Effect of Leaves Aqueous Extract of Castor (Ricinus communis L.) on the Chromosomes of Six-rowed Barley During Mitosis.

Abstract

This study was conducted in the Genetics Laboratory, Department of Crop Science, Faculty of Agriculture, University of Tripoli, during 2021-2022. The aim of this study was to assess chromosomal aberrations of the six-rowed barley plant (Hordeum vulgare L.) during the stages of mitosis after applying different concentrations of hot aqueous extract of castor (Ricinus communis L.). Leaves. Ten initial concentrations (0, 10, 20, 30, 40, 50, 60, 70, 80, and 90 %) were prepared as stock extract to test the LC50 of barley seeds; variety “Raihan”. It was found that using concentrations higher than 20% had toxic effect on the germination rate, and thus new concentrations (2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0%) of the extract were prepared within the limits of the critical concentration LC50. The cytogenetic behavior of barley plants treated with these concentrations was analyzed. The results showed that the aqueous extract of castor leaves had a significant effect on seed germination and seedling growth. The levels of the used concentrations were enough to stimulate the chromosomal mutations in the root tip cells. Concentrations ranged between 2.5 and 20% of the aqueous extract stimulated the appearance of a large group of chromosomal aberrations. These include condensation and damage of the nucleus, the decomposition and disappearance of genetic material in the metaphase, the appearance of binucleate cells and cells with micronuclei, chromosomal rings and chains, and the scattering of chromosomes in the metaphase. The appearance of chromosomal fragments, irregular distribution and separation of chromosomes, multipolarity in anaphase, and the appearance of lagging chromosomes in telophase were noticed too.