VARIABILITY PATTERNS IN SOIL MOISTURE AND SOIL PH VALUES UNDER SANDY CANOPIES OF BLEPHARIS SINDICA T. ANDERS IN CHURU REGION – A PART OF INDIAN THAR DESERT

Abstract: Soil parameters constitutively frame the edaphic environment for the naturally
growing plants. Proper response to these dynamic parameters enables the plants to survive and
reproduce. Blepharis sindica T. Anders (Acanthaceae) is a threatened medicinal plant of Indian
arid zone and reported to grow with progressively declining patchy populations at sandy
habitats in Churu region. Micro-environment especially edaphic characteristics, under the
canopies of plants impact largely on plant development. In the present study an attempt has
been made to evaluate yearlong variations in soil moisture contents (as percentage value) and
soil pH at natural sandy sites of this threatened species. Values were estimated for both surface
soil (0-5 cm) and depth soil (20-25 cm) layers under plant canopies. Data revealed that moisture
percentage values remain higher only in rainy months that support seed germination and
subsequent vegetative growth of plants. Progressive decline in soil moisture contents as well as
increase in soil pH during late growing season seems to exert their effect as culmination of
growth in this species.

Key words: Soil Moisture, pH, Arid Zone, Rain Fall, Sandy Areas, Medicinal, Threatened

Introduction
Soils form the heart of the Earth’s “critical zone”, on which living beings mostly rely for their
various resource requirements. Physically, it is an extra-ordinary complex that controls carbon,
nutrients and water cycling (Brantley, 2010). The sustainable productivity of a soil mainly
depends upon its ability to supply essential nutrients to the growing plants (Chaudhari and
Ahire, 2013). Organisms in the soil food web decompose soil nutrients and make them available
to plants (Brussaard et al., 2007). The rate of soil nutrient decomposition and turnover mainly
depends upon the interplay between soil biota, temperature, moisture and soil chemical and
physical composition (Taylor et al., 2009). Optimum plant growth and crop yield depend not only
on total amount of nutrients present in the soil at a particular time but also on their availability,
which in turn, is controlled by physico-chemical properties such as soil texture, organic carbon,
cation exchange capacity, pH, etc

The suitability of soil as a medium of plant growth depends on both its chemical and
physical properties. The adverse physical soil environment conditions limit root growth and root
activity that manifest reduced nutrient absorption and plant growth (Chaudhary and Sandhu,
1983; Peterson et al., 1984). As per Rodriguez-Iturbe and Porporato (2004), soil is the primary
store and regulator in the water flow of ecosystems, by intercepting precipitation input and
controlling its use by organisms, especially by plants. Soil moisture is a comprehensive indicator
in hydrological processes and ecosystems functioning (Chang and Wetzel, 1991). Soil moisture
availability primarily influences plants by two routes, either by being directly limiting as a
resource, or indirectly by filling pore spaces in soil and thereby excluding air, causing oxygen
availability to become limiting for the activity of plant roots (Golhar and Chaudhari, 2013).
Increased soil water concentrations positively affect nutrient input, decomposition,
mineralization and physical transport of nutrients in soil, all of which should increase plantavailable nutrients (Schimel et al., 1997).

Soil pH depends upon a variety of factors including all soil-forming factors plus the
season of the year, cropping practices, the soil horizon sampled, the water content at sampling
time and the way pH is determined (Tisdale et al., 1995). The soil pH influences the rate of
weathering processes, which in turn affect the solubility of many of the nutrients in the soil
needed for proper plant growth and development (Evrendilek et al., 2004). The most universal
effect of pH on plant growth is nutritional, as it determines the nutrient availability to plants
(Hoffmann, 2010). Soil pH ranges facilitate a respective vegetation to grow, and in turn the
growing vegetation influences the soil pH by organic matter production and leaching actions
(Rowell, 1994).

Indian arid zone is a home of unique phyto-diversity including an array of medicinal plant
species. Desertic conditions are life limiting for these plants and also determine their future.
Blepharis sindica T. Anders is an IUCN declared threatened medicinal plant species of
Acanthaceae family (UNDP, 2010) being locally known as Billi-khojio/Unt-kantalo/Bhangaro.
The plants are medicinally important for aphrodisiac and invigorating benefits (Singh et al.,
1996; Khare, 2007). During vegetative growth, B. sindica plants attain 10-55 cm above ground
height with a characteristic dichotomously branching habit and seed loaded spikes at their
nodes. The plants thrive well at sand dunes and undisturbed margins of field fencings (Lal et al.,
2014). The growing season of the species starts with the seed germination in June last of early
July as the first monsoon showers precipitate in the area. The plants culminate their life in form
of dried lignified plants standing rooted in their natural sandy habitat in months of DecemberJanuary each year. The present study was aimed to investigate the yearlong variability in the
levels of soil moisture (percent) and pH values underneath/nearby canopies of Blepharis sindica
plants at two different selected sites in Churu region – a part of Indian Thar desert.

Materials and Methods
In the present study, two different study sites of B. sindica populations were selected in Churu
region, viz. Shyampura village (Site-A; 28.2647533 N, 74.8945098 E) and Buntia village (Site-B;
28.3528630 N, 75.0090939 E). Climatic data from meteorological Centre, Jaipur revealed that
various factors, viz. rainfall, temperature and humidity, showed great monthly variation and also
influenced each other. Rainy months (July-August) were reported with highest amount of
precipitation (up to 345mm in August). In summer months (April-June), the area experiences
high temperature peaks (up to 500C in May) with frequent dust storms while in winter months
(November-February) the temperature deeps as low as -2 0C (in January month). Besides rainy
spells, the area faces low amount of relative humidity and high rates of evopo-transpirational
loses.

Soil samples were collected from these sites beneath B. sindica plants (green plants in
growing season, while dried plants in rest of the year) during July 2017 to June 2019. The soil
samples were collected (in glass bottles fitted with air tight rubber caps) monthly from surface
(0-5 cm) and 20-25 cm depth levels from above-mentioned sites and analyzed for moisture
percent and pH parameters. The mean values of these parameters for two consecutive years
are presented graphically and also in tabular forms. The soil moisture was estimated
immediately after sampling was done, while pH was analyzed from air-dried samples sieved
through 2 mm sieve. The percentage of soil moisture was measured on oven dry weight basis
as described by Pandeya et al. (1968) and calculated as follows:

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By:

Purushottam Lal1
and Sher Mohammed2
1Assistant Professor Department of Botany, Govt. College, Dholpur (Rajasthan), India
2Associate Professor Department of Botany, Govt. Lohia PG College, Churu (Rajasthan), India
Corresponding author Email: bansiwal.purush@gmail.com