To its fans, jatropha is a miracle crop, an eco-friendly answer to India's growing energy needs, but some experts are starting to question whether the wonder-shrub is too good to be true.
The seeds of the wild plant, which grows abundantly across India, produce non-edible oil that can be blended with diesel, to make the biofuel that is part of government efforts to cut carbon emissions and combat climate change.
That, combined with the shrub's much vaunted ability to flourish on poorly irrigated land, should make it the perfect crop for wasteland in the drought-prone nation.
But new research shows jatropha, which has received huge government backing in recent years, yields less than experts had first predicted and is now being grown on fertile farmland - undermining two of its best selling points.
"Jatropha is being talked of as a crop that will grow on marginal and uncultivated land, and which will not compete with mainstream cultivation," said Sharachchandra Lele, a senior fellow at ATREE, an Indian environmental research group promoting sustainable development.
"But this is not what is happening in practice. Some state governments are promoting its cultivation on regular agricultural land, where it will displace existing crops, including food crops," said Lele.
"We are basically subsidising the urban elite's petrol consumption at the cost of rural livelihoods and food production."
The Indian government has aggressively promoted production of the crop, setting its sights on 11 million hectares (27 million acres) of plantations nationwide by next year.
Government policy stipulates that by 2017 all petrol and diesel fuel must have 20 percent biofuel content, one of many moves aimed at reducing greenhouse gas emissions blamed for climate change.
K.D. Gupta, chairman of the Institute of Applied Systems and Rural Development, one of the staunchest backers of jatropha for biofuel, denied that good agricultural land was being used to cultivate the crop.
"Farmers are not going to plant jatropha, because other crops are yielding more returns," said Gupta.
Two Indian research institutes initially reported a yield of 7.5 tonnes of jatropha seeds per hectare (three tons per acre) under irrigated conditions.
Similarly, a 2007 report by the state-run National Oilseeds and Vegetable Oils Development Board (NOVOD) predicted yields of three to five tonnes per hectare.
But research by ATREE has shown that yields under normal conditions were less than one tonne per hectare and suggested it was doubtful yields could ever reach those touted by the crop's supporters.
The poor results have not dashed the hopes of businesses keen to promote the plant.
"It all depends on how you manage the crop," said Subhas Patnaik, chief operating officer of Mission Biofuels, which started cultivating jatropha in 2007 and currently owns around 130,000 hectares in five states.
"The whole challenge is how to get better yields from this crop and once you're able to prove that to the farmer and to everybody then definitely it is going to be a miracle crop," said Patnaik.
Gupta said his Institute of Applied Systems and Rural Development had planted two million jatropha saplings over 1,300 hectares mostly in northern India and said it was too early to judge the crop, because it took years to fully develop and produce desirable returns.
But ATREE's Lele remains unconvinced.
"Neither for energy security nor for mitigating carbon emissions is jatropha cultivation by any means the first option," he said.
"Much more could be achieved through investments in public transport and reductions in private vehicle use."Reuse content