Structural and functional traits underlying the capacity of Calotropis procera to face different stress conditions

Calotropis procera (Aiton) W. T. Aiton, originally native to tropical and sub-tropical regions of northwestern Africa to southwest Asia through the Arabian Peninsula. The present study was engaged to uncover the underlying mechanism (structural and functional) of C. procera sampled from six different ecological regions. The population of normal irrigated agriculture field (IAF) had better growth, high K+ ion content, photosynthetic pigments (chl a chl b, Tchl and caro) and stomatal density. The population of dust and pollution stressed habitat (IWD) exhibited enlarged epidermal cells in stem and leaf, enhanced cortical proportion with largest cells in stem and phloem area in leaf. The population of drought and aridity stressed habitat (ARS) showed increased root cellular area, cortical region thickness and its cell area, and phloem region. The population from salt-affected habitat (SLF) possessed high root and shoot ionic contents (Na+ and Ca2+), total soluble sugars, total antioxidant activity, chlorophyll a/b, widened metaxylem vessels and phloem area in the stem, while intensive sclerification observed in both stem and leaf. The population native to waterlogged and salinity stressed habitat (APC) represented vigorous root growth, total free amino acids, well-developed metaxylem vessels and stomatal area in leaf. The population from drought and salinity-prone habitat (UBL) indicate increased storage of parenchymatous tissue (pith region and its cells area) and epidermal cell area in leaf. It is concluded that C. procera showed much outmost behavior in view of growth, structural and functional attributes in response to prevailing environmental condition.

An Overview of the Characteristics and Potential of Calotropis procera From Botanical, Ecological, and Economic Perspectives

Calotropis procera (Aiton) Dryand. (commonly known as the apple of sodom, calotrope, and giant milkweed) is an evergreen, perennial shrub of the family Apocynaceae, mainly found in arid and semi-arid regions. It is a multipurpose plant, which can be utilized for medicine, fodder, and fuel purposes, timber and fiber production, phytoremediation, and synthesis of nanoparticles. It has been widely used in traditional medicinal systems across North Africa, Middle East Asia, and South-East Asia. At present, it is being extensively explored for its potential pharmacological applications. Several reports also suggest its prospects in the food, textile, and paper industries. Besides, C. procera has also been acknowledged as an ornamental species. High pharmacological potential and socio-economic value have led to the pantropical introduction of the plant. Morpho-physiological adaptations and the ability to tolerate various abiotic stresses enabled its naturalization beyond the introduced areas. Now, it is recognized as an obnoxious environmental weed in several parts of the world. Its unnatural expansion has been witnessed in the regions of South America, the Caribbean Islands, Australia, the Hawaiian Islands, Mexico, Seychelles, and several Pacific Islands. In Australia, nearly 3.7 million hectares of drier areas, including rangelands and Savannahs, have been invaded by the plant. In this review, multiple aspects of C. procera have been discussed including its general characteristics, current and potential uses, and invasive tendencies. The objectives of this review are a) to compile the information available in the literature on C. procera, to make it accessible for future research, b) to enlist together its potential applications being investigated in different fields, and c) to acknowledge C. procera as an emerging invasive species of arid and semi-arid regions.

The cutting depth required to control calotrope (Calotropis procera) plants using mechanical techniques

Calotrope (Calotropis procera (Aiton) W.T. Aiton) is an exotic woody weed that has invaded northern Australia’s rangelands since being introduced in the early 1900s. To expand the range of control options beyond herbicide-based methods, we undertook a stem/root cutting experiment that helped quantify the potential for using mechanical control techniques. Individual, medium-sized (1.72±0.03m high) calotrope plants were cut off at ground level (0cm) or below ground (10 or 20cm) using either a pruning saw or mattock respectively. All calotrope plants cut at ground level reshot vigorously. After four months they had more than twice the number of stems (7.4±0.54) of the uncut control plants and by 12 months they were only 26cm shorter than the control plants. In contrast, all plants cut at 10 or 20cm below ground were killed. Some mortality also started occurring in the control and ground level (0cm) treatments after eight months, but appeared to be associated with a dieback phenomenon. Nevertheless, the results demonstrate the potential to use equipment that severs the root system below ground, such as blade ploughs and cutter bars. A subsequent stick raking demonstration achieved moderate plant mortality (72%) after 13 months, yet produced a six-fold increase in original plant density as a result of new seedling emergence. This finding supports the view that mechanical disturbance will often promote seedling recruitment, and land managers need to have the capacity to undertake follow-up control practices to avoid exacerbating the problem.