Evaluation of Ocimum lines for herbage yield oil content and eugenol

Abstract

Investigations on “Evaluation of Ocimum lines for herbage yield, oil content and eugenol” was carried out at the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during 1985-86. Twentyfour Ocimum lines collected from different places from the state and the country along with one strain (Clocimum) released from RRL-Jammu were evaluated adapting simple lattice design with the following objectives. 1) To select better types based on leaf colour aroma and flavour, 2) To study the growth and flushing behaviour of each type and to isolate superior ones having better flushing characters; 3) To select a purple coloured O. sanctum line for the Kerala homesteads; 4) To select eugenol rich strains to undertake large scale cultivation of Ocimum for essential oil production; 5) To explore the possibility of growing Clocimum under Vellanikkara conditions. The crop was raised adopting the standard package of practices recommendations. The main growth parameters studied were plant height, spread, height at first branching, total number of branches per plant, number of days to blooming, intervals of flushing and leaf area. The yield parameters studied were herbage yield per plant, herbage yield per hectare, oil content, oil yield per hectare. An attempt was also made to relate leaf colour and aroma with the eugenol content of different Ocimum lines. The results indicated that the plant height increased with the age of plants. The plant spread and total number of branches per plant were maximum during July-August and afterwards a definite pattern was not observed. Clocimum and O. gratissimum lines branched at lower heights compared to O. sanctum lines. In general, all the lines tested took more time to initial flowering after transplanting, than after first or second harvests. Clocimum and O. gratissimum lines exhibited a tendency for quick flushing but took more days for flowering after each harvest compared to O. sanctum lines. O. gratissimum lines including Clocimum have higher leaf area. The studies on yield parameters revealed that Clocimum was most superior with regard to herbage yield, oil content and eugenol followed by O. gratissimum lines. Clocimum produced a herbage yield of 59.36 tonnes/ha/year. While the highest yielder of O. sanctum produced only 22.93 tonnes/ha/year. The different lines in general, produced maximum herbage and oil yield during second harvest, followed by the third and first harvests, whereas the oil content was maximum during the third harvest followed by the second and first harvests. The percentage of eugenol was maximum in Clocimum (71.82 per cent) followed by a purple coloured O. sanctum line (59.05 per cent) collected from Nellankara, near Trichur. Clocimum produced maximum eugenol per hectare followed by O. gratissimum lines. The scoring on leaf colour and aroma with respect to eugenol content revealed that, green leaved lines had better aroma than purple leaved with one purple coloured line as exception. Here also Clocimum proved its superiority. Economics of cultivation and distillation of different ocimum lines revealed that cultivation of Clocimum is more profitable than all other Ocimum lines evaluated. When we consider the various characters of 25 different Ocimum lines, it is very well clear that Clocimum can be groomed as a commercial crop under Kerala conditions. If there is a preference for purple coloured type of O. sanctum (Krishna Thulsi) the line from Nellankara can be recommended especially for the homesteads. Hence, further investigation to probe the possibilities of growing these promising lines as pure and mixed crops in Kerala and techniques for identifying valuable chemical constituents other than eugenol is suggested.