Assessment of morpho-biochemical diversity of Lemongrass in Khunti district of Jharkhand
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Date
2024
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Birsa Agricultural University, Ranchi
Abstract
The microclimatic conditions of an area affect largely on the quality of any species which is a base for attaining Geographical Indication (GI) tag. It is seen in many species of plants that the climatic and edaphic conditions of a particular area contribute to the uniqueness; that is seen in many species. However, in the area of medicinal plants, very scanty research has been done to screen out unique cultivar having specific properties to meet the demand of GI tag. It has been observed in Jharkhand in case of Lemongrass, the biochemical content (Citral) is found significantly superior irrespective of the species rather due to local climatic and edaphic conditions. So, in this research work, impact of climatic and edaphic conditions on the biochemical constituents, growth and yield parameters of Lemongrass under in-vivo conditions was evaluated to screen out the superior variety and to establish that the biochemical constituent in Khunti zone (Marker area) was mostly influenced by the climatic and edaphic conditions. So to assess the different germplasm of Lemongrass in search of superior chemotypes, which are influenced by local climatic and edaphic conditions irrespective of varieties under in-vivo conditions, a systematic research namely “Assessment of morpho-biochemical diversity of Lemongrass in Khunti district of Jharkhand” was undertaken for geo-referencing of traits and to analyse its biochemical constituents with a reference line of Khunti district and its adjoining areas with the following objectives (i) To assess morpho-biochemical diversity of Lemongrass in all three agro climatic zones of Jharkhand under in-vivo conditions (ii) To conduct geo-referencing of morpho-biochemical traits of Lemongrass in all three agro climatic zones of Jharkhand under in-vivo conditions (iii) To analyse the traits association studies with local climatic and edaphic conditions to screen out striking factors contributing towards uniqueness of Lemongrass.
The study involved 50 different Lemongrass germplasm as treatments, with three replications and 30 plant samples in each treatment. Forty germplasm were collected from agro-climatic zone V and five each from zones IV and VI, respectively. At every location, details like coordinates, altitude, plant growth, yield measurements, and soil samples were carefully recorded. Biochemical analysis of Lemongrass oil was done using GCMS at CIMAP in Lucknow. Weather data was collected throughout the plants' growth stages until they were ready for harvesting. To understand the diversity, geo-referencing and grid mapping were done using DIVA-GIS (Version 7.5). Statistical evaluations were carried out using OPSTAT, INDOSTAT and independent t-test.
Lemongrass germplasm had two types of plant growth habits, erect and semi-erect and most of them belongs to semi-erect types (64.00 %). Based on leaf blade color, 28 germplasm (56.00 %) exhibited a green hue. 70.00 % germplasm exhibited stem colour as green with reddish-purple tinges. Highly significant difference was observed in mean plant height and mean culm diameter between the germplasm collected from agroclimatic zone IV & V and V & VI. Maximum plant height was recorded for T4 (162.33 cm) followed by T7 (157.67 cm) and T6 (156.00 cm). Maximum culm diameter was recorded for T3 (0.82 cm) followed by T12 (0.80 cm) and T13 (0.81 cm). Highly
significant difference was observed in mean leaf blade length between the germplasm collected at agroclimatic zone IV & V and V & VI. Maximum leaf blade length was recorded for T7 (76.33 cm) followed by T3 (75.67 cm) and T4 (74.00 cm). Non-significant difference was observed in mean leaf blade width and mean number of effective tillers/culm between the germplasm collected from all three agroclimatic zones. Non-significant difference was also observed in mean herbage yield/plant between the germplasm collected from all three agro climatic zones. Maximum herbage weight per plant was recorded for T16 (1.07 kg) followed by T11 (1.06 kg) and T2 (1.02 kg). Highly significant difference in the essential oil content (%) was observed between different the germplasm collected from IV and V as well as IV and VI. Maximum essential oil content was recorded at T17 and T40 (0.65 %) which was at par with 27 treatments. Highly significant difference was observed in mean refractive index of oil between the germplasm collected from agro climatic zone IV & VI. Total citral % of Lemongrass germplasm collected from different agro climatic zones varied from 77.27 to 63.42%. Highly significant difference was observed in citral content between the germplasm collected at agro climatic zone IV & V and IV & VI. Number of compounds isolated from Lemongrass oil varied highly significantly and its maximum value was recorded for T49 (43) and minimum of T50 (16).
Citral content of Lemongrass showed highly positive significant correlation with essential oil content (0.503), plant height (0.559), culm diameter (0.529), leaf blade length (0.638), however among climatic factors it had significant positive correlation with mean temperature (0.366) but highly significant negative correlation with rainfall (-0.717). In case of soil physical parameters, citral content of Lemongrass showed significant negative correlation with bulk density (-0.367) of soil, while in case of soil chemical parameters, citral content of Lemongrass oil showed non-significant positive correlation with organic carbon (0.162), available nitrogen (0.162) and available phosphorus (0.271) of soil. Regression analysis of climatic factors indicated that mean temperature (1.481) of the location had a significant impact while among the soil physical parameters indicated that sand % (1.245) and silt % (1.429) of the soil had a significant impact on the citral content of Lemongrass oil. Again, among the soil chemical parameters, only available phosphorus of soil (1.447) had significant positive impact on the citral content. Path value analysis of climatic factors revealed that mean temperature (0.272) and mean relative humidity (0.009) had direct positive impact on citral content and among soil physical parameters maximum positive direct impact of citral content was shown by sand % (7.57). In soil chemical parameters, only available phosphorus (0.483) had direct positive direct impact of citral content. Among the sources of diversity, herbage yield/culm (22.53%), essential oil content (20.65%) and leaf blade width (20.49%) contributed maximum diversity of collected Lemongrass germplasm.
As regards the first objective namely “Morpho-biochemical diversity of Lemongrass in all three agro climatic zones of Jharkhand under in-vivo conditions”, significant differences in various traits among collected Lemongrass germplasm was observed. Highly significant difference was observed between ACZ V (Khunti) & IV (Hazaribag) as regards to plant height, culm diameter, leaf blade length, geranial, neral,
citral, essential oil content, whereas, highly significant differences was observed between ACZ IV (Hazaribag) & VI (Chandil) with regards to essential oil content, refractive index, geranial and citral of Lemongrass germplasm. Among the sources of diversity, herbage yield/plant (22.53%) and essential oil content (20.65%) created maximum contribution towards the diversity of Lemongrass germplasm. 3D cluster diagram analysis indicated that the germplasm (T46 to T50) from ACZ VI (Chandil) was quite diverse from ACZ IV and V. Similarly, the germplasm of ACZ V (T2, T22, T31, T35 and T38) also shown significant diverse status from other germplasm. Superior germplasm of Lemongrass identified with high citral content were from ACZ V, T14 (77.27%) and T13 (76.60%).
As regards to the second objective namely “Geo-referencing of morpho-biochemical traits of lemongrass in all three agro climatic zones of Jharkhand under in-vivo conditions” it may be inferred that plant height of Lemongrass germplasm from ACZ V was significantly superior than ACZ IV and VI, however number of effective tillers/culm was same for ACZ V and VI, which was more than ACZ IV. Maximum total citral content was found for ACZ V, followed by ACZ VI and minimum for ACZ IV.
As regards to the third objective namely “Traits association studies with local climatic and edaphic conditions” it may be inferred that mean temperature (0.366) showed significant positive impact on citral content but total rainfall (-0.717) had highly significant negative impact on it, which is also confirmed by regression analysis and path value analysis. Bulk density (-0.367) of soil had significant negative impact on citral content, while available phosphorus of soil (1.447) had significant positive impact on the citral content but total rainfall (-0.275) had direct negative impact on it.
The study suggests that agro-climatic zone V of Jharkhand demonstrated superior growth, yield, and biochemical production of Lemongrass. Hence it can be firmly concluded that the Lemongrass germplasm of ACZ V (Khunti zone) has potentially superior biochemical constituents, which may be screened out to be suitable candidate for GI tagging. To reinforce these findings, further investigations, including expanding the sample size and conducting molecular analyses on Lemongrass can be pursued.