesis, stomatal conductance and transpiration rates were determined in the fifth leaf at the beginning of the flowering stage by an infrared gas analyzer. The data were subjected to ANOVA and regression analyses. The results indicate that the ornamental sunflower 'Sunbright' accumulates Si in leaf trichomes, and that leaf thickness is not affected by Si application to the substrate; however, transpiration rates decrease while net photosynthesis rate and stomatal conductance increase in response to Si application.

Silicon sources for studies of rice plants in nutrient solutions

“…Higher DMYS may be due to an increased photosynthetic activity and a lower rate of transpiration, both enhanced by Si (ZANÃO JÚNIOR et al, 2017), although not evaluated here, which probably contributed to the increase of this variable. The presence of Si also promotes lignification and suberization of the root tissue (FLECK et al, 2011), which may explain the higher DMYR observed in plants grown with Si.…”

Agronomic Investigation of Spray Dispersion of Metal-Based Nanoparticles on Sunflowers in Real-World Environments

“…The most abundant trichomes with shortest size-NGTs-were found on adaxial side of leaves in AuSi-NPs treatment (Table 3). Silica was most likely integrated and accumulated directly to the basal part of leaf trichomes with phytolites formation [61]. In general, elemental silica does not belong to essential nutrients, but several works pointed to its higher plant-tolerant function against abiotic and biotic stress [61], ability to reduce accumulation of reactive oxygen species (ROS), membrane lipid peroxidation, access inhibition to toxicants, and enhanced plant defense to pathogens [62].…”

Potassium silicate as a new micronutrient agent in the initial development of sunflower (Helianthus annuus L.)

“…Ma & Yamaji (2016) adds that plants where there is a rich source of Si, have greater tolerance to toxic metals such as Aluminum (Al), Manganese (Mn) and Iron (Fe) and heavy Cadmium (Cd) and Lead (Pb) and gains in quality and productivity in agricultural crops. Carvalho et al (2009) and Zanão Júnior et al (2017) further discusses that Si considerably influences sunflower plants grown in pots for floristic or experimental interest where they report gains in production and quality of flowering and seed production.…”