Introduction

The common bean (Phaseolus vulgaris L.) is an edible legume of high consumption worldwide and great source of proteins, vitamins and mineral, so it includes in the diet of diverse developing countries of the American continent (^{Suárez-Martínez et al., 2016}).

With the indiscriminate use of agrochemicals in agriculture, resistance of pest-organisms has increased causing a negative impact in the environment; these type of products have been applied in increasing amounts to combat them and periodically substituted by new generation agrochemicals each time more potent and also more harmful to the environment (^{Meneses, 2017}). The new generation agrochemicals also bio-accumulate toxic substances in the plants treated, which also accumulate in animals or humans that finally feed on them. In this context, research and development of ecofriendly alternatives with a high degree of innocuousness and elicitor activity facing biotic and abiotic stress are totally justified to partially or totally substituting other products highly contaminant in agroecosystems (^{Mazón-Suástegui et al., 2019}). One of these alternatives is the use of that promote growth microorganisms in plants that can foster growth of their radicle system and strengthen their response capacity facing different pathogens besides increasing plant biomass production (^{Leal-Almanza et al., 2018}). Another alternative is the use of bio-stimulants rich in amino acids that belong to the plant cellular metabolism, such as VIVA^®, FitoMas-E^® and other commercial products capable of influencing physiological plant processes, which stimulate plant development, growth, and biological production (^{Kocira et al., 2015}; ^{Koleska et al., 2017}; ^{Batista et al., 2017}).

A third and less studied option is homeopathic medicine. Homeopathy is a discipline of universal medical science based on recognizing the innate capacity of the organism to maintain itself in equilibrium and with its environment, which could be applied to all living beings (Andrade, 2004¹; ^{Mazón-Suástegui et al., 2018}). The application of this medical therapy in agriculture has been recently intensified under the denomination of “Agricultural Homeopathy” since it is already an ecofriendly and economic alternative for agricultural and livestock farmers, compatible with traditional, organic, ecological, bio-dynamic, including traditional agriculture (^{Mazón-Suástegui et al., 2019}). Agricultural homeopathy is defined as the productive application of scientific knowledge that uses ultra-diluted substances to promote a favorable response in plants cultivated according to the principles of this medicine. Homeopathy strengthens in the plants cultivated their own vital force favoring their dynamic equilibrium with soil and promoting the symptomatology associated to a disease, infection or stressing agent through a systemic focus in a lasting manner and without any collateral effect. All this is possible in any living organism, including plants because they possess a genetic memory, which is continuously enriched (^{Barberato, 2002}).

Homeopathic medicine can affect the plant biological processes positively to control health problems caused by fungi, viruses, and bacteria, contributing to pest control and affecting cultivation growth and development favorably (^{Meneses, 2017}). ^{Ruiz et al. (1997)} demonstrated the stimulating effect of homeopathic preparations in the cultivation of P. vulgaris by increasing biomass in treated plants. Another research performed in the cultivation of Allium fistolosum revealed an increase in plant biomass when it was treated with homeopathic medicine (^{Sánchez and Meneses, 2011}). On the other hand, ^{Bonato et al. (2009)} found that with the use of homeopathic medications, such as Sulphur and Arsenicum (dynamizations 6, 12, 24 and 30 CH) applied weekly for 98 days in Mentha arvensis, obtained an increase in plant height and fresh and dry biomass. ^{Rossi et al. (2003)} applied the homeopathic medicine Carbo vegetabilis 30 CH to lettuce Lactuca sativa for 48 h, reporting and increase in plant dry weigh of 22% with respect to the control group. ^{Arellano-Rodríguez et al. (2017)} assessed homeopathic dynamizations prepared from alkaloid extracts of Lupino (Lupinus rotundiflorus) in tomato (Solanun lycopersicum) plants as growth promoters and found that the plants with such treatments showed a significant increase in stem length. Such results confirmed the efficiency of homeopathic medicine in plants. Thus, the objective of this study was to assess the response of the bean Phaseolus vulgaris L. variety Quivican plant to homeopathic medicine application as growth promoters.

Materials and Methods

Results and Discussion

When the experiment ended (T₃₅), the common bean P. vulgaris L. var. Quivican that received the homeopathic treatments (TH1, TH2 and TH3) responded favorably recording increase in the majority of the response variables studied. A higher response was observed in the plants treated with TH3 (MgM-31CH + MaMnP-3CH), which contained metallic and magnesium phosphate and manganese, homeopathically diluted and dynamized. With this treatment (TH3), statistically significant average values and percentages (%) were obtained, higher than those recorded in the plants of the control group (distilled water) for the following response variables: LT 47.14%, LR 30.27%, BFR 13.57%, BFT 11.88%, BFH 68.36%, BST 36.11%, BSH 84.72 %, AF 21.74%, DT 39.54% and number of leaves 16.66%. These results showed that TH3 favored P. vulgaris growth, under the cultivation conditions applied (Table 1), which agree with that reported by Castro (2002²) who observed leaf area increase on both carrot and beet when different homeopathic dynamizations of Phosphorus were applied, impacting their yield positively. With the application of this same medicine, an increase in stem diameter of white Eucalyptus globulus was also recorded (Duarte, 2007³).

TH3 is a mix of two homeopathic medicines: Magnesium metallicum in the 31^st Hahnemanian Centesimal dilution (MgM-31CH) and Magnesium-Manganum phosphoricum 3^rd Hahnemanian Centesimal dilution (MaMnP-3CH). The results obtained in the common bean P. vulgaris morphometric variables when TH3 was applied can be explained in function of the mother tincture (MT) components or initial concentration, starting from the initial dynamization process (serial dilution and agitation) of both homeopathic medicines. The importance of magnesium, manganese, and phosphorus is sufficiently known because they are mineral nutrients that act in diverse plant metabolic routes and physiological processes. Magnesium is essential for growth of any live cell; it is a secondary macronutrient essential for plant growth and development and forms part of the chlorophyll molecule (^{Cakmak and Yazici, 2010}).

Magnesium phosphate, included in TH2 (Magnesium-Manganum phosphoricum 3CH) and also in TH3 because it is the sum of TH1 and TH2, plays an important role in plant nutrition and in its resistance to diseases (^{Huber, 1980}); 75% of leaf magnesium is known to be involved in protein synthesis, and 15-20% of total magnesium is associated with photosynthetic pigments (^{White and Broadley, 2009}). Magnesium acts mainly as a cofactor of a series of enzymes involved in photosynthetic carbon fixation and metabolism (^{Cakmak and Kirkby, 2008}; ^{Maathuis, 2009}; ^{Hermans et al., 2013}). Phosphorus is, after nitrogen, the second nutrient in quantitative importance for the development of agricultural cultivations; it is found in organic and inorganic forms in soils, but only is a small part available for plants due to its chemical fixation and its low solubilization (^{Sindhu et al., 2010}). Phosphorus is an essential element that plants require in large amounts to perform different physiological processes, such as respiration, photosynthesis, glycolysis (^{Shen et al., 2011}), and enzyme activation and inactivation (^{Vance et al., 2003}). The results observed during this research study confirmed the hypothesis that the homeopathic medicines used had a stimulating effect on common bean (Phaseolus vulgaris L.) var. Quivican plant. This assertion is based on the activity of its active ingredients, assuming that TH3 contains magnesium nanoparticles, manganese, and phosphorus, and it could also contain, in some measurement, metallic magnesium nanoparticles. The separated action of the TH3 components can explain a greater efficiency of this combined homeopathic treatment besides the potential synergies that result from the interaction TH1 + TH2 = TH3 (Figure 1). The presence of nanoparticles of the “active principle” originally contained in the MT has been demonstrated even in high centesimal dilutions (30CH and 200CH) of homeopathic medicines by physical-chemical studies (^{Chikramane et al., 2012}).

Figure 1: Effect of homeopathic medicines on the photosynthetic rate of plants of common bean (Phaseolus vulgaris L.) variety Quivican. 

The TF of the treated plants with the homeopathic medicine mix (TH3) had a better development when compared to the other treatments (Figure 1). This result can be attributed to the increase in leaf area that favored plants treated with TH3 to have a greater light reception area and more efficient use in the physiological processes involved, such as photosynthesis. At the same time, it impacted biomass production in the plants treated with the TH3 mix. On the other hand, the number of leaves is known to be closely related to photosynthetic activity (^{Honório et al., 2016}), and precisely, the plants that received this treatment had a greater number of leaves (6.25), compared with the control group (distilled water) without homeopathic medicine.

The revealed results agree with that reported by ^{Panda et al. (2013)} who assessed three homeopathic dynamizations in growth of pea (Pisum sativum L.) plants, observing a positive impact in TF on those treated with homeopathy, which also increased their fresh biomass. In another study performed by ^{Mazón-Suástegui et al. (2019)} in basil O. basilicum plants treated with homeopathic medicine showed a favorable response in TF and a significant increase in fresh biomass. The results of the PR demonstrated in this research may be related directly with the presence of magnesium nanoparticles in TH3, favoring the formation of chlorophyll molecules and stimulating the photosynthetic process (^{Mazón-Suástegui et al., 2018}).

The use of homeopathic medicines in agriculture, particularly in the cultivation of P. vulgaris, can be of great interest in general and practical relevance. Homeopathic dynamizations are much more economic than agrochemicals and their application is simple and effective. They are highly diluted substances of high innocuousness, and their environmental impact is greatly reduced or practically inexistent. To summarize, agricultural homeopathy has a great potential because homeopathic dynamizations have a measurable positive impact in the plants treated and lack toxicity, their cost is low and they are innocuous (^{Ruiz, 2004}; ^{Mazón-Suástegui et al., 2019}).

Conclusions

The application of homeopathic medicines in common bean (Phaseolus vulgaris L.) var. Quivican plants favored their growth significantly. An increase in photosynthetic rate, length of stem and root, fresh root biomass, fresh and dry stem and leaf biomass, leaf area, stem diameter and number of leaves. The best results were obtained with the mixed TH3 (MgM-31CH + MaMnP-3CH) that contained the homeopathic medicines Magnesium metallicum and Magnesium-Manganum phosphoricum. These results showed that agricultural homeopathy is an alternative with application in production, totally compatible with organic agriculture. Specifically, the application of TH3 is recommended during the initial growth stage of the common bean (Phaseolus vulgaris L.) var. Quivican white cowpea plant.