In vitro allelopathic effects of extracts and fractions of five plants on tomato seed germination and vigor index

Abstract

In nature, allelopathic substances are likely to influence the germination of seeds. Callistemon viminalis, Tephrosia vogelii, Senna spectabilis, Cupressus lusitanica, and Polyscias fulva are found around some tomato culture fields in Cameroon. These plants may produce allelochemicals that can influence tomato seed germination and seedling characteristics. Methanol extracts and their fractions were prepared from leaves of these plants and tested on seed germination rate, shoot diameter, root and stem lengths, and vigor index of seedlings. The tested substances did not significantly (p > 0.05) affect the seed germination rate. Aqueous extracts of T. vogelii, C. lusitanica, and C. viminalis exerted the highest inhibition on seed germination while methanol extract, hexane, and ethyl acetate fractions of all the plants induced significant increases in diameters of seedlings. Aqueous extracts were effective on the stem length. All treatments generally reduced the root length. Methanol extracts induced significantly higher vigor indices (p < 0.05).

Keywords:

• Allelopathy
• germination
• vigor index
• extract
• fractions

Public Interest Statement

With increasing global population and decreasing arable soil superficies, achieving food security has become a challenge for most of governments. The major threats to crop production are weeds, insect pests, diseases, and drought. Unfavorable but unavoidable climatic changes are other important threats to food security. In order to face some of these challenges, there is use of great quantities of chemical inputs whose excessive use has negative impacts of the quality of agricultural commodities, environment, and human health. That is why aware and well-adviced consumers increasingly prefer produces which are not susceptible to negatively affect their health. Allelopathy has emerged as one of the sustainable and integrated approaches (e.g. crop rotations, cover crops, intercropping, use of powder, or extracts of biological material) to tackle these problems. The present findings, that some plant extracts led to the improvement in tomato seedling growth parameters, are in straight line with this approach.

Competing Interest

The authors declare no competing interest.

Additional information

Funding

Funding. The authors received no direct funding for this research.

Notes on contributors

Kuiate Jules-Roger

Our main research domain is the physiology of growth and development of the plant, ripening and senescence of fruits. Events occurring in the field greatly influence these processes. The conventional cultivation methods of plant like tomato require the use of important quantities of chemical inputs, which can impair the nutritional virtues of fruits and harm the environment. Thus, an integrated management of the production of fruits with known health-promoting properties should involve pre-harvest treatments based on biological material. In this regard, many of our research activities in the past years have been focused on bioregulators/biostimulants, emerging notions that refer to any biological organism, its powder or extracts that can induce positive alterations in plant growth and development parameters. The use of allelochemicals in the cultivation of tomatoes is one of pragmatic approaches to reduce biotic and abiotic stresses effects, enhance growth and yield, and preserve fruit quality.