Harvesting stages and chitosan sprays on curcumin yield in tumeric (Curcuma longa L.)

Abstract

Turmeric (Curcuma longa L.) the golden spice, is highly valued as a medicinal plant. The major active constituent of turmeric is curcumin. The curcumin content varies with the agro climatic regions, cultivars, agronomic practices and the stages of harvest. The present study entitled „Harvesting stages and chitosan sprays on curcumin yield in turmeric (Curcuma longa L.)‟ to identify the influence of chitosan sprays and stages of harvesting on curcumin yield of turmeric genotypes. There were twenty seven treatment combinations of genotypes, harvesting stages and foliar application of chitosan. Among the turmeric genotypes Wayanad local (Acc WCL 23) was found superior in morphological characteristics like plant height (94.49 cm, 127.70 cm, 140.20 cm, respectively), number of tillers (2.97, 3.59 and 3.71, respectively) and leaf area (529.06 cm2, 657.38 cm2 and 696.28 cm2, respectively) in all the three growth stages of plant at 100, 120 and 150 Days After Planting (DAP). The foliar sprays of chitosan at 1g L-1 at monthly interval had a pronounced in morphological characters like plant height (133.58 cm), number of tillers (3.78) and girth of tillers (10.36 cm) at 150 DAP. However, the interaction effect of turmeric genotypes and foliar application of chitosan on morphological characters was found non significant. The photosynthetic rate was found higher in turmeric genotype, Wayanad local sprayed with chitosan (35.60 μmol m-2s-1). The lowest disease sevearity index for leaf spot was remarkable in chitosan sprayed plants (23.82%). The rhizome characters like length of primary rhizome and number of secondary rhizomes were found to be significantly high in Sobha (10.68 cm and 18.67 cm, respectively) and Wayanad local (11.07 cm and 18.35, respectively). The genotype Prathibha was found superior in width of rhizome (2.79 cm). The highest number of primary rhizomes was recorded in genotype Wayanad local (6.78) and Prathibha (6.67). When the main effect of harvesting stages were analysed, harvesting at 270 DAP was found superior in improving length, width and number of primary rhizome (10.58 cm, 3.19 cm and 7.10 cm, respectively). Chitosan sprayed plants recorded highest number (7.32) and width (2.59 cm) of primary rhizomes. Among the turmeric genotypes Wayanad local (255.86 g plant-1) and Sobha (246.01 g plant-1) recorded highest fresh rhizome weight. The rhizome harvested at 270 DAP recorded the highest fresh rhizome weight (266.52 g plant-1). Chitosan at a concentration of 1g L-1 significantly improved the fresh rhizome yield per plant (273.18 g plant-1). From the interaction effect it was evident that the fresh rhizome yield per plant was significantly superior in chitosan sprayed plants of Wayand local (314.00 g plant-1) harvested at 210 DAP (V3H1C1 ) and in chitosan sprayed plants of Sobha (311.25 g plant-1) harvested at 240 DAP (V1H2C1). The treatment combination V2H3C1- Prathibha sprayed with chitosan and harvested at 270 DAP was found on par (297.55 g plant-1). The chitosan sprayed plants of Wayanad local (18.44 %) harvested at 240 DAP (V3H2C1) recorded highest curing percentage. The curcumin content was significantly high in Prathibha (4.36 %). Harvesting of turmeric at 240 DAP (4.34 %) and 270 DAP (4.33 %) was found to be significantly superior in the curcumin content. Chitosan sprays significantly improved the curcumin content (4.81%). When influence of genotypes, harvesting stages and chitosan spray on curcumin content was analysed in detail, the treatment combinations of V1H2C1 - chitosan sprayed plants of Sobha harvested at 240 DAP (5.26%), V2H2C1- Prathiba at 240 DAP with chitosan sprays (5.14%), V3H1C1- Chitosan sprayed plants of Wayanad local harvested at 210 DAP (5.11%) and V3H3C1- Wayanad local harvested at 270 DAP (5.20%) were found superior. The curcumin yield improvement by foliar sprayings of chitosan was more pronounced in Sobha (52.96%) followed by Wayanad local (Acc WCL 23) (45.71%) and Prathibha (40.52%). Significantly higher curcumin yield was obtained from the treatment combinations involving genotype Sobha sprayed with chitosan 1 g L-1 and harvested at 240 DAP (V1H2C1) - (385.16 kg ha-1) and Wayanad local (Acc WCL 23) sprayed with chitosan 1 g L-1 and harvested at 210 DAP (V3H1C1) - (378.54 kg ha-1). However, foliar application of chitosan at 1g L-1 is effective in enhancing the weight of fresh rhizome, curcumin content and curcumin yield in turmeric. Harvesting at 240 and 270 days after planting are equally good in getting higher weight of fresh rhizome and curcumin.