By planting on ridges in February
Mint, Mentha arvensis, is a highly valued plant due to the presence of menthol. But the crop requires lots of water. And the plant grows slowly, has low productivity. This increases the cost.
How do we make mint more attractive to farmers?
To optimise and enhance productivity of mint plantation, Devendra Kumar and his team from the CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow did a series of experiments.
Mint rhizomes can be planted on flat, raised or ridged beds. They planted them on all three types of beds.
Mint is a summer crop and can be planted in February, March or April. They planted mint in the first week of all three months.
The crop can be grown with different densities of planting. They tested separating the rows by 30 centimetres or 60. And they separated the plants on each row by 20 centimetres or 25. Thus they tested four options in the density of planting.
They did this series of experiments for two years.
The researchers noticed that crops sown in February, grown on ridge beds with low plant density, always matured earlier.
“Ridge beds provide proper aeration and water distribution”, explains Saudan Singh, CSIR-CIMAP, Lucknow.
Crops planted on ridges in February yielded more than those planted in March or April.
“February has low temperatures and relatively higher humidity. The sun is less harsh and less soil moisture evaporates. So you save on water for irrigation”, explains Devendra Kumar, CSIR-CIMAP.
The researchers then extracted and quantified mint essential oil from each set up.
Oil content was higher in mint grown on ridge beds.
“Leaf fall was lower in plants grown on ridges. And there were more leaves on stems”, explains Kirti Verma, CSIR-CIMAP.
The researchers estimated menthol content using chromatography. It was more in plants grown on ridge beds with low plant density.
‘In March and April, soil temperature increases inducing stress on plants. As a response, menthol production also increases”, says Vivek Singh, CSIR-CIMAP.
The team analysed the total number of irrigations and the depth of irrigation in each bed. Ridge beds had the least water requirement.
“This is due to the upward movement of water in ridge beds. In other systems, water percolates down with gravity, increasing water requirement”, explains Nilofer, CIMAP.
The team analysed the costs and benefits to farmers. February had the lowest cost of cultivation and provided high income with ridge beds separated by 30 centimetres and plants separated by 25 centimetres.
“Planting mint early reduces the chances of weeds competing with the crop”, says Rakesh Kumar, CSIR-CIMAP, Lucknow.
“So, planting mint on ridges in February at the right density of plantation can provide good income to farmers in Gangetic Plains”, says Anjali Singh, his colleague.
Industrial Crops and Products, 162: 113233 (2021);