Intoduction broadoutine
Phd
India, a major contributor, produced 106.84 million tonnes of wheat and 33.62 million
tonnes of maize in 2021–22, ranking second globally in wheat production (pib.gov.in). In
Himachal Pradesh, maize and wheat are principal crops. In 2021–22, the state produced
approximately 703,260 metric tonnes of maize and 590,000 metric tonnes of wheat
(agriculture.hp.gov.in, ceicdata.com). Acid Alfisols are commonly associated with low
phosphorus (P) and zinc (Zn) availability due to strong fixation by aluminum and iron oxides
(Fageria & Baligar, 2008). However, in intensively cultivated regions under maize–wheat
systems, repeated application of P fertilizers—often without corresponding Zn
supplementation—has led to an atypical buildup of available P in these inherently acidic
soils (Shukla et al., 2014; Singh et al., 2017). This overapplication, intended to address
traditional P deficiency, has resulted in a new imbalance: high soil P levels that exacerbate Zn
deficiency through antagonistic interactions (Alloway, 2008; Cakmak, 2000).
Interestingly, the P–Zn interaction is not strictly antagonistic. Several studies have reported
that at optimal levels, co-application of P and Zn can have synergistic effects on nutrient
uptake and crop productivity (Hafeez et al., 2013; Singh et al., 2018). These beneficial
effects, however, are dose-dependent and strongly influenced by soil type, existing nutrient
status, and crop species. In systems where residual P is high, even moderate Zn deficiency
can limit yield potential and nutrient use efficiency, making it crucial to re-assess fertilization
strategies based on actual soil conditions rather than generalized recommendations.
This research is grounded in this shift from the classical view of nutrient deficiency to a
more complex understanding of nutrient interactions in modern agriculture. It seeks to
examine the interactive effects of P and Zn under non-typical conditions—specifically, in
high-P acid Alfisols where Zn may be the more limiting factor. By studying how varying
combinations of P and Zn influence nutrient dynamics, uptake efficiency, and yield
performance of maize and wheat, this work aims to generate practical insights for balanced
nutrient management tailored to changing soil fertility trends.
References:
Alloway, B. J. (2008). Zinc in soils and crop nutrition. International Zinc Association.
Cakmak, I. (2000). Possible roles of zinc in protecting plant cells from damage by
reactive oxygen species. New Phytologist, 146(2), 185–205.
Fageria, N. K., & Baligar, V. C. (2008). Ameliorating soil acidity of tropical oxisols by
liming for sustainable crop production. Advances in Agronomy, 99, 345–399.
Graham, R. D., & Rengel, Z. (1993). Genotypic variation in Zn uptake and utilization by
plants. In Zinc in Soils and Plants (pp. 107–118). Springer.
Shukla, A. K., Tiwari, P. K., & Prakash, C. (2014). Micronutrients deficiencies vis-à-vis
food and nutritional security of India. Indian Journal of Fertilisers, 10(12), 94–112.
Singh, M. V., et al. (2017). Micronutrient management in soils and crops for
improving crop productivity and minimizing environmental impacts. Indian Journal of
Fertilisers, 13(4), 92–112.
Alloway, B. J. (2008). Zinc in soils and crop nutrition (2nd ed.). Brussels, Belgium:
International Zinc Association (IZA) and Food and Agriculture Organization of the
United Nations (FAO).
Cakmak, I. (2000). Possible roles of zinc in protecting plant cells from damage by
reactive oxygen species. New Phytologist, 146(2), 185–205.
https://doi.org/10.1046/j.1469-8137.2000.00630.x
Fageria, N. K., & Baligar, V. C. (2008). Ameliorating soil acidity of tropical oxisols by
liming for sustainable crop production. Advances in Agronomy, 99, 345–399.
https://doi.org/10.1016/S0065-2113(08)00407-0
Hafeez, B., Khanif, Y. M., & Saleem, M. (2013). Role of zinc in plant nutrition: A
review. American Journal of Experimental Agriculture, 3(2), 374–391.
https://doi.org/10.9734/AJEA/2013/2746
Shukla, A. K., Tiwari, P. K., & Prakash, C. (2014). Micronutrients deficiencies vis-à-
vis food and nutritional security of India. Indian Journal of Fertilisers, 10(12), 94–112.
Singh, M. V., Shukla, A. K., & Dwivedi, B. S. (2017). Micronutrient management in
soils and crops for improving crop productivity and minimizing environmental
impacts. Indian Journal of Fertilisers, 13(4), 92–112.
Singh, R., Meena, M. C., & Singh, S. (2018). Effect of integrated phosphorus and
zinc fertilization on yield, nutrient uptake and economics of wheat. Journal of Plant
Nutrition, 41(5), 574–586. https://doi.org/10.1080/01904167.2017.1415382
Phytase activity
Spectrophotometric Assay:
Soil samples are mixed with sodium phytate and a buffer solution (like acetate buffer
at pH 5.5).
The reaction is incubated, and then terminated with a color-developing solution.
The absorbance of the solution is measured at a specific wavelength (e.g., 415 nm) to
determine the amount of phosphate released.
1. Soil Sampling and Preparation:
Soil Sampling: Collect representative soil samples from the area of interest.
Homogenization: Mix the soil samples thoroughly to ensure a representative
sample.
2. Isolation and Screening:
Dilution and Spread Plate Technique:
Dilute the soil sample and spread aliquots onto appropriate growth media, like Nutrient Agar
or Pikovskaya (PVK) agar.
Incubation:
Incubate the plates under suitable conditions (e.g., 30°C) for a few days, allowing colonies to
grow.
Selection:
Identify colonies that produce clear zones (haloes) around them on the media, indicating
phosphate solubilization.
3. Purification and Characterization:
Purification:
Isolate and purify individual colonies from the plates to obtain a pure culture.
Further Analysis:
Characterize the isolates by:
Molecular Methods: Using techniques like 16S rRNA gene sequencing or PCR
to identify the microbial species.
Biochemical Tests: Performing biochemical tests to determine their ability to
produce specific enzymes or metabolites involved in phosphate
solubilization.
P-Solubilizing Capacity Assessment: Quantify the amount of phosphate
solubilized by the isolates under controlled conditions using various media or
soil incubation experiments.
