Onion roots do not penetrate far into the soil. So they require fertilizers for good yield. However, excessive fertilising impacts the environment negatively. But how do we increase yield without contaminating the environment?
Image: Bishnu Sarangi via Pixabay
Some root-associated bacteria help plants assimilate nutrients, grow better, and manage environmental stress. Among these, which rhizobacteria can we use in tomato crops to reduce our use of chemical fertilisers?
Diksha Tinna, a young researcher, and her supervisor, Neena Chawla, in collaboration with other faculty from the Punjab Agricultural University, now have the answer.
They picked nursery-grown seedlings of the onion cultivar, Punjab Naroya, dipped the roots in culture containing six different combinations of bacteria – Azotobacter sp., Bacillus sp., Burkholderia sp., and Sphingobacterium sp. that they had isolated from soils.
After transplanting the seedlings, along with the rhizobacteria combinations, the team used the mineral fertilizers, nitrogen, phosphorus and potassium, at 100% and 75% of the recommended dose.
The plants showed better height and leaf count when 100% fertilizers were used, irrespective of bacterial treatment. But the rhizobacterial consortia containing Azotobacter sp., Burkholderia sp. and Sphingobacterium sp. acted as potential supplement to increase both onion yield and bulb weight by more than 10 percent. This was more than seen in the uninoculated control in the two-year data.
The plants provided with 75% fertilisers and treated with the triple bacterial culture showed about 8% increase in the yield. Although this is lower than the yield from plants grown with 100% fertilisers, the increase is more significant than what is seen in the control, say the scientists.
“This consortium of rhizobacteria can reduce the use of chemical fertilisers by 25% and yet provide higher yield,” beams Diksha Tinna, Punjab Agricultural University.
“It can change the economics of growing onions in the country”, adds her mentor, Neena Chawla.
“India has about one million hectares under onion cultivation and presently contributes to nearly 20 percent of the world’s total onion production. Even a 8 percent increase in production can help India become the largest producer of onions”, says Naveen Garg, Punjab Agricultural University.
Scientia Horticulturae, 270:109432 (2020);
Freelance Writer, Bangalore
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