M. R. Latha

Background: Naturally occurring iodide iodine exhibits complex soil behavior. Even though higher plants don’t consider iodine a vitamin, living things need it. Iodine is part of the thyroid hormone, which is vital to human health and metabolism. Potassium is the most effective cation for tomato plants and has a crucial role in improving several post-harvest quality characteristics in tomato fruits as well as in almost all vegetables. Methods: In the present work, we assessed the growth, yield and quality (Ascorbic acid, Titrable acidity and soluble solids) of tomatoesfrom different sources of chitosan and potassium iodate alone and combinations. The field experiment was carried out in the Thondamuthur block of Viraliyur village in the Coimbatore district of Tamil Nadu in 2022. The experiments were performed in randomized block design with three replications in palaviduthi soil series using hybrid tomato “Shivam”. Result: The chitosan iodate complex and foliar application combination enhanced the growth, yield and quality of tomato. Potassium iodate alone applied to soil and foliar, improved fruit quality but did not prevent acid loss during ripening. Chitosan reduces respiration and oxygen permeability to preserve losses. Thus, potassium iodate chitosan complex was favoured for boosting plant growth, fruit yield and quality.

Background: Iodine is found in soils in both inorganic and organic forms [Iodate-(IO3-) and Iodide-(I-)]. Iodine is highly prone to leaching and volatilization which results in iodine depletion in soils. Crops cultivated in these soils will be lacking in iodine and humans and animals eating food grown in these soils will be deficient in iodine. Numerous studies have focused on the process by which iodine is absorbed from the soil, but there is still paucity of knowledge on different fractions of iodine in soils. Methods: In our work, we assessed different fractions of iodine (Water Extractable, Exchangeable, Organic bound, Oxide bound and Residual iodine) in soil from different sources of chitosan and potassium iodate alone and combinations. The incubation experiment was carried out in the department of soil science and agricultural chemistry, Tamil Nadu Agricultural University, Coimbatore in 2022. Potassium iodate and chitosan were applied in the form of soil alone, soil drenching and chitosan iodate complex at different stages of incubation. Result: The results suggested that combination and potassium iodate and chitosan complex has increased the iodine stability throughout the incubation experiment. As electrostatic interaction between chitosan and iodate prevents volatilization and gradually stabilizes the availability of iodine. Our findings offer more details on iodine mobility and behaviour in soil when it is used alone and combination with chitosan at different rates.

Background: Even though iodine is not an essential micronutrient for the plant, it is very much needed for a person's mental and physical development. Due to the presence of negative charge on iodine it is highly susceptible to leaching. Further iodine is also highly prone to volatilization loss due to biochemical and physiochemical properties of soil leading to iodine deficiency. Agronomic biofortification of iodine is one of the ways to address iodine deficiency globally. Numerous studies have focused on the process by which plants absorb iodine from the soil, but there is still paucity of knowledge on stability of biofortified iodine in fruits. Methods: In our work, we assessed iodine bioavailability (Cooking, soaking and digestion) in tomato fruit from different sources of chitosan and potassium iodate alone and combinations using main and residual crop trials. The field experiment was carried out in Thondamuthur block of Viraliyur village at Coimbatore district of Tamil Nadu in 2021. Potassium iodate and chitosan were applied in the form of soil, foliar, and chitosan iodate complex at different stages of plant growth. Results: The results suggested that combination and potassium iodate and chitosan complex has increased the iodine stability in fruits of main crop and also retained the iodine in residual crop. As electrostatic interaction between chitosan and iodate prevents volatilization and gradually stabilizes the bioavailability of iodine in fruits. Our findings offer more details on iodine mobility and behaviour in fruits when it is used alone and combination with chitosan at different rates.

Background: Sulphur is rapidly being recognized as fourth key nutrient for plants after nitrogen, phosphorus and potassium. It functions in several critical metabolic and physiological processes, such as Chlorophyll synthesis, Protein synthesis, Activation of enzymes, Stress tolerance and Seed production. This study was carried to investigate the effect of synthesized nano sulphur in combination with organic amendment to study available sulphur status in calcareous soil. Methods: Nano sulphur was synthesized using reverse microemulsion (water-in-oil microemulsion) technique and characterized at the Centre for Agricultural Nanotechnology, TNAU, Coimbatore. An incubation experiment was carried out with synthesized nano sulphur and gypsum as sulphur source with and without FYM to determine sulphur release at various intervals (7th,15th,30th,45th and 60th days after incubation). Result: It was observed that nano sulphur applied at 40 kg S ha-1 with FYM showed high release of sulphur in calcareous soil in all intervals analysed during the experiment. The addition of organic manures aids in proliferation of heterotrophic sulphur oxidising bacteria which enhances the sulphur oxidation in alkaline soil.

Background: The study on the effect of varied plant density with different pruning levels on growth and flower yield in Jasminum sambac (L.) was carried out at the Department of Floriculture and Landscape Architecture, TNAU, Coimbatore during 2021-2022. Methods: The experiment was laid out in Factorial Randomized Block Design (FRBD) with eight treatment combinations and replicated thrice. The treatments comprised of T1 (D1P1)- Control = One plant pit-1 + one pruning year-1, T2 (D1P2) = One plant pit-1 + two prunings year-1, T3 (D2P1) = Two plants pit-1 + one pruning year-1, T4 (D2P2) = Two plants pit-1 + two prunings year-1, T5 (D3P1) = Three plants pit-1 + one pruning year-1, T6 (D3P2) = Three plants pit-1 + two prunings year-1, T7 (D4P1) = Four plants pit-1 + one pruning year-1, T8 (D4P2) = Four plants pit-1 + two prunings year-1 respectively. Pruning treatments were imposed on one year after planting of J. sambac (L.) a new clone (nine budded clone) which is prolific and high yielder. Most of the growth and yield parameters were significantly influenced by increased plant densities and pruning levels. Result: Considering the growth and flowering traits in Jasmine, the pooled data indicated that the treatment T6 (D3P2) i.e. three plants pit-1 + two prunings year-1 was found superior for growth and flowering parameters namely plant height (84.47 cm), canopy spread (0.350 m2), number of primary branches plant-1 (16.27), number of secondary branches plant-1 (36.73), number of cymes plant-1 (1989.7), number of nine budded cymes plant-1 (911.0), number of flower buds plant-1 (2875.0), flower yield plant-1 (730.3 g) and flower yield ha-1 (5071.0 kg) whereas, lowest yield (3241.5 kg/ha) was observed in T1 (D1P1) i.e. one plant pit-1 + one pruning year-1. But the parameter on days taken for first harvest of flower buds, number of flower buds cyme-1 and weight of hundred flower buds was found to be non-significant. The results might be due to increased plant density combined with alteration in pruning have enhanced not only speedy plant growth and vast canopy spread but also other yield attributing parameters such as increased number of cymes with nine buds per hectare which in turn might have resulted in higher flower production when compared to conventional planting.