Designer Vetiver genotypes for environmental and industrial applications

Background and Aims: The Vetiver grass [Vetveria zizaniodes (L) Nash. syn. Chrysopogon zizaniodes (L.) Roberty], traditionally valued in aroma industry for its essential oil extracted from roots is now extensively used as a green technology for its multifarious environmental applications. With rising global interest in Vetiver Grass Technology, it becomes desirable to identify / develop designer genotype/s of vetiver for specific application/s to realize its efficient implementation. Whereas the penetrating roots reaching deep into subsoil horizon promises vetiver as a suitable candidate for carbon sequestration likened to trees, its web forming tufted roots supported with lateral roots make this grass a model soil binder. Further, owing to its efficient phyto-absorption potential for toxic chemicals and metalloids that are primarily stabilized in root zone, the above ground shoot mass of this grass could also be utilized as a forage when combined with nutritional qualities required in a fodder. On the other side for its utilization as an essential oil crop it is desirable to develop short duration genotypes that could yield maximum productivity of high-quality essential oil keeping in fitness with the requirements of aroma industry. Therefore, it was endeavored to develop designer genotype/s to aim the following specifications: (a) Efficient soil binder and soil ameliorator combined with fodder qualities, (b) Root based sequestration of atmospheric carbon deep into subsoil horizon likened to trees, (c) Short duration crop for high essential oil productivity. Methods: Keeping in fitness with the concept of ‘root ideotype’ and ‘root phenomics’ suggested for vetiver grass for specific applications, extensive efforts were made to isolate genotypes from the range of diversity prevalent across the length and breadth of India. Further selection pressure and genomic manipulation was applied to identify genotypes that meet the ‘best fit’ to realize the requirement of environmentalists in a global perspective, including non-invasiveness. The genotypes were tested for their efficiency as a soil ameliorator by growing them in iron mine spoil dumps, nutritional and palatability qualities of leaves desirable as a fodder, growth efficiency and deep penetrability of roots for carbon sequestration potential, and concentration and quality of essential oil in the roots harvested after six months.  Key results: The following three kinds of designer genotypes are developed for environment and industry specific applications: (i) A non-seeding ideal plant type that sports profuse rooting with high secondary roots (with least oil) for enhanced soil binding properties, coupled with profuse tiller and shoots rich in high fiber content and nutritional qualities suitable for fodder. This genotype is suitable for ecological plantations in degraded soil / iron mine spoil dump; (ii) A seed infertile plant type that has thick deep penetrating roots with least secondary roots and high biomass. This plant type is ideal for sequestration of atmospheric carbon deep into subsoil region likened to trees as well as suitable for improving soil fertility through enriching the soil carbon pool; (iii) A short duration clone that could yield high amount of essential oil of desirable quality from its roots harvested just after six months of plantation, otherwise obtainable after 18 months in the standard cultivars. Conclusions: Keeping in view the two diverse requirements i.e. for environmentalists on one side and industrialists on the other, intensive efforts were exercised that led to development of three designer genotypes : (i) Genotype ‘CIMAP-FORAGIKA’ : It is suitable as an efficient soil binder on account of its designer root architecture that sports intense root-web, as well as soil ameliorator on account of its high iron / heavy metal absorption potential in the root zone, and at the same time possessing shoot characteristics that make it suitable for usage as fodder under ecological plantations, (ii) The clone ‘CIMAP-KH40’ : This clone sports deep penetrating fast growing smooth roots with efficient carbon sink, and is thus ideal for carbon sequestration deep into the subsoil likened to trees. Further, this clone was made seed infertile through genomic manipulation to realize non-invasiveness for its suitability in ecological plantations, (iii) The genotype ‘CIMAP-KHUSINOLIKA’: This is a short duration clone that could yield essential oil of desirable quality just after 6 months crop cycle against the existing varieties that require 18 months crop cycle