1. Introduction
Indigenous techniques (ITKs) are treasure troves of ancient wisdom and developed through trial-and-error, experiences gained over the centuries, and are time tested (Mohapatra, Reference Mohapatra2018) but, generally not substantiated by any scientific evidences. Seeds of Abrus precatorius L. (Fabaceae) an indigenous medicinal plant commonly known as Rosary pea, Ratti or Gunja are very attractive, uniform in size and shape (Fig. 1) and are used as weight measure by indigenous people including Indian gold smiths. Where, the seeds were referred as Ratti, a traditional Indian unit of mass measurement (Shrivastava, Reference Shrivastava2017). Generally, seed weight changes or fluctuate with change in environmental conditions (temperature, relative humidity), storage-period and storage-conditions (McGilp et al., Reference McGilp, Duquette, Braaten, Kimball and Porter2020). Further, seeds weight generally decline with the progression of storage/ageing due to metabolic breakdown of stored food, microbial degradation, pest infestation, and also due to bear-and-tear (Baskin & Baskin, Reference Baskin and Baskin2000). Therefore, the use of A. precatorious seeds as a weighing unit especially, where precious metals (gold, silver, platinum), stones and gems have to weigh become dubious and need to be scientifically validated. The later has never been doubted nor scientifically validated ever.
Figure 1. Abrus precatorious (Ratti) seeds.
2. Objective
The objective of the present study was to find out the rationale behind the use of A. precatorious seeds as a weighing unit by Indigenous people and to scientifically validate the indigenous technique.
3. Methods
Fully ripened and viable seeds of A. precatorious collected from Kangra, Himachal Pradesh, India were used in this experiment. Seed viability was determined through TTC (2,3,5-triphenyl tetrazolium chloride) reduction test. To monitor the change in seed weight, Seeds were subjected to different moisture conditions (soaked in distilled water, placed on moist substratum, kept in a container with high relative humidity, kept in desiccator) and also acid scarified with concentrated H2SO4 for different durations i.e. 0, 30, 60, 90, 120, 150 min., washed thoroughly and soaked in distilled water for 24 h and periodically monitored for any change in weight. In another set of seeds were mechanically scarified at chalazal end with the help of sand paper were also monitored. Further, seeds were transferred to petri-plates lined with moist substratum for germination. Data are presented as arithmetic mean of 100 seeds each. The significance of difference was assessed based on the Student’s t-test.
4. Results and discussion
The seeds of A. precatorious showed 100% viability. The later was confirmed by both TTC reduction test and seed germination (98% germination). To evaluate the validity of ITK, seeds were subjected to different moisture conditions. Surprisingly, there was no change in seed weight was observed even after 48 h of exposure to the above conditions (Tables 1, 2). The seed weight remains constant, indicating the complete impermeability of seed coat towards water and air. In contrast, the seed weight of Cicer arietinum L. (used for comparison purpose, procured from IARI, New Delhi, India) increased significantly with increase in relative humidity/moisture (Table 2). The findings strongly supported the use of A. precatorious seeds as a weighing unit. To confirm the impermeability of seed coat toward water the seeds were mechanically (through sand-paper) as well as chemically (conc. H2SO4) scarified. The treatments effectively removed the impermeability of seed coat and resulted in significant increase in seed weight and of course resulted in further germination (Table 1). Seed dormancy in A. precatorious is known (Nautiyal & Singh, Reference Nautiyal and Singh2015) but, the type of dormancy has never been classified. According to the new seed dormancy classification by Baskin and Baskin (Reference Baskin and Baskin2004), the type of dormancy exhibited by A. precatorious seeds in present study should be classified as physical dormancy (PY). Physical dormancy is caused by water-impermeable seed coat due to the presence of one or more palisade layers of lignified malphigian cells (macrosclereids) tightly packed together and impregnated with water-repellant chemicals and known to occur in some 15 plant families including the Fabaceae (Baskin et al., Reference Baskin, Baskin and Li2000). In nature, seeds with physical dormancy remain dormant until some factors (high temperature, widely fluctuating temperature, fire, drying, freezing and passage through the digestive tracts of animals) render the covering layers permeable to water (Baskin, Reference Baskin2003). In the present study, the seeds of A. precatorious required more than 2 hours of acid (conc. H2SO4) scarification to achieve maximum water uptake and seed germination (Table 1). The later indicates the depth of physical dormancy in A. precatorious. Physical seed dormancy can also be affected by microbial action and abrasion by soil particles (Baskin & Baskin, Reference Baskin and Baskin2000). However, the presence of abrin, a potent toxin similar to ricin but even more poisonous, in the seed coat of A. precatorious (Dickers et al., Reference Dickers, Bradberry, Rice, Griffith and Vale2003; Zhang et al., Reference Zhang, Ma and Wang2019) protects the seed from pests and microbes, which eventually contribute to the maintenance of impermeability of seed coat/physical dormancy (thereof constant seed weight) for longer period of time. In addition, the smooth, glossy and shiny seed coat significantly reduces the chances of bear and tear/abrasion by soil particles during long run, which further strengthen and validates the ITK. Thus, the present study strongly confirms and validates the use of A. precatorious seeds as a weighing unit (ratti) by indigenous people and is reported first time.
Table 1. Effect of acid- (concentrated H2SO4) and mechanical-scarification of seeds on seed coat permeability in Abrus precatorious L. Data are average of 100 seeds each, all the differences are significant at p ≤ 0.01.
Table 2. Comparison of change in seed weight of Abrus precatorious L and Cicer arietinum L as affected by different relative humidity. Data are average of 100 seeds each. All the differences are significant at p ≤ 0.01.
Acknowledgements
The financial support by Department of Biotechnology, Government of India under DBT-Star-College scheme is thankfully acknowledged.
Conflicts of interest
None.
Data Availability
Data will be provided whenever requested.
Open access
Comments
Comments to the Author: Overall, a very well written paper on an important subject. The study was well designed and executed taken into account all important parameters. Results were appropriately described and discussion was up to the mark. However, it needs some improvement in introduction section. Goals/objectives are not clearly defined and followed throughout the manuscript. Also, abstract should indicate data from results and discussion section.