MSc.

The study on “Influence of light intensity and nutrient source on yield and quality of Iruveli (Plectranthus vettiveroides)” was conducted during 2011-2012 at College of Horticulture, Vellanikkara. Iruveli (Plectranthus vettiveroides), is an aromatic annual herb with an escalating demand in the pharmaceutical industry worldwide due to its notified curative property against skin diseases, bronchitis, ulcers, heart attacks, chronic allergies etc. The objectives of the experiment were to study the effect of light intensity and nutrient source on yield and quality of Plectranthus vettiveroides and to standardize the nutrient source and optimum light intensity requirement of Iruveli for maximum yield and quality.
The experiment, which was laid out as split plot in randomized block design with three replications consisted of different levels of light intensity and nutrient sources. Top shoot cuttings were planted at a spacing of 30 X 30 cm. Shade nets with mesh size, viz 25 and 50 per cent were used to regulate 75 and 50 per cent light intensity respectively. The sub plot treatments comprised of various source of nutrients viz. FarmYard Manure (FYM) and Biovermi (an enriched product of vermicompost with Trichoderma viridae and Pseudomonas flourescence) alone and in combination with Azospirillum and AMF and inorganic fertilizers. Inorganic sources of nutrients were urea, rock phosphate and muriate of potash for N, P and K.
Light intensity had profound influence on the biometric characteristics of the crop. Light intensity level of 75 per cent had the tallest plants while open condition was found to be better, regarding the number of leaves, at 30 and 60 days after planting. Light intensity variation also influenced the root: shoot ratio and open condition proved to be the best for maximum root: shoot ratio. Maximum biomass and dry matter production was noticed in plants grown under 75 per cent light intensity. Significant difference was also noticed in the biometric characters of the plants with variation in the source of nutrients. Maximum plant height was found when it was applied with FYM +Azospirllum +AMF while combined application of Biovermi, Azospirillum and AMF was found to be better for higher leaf production, root: shoot ratio, bio mass and dry matter production.
The data on nutrient contents of the plants revealed that higher nitrogen and potassium content were noticed under 75 per cent light intensity level while open condition
resulted in maximum phosphorus content. Maximum nitrogen and potassium uptake were shown by the plants maintained under 75 per cent light intensity level while phosphorus uptake was maximum with open condition. Application of Biovermi alone yielded maximum nitrogen content and the plant applied with no organics recorded the maximum content of phosphorus. Highest potassium content was in plants applied with a combination of FYM and inorganic fertilizers @ 30:15:30 kg ha-1. The highest nitrogen, phosphorus and potassium uptake were noticed in the plants applied with combination of Biovermi+ Azospirillum +AMF.
Maximum amount of available nitrogen, phosphorus and potassium of the soil were noticed under 75 percent light intensity level while open condition showed maximum organic carbon content. Application of FYM alone gave the maximum available nitrogen content and the combined application of Biovermi, Azospirillum and AMF recorded the highest amount of available phosphorus. Highest amount of available potassium was observed with integrated nutrient application of FYM and inorganic fertilizers at the rate of 30:15: 30 kg ha-1 of NP and K and the application of Biovermi alone gave the maximum organic carbon content.
Plants showed significant variation in the oil yield under varying light intensity levels. Open condition produced maximum essential oil content but oil yield was maximum at 75 per cent light intensity. Significant difference was also noticed in the essential oil content of the herb with variation in the source of nutrients used. Application of Biovermi alone recorded the maximum essential oil content and the maximum essential oil yield was noticed with the combined application of Biovermi, Azospirillum and AMF .
From the results of the experiment, it can be concluded that 75 per cent light intensity and combined application of Biovermi with Azospirillum and AMF were found to be the best management practice for maximum herbage yield and essential oil content in Plectranthus vettiveroides.