P. Subramanian

• Head of Faculty at PSN College of Engineering and Technology (Autonomous)

Coconut (Cocos nucifera L.), the perennial tree crop, has a productive lifespan of six to seven decades. During its life cycle, soil plays a crucial role in sustaining its productivity, by providing the necessary physico-chemical and biological soil quality attributes for its sustenance. Soil health is the foundation for sustainable coconut product...

Coconut husk is widely used as a source of natural fibers in the tropics. Dehusking and fiber extraction are some of the important unit operations in coir manufacturing. For the development of an efficient and economically viable fiber extraction machine, the engineering properties of conventional and organically grown coconuts were evaluated. Sele...

Phosphorus is one of the major nutrients required for coconut production. The information about the fate of native and applied phosphorus in soil is essential for better management of the nutrient. The changes on inorganic P fractions and P availability in soil after 43 years of coconut cultivation were studied from a long term fertilizer cum manur...

The present field experiment was conducted to investigate the impact of various combinations of organic inputs on the growth of fodder grass in a coconut [Cocos nucifera (L.)]-based mixed farming during 2013-17 at ICAR-Central Plantation Crops Research Institute, Regional Station, Kayamkulam, Kerala and refined in farmer's field during 2018-21. The...

A range of plantation crops, viz., coconut palm, areca-nut palm, oil palm, cashew, cocoa, coffee, rubber and spices are cultivated in the tropical coastal agro-ecosystem to meet the needs of food, oil, beverage, industrial raw materials and fiber. Predominantly grown in small and marginal holdings, the sustainability of these crops is confronted wi...

Rose (Rosa × hybrida L.) as an intercrop in coconut plantation under tropical wet climate at Kasaragod district of Kerala state in India using 10 Indian cultivars including Hybrid Tea and Floribunda groups were grown under 3 years and 52 years old coconut plantations separately. The performance of roses was assessed based on its survival percentage...

A field experiment on drip irrigation for Chowghat Orange Dwarf X West Coast Tall (COD X WCT) coconut hybrid was conducted in laterite soil at Central Plantation Crops Research Institute, Kasaragod (Kerala, India) to study the drip irrigation requirement and its influence on growth and yield. The treatments included were three levels of drip irriga...

Coconut based high density multi-species cropping system (HDMSCS) is recommended to obtain maximum income and better utilization of resources. The crops grown under HDMSCS include fruits, vegetables, spices etc. Black pepper (Piper nigrum L.), an important spice crop, is generally a component under coconut based cropping systems. In the present stu...

Pulverization of coconut leaves including its woody petiole base improves the recycling efficiency of vermicomposting unit by 20-25% compared to using chopped coconut leaves minus the woody petiole base. The vermicompost produced by this method has better physico-chemical and microbiological properties which will be suitable for acid soils. The met...

A field experiment on evaluation of coconut based high density multi-species cropping system under organic and integrated nutrient management was initiated during 2007 in coconut based cropping system at Central Plantation Crops Research Institute, Kasaragod. Three treatments viz., T1: 2/3rd of recommended NPK fertilizer + recycling biomass (vermic...

Field investigations were carried out on arecanut based high density multi-species cropping system at Central Plantation Crops Research Institute, Research Centre, Kahikuchi, Guwahati from 1998 to 2008 to find out productivity and economics of the system. Arecanut, banana, citrus and black pepper crops were tried in two models with full, 2/3 rd and...

Investigations were carried out to assess the biomass available for recycling from coconut based high density multispecies cropping system (coconut, clove, banana and pineapple) under graded levels of fertilizers (full, two-third, one-third, one-fourth and one-fifth of the recommended level of fertilizer for each of the component crops and control)...

A field experiment on drip irrigation for West Coast Tall (WCT) coconut was conducted in laterite soil at Central Plantation Crops Research Institute, Kasaragod (Kerala, India) to study the drip imgation requirement and its influence on growth and yield. The treatments included were three leveIs of drip imgation (at 33,66 and 100% E, daily), basin...

A field experiment on drip irrigation for West Coast Tall (WCT) coconut was conducted in laterite soil at Central Plantation Crops Research Institute, Kasaragod (Kerala, India) to study the drip imgation requirement and its influence on growth and yield. The treatments included were three leveIs of drip imgation (at 33,66 and 100% E, daily), basin...

A field experiment on drip irrigation for Chowghat Orange Dwarf X West Coast Tall (COD X WCT) coconut hybrid was conducted in laterite soil at Central Plantation Crops Research Institute, Kasaragod (Kerala, India) to study the drip irrigation requirement and its influence on growth and yield. The treatments included were three levels of drip irriga...

A field experiment was conducted at Central Plantation Crops Research Institute, Kasaragod, India for six years (1993-1999) to study the impact of drip irrigation levels and mulching on coconut in littoral sandy soil. The treatments consisted of three levels of drip irrigation (66, 100, and 133 % of open pan evaporation (E0)) along with basin irrig...

Visible light irradiation of thin films of a main-chain liquid crystalline poly(aryl cinnamate) using ketocoumarins as triplet sensitizers leads to photochemical crosslinking and UV-vis and FTIR spectroscopic changes associated with saturation of the cinnamate double bond, most likely by 2 + 2 photocycloaddition. The triplet sensitizers are themsel...

Triplet lifetimes of semifluorinated polyimides and related model compounds were determined using laser flash photolysis. It was found that the triplet lifetimes of polyimides in relatively good solvents were about 10 times less than those of N-arylphthalimide models. The significant reduction in the triplet lifetimes of the polymers is attributed...

Polyimides such as 6F-6F and 6F-ODA and model N-arylphthalimides are stabilized against photooxidative degradation by their electron donor (D) – acceptor (A) character. We have investigated the precise origin(s) of this effect using D and A substituents on the N-aryl groups of these compounds. The lowest excited singlet state (S1) of N-arylphthalim...

Several aspects of the photophysics and photochemistry of liquid crystalline polymers containing aryl cinnamate and stilbene chromophores are reported. UV-VIS spectra of these materials in various phases in thin films are perturbed relative to spectra in solution. These perturbations are attributed to chromophore aggregation that is dependent on th...

The photophysical and photochemical behavior of poly(methylphenylphosphazene), PMPP, and poly(methylphenylphosphazene)-graft-polystyrene copolymers have been studied. In both types of polymers a broad red-shifted emission at about 430 nm is attributed to fluorescence from a singlet with a significant geometry change in the excited state relative to...

The photophysical properties of poly(methylphenylphosphazene), PMPP, with methyl and phenyl groups attached to the phosphazene phosphorous have been investigated using absorption and emission spectroscopy, as well as laser flash photolysis. The fluorescence spectrum of PMPP shows a red-shifted emission (decay time of 1.9 ns) with a maximum at 430 n...

The photophysics of polyimides and several N-arylphthalimide model compounds has been investigated as part of an effort to understand the factors that control the oxidative photodegradation of these materials. Substituents that increase the donor-acceptor (D-A) character of both polymers and models cause an enhancement of the red-shifted electronic...

The photophysics of polyimides and several N-arylphthalimide model compounds has been investigated as part of an effort to understand the factors that control the oxidative photodegradation of these materials. Substituents that increase the donor-acceptor (D-A) character of both polymers and models cause an enhancement of the red-shifted electronic...

Based on analysis of the photochemistry of a model compound, N-phenylphthalimide, the photolysis of a polyimide derived from 4,4′-oxydianiline (ODA) and a diarylanhydride with a hexafluorinated isopropylidine bridging group (6F) is proposed to proceed via formation of a phthalic anhydride type photoproduct. The quantum yield for product formation o...

The photolytic decomposition in air of a polyimide film based on a dianhydride and a diarylamine with hexafluoroisopropylidene 6F bridging groups is extremely rapid, leading to efficient chain cleavage and subsequent photooxidative decomposition. Only relatively short photolysis times with an unfiltered medium-pressure mercury lamp are required to...

Thin films of a liquid crystalline polyaryl cinnamate have been irradiated at (lambda) > 400 nm in the presence of ketocoumarin triplet sensitizers. The aryl cinnamate chromophore disappears upon irradiation with concomitant loss of solubility attributed to cross-linking by interchain cyclobutane photoproduct formation. Competing loss of sensitizer...

The photo-oxidation of certain polyimides has been found to be extremely efficient provided that the photolysis is conducted in the presence of oxygen. The apparent rate of decomposition depends on the chemical composition of the components composing the polyimide backbone as well as the spectral properties of the light source. In the case of polyi...

The photo-Fries rearrangement has been observed for the aryl cinnamate chromophore in both polyaryl cinnamates and small-molecule models. Laser flash photolysis of solutions of aryl cinnamates and the corresponding polymers leads to phenoxy and cinnamoyl radicals from the cleavage of the CO ester bond. The formation of these radicals has been veri...