6-Benzylaminopurine Alleviates the Impact of Cu2+ Toxicity on Photosynthetic Performance of Ricinus communis L. Seedlings

Copper (Cu) is an essential element involved in various metabolic processes in plants, but at concentrations above the threshold level, it becomes a potential stress factor. The effects of two different cytokinins, kinetin (KIN) and 6-benzylaminopurine (BAP), on chlorophyll a fluorescence parameters, stomatal responses and antioxidation mechanisms in castor (Ricinus communis L.) under Cu2+ toxicity was investigated. Ricinus communis plants were exposed to 80 and 160 μM CuSO4 added to the growth medium. Foliar spraying of 15 μM KIN and BAP was carried out on these seedlings. The application of these cytokinins enhanced the tissue water status, chlorophyll contents, stomatal opening and photosynthetic efficiency in the castor plants subjected to Cu2+ stress. The fluorescence parameters, such as Fm, Fv/Fo, Sm, photochemical and non-photochemical quantum yields, energy absorbed, energy trapped and electron transport per cross-sections, were more efficiently modulated by BAP application than KIN under Cu2+ toxicity. There was also effective alleviation of reactive oxygen species by enzymatic and non-enzymatic antioxidation systems, reducing the membrane lipid peroxidation, which brought about a relative enhancement in the membrane stability index. Of the various treatments, 80 µM CuSO4 + BAP recorded the highest increase in photosynthetic efficiency compared to other cytokinin treatments. Therefore, it can be concluded that BAP could effectively alleviate the detrimental effects of Cu2+toxicity in cotyledonary leaves of R. communis by effectively modulating stomatal responses and antioxidation mechanisms, thereby enhancing the photosynthetic apparatus’ functioning.

IDENTIFICATION OF Ricinus communis HYBRIDS FOR LOW PLANT HEIGHT1

ABSTRACT Castor bean (Ricinus communis L.) is a plant native to Africa that presents important socioeconomic value for many countries, and has been the subject of breeding programs. In this context, the objective of this work was to identify genotypes with potential for improvement, focused on lowering plant height, using 19 hybrids and eight parents of R. communis. The study was developed at the experimental area of the Federal University of Recôncavo da Bahia in Cruz das Almas, BA, Brazil. The experiment was conducted in 2017 using a randomized block design with three replications, consisting of eight parents and 19 hybrids resulting from hybridization of these parents, grown with spacing of 3 meters between rows and 1 meter between plants. The characters stem diameter (SD), primary raceme insertion height (PRI), number of stem internodes (NSI), mean stem internode length (SIL), plant height (PH), number of harvested racemes (NHR), primary raceme length (PRL), and effective raceme length (ERL) were evaluated by analyzing the genetic parameters of variances and correlation between them. Five (H17, H2, H11, H13, and H6) of the 19 hybrids evaluated have potential to decrease PH of castor bean plants, presenting heights below 1.07 m. Direct selection for plant height is the most indicated for this purpose due to the high heritability of the character. However, the characters SD, PRI, and SIL stood out by assisting in indirect selection to decrease plant height because they can be early measured and present high heritability and strong correlation with PH.

Optimal fertilization dose in castor bean (Ricinus communis L.) using partial budgets analysis

Objective: To determine the economically adequate fertilization dose for a castor bean (Ricinus communis L.) crop that improves the producer's benefits using the partial budgeting technique. Design / methodology / approach: The experiment was established at a site located 500 m from the Centro de Chiapas experimental field, with an altitude of 800 m. Two production factors were studied: nitrogen (40, 60, and 80) and phosphorus (20, 40, and 60) with three levels each. The treatments had nine combinations in a randomized complete block experimental design and four replications. Phenological and morphological variables, seed yield, and variable costs economic components were evaluated as a response. Results: With the average yields the obtained net benefits were determined; an adjustment of the benefits was made, and its dominance was determined. Four experiments were dominated, and five showed favorable profits for the producer. The 80-60-00 formulation had a return rate (RR) of 23 %. Conclusions: The 40-20-00, 40-40-00, 40-60-00, 80-40-00 and 80-60-00 formulations were dominant. The 80-60-00 formulation reported the highest RR, an increase in variable cost of US$9.64, like other doses of lower costs and benefits. For this dose, the net benefits increase was us$ 222.61.

Phytochemical Constituents and Toxicity of the Ethanol Extract of Ricinus communis (L.) in Drosophila melanogaster

The study aimed to evaluate the toxic ability of the ethanol extract of Ricinus communis (L.) in Drosophila melanogaster fruit fly model. The toxicity was determined through different criteria, including the ability to cause harmful effects on second instar larvae, reproduction, growth and development, and the movement ability of fruit flies. The results showed that the ethanol extract of Ricinus communis expressed its high toxicity against 2nd instar larvae of Drosophila melanogaste with the LD50 value of 64.63 mg/mL. In addition, Ricinus communis extract reduced the growth rate, reproduction and decreased the movement ability of Drosophila melanogaster. The total flavonoid and polyphenol content of the ethanol extract of Ricinus communis were 338.26 mgQE/g extract and 160.43 mgGAE/g extract, respectively. These findings contribute to confirming the toxic properties of ethanol extract of Ricinus communis and their potential use in preventing and controlling pest.