Ameliorative Potential of Vetiver for Reclamation of Sodic Soils

By Arun Prasad and DD Patra, Central Institute of Medicinal and Aromatic Plants, Lucknow, India, <ddpatra@rediffmail.com>

Soil sodicity as such causes marked imbalance in nutrient absorption by plants. A high concentration of sodium restricts potassium and calcium accumulation in plant tissues. The great ability of Vetiver to limit sodium entry into shoot tissues and to maintain sufficient potassium and calcium concentration at high sodicity levels indicate tolerance of vetiver to sodic stress. Significantly greater accumulation of Na+ in the root than in the shoot tissues indicates that vetiver regulates the Na+ concentration by restricted translocation of Na+ from root to shoot tissues.

Ability of Vetiver to withstand higher pH and water-logging makes it suitable for cultivation in sodic lands which have low infiltration capacities. We conducted several experiments under glasshouse, microplots and field condition. Our results from experiments indicate that Vetiver could withstand high soil alkalinity upto pH 10.0. However, the performance of the crop is not that satisfactory under saline condition. Soil and irrigation water salinity beyond  10.0 and 12.0 dSm-1, respectively decreased the root yield to a great extent. On the other hand shoot and root yields of Vetiver were not significantly affected with the high sodium adsorption ratio (SAR) of 31.9 me/L(with EC 12.5 dS/m) and residual sodium carbonate (RSC) of 2.0 me/L (EC 3.0) of irrigation water. The soil sodicity did not have an adverse effect on the quality of the oil as this was found to be at par with the market specifications; in some cases it is even better.

             Growing of Vetiver in sodic soil resulted in significant reduction in pH, EC and ESP and increase in organic carbon content in soils after harvest of crop due to biological action of

roots. The result of an experiment indicate that the soil pH was reduced from 10.5 and 9.5 to 9.5 and 9.0, respectively with growing of Vetiver for a period of eighteen months.

Utilization of sodic soils for cultivation of Vetiver will create a tremendous employment generation (estimated to be 167 m man days/ha/year) in rural India. Thus, the benefits of cultivation of Vetiver in barren sodic lands are quite encouraging in terms of higher crop productivity to meet the demands of raw materials in national or international market, high economic return, bio-reclamation of sodic soils and employment generation in the rural areas. However, the oil yields are sometimes  lower. Therefore,there is a need to develop the varieties which can withstand high salinity and sodicity without reduction in the oil yield..

Tolerance of Vetiver to Salt Stress under Simulated and Natural Field Condition

Vetiver is very hardy in nature and can be grown on a variety of problem soils including soils low in fertility, marginal lands, periodically waterlogged soils, eroded lands, salt-affected soils, and water stressed soils with minimal inputs. It has been observed that the ability of vetiver  to withstand higher pH and waterlogging makes it suitable for cultivation in sodic lands which have low infiltration capacities. We conducted several experiments under glasshouse, microplots and field condition. Our results from experiments indicate that vetiver could withstand high soil alkalinity upto pH 10.0. However, the performance of the crop is not that satisfactory under saline condition. Soil and irrigation water salinity beyond  10.0 and 12.0 dSm-1, respectively decreased the root yield to a great extent. On the other hand  shoot and root yields of vetiver were not significantly affected with the high sodium adsorption ratio (SAR) of 31.9 me/L (with EC 12.5 dS/m) and residual sodium carbonate (RSC) of 2.0 me/L (EC 3.0) of irrigation water. The soil sodicity did not have an adverse effect on the quality of the oil as this was found to be at par  with the market specifications: in some cases it is even better.

          Soil sodicity as such causes marked imbalance in nutrient absorption by plants. A high concentration of sodium restricts potassium and calcium accumulation in plant tissues. The great ability of Vetiver to limit sodium entry in shoot tissues and  to maintain sufficient potassium and calcium concentration at high sodicity levels indicate that it is a tolerant to sodic stress. The significantly greater accumulation of Na+ in the root than in the shoot tissues indicates that vetiver regulates the Na+ concentration by restricted translocation of Na+ from root to shoot tissues.

The cost and benefits of cultivation of medicinal and aromatic crops in salt affected soils  indicate that the net benefits derived from the cultivation of Vetiver in salt affected soils is higher than the traditional agricultural crops (Rice - wheat cropping system).

Vetiver has a great ameliorative potential for reclamation of sodic soils. Growing of Vetiver in sodic soil resulted in significant reduction in pH, EC and ESP and increase in organic carbon content in soils after harvest of crop due to biological action of roots. The result of an experiment indicate that the soil pH was reduced from 10.5 and 9.5 to 9.5 and 9.0, respectively with growing of Vetiver  for a period of eighteen months. Utilization of sodic soils for cultivation of Vetiver will create a tremendous employment generation (estimate to be 167 m man days/ha/year) in the rural areas in India. Thus, the benefits of cultivation of Vetiver in barren sodic lands are quite encouraging in terms of higher crop productivity to meet the demands of raw materials in national or international market, high economic return, bio-reclamation of sodic soils and employment generation in the rural areas. However, the oil yields are sometimes  lower. Therefore,there is a need to develop the varieties which can withstand high salinity and sodicity without reduction in the oil yield, using the recent techniques of  plant molecular biology and genetic engineering.