Journal of Hill Agriculture 8(3): 253-256, July – September, 2017 DOI 10.5958/2230-7338.2017.00050.7
SHORT REVIEW
Conceptual ideas of carnivorous plants to utilize in the field of agriculture M ANBARASU
Received: June 6, 2017, Revised: August 20, 2017, Accepted: September 3, 2017
ABSTRACT Usually, when we think of "carnivorous," animals come to our mind. Yet there are some wonderfully fascinating plants that eat animals. It seems a contradiction, but this meat eating habit of some plants is an interesting and normal adaptation of nature. Carnivorous plants have evolved in places where the soil is poor and low in nutrients. Here, animals can provide them missing ingredients needed for survival. The carnivorous plants have fascinating methods of luring, trapping and digesting animals which provide an adequate supply of necessary nutrients. Green plants require sunlight for photosynthesis. Some selected carnivorous plants like venus flytrap, flypaper and pitfall, trap plants to use as catch crops or emergency crops, smother crops, trap crops, replacement inter crops and avenue crops which had naturally habit evolved to eat the insects. This habit can be used in agriculture, mainly for pest control (especially in sucking pest especially when they are more resistant to pesticides), weed management and nutrient management etc. These management strategies are mainly maintained through inorganic ways, as pesticides, weedicides and fertilizers are being discouraged by researchers as well as farmers. Carnivorous plants thus may occupy important place in future agriculture. This paper presents some of such ideas of better use of nature to maintain sustainable ecology / environment. KEYWORDS Carnivorous plants, pest nutrient management, agriculture field
control,
Anbarsu M Department of Agronomy, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai- 625 104, Tamil Nadu
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M Anbarsu E mail:
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INTRODUCTION About 650 species of vascular carnivorous (Latin: carnis - flesh, vorare - to swallow) plants occur throughout the world, out of the total of about 300,000 species of vascular plants (Rice 2006). Carnivorous plants belong to 15-18 genera of 8-9 botanical families and 5 orders (Heubl et al. 2006, Porembski and Barthlott 2006). Due to many remarkable and striking morphological, anatomical, physiological and ecological features, carnivorous plants have always attracted considerable interest of both researchers and gardeners. Nevertheless, the degree and extent of knowledge of the main disciplines studying this particular ecological functional plant group, has always considerably lagged behind the study of noncarnivorous plants. In modern days, eco-physiological research of carnivorous plants has progressed considerably within the last decade and has elucidated most of the particulars of carnivorous plants (Darwin 1875). Uses of carnivorous plants in agriculture In agricultural field, research on utilization of carnivorous plant has begun. Many plants have evol ved adaptations in order to survive in low nitrogen environments. Insect carnivorous plants, such as pitcher plant and sundews (Nepenthes and Drosera, respectively) are able to obtain substantial amounts of nitrogen from the insects that they capture. Secondly, numerous plants form associations with mycorrhizal fungi that can provide soluble nitrogen from the soil, some of which may be insect-derived nitrogen, obtained from decaying insects or insect frass. Finally, a specialized group of endophytic insect-pathogenic fungi (EIPF) provide host plants with insect-derived nitrogen. These soil-inhabiting fungi form a remarkable symbiosis with certain plant species (Scott et al. 2013). The concept of murderous plants and inclusion of carnivorous plants as a subset, was
254 introduced by MW Chase (Chase et al. 2009). Use of the word "murderous" in this context is a slight hyperbole, because, it does not conform to the usual definition of the word. The dictionary definition usually has words like "unlawful" and implies killing of an individual of the same species. However, the root of the word simply implies death or causing death. Either way, the word "murder" presents an image that is quite useful in the discussion of carnivory in plants. We need a word for plants, that at first glance, appear carnivorous, but in fact are not. Carnivorous plants are simply feeding themselves with prey. Murderous plants are conspicuously killing victims or at least apparent victims without utilizing the corpses for food.
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of the whorl of leaves, seal to form a cup to catch water. Prey slips down the leaves into the pool at the base and drown. The other carnivores with pitfall traps have highly modified leaves, where, each leaf is a separate trap. The traps may have nectaries, bright colours, or a flower-like scent to attract prey. The traps may have hairs to direct prey to the trap opening or cause the prey to fall into the trap. The lip of the trap is usually slippery and the inside of the trap waxy. The open pool traps have pools of water to drown victims (Takahashi et al. 2009).
Carnivorous plants and evolution mechanism Carnivorous plants are those that derive some or most of their nutrients (but not energy) from trapping and consuming animals or protozoans, typically insects and arthropods such as the Venus flytrap. Carnivorous plants have adapted to grow in places with light, where the soil is thin or poor in nutrients, nitrogen, especially such as acidic bogs and rocks (Adamec 1997). Carnivorous plant trapping mechanisms Carnivorous plants have six basic trapping mechanisms (with representative genera or species) but some plants with complex traps have multiple mechanisms. Adhesive The simplest trapping mechanism is the adhesive trap. The flypaper-like leaves of Pinguicula gigen have specialized short stalked glands that secrete sticky mucilage that traps small creatures. The glands are stalked so the leaf itself doesn't smother in slime while it waits for a prey (Plachno et al. 2008).
Fig 2 Nepenthes hamata leaf - is an example of a pitfall trap with a pool of wat er at the bottom
Fig 3 Darlingtonia californica
Fig 1 Pinguicula gig en leaf showing the remains of fungus gnats
Pitfall Pitfall traps are leaves modified into pit-like structures. The bromeliad carnivores (Brocchinia and Catopsis) are the simplest pitfall traps, where, the base
Lobster pot Darlingtonia and Sarracenia psittacina have a trap similar to the traps used to catch lobsters. A lobster pot has an entrance prey can easily find on the outside and enter but the entrance is difficult to find or exit from the inside. Once inside, if the prey finds the entrance or figure it out can easily leave.
Journal of Hill Agriculture (Volume 8, No. 3 July – September, 2017) Pigeon trap Genlisea plants are found in water or water saturated soil. Its primary prey is protozoans. The prey enter the trap by pushing past inward pointing hairs. Once inside the trap, they cannot get back out past the hairs. This is the way pigeon traps work except thin metal rods are used instead of hairs. Sarracenia psittacina uses similar concepts where hairs in the neck of the trap allow prey to move only in one direction to you know where (Juniper et al. 1989).
Fig 4 Sarracenia psittacina (Parrot pitcher plant)
Snap trap Snap trap (Dionae and Aldrovanda) bends the halves of the trap to enclose the prey. The trap closes by almost explosi vely expanding the cells on the outer surface of the leaf. You can verify this by noting that before the trap is triggered, each half of the leaf is flat. After being triggered the halves are cupped. The trap will then slowly seal and digest the prey, reopening when it is done (Juniper et al. 1989). Suction trap Suction (Utricularia) traps move too fast to see the action. But snap traps leave little to the imagination. A prey moves into the trap, brushes against the trigger hairs, and you see the trap very quickly enclose the prey.
Fig 5 Aldrovanda
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Carnivorous plant digestion and nutrient assimilation Once a carnivorous plant has procured an item for food, it has to have some way to turn it into fertilizer. What carnivorous plants do is very similar to what humans do with their dinner after they have eaten it (Graeme 1978). Most carnivorous plants have glands that secrete acids and enzymes to dissolve proteins and other compounds. The plants may also enlist other organisms to help with digestion. The plants then absorb the nutrients made available from the prey (Plachno et al. 2009). Digestion methods (with representative genera or species) 1. Leaf surface Leaf rolls and tentacles bend for increased prey contact (Drosera) Leaf rolls or is rolled to contain digestion fluid (Pinguicula) Leaf doesn't move (Drosophyllum, Triphyophyllum, Byblis, Roridula) 2. Sealed trap (Dionaea, Aldrovanda, Utricularia) 3. Pit or stomach (Sarracenia, Genlisea) 4. Water pool (Nepenthes, Darlingtonia, Heliamphora, Cephalotus, Sarraceniapurpurea and S. rosea) 5. Commensal organisms (Roridula, Byblis, Darlingtonia) Conceptual ideas Many plants have evolved adaptations in order to survive in low nitrogen environments. One of the bestknown adaptations is that of plant symbiosis with nitrogen-fixing bacteria. This is the major route by which nitrogen is incorporated into plant biomass. A portion of this plant-associated nitrogen is then lost to insects through herbivory, and insects represent a nitrogen reservoir that is generally overlooked in nitrogen cycles (Scott et al. 2013). Insect carnivorous plants such as pitcher plants and sundews (Nepenthes / Sarracenia and Drosera) are able to obtain substantial amounts of nitrogen from the insects that they capture. Also, they reduce agricultural pest population of many insects like stem borer, gall midge, caterpillars, skippers and some lepidoptera’s, sucking pests like thrips, leafhoppers, aphids, white flies, mealy bugs, scale insects and bugs all are attracted by insectivorous plants to get absol ved and digested for their nutrients (Porembski and Barthlott 2006). Ideas to planting field for carnivorous plants Catch crops / emergency crops / restorative crops Normally these crops are cultivated to catch the forthcoming season. They replace the carnivorous plants for more pest areas. After reducing the pest
256 population, in the field itself, carnivorous plants incorporate into the soil to improve the soil fertility and productivity. Smother crops / cover crops - These crops protect the soil surface as well as have dense foliage to reduce the weeds populations. In areas where soil is low in fertility and of erosive nature, planting carnivorous plants, would enhance the nutritional status of soil and reduce the pest, weeds problems. Trap crops / border crops - To trap soil borne biotic agents, parasitic insects and other insects to attract and digestion for their nutrients can be used. Replacement inter crops / green manure crops Wide spacing crops to adopt in between inter row spacing to reduce the pest during crop period and give symbiosis nitrogen to the crop. Also moderate foliage carivory plants to grow green manure crops means insect’s nitrogen is also added to the soil when incorporated. Avenue crops / augmenting crops - The crops grown along the roads and fences, when augmenting crops to supplement the nutrient for main crops. So carnivorous have good aesthetic value as well as give nutrients from nearby avenue crops (Reddy 2014, Sunda 2016). CONCLUSION Carnivorous plants naturally have a habit evolved to eat the insects. This habit can be of great use in agriculture, mainly for pest control (especially in sucking pest for more resistant to pesticides), weed management and nutrient management. Nowadays quality is more important than quantity, that’s mean consumers prefer more organic agricultural products. Crop management, through use of carnivorous plants, being purely organic, reduces use of pesticides, weedicides and fertilizers. Considering the above ideas, this wonderful habit of carnivorous plants can prove immensely effective for better use of nature and to maintain sustainable ecology and environment. ACKNOWLEDGEMENTS The author expresses heartfelt gratitude to his PhD advisory committee of for their support in creation of this article. REFERENCES Adamec L 1997. Mineral nutrition of carnivorous
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plants - a review. Botanical Review 63:273-299. Darwin Charles 1875. Insectivorous Plants. John Murray, London. Chase Mark W, Maarten JM, Christenhusz Dawn Sanders, Michael F Fay 2009. Murderous plants Victorian Gothic, Darwin and modern insights into vegetable carnivory. Botanical Journal of the Linnean Societ y 161(4): 329-356. Graeme Chandler 1978. The uptake of digestion products by Drosera. Carnivorous Plant Newsletter 7(1): 11-13. Heubl G, Bringmann G, Meimberg H 2006. Molecular phylogeny and character evolution of carnivorous plant families in Caryophyllales – revisited. Plant Biol ogy 8: 821-830. Juniper BE, Robins RJ, Joel DM 1989. The Carnivorous Plants. Academic Press, London, UK. Plachno JB, Kozieradska-Kiszkurno M, Swiatek P, Darnowski WD 2008. Prey attraction in carnivorous Genlisea. Acta Biologica Cracoviensia S Botanica 50: 87-94. Plachno JB, Lubomir Adamec, Herve Huet 2009 . Mineral nutrient uptake from prey and glandular phosphatase activity as a dual test of carnivory in semi-desert plants with glandular leaves suspected of carnivory. Annals of Botany 104: 649–654. Porembski S, Barthlott W 2006. Advances in carnivorous plants research. Plant Biology 8 : 737739. Reddy SR 2014. Introduction to Agronomy and Principles of Crop Production . Kalyani Pub, New Delhi. Rice AB 2006. Growing Carnivorous Plants, Timber Press, Portland, USA. Scott W Behie, Michael J Bidochka 2013. Insects as a nitrogen Source for Plants. Insects 4: 413-424. Sunda Nem Raj 2016. A Competitive Book of Agriculture. Surahee Pub, Jaipur. Takahashi Kenji, Koji Matsumoto, Wataru Nishii, Miho Muramatsu, Keiko Kubota, Chiaki Shibata, Senareth BP Athauda 2009. Comparative studies on the acid proteinase activities in the digestive fluids of Nepenthes, Cephalotus, Dionaea, and Drosera. Carnivorous Plant Newsletter 38(3): 7582.
