Effects of drought stress on growth and physiological characteristics of roselle (Hibiscus sabdariffa L.)

Drought is the major abiotic stress which causes major losses to agriculture production. This study was conducted to determine the effect of drought stress on the growth and physiological characteristics of Hibiscus sabdariffa. The drought stress treatments were 33, 67 and 100% of the field capacity. Each treatment was replicated five times in a randomized complete block design. According to the results, drought stress had significant effects on the growth and physiological traits of H. sabdariffa. As the drought stress increased, the plant height, leaf area, specific leaf area, fresh and dry weight of shoot and root, photosynthetic rate, stomatal conductance, intercellular CO2 concentration and the transpiration rate decreased. The root-shoot ratio was significantly increased in stressed plants. The changes in number of branches per plant and chlorophyll content were, however, not significant. These findings suggested that H. sabdariffa might be able to tolerate drought stress by increasing the root-shoot ratio and stability of chlorophyll content

Alleviation of water stress in roselle (Hibiscus sabdariffa L.) using zeolite

Water stress is one of the major limiting factors for plant growth and yield. Water stress affects plants by imposing numerous morphological, physiological and molecular changes. There are various approaches for mitigation of plant under water stress. One of the approaches is through the zeolite application by improving growth, physiological and biochemical attributes. The response of roselle plant variety UMKL-1 subjected to different soil moisture content (100%, 67% and 33% FC) was investigated under rain shelter. The objective of this study was to determine the effects of different soil moisture content on growth performance and physiological changes, calyx yield and quality in H. sabdariffa. Severe water stress (33% FC) significantly decreased dry matter production, harvest index and photosynthetic rate due to limitation in the efficiency of assimilate translocation. LWP, relative growth rate and nutrient content (N, P, and K) in H. sabdariffa was also significantly decreased at 33 % FC. Root to shoot ratio, accumulation of proline were increased when plants at 33 % FC. The changes in the number of branches and chlorophyll content were not significant. Moreover, H. sabdariffa calyx yield was not significantly different at 100 % and 67 % FC. On the other hand, higher content of total soluble solids, ascorbic acid and anthocyanin were observed at 33% FC. In the 2nd experiment, zeolite used to minimize the adverse effects of water stress on growth, and calyx yield under rain shelter condition. Zeolite application improved growth and yield due to improved dry matter production, nutrient content (N, P, and K) stomatal conductance and photosynthetic rate. Quantitative gene expression studies indicate that the expression pattern of P5CS gene was up-regulated and PDH gene was down-regulated at 33% FC as compared to 67% FC. When zeolite was applied under water stress conditions, the expression pattern of P5CS gene was down-regulated and PDH gene was up-regulated. These results suggested that severe water stress (33% FC) had negative effects on H. sabdariffa yield by reducing growth, photosynthetic rate and nutrient uptake. Zeolite application can be useful to save water that leads more yield under water stress conditions. 67 % FC with 2.50 g zeolite kg−1 soil was found to be more effective in improving growth and calyx yield. This study also established and validated Actin-7 and alpha tubulin-4 as the reference genes in H. sabdariffa under water stress conditions and provides a powerful tool for the quantitative expression analysis of P5CS and PDH in H. sabdariffa. Furthermore, P5CS could participate in the drought resistance process by regulating proline content in H. sabdariffa leaves

Impact of drought on gas exchange and yield parameters in roselle (Hibiscus sabdariffa L.)

Effect of drought stress on gas exchange and yield parameters in roselle (Hibiscus sabdariffa L.) was investigated under pot culture conditions in rainout shelter. Experiment was laid out in a randomized complete block design with five replications and three treatments viz, 100%, 67% and 33% field capacity. As the stress increased, reduction in photosynthesis rate, stomatal conductance, intercellular CO2 concentration and transpiration were observed. The number of fruits, fruits weight and calyx yield per plant were not significantly different at 100% and 67% field capacity. These findings suggested that optimum calyx yield can be obtained at 67% field capacity

Review of Flower Pollination Algorithm: Applications and Variants

Flower Pollination Algorithm (FPA) is a nature inspired metaheuristic algorithm that mimics the behavior of pollination of flowering plants. FPA has been created by Yang in 2012 showing its better performance than other metaheuristic algorithms. Many variants of FPA have been established since 2012 to solve complex problems of different research domains. In this paper, application of different FPA variants are discussed based on modifications, tuning parameters and hybridizing FPA with other algorithms. This paper is very useful for researchers as it introduces general pollination process of flowers, its conversion to algorithm, application of FPA in different domains and particularly to parameter estimation problem of PV cells and modules. Future recommendations have also been given for new researchers

Facile fabrication of CuScS2/CoO as an efficient electrocatalyst for oxygen evolution reaction and water treatment process

Producción CientíficaA major issue is the production of green and sustainable energy while the development of an effective, affordable, readily available with a higher rate of oxygen and hydrogen evolution reactions is need of the time. Here in present work, we fabricated CuScS2, CoO, and CuScS2/CoO to replace the extremely expensive Pt/C and IrO2 that are employed as the benchmark materials for water electrolysis. We have also investigated their electrochemical performance in an alkaline environment for the oxygen evolution reaction (OER). The CuScS2/CoO nanocomposite is more effective electrode material than CuScS2 and CoO. The composite material shows smaller overpotential (179 mV) and reduced Tafel slope (46 mV dec−1) value than individual materials to attain a current density of 10 mA cm−2. The better efficiency of the composite material is due to well-distinct good shape with greater BET surface area, and relatively small resistance to charge transfer. Furthermore, the CuScS2/CoO exhibits remarkable electrocatalytic as well as photocatalytic performance in comparison to CuScS2 and CoO. This research provides a valuable guide for developing an OER electrocatalyst in an alkaline medium and shows better electrochemical as well as photocatalytic performance of CuScS2/CoO nanomaterials.This work was funded by the Researchers Supporting Project Number (RSP2023R243) King Saud University, Riyadh, Saudi Arabi

Facile synthesis of NiMn2O4/ZnMn2O4 heterostructure nanocomposite for visible-light-driven degradation of methylene blue dye

Nowadays, waste discharge and contaminants in drinking water have emerged as a significant global problem. Therefore, it is necessary to remove these pollutants from the water and photocatalysis is the best technique for this purpose. The co-precipitation technique was employed to produce NiMn2O4 and ZnMn2O4 and a photocatalyst containing NiMn2O4/ZnMn2O4 heterostructure nanocomposite. Various analytical techniques have been ascribed to examine the physical, morphological and optical features of the fabricated catalysts. XRD diffraction peak patterns were utilized to confirm the presence of cubic NiMn2O4, tetragonal ZnMn2O4 and NiMn2O4/ZnMn2O4 phases in a nanocomposite. In photodegradation tests, the nanocomposite catalyst outperformed the individual catalysts. After 60 minutes of visible light exposure, this nanocomposite catalyst eliminated the methylene blue (MB) dye, attaining substantially higher degradation rates than pure NiMn2O4 (66%) and ZnMn2O4 (77%). The nanocomposite catalyst was highly effective against methylene blue (MB) dye with a degradation efficiency of 92%