BIOFORTIFICATION WITH NANO ZINC AND IRON IN FINGER MILLET-GREENGRAM SEQUENCE
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Date
2023-11-10
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Abstract
The present experiment entitled “Biofortification with nano zinc and iron in finger millet- greengram sequence” was conducted as four sub-experiments viz., characterization of ZnO and FeO nanoparticles, in-vitro germination test, pot culture experiment and field experiment with finger millet-greengram sequence.
Nano ZnO and FeO prepared at IFT, RARS, Tirupathi were characterized through XRD (X-Ray Diffraction) Analysis, SEM (Scanning Electron Microscopy) analysis, Fourier Transform Infrared spectroscopic analysis (FT-IR) and Zeta potential for confirmation of its size, shape and stability at nano laboratory, University of Agricultural Sciences, Raichur and IFT, RARS, Tirupathi. The shape of the ZnO and FeO nanoparticles were Hexagonal wurtzite structure and Rhombohederal structure respectively. The mean size of the ZnO and FeO nanoparticles were 38.9 nm and 77.4 nm respectively and the zeta potential values were 70.1mV and -40.9mV respectively for ZnO and FeO nanoparticles.
Invitro-germination tests were conducted at Agricultural College, Bapatla in finger millet and greengram with ZnO and FeO separately for fixing of optimum doses of these nutrients for seed priming. Different concentrations of nano ZnO / nano FeO were tested along with control (distilled water) and corresponding bulk ZnSO4 /FeSO4 and found that the highest germination per cent, seedling vigour index and speed of germination of finger millet were observed with 50 ppm nano ZnO and nano FeO. A similar response was observed with nano ZnO @ 50 ppm and nano FeO @ 50 ppm in greengram. Hence, 50ppm concentration of these nano nutrients was considered as optimum doses for seed priming in these crops.
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Pot culture experiment was carried out with different concentrations of nano ZnO and FeO separately on finger millet and greengram crops during pre kharif, 2018 at Agricultural College, Bapatala and identified that 200ppm of nano ZnO, 200ppm of nano FeO in finger millet, 100ppm of nano ZnO, 100ppm of nano FeO in greengram as optimum doses for foliar applications as they produced highest plant height, drymatter accumulation and chlorophyll contents.
The field experiment was conducted for two consecutive years (2018-19 and 2019-20) with finger millet (kharif) - greengram (rabi) sequence at Agricultural Research Station, Vizianagaram, Andhra Pradesh on deep red loamy soils containing low OC, neutral pH, low in available N, high in available P2O5, medium in available K2O, low in Zn and low in Fe. In finger millet, seven treatments of nano and bulk sources of Zn and Fe applied through various methods at different stages of the crop were tested in randomized block design with three replications. During rabi, greengram was sown in the same field without disturbing the previous layout with various treatments including carryover influence of Zn and Fe applied to previous crop as well as seed priming and foliar spray of bulk and nanoforms of Zn and Fe applied at various stages of the crop. 100% RDF was applied to all the treatments as per recommendation in finger millet and greengram crops.
In kharif finger millet, growth attributing characters (plant height, leaf area index and drymatter accumulation), yield attributing characters (number of productive tillers per hill, earhead length, number of fingers per ear, earhead weight and test weight), grain yield and straw yield were found highest with T4, however, it remained on par with T3 and T7 during both years of study and in pooled data. The lowest growth, yield attributes, grain and straw yields were recorded with T1 (control), where RDF alone was applied.
The grain zinc and iron contents and uptakes were highest with T4, however, it remained on par with T7 but significantly superior over T3. Whereas in the case of straw, zinc and iron contents and uptakes recorded with T4, T7 and T3 were on par with each other. Zn harvest index was highest with T7 and Fe harvest index was highest with T4. Control was found with the lowest zinc and iron contents and uptakes in both grain and straw. The highest grain protein content was observed with T4, however, it remained at par with T3 and T7. Grain anti-nutritional parameters like phytic acid and tannin contents were lowest with T4, but it was in statistical parity with T3 and T7.
Concerning the economics of various treatments in finger millet, the highest gross returns were registered with T4, T3 and T7 as compared to other treatments. However, the net returns and benefit-cost ratio were found highest with T3.
The zinc and iron treatments applied in rabi greengram had a tremendous effect during both years of study and found that all the yield attributes (number of pods per plant, number of seeds per pod and test weight), grain yield and haulm yield were significantly higher with T7 but it remained on par with T4.
Grain Zn and Fe contents were highest with T7, but they remained in statistical parity with T4. But Zn and Fe uptakes in grain were significantly highest with T7 as compared to the rest of the treatments. Haulm uptake of Zn and Fe was highest with T7 but found at par with T4.
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The economics of rabi greengram showed that the T7 realized the highest gross and net returns but it remained on par with T4. Concerning the benefit-cost ratio, T3 realized the highest but was found on par with T7. The lowest benefit-cost ratio was obtained with control.
Based on the above discussion it can be concluded that from the pre kharif in-vitro germination test, 50 ppm of nano ZnO and nano FeO were optimum for seed priming in finger millet and greengram crops. From the pot culture study with nano ZnO and FeO, it could be inferred that 200ppm of nano ZnO and 200ppm of FeO in finger millet, 100ppm of nano ZnO and 100ppm of nano FeO in greengram were found as optimum doses for foliar applications. Basal ZnSO4 (50 kg ha-1) and FeSO4 (25 kg ha-1) + Foliar nano ZnO (200 ppm) and FeO (200 ppm) at pre flowering and grain filling along with RDF significantly enhanced growth and yield attributing characters, grain and straw yield in finger millet, zinc and iron contents and uptakes in grain and hence was found as the optimum combination for finger millet. The performance of greengram was found best with respect to growth and yield attributing characters and grain and haulm yields, grain biofortification with zinc and iron when it was supplemented with RDF+ seed priming with nano ZnO (50 ppm) and nano FeO (50 ppm) + Foliar nano ZnO (100 ppm) and nano FeO (100 ppm) at peak vegetative stage and at appearance of 1st flower. System economics of finger millet-greengram sequence revealed that the gross returns were highest with T7, whereas the net returns and BCR were highest with T3. However, highest system productivity in terms of finger millet equivalent yield was observed with seed priming with nano ZnO (50 ppm) and FeO (50 ppm) + Foliar nano ZnO (200 ppm) and FeO (200 ppm) at maximum tillering and pre flowering stage and hence can be recommended as the best treatment provided the present cost of nano fertilizers is not a hindrance for its future adoption by the farmers taking into consideration the huge reduction in application of bulk fertilizers, environmental safety and reduction in micronutrient malnutrition in humans as the major priorities.