Growth Behavior of Coleus (Plectranthus scutellarioides L.) Cuttings In Relation To Light Emitting Diodes (LED) Intensities

Abstract

Background: Coleus is a perennial herbaceous foliage plant belongs to the family Lamiaceae with long history of medicinal and food uses. Coleus plant have reputed medicinal uses, which includes anti-aggregate, anticancer, antidepressant, antidiuretic, antiglaucomic, antimetastatic, antispasmodic, bronchodilator, bronchospasmolytic, cardiotonic. Hypothesis: Harsh environmental conditions including irregular temperature, unexpected rains and natural calamities have made the production of ornamental plants difficult. Therefore, coleus plants were cultivated under LED intensities to make its availability possible under harsh environmental conditions. Study site and dates: The study was carried out during Feb-May (summer) 2017 at Horticulture Garden, Sindh Agriculture University Tandojam, Sindh, Pakistan. Methods: Vegetative as well as chlorophyll contents were measured using different plant observations in plants grown under different light intensities. Some parameters of economic importance were studied which included: Sprouts cutting-1, sprouting index (SI), plant height (cm), branches per plant, leaves per plant, leaf length (cm), leaf width (cm), leaf area (cm2), single leaf weight (g), chlorophyll content (SPAD) and root length (cm). Results: Growth of coleus varieties were significantly (P<0.05) affected by various LED intensities. The two coleus varieties treated with 1204 μmol. m-2 S-1 produced maximum 3.08 sprouts cutting-1, 0.30 sprouting index, 14.60 cm plant height, 5.05 branches plant-1, 10.23 leaves plant-1, 11.39 cm leaf length, 8.88 cm leaf width, 101.20 cm2 leaf area, 1.75 g single leaf weight, 27.51 chlorophyll content (SPAD) and 9.37 cm root length. However, minimum coleus varietal performance was observed under low light intensity (LI1= 301 μmol m-2 s-1) having 1.08 sprouts, 0.10 sprouting index, 6.58 cm plant height, 1.05 branches, 2.27 leaves, 2.99 cm leaf length, 1.83 cm leaf width, 5.55 cm2 leaf area, 0.28 g single leaf weight, 10.41 chlorophyll content (SPAD) and 4.66 cm root length. Conclusions: Growth of coleus plant increased simultaneously with increasing LED light intensities. 1204 μmol m-2 s-1 resulted in maximum growth of coleus. In case of varieties, “Coleus Brown” resulted in significantly maximum vegetative and flowering traits as compared to variety “Coleus Fairway Rose”.