A method for simultaneously monitoring phloem and xylem reconnections in grafted watermelon seedlings

Grafting is an effective way to increase watermelon tolerance to biotic and abiotic stresses. However, the survival of grafted seedlings largely depends on successful graft formation. Therefore, understanding the graft formation process, particularly the vascular reconnection process is of critical importance. This study found that lignin in watermelon stem shows strong auto-fluorescence under blue-light excitation which makes blue-light excited fluorescent tracers (FTs) such as 5(6)-carboxy fluorescein diacetate (CFDA) become unsuitable for assaying vascular connectivity in watermelon. In contrast, UV-light excited esculin and red-light excited acid fuchsin were proved to be efficient FTs for monitoring the phloem and xylem connectivity, respectively, in self-grafted watermelon. Furthermore, a combined application of esculin to the scion cotyledon and acid fuchsin to the rootstock root enabled simultaneous monitoring of the phloem and xylem connectivity in individual self-grafted watermelon seedlings. In addition, this method is also applicable in investigating the phloem and xylem reconnections in self-grafted melon and cucumber, and heterograft of watermelon, melon and cucumber onto pumpkin rootstock. Based on this established method, we found that phloem and xylem reconnections are not timely separated in self-grafted watermelon. Furthermore, low temperature and removal of the rootstock cotyledons both delayed the vascular reconnection process in watermelon. In conclusion, this new method provides a convenient, accurate and rapid way to analyze the vascular connectivity not only in watermelon, but also in other cucurbit crops.

Preparation of Activated Carbon From Sunflower Straw by H3PO4 Activation and Its Application for Acid Fuchsin Adsorption

In this work, sunflower straw (SS) was used as the raw material, H3PO4 was used as the activator, and the sunflower straw activated carbon (SSAC) was prepared by the one-step activation method under the impregnation ratio of 1:1, 1:2, 1:3, 1:5 (SS/H3PO4, g/g). The adsorption of acid fuchsin (AF) simulated dye wastewater by SSAC prepared under different immersion ratios has been studied. As the impregnation ratio increases, the pore structures of SSAC changed greatly. SSAC3 had the largest specific surface area (1794.01 m2/g), and SSAC4 had the smallest microporosity (0.0527 cm3/g) and the largest pore volume (2.549 cm3/g). The adsorption kinetics of four types of SSAC to AF were more in line with the quasi-second-order adsorption kinetic model. The Langmuir isotherm model was suitable for describing SSAC3 and SSAC4, and the Freundlich isotherm model was suitable for describing SSAC1 and SSAC2. Thermodynamics showed that the adsorption process was spontaneous and endothermic. At 303 K, SSAC4 showed a removal rate of 97.73% for 200 mg/L AF, and the maximum adsorption capacity of 2763.36 mg/g, which was the highest among the four types of SSAC. This study shows that the sunflower straw activated carbon prepared by the H3PO4 one-step activation method is a green and efficient carbon material and has great application potential in the treatment of dye-containing wastewater.

Adsorption, Kinetic, Equilibrium, Thermodynamic and Photocatalytic Investigations of the Removal of Nigrosin, Alizarin, Indigo and Acid Fuchsin Dyes on Modified CaO Surface

Calcium oxide was obtained from eggshell and modified with Sulfur, Nitrogen and, Oxygen. The adsorbents were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and, scanning electron microscopy (SEM). The adsorbents were used for the removing of the dyes of Nigrosin, Alizarin red S, Indigo carmine, and Acid fuchsin from their aqueous solutions. The adsorption isotherm experiments were studied, and the equilibrium adsorption found either obeyed the Langmuir or Freundlich isotherm depending on the Sips isotherm results. Thermodynamic studies showed that the adsorption processes of the studied dyes were spontaneous, endothermic and randomness increases according to their ΔG, ΔH and ΔS values, respectively. The kinetic studies revealed that the pseudo second-order model best represented adsorption kinetics. Moreover, the photocatalytic ability of adsorbents was investigated under the sunlight, the results revealed the adsorbents have a strong photo-catalytic ability to absorb the dyes, particularly that observed for Acid fuchsin.