Cocktail of bacteria/fungi addresses zinc deficiency in rice

Almost half of the soils in the world are deficient in zinc.
Image used for representational purposes only
Image used for representational purposes only

Good news for paddy farmers. Researchers at the Department of Soil Science and Agricultural Chemistry in the Institute of Agriculture Sciences-Banaras Hindu University (IAS-BHU), Varanasi have developed a consortia of bacteria and fungi, which holds the promise of offering an economical and effective mechanism to paddy farmers for addressing zinc deficiency in their crop.

Zinc (Zn) deficiency is reportedly the most widespread micronutrient disorder in rice worldwide, including India. Its occurrence has increased particularly with the introduction of modern varieties, crop intensification and increased zinc removal.

Almost half of the soils in the world are deficient in zinc. Since cereal grains have inherently low concentrations, growing these on potentially zinc-deficient soils further decreases grain zinc concentration. There is a high degree of correlation between zinc deficiency in soils and in human beings, particularly as zinc is an essential nutrient for human health.

According to the World Health Organization (WHO), about 8,00,000 people die annually due to zinc deficiency, of which 4,50,000 are children under the age of five. About one-third of the world’s population suffers from zinc deficiency

To address the zinc deficiency in rice, the researchers led by Dr Janardan Yadav, Head of the Department of Soil Science and Agricultural Chemistry (IAS-BHU) in Varanasi, isolated and developed a set of 8-10 microorganisms (bacteria and fungi), which have the potential of zinc solubilizing, ultimately leading to the critical micronutrient’s better uptake by the paddy plant through its entire life cycle.

By integrating the consortia of the zinc solubilizing bacteria and fungi with nano zinc oxide and applying the resultant product to the paddy seedling or spraying it on the growing crop, Dr Yadav and his team claim to have achieved the same results as is found by applying zinc sulphate fertiliser, but at seven to eight times lesser cost. “The research spanning from the lab to the pot culture at the big net house and finally at the institute’s agriculture farm took around 6-7 years and the results are encouraging. The same zinc uptake by the rice plant achievable currently by administration of 25-30 kg zinc sulphate in one hectare area, is now achievable at seven to eight times lesser investment by nano zinc obtained through integration of our consortia of zinc solubilizing bacteria-fungi with one kg of zinc oxide,” Dr Yadav told this newspaper.

“In our consortia (whose culture will be deposited with the ICAR-National Bureau of Agriculturally Important Microorganisms in Mau Nath Bhanjan, UP for preservation and future use) we’ve placed the most effective of the 8-10 bacteria and fungi, whose isolation helped in the effective biosynthesis of the nano zinc oxide (ZnO). Treatments with nano ZnO significantly improved plant height, chlorophyll content (SPAD values), tiller numbers, panicle length, and grain and straw yields. Higher doses and multiple applications of nano ZnO outperformed conventional zinc fertilisers. Zinc fertilisation had minimal impact on soil pH but influenced electrical conductivity (EC) and enhanced soil organic carbon (SOC) levels. Available nitrogen, phosphorus, potassium and zinc levels in post-harvest soil were positively affected, especially with root dipping methods. Enzyme activities (dehydrogenase and alkaline phosphatase) and microbial proliferation in soil increased with higher zinc concentrations and specific application methods,” Yadav said while sharing the outcome of the research, involving two successful PhD scholars Pukhrambam Helena Chanu and Jaya Prajapati.

“With the paddy sowing season about to begin, we’re also working on creating packets of nano zinc particles with the help of the consortia of the zinc solubilizing microorganisms for distribution, among the paddy farmers of Varanasi and adjoining regions,” Yadav informed. The findings have already been reported in the Geomicrobiology Journal and are being submitted for publication in Soil Biology and Biochemistry Journal.

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