Exploration of plant biodiversity for nutrient harvesting
Abstract
There are considerable differences among plant species in the amount of nutrients required for biomass production, indicating the differential ability of the species to utilize nutrients for growth. Exploitation of this ability for nutrient absorption is a good option for nutrient management in organic agriculture. Different plant species growing in the wild habitats in the Western Ghats and wastelands of the western coasts were screened for phyto-accumulation capacity with respect to macro and micronutrients. Based on the analysis, phyto-accumulators of each nutrient was identified. Considering the overall nutrient concentration, ten plant species were identified as potential plants which can be utilized for nutrient management in organic farming. Plants like Mirabilis jalapa and Canna indica which are super accumulators and possess underground stems are promising plant species for nutrient harvesting as the above ground portion can be harvested without destroying the plants.
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Introduction
Crop nutrition with organic supplements is emerging as a challenge with the adoption of organic crop production in commercial scale. Among various nutrient management options, green manuring, green leaf manuring and use of composts are the major alternatives. Apart from crop residues, biomass of many plant species specifically utilized for crop nutrient management. Plant growth depends on the amount of nutrients present in biomass. However there are considerable differences between species in the amount of nutrients required to produce biomass (Wang et al.1991), indicating the differential ability in species to utilize nutrients for growth. Glyricidia maculeata, Calatropis gigantean, Sesbania aculeate etc. are traditionally utilized for nutrient management mainly to exploit the nitrogen fixing capacity of these plants. There are many plant species which have the capacity to selectively absorb and accumulate mineral elements. Plants such as Thalaspi cearulescence, Alpine pennycress (Gerbisu et al 2002) and Brassica carinata (Purakayastha et.al 2008) are used for phyto remediation. Majority of these are targeted to remove the heavy metal contaminants from the ecosystem. The ionome of plant species is highly plastic but tightly controlled by genes and plant gene interactions (Ivan Bexter et al.2012 ) Utilization of plant characteristics to absorb plant nutrients and exploitation of these properties for crop nutrition management is a un attended area of plant nutrition.
Humid tropics which receive abundant rainfall and have highly weathered soil experiences heavy nutrient loss due to leaching. Abundant plant growth in waste lands and river banks plays major role in catching these nutrients. Plants differ widely in their ability to absorb nutrients. Green manures and green leaf manure, especially for nitrogen fixing plants with high nitrogen content are widely used to enrich soils.. Imbalance of major nutrients especially potassium is a major problem in organic farming specifically for crops like coconut and banana which need high potassium. Agricultural biodiversity also include habitats and species outside farming system that benefit agriculture and enhance ecosystem functions(Heywood 2003). Identification of plant species with high and multiple nutrient content will be useful for crop nutrient management especially in organic farming.
Conclusion
Nutrient addition through organic source is an integral part of organic farming and green manuring is one of the options available. Identification and utilization of plant species which are hyper accumulators and capable of coming up in marginal lands is essential. The identified phyto-accumulators can be utilized as nutrient harvesters from waste lands and maginal lands. It also provides an option to correct specific nutrient deficiencies in organic management systems utilizing specific phyo-accumulators. Plant species with specific accumulation as well as multinutrient accumulation capacity have been identified in this study. Plant species like Mirabilis jalapa and Canna indica are waste land species with profuse growth and underground stem. These plants have good potential as nutrient harvesting plants.
